Neuroanatomy Flashcards Preview

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Flashcards in Neuroanatomy Deck (499):
1

What is the peripheral cortex?

Folded, multilayered sheet of grey matter on the surface of the brain that is thrown into folds forming gyri and sulci

2

List the three types of cerebral cortex (telencephalon)

1. Paleocortex 2. Archicortex 3. Neocortex

3

Where is the hippocampus located?

Medial part on interior surface of temporal lobe

4

List the 3 main parts of the hippocampus

Uncus, fornix, dentate gyrus

5

Which cortex is known as the place where the 'interoceptive self' meets the 'exteroceptive self'?

Entorhinal

6

Which part of the human cortex is strongly affected in Alzheimer's disease?

Entorhinal

7

Which structures make up the limbic lobe?

Parahippocampal gyrus, septal area and cingulate gyrus

8

The entorhinal cortex and hippocampus are the mediators of what functions?

Declarative/conscious memory

9

The limbic lobe is on the medial aspect of the brain and it's components encircle which structures?

Corpus callosum and diencephalon

10

List at least 3 functions of the hippocampus

1. Formation and retrieval of sptial memory 2. Processing and categorisation of new information 3. Differentially modulates aggression and rage 4. Modulates endocrine functions of the hypothalamus

11

Hippocampal lobectomy results in what outcomes?

Inability to form new memories but long-term memories and intellectual skills not affected

12

Stimulation of the pole of the hippocampus closest to the amygdala promotes ______ behaviour; activation of he pole nearest the septal area suppresses ______ behaviour

Attack

13

What is the septal area of the limbic lobe?

A relay nucleus of the hippocampus to the hypothalamus

14

List at least 3 functions of the septal area of the limbic lobe

Control of aggression and rage, regulation of endocrine functions, reward/pleasure centre (self-stimulation; drinking behaviours), regulates the discharge of hippocampal neurons during learning of new tasks/goal-directed behaviour

15

Which brain structure is also known as the brain's alarm system?

Amygdala

16

What are the 2 major functions of the amygdala?

1. Mediates adaptive responses 2. The most powerful regulator of the hypothalamus/endocrine functions

17

Which brain structure is the most powerful regulator of the hypothalamus/endocrine functions?

Amygdala

18

Which type of human cortex is comprised of 6 layers?

Neocortex

19

What is primary neocortex?

Main input from a particular modality (i.e., vision, touch on skin, sound waves) = one function. All information must go through thalamus, and these two areas are reciprocally connected.

20

What is secondary neocortex?

Limited to particular modality but may be limited to a speicifc feature of that modality (i.e., specific area of visual cortex dealing with colour)

21

What is association neocortex?

Area that gets inputs from a number of different modalities (e.g., visual and auditory like Wernicke's).

22

The majority of cells in the neocortex are whay types of cells?

Large excitatory pyramidal cells with very long axons (and most non-puramidal cells are inhibitory GABAergic)

23

All sensory input enters which layer of the neocortex?

Layer 4

24

Why is layer 4 of the neocortex also known as the striatal layer?

So many axons come into this layer and synapse that a dark stripe can be seen on sectioning

25

Different cortical areas interact with each other through cells located in which layers of neocortex?

II and III

26

Primary sensory cortex has high density of inputs into which layer of the neocortex?

V

27

Primary motor cortex has high density of inputs into which layer of the neocortex?

Pyramidal cells in layers V and VI

28

What is the name of the structure comprised of alternating columns of striate cortex receiving inputs from one eye and then the other?

Ocular dominance columns

29

What process results in amblyopia?

Visual deprivation involving one eye results in the non-deprived eye taking over the territories of the deprived eye

30

Within each ocular dominance column, there are ____ columns

Orientation

31

____ sensicite regions are regulary spaces within each ocular dominance column

Colour

32

Commisural fibres originate in which layer of neocortex? What is their target?

III; contralateral cortex

33

Association fibres originate in which layer of neocortex? What is their target?

III; ipsilateral cortex

34

List the 5 major association bundles of cortical white matter

1. Uncinate fasisculus 2. Superior occipitofrontal fasisculus 3. Superior longitudinal (arcute) fasisculus 4. Inferior occipitofrontal fasisiculus 5. Cingulum

35

What is hydroencephalus?

Enlargement of the ventricles causing raised ICP

36

Areas of the skull where the dura is folded back onto itself results in the formation of which features?

Venous dural sinuses

37

What is the falx cerebri?

Large, crescent-shaped fold of meningeal layer of dura mater that descends vertically in the longitudinal fissure between the cerebral hemispheres

38

What is the tentorium cerebelli?

An extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes

39

What is the diaphragm sellae?

flat piece of dura mater with a circular hole allowing the vertical passage of the pituitary stalk. It retains the pituitary gland beneath it in the fossa hypophyseos as it almost completely roofs the fossa hypophyseos of the sella turcica, a part of the sphenoid bone

40

List the venous sinuses of the brain

Sagittal (superior and inferior), straight sinus, cavernous sinus, transverse, petrosal and signmoid

41

Where does the falx cerebri attach to the anterior skull?

The falx cerebri attaches anteriorly at the crista galli in proximity to the cribriform plate and to the frontal and ethmoid sinuses

42

Where does the falx cerebri attach to the posterior skull?

Posteriorly, it is connected with the upper surface of the tentorium cerebelli

43

Which sinus is contained in the superior margin of the falx cerebri and overlies the longitudinal fissure of the brain?

Superior sagittal

44

What is the final dumping ground for all fluid leaving the skull?

Sphenoid sinus

45

The anterior meningeal artery is a branch of which other artery?

Internal carotid > ophthalmic artery > internal ethmoidal artery > anterior meningel artery

46

Where does the anterior meningeal artery enter the cranium?

Lateral part of cribriform plate, from the orbit

47

The middle meningeal artery is a branch of which other artery?

Maxillary artery (terminal branch of external carotid)

48

Where does the middle meningeal artery enter the cranium?

Foramen spinosum

49

The posterior meningeal artery is a branch of which other artery?

Ascending pharyngeal artery

50

Where does the posterior meningeal artery enter the cranium?

Could be jugular foramen, foramen mangnum, hypoglossal canal (or all 3)

51

Which is the largest vessel supplying the dura region of the posterior fossa?

Posterior meningeal artery

52

Which major vessel that supplies the dura mater is epidural?

Middle

53

Why is the middle meningeal artery much more likley to cause haemorrhage than the anterior and posterior meningeal arteries? Why is this type of haemorrhage particularly dangerous?

Lies embedded within the skull bone directly behind the weak point between the temporal and parietal bones (pterygoid). Even a light blow to the side of the head can dissect the artery, causing an epidural bleed. This is dangerous because the patient may not know it is happening, which is why someone with a concussion should be advised to stay awake, so that their consciousness can be monitored. If they were to go to sleep and then develop so much bleeding that they become unconscious, they would never wake up and you would never know the difference

54

What structures are formed when the arachnoid mater skils from gyrus to gyrus and around the brainstem, leaving large spaces between the pia and arachnois mater?

Cisterns

55

Anatomically, how are the cerebral artery vessels separated from the neural environemnt? What is the advantage of this arrangement?

As they invaginate into the brain, they take the pia mater with them, which forms the barrier between the vessel and the brain. This helps to minimise passive diffusion of blood-born substances into the neural tissues

56

What is the purpsoe of tight junctions between endothelial cells in the BBB?

Prevent blood cells and large molecules from squeezing between cells and entering the neural microenvironment (i.e., physical barrier)

57

What are some of the mechanistic adaptations of the BBB?

Virtual absence of vesiscular transport across the membranes f vascular endothelial cells of the cerebral vessels

58

Unknown factors derived from _____ appear to play a role in maintaining the integrity of the blood brain, and blood retinal, barriers

Astrocytes

59

Mechanistic adaptations of the BBB are maintained via what signals? What disrupts these signals?

Cell-cell signals; disrupted by inflammatory events

60

Astrocytes are located in the neural environment and define a _____ space

Perivascular

61

Which major artery do the vertebral arteries branch from? Where does this originally branch?

Subclavian; as it loops over the first rib

62

What region does the anterior spinal artery supply? What are some of the important structures in this region?

Anterior 2/3 spinal cord, and anterior medial brainstem below the open medulla. Important structures in this area of the brainstem include the pyramids (corticospinal tracs) and some of the medial lemniscus (some sensory) etc.

63

What region does the posterior spinal artery supply? What are some of the important structures in this region?

Posterior 1/3 of spinal cord, posterolateral midbrain. Important structures = dorsal column pathway

64

At what level do the vertebral arteries unit to form the basilar artery?

Ponto-medullary junction

65

What do the paramedian branches of the basilar artery supply?

Pons adjacent to the midline (including corticospinal tracts)

66

What do the short circumferential branches of the basilar artery supply?

Supply more lateral regions of pons

67

What do the long circumferential branches of the basilar artery supply?

Perforate the brainstem and supply the region between the pontocerebellar fibres and the 4th ventricle

68

Which 3 branches of the basillar artery supply the pons and region between the pontocerebrallar fibres and 4th ventricle?

Paramedian branches (midline), short circumferential (lateral pons) and long circumferential (region betweeen pontocerebellar fibres and fourth ventricle)

69

What region is supplied by the posterior inferior cerebellar artery?

Most of the inferior surface of the cerebellum, lateral upper medulla including the inferior cerebellar peduncle

70

What regions are supplied by the anterior inferior cerebellar artery? What are the important structures in this area?

Anterior segment of inferior cerebellar surface,middle cerebellar peduncles and inferolateral parts of the pons' ponto-cerebellar fibres

71

What regions are supplied by the superior cerebellar artery? What important structures lie in this region?

Superior surface of the cerebellum, superior cerebellar peuncle; mainly efferent fibres of cerebellothalamic tract, cerebellorubral tract. Also has afferent tracts tectocerebellar etc.

72

What are the terminal branches of the basilar artery?

Posterior cerebral arteries (L and R)

73

What structures in the brainstem are supplied by the posterior cerebral arteries?

Most of cerebral peduncles and almost all of the tectum

74

Unilateral infarction of the posterior cererbral artery causes what visual field defect?

Homonymous hemianopia

75

List the 3 stroke syndromes of the midbrain

Webers, Benedikt, Claude syndromes

76

What is Weber syndrome? What is the likley presentation

Midbrain stroke syndrome that involves the occulomotor nerve resultin in ipsilateral CNIII palsy and contralateral hemiplegia or hemiparesis

77

What is Benedikt syndrome? What is the likley presentation

Midbrain stroke syndrome that involves the occulomotor nerve and red nucleus. Results in an ipsilateral CNIII palsy and crossed hemitaxia and chorea

78

What is Claude syndrome? What is the likley presentation

Midbrain stroke syndrome where there is infarction to the dorsomedial aspect of the midbrain secondary to occlusion of small perforating branches of the posterior cerebral arteries. Infarction involved red nucleus, CNIII nucleus and superior cerebellar peduncle. Clinical picture includes ipsilateral CNIII nerve palsy and contralateral upper and lower limb ataxia

79

Which nerves traverse the lateral wall of the cavernous sinus, and which lies closes to the internal carotid artery?

1. CN III, IV, V1, V2; the nerve closes to the internal carotid is abducens (VI)

80

After winding around the ____ peduncles, the Pca crosses the gap between the brainstem and the _____ lobe, where is branches into the ______ and _____ PCA.

Cerebral; temporal lobe; lateral and medial PCA

81

The ACA winds laterally around the ___ ____ then passes medially towards the medial aspect of the _____ lobe

Optic chiasm; frontal

82

The medial cerebral artery enters the lateral _______

Fissure

83

Which cortical territories are supplied by the anterior cerebral artery?

Superior parietal lobule, superior frontal gyrus,medial strip of the cortex from the frontal lobe bakc to the beginning of the occipital lobe, and basically all of the inner parietal lobes (extending up and over the ventricles)

84

Which cortical territories are supplied by the middle cerebral artery?

Inferior frontal gyrus, superior temporal gyrus, most of the temporal lbe, precentral and post central gyri, inferior parietal lobule, inferior parietal lobe

85

Which cortical territories are supplied by the posterior cerebral artery?

Occipital lobe, inferior temporal gyrus, inferior part of the temporal lobe

86

The deep cerebral structures of the brain are supplied by which vessels?

1. Perforating branches of the cerebral arteries on the base of the brain 2. Communicating arteries of the circle of willis

87

Which vessel supplies the hippocampus and amygdala?

Anterior choroidal artery (branch of internal carotid or sometimes the middle cerebral)

88

Which deep territories of the brain are supplied by the perforating branches of the anterior cerebral artery?

Anterior limb of the internal capsule, the inferior portions fo the head of the caudate and anterior globus pallidus

89

From which cerebral artery do the medial and lateral striate arteries originate?

Middle cerebral

90

What deep structures of the cortex do the lateral and medial striate branches of the medial cerebral ateries supply?

Internal capsule and reticular formation

91

What strcuctures are supplied by the anterior choroidal artery (branch of internal carotid)?

Choroid plexus of lateral and third ventricles, optic chiasm and tract, internal capsule, lateral geniculate body, globus pallidus, tail of caudate nucleus, hippocampus, amygdala, substantial nigra, red nucleus and crus cerebri

92

List the 3 main features of system of venous drainage of the brain. What is the purpose of this organisation?

1. A limited number of large veins that make contact with brain matter 2. Direct course of veins into venous dural sinuses 3. Dural sinuses separated from the brain surface by CSF in the subarachnoid space (helps prevent brain from overheating)

93

Describe the venous drainage of deep cortical structures

Composed of dural venous sinuses. Most prominent is the superior saggital sinus, which forms the confluence of sinuses where it meets the sinus that drains the deep structures. From here, 2 transverse sinuses bifurcate and travel laterally and inferiorly in a S-cruve that form the sigmoid sinuses, which then go on to form the jugular veins.

94

Describe the venous drainage of superficial cortical structures

Primarily composed of traditional veins inside the deep structures of the brain, which join behind the midbrain to form the vein of Galen (great cerebral vein). This vein merges with the inferior saggital sinus to form the straight sinus, which then joins the superficial venous system at the confluence of sinuses. Blood then collects into the transverse sinuses > sigmoid sinuses > jugular veins > SVC

95

What is the functional significance of the pyramids?

Contain descending fibres from motor cortex

96

What is the functional significance of the pons?

Contains fibres that cross the midline to enter the cerebellum

97

What is the functional significance of the cerebral peduncles?

Contains descending fibres from all over the cortex, which terminate in the brainstem (corticobulbar) or spinal cord (corticospinal)

98

What is the functional significance of the mamillary bodies?

Part of the hypothalamus

99

What is the functional significance of the occulomotor nerve?

Supplies motor fibres to 4 out 6 extra ocular muscles, and includes parasympathetic fibres to the iris and ciliary body

100

What is the functional significance of the facial nerve?

Innervates muscles of facial expression

101

What is the functional significance of the trigeminal nerve?

Sensory nerve to the face

102

What is the functional significance of the thalamus?

All fibres on their way to cerebral neocortex pass through the thalamus.

103

What is the functional significance of the optic tract?

Carries axons from both eyes, that encode information from the opposite visual hemifield

104

What is the functional significance of the pineal gland?

Endocrine gland that regulates our circadian rhythms by releasing melatonin

105

What is the functional significance of the trochlear nerve?

Fourth cranial nerve which provides motor innervation to the superior oblique muscle

106

What is the functional significance of the superior colliculus?

Receives a mapped input from the retina, which guides reflexes responses to stimuli of auditory (e.g. scary sound), somatosensory (e.g.,creepy crawlies on the skin), or visual (e.g. ducking to avoid a fast moving /dangerous object coming towards you unexpectedly) origin

107

What is the functional significance of the dorsal columns?

Carry pressure and fine touch fibres from the body surface (proprioception)

108

What is the functional significance of the middle cerebellar peduncle?

Comprises the major descending input from cortex to cerebellum: cortico-pontine > ponto-cerebellar fibres

109

The lateral horn of the spinal cord is only present at which spinal cord levels?

T1-L2

110

What are the 3 divisions of CN V?

V1: ophthalmic division V2: Maxillary division V3: Mandibular division

111

What are the main functions of V1 (CN V)?

Ophthalmic division: sensory to upper face and eye, anterior nasal cavity and some sinuses

112

What are the main functions of V2 (CN V)?

Maxillary division: sensory to the middle face, maxillary sinus and nasopharynx

113

What are the main functions of V3 (CN V)?

Mandibular division: sensory to the lower face, motor supply to msucles of mastication

114

What are the main functions of CN VII (facial)?

Motor to muscles of facial expression. Parasympathetic/secretomotor supply to lacrimal, sublingual and submandibular glands. Taste (special sense) to anterior 2/3 of tongue

115

What are the main functions of CV VIII?

Vestibulocochlear: special senses hearing (cochlear) and balance (vestibular apparatus)

116

What are the main functions of CN X?

Vagus - Visceromotos fibres (from dorsal motor nucleus of vagus - parasympathetic) to heart and bronchi, digestive tract as far as the left colic flexure. Sensory to external acoustic meatus and part of auricle. Carries motor fibres to striated muscles of larynx and pharynx (derived from nucleus ambigulous via cranial accessory nerve)

117

What are the main functions of CN XII?

Hypoglossal: motor fibres to the intrinsic muscles of the tongue (four paired intrinsic muscles of the tongue originate and insert within the tongue, running along its length. They are the superior longitudinal muscle, the inferior longitudinal muscle, the vertical muscle, and the transverse muscle)

118

List the name of the nuclei, location and function of the occulomotor nerve

1. Motor nucleus at level of superior colliculus - controls SR, MR, IR and IO muscles of the eye. 2. Edinger Westphal nucleus at level of superior colliculus - controls ciliary and pupillary muscles

119

What ganglion serves the Edinger Westphal nucleus of the occulomotor nerve?

Ciliary (parasympathetic)

120

List the name of the nuclei, location and function of the trochelar nerve

Motor nucleus at level of inferior colliculus - controls the SO muscle

121

List the name of the nuclei, location and function of the trigeminal nerve

1. Motor nucleus at level of superior colliculus - pons: controls muscles of mastication, tensor vali palinitin, tensor tympani and anterior digastric 2. Principal V nucleus at the level of the pons: controls sensation (touch) to the face 3. Spinal V nucleus at the level of the medulla - upper spinal cord: controls sensation (pain and temperature) of the face 4. Mesencephalic nucleus at the level of the superior colliculus - upper pons: controls sensation (proprioception) of face

122

Which ganglion serves the Principal V and spinal V nuclei of the trigeminal nerve?

Semilunar (sensory)

123

List the name of the nuclei, location and function of the abducens nerve

Motor nucleus at level of the pons - controls LR muscle of the eye

124

List the name of the nuclei, location and function of the facial nerve

1. Motor nucleus at lower pons - muscles of facial expression, stapedius, posterior digastric and stylohyoid 2. Super salivatory nucleus at lower pons - lacrimal, submandibular and sublingual glands 3. Solitary nucleus (taste) in medulla for taste to anterior 2/3 tongue 4. Spinal V nucleus in medulla - upper spinal cord for somatic sensation around the ear

125

Which ganglion serves the super salivatory nucleus of the facial nerve?

Pterygoipalatine and submandibular (parasympathetic)

126

Which ganglion serves the solitary nucleus and spinal V nucleus of the facial nerve?

Genticulate (sensory)

127

List the name of the nuclei, location and function of the vestibulocochlear nerve

1. Superior, lateral, medial and inferior vestibular nuclei at the ponto-medullary junction for balance 2. Cochlear nucleu at the ponto-medullary junction for hearing

128

Which ganglion serves the vestibular nuclei of the vestibulocochlear nerve?

Vestibular (sensory)

129

Which ganglion serves the cochelar nuclei of the vestibulocochlear nerve?

Spiral ganlgion (sensory)

130

Where are the rostral and caudal solitary nuclei of the glossopharyngeal nerve located, what ganglion are they served by, and what is the function of each?

Located within open and closed medulla and served by inferior ganglion of IX (in jugular foramen). Rostral is responsible for taste in the posterior 1/3 of tongue and caudal is responsible for baroreceptors and chemoreceptors (carotid)

131

List the 5 nuclei of the glossopharyngeal nerve

1. Solitary (rostral) 2. Solitary (caudal) 3. Spinal V 4. Nucleus ambigulous 5. Inferior salivary

132

Which ganglion serves the spinal V nucleus of the glossopharyngeal nerve?

Superior ganglion of IX (in jugular foramen)

133

Which ganglion serves the inferior salivatory nucleus of the glossopharyngeal nerve?

Otic (paracympathetic)

134

Where is the spinal V nuclei of the glossopharyngeal nerve located and what is it's function?

Medulla - upper spinal cord, responsible for somatic sensation behind auricle of ear

135

Where is the nucleus ambiguous of the glossopharyngeal nerve located and what is it's function?

Open and closed medulla - responsible for branchiomeric muscles of the pharynx and larynx

136

Where is the inferior salivatory nucleus of the glossopharyngeal nerve located and what is it's function?

Open medulla and responsible for action of parotid gland

137

List the name of the nuclei, location and function of the vagus nerve

1. Dorsal motor nucleus of X in open medulla - thoracic and abdominal organs (visceral afferent) 2. Spinal V nucleus in medulla - upper spinal cord for somatic sensation to external ear, external auditory canal, external surface of tympanic membrane 3. Solitary nucleus in open and closed medualla for taste (epiglottis); pharynx, larynx, trachea, esophagus, thoracic and abdominal viscera (visceral afferent)

138

Which ganglion serves the dorsal motor nucleus of X (vagus)?

Walls of viscera (parasympathetic)

139

Which ganglion serves the Spinal V nucleus of the vagus nerve?

Superior ganglion of X (in jugular foramen)

140

Which ganglion serves the solitary nucleus of the vagus nerve?

Inferior ganglion of X (in jugular foramen)

141

List the name of the nuclei, location and function of the accessory nerve (cranial)

Nucleus ambiguous in open and closed medulla - responsible for intrinsic muscles of the larynx

142

List the name of the nuclei, location and function of the hypoglossal nerve

XII motor nucleus in open and closed medulla - responsible for muscles of the tongue except that palatoglossus

143

The hypoglossal nerve is responsible for all muscles of the tongue EXCEPT for which one?

Palatoglossus

144

What are the main functions of the medulla?

contains theÊcardiac,Êrespiratory,ÊvomitingÊandÊvasomotorÊcenters and therefore deals with the autonomic functions ofbreathing,Êheart rateÊandÊblood pressure

145

What are the open and closed parts of the medulla?

Superior part is openÊwhere the dorsal surface is formed by theÊfourth ventricle (creates the caudal half of the rhomboid fossa (floor of the 4th ventricle). The inferior part is closed, where the fourth ventricle has narrowed and surrounds part of theÊcentral canal.

146

Describe the location of the tectum

On the dorsal surface of the midbrain

147

Which CNs exit from the midbrain?

III (occulomotor) and IV (trochlear). Note that the trochlear nerve is the only nerve to exit dorsally from the brainstem

148

Which CNs exit from the pons?

V (trigeminal), VI (abducens) and VII (facial)

149

Which CNs exit from the medulla?

VIII (vestibulocochlear), IX (glossopharyngeal), X (vagus) and XII (hypoglossal)

150

What is the clivus, and what brain structure is it closely related with?

part of theÊcraniumÊat the skull base, a shallow depression behind theÊdorsum sell¾Êthat slopes obliquely backward. The pons sits on the clivus.

151

What is the sella turcica, and what brain structure is it closely related with?

a depression in the sphenoid bone, containing the pituitary gland

152

What is the optic groove (chiasmatic groove), and what brain structure is it closely related with?

Ridge on the superior body of the sphenoid that forms the anterior border of a narrow, transverse groove, theÊchiasmatic groove, above and behind which lies theÊoptic chiasmaÊof cranial nerve 2 (the optic nerve)

153

Consider CNI: What is the site of nerve attachment and the site of exit from the skull?

Olfactory bulb; cribiform plate

154

Consider CNII: What is the site of nerve attachment and the site of exit from the skull?

Lateral geniculate nucleus (thalamus) and midbrain; optic canal

155

Consider CNIII: What is the site of nerve attachment and the site of exit from the skull?

Interpeduncular fossa; superior orbital fissure

156

Consider CNIV: What is the site of nerve attachment and the site of exit from the skull?

Midbrain tectum inferior to inferior colliculus; superior orbital fissure

157

Consider CNV: What is the site of nerve attachment and the site of exit from the skull?

Lateral margin of the mid-pons; V1 exits at superior orbital fissure, V2 exits at foramen rotundum and V3 exits at foramen ovale

158

Consider CNVI: What is the site of nerve attachment and the site of exit from the skull?

Medial edge of pontomedullary sulcus; superior orbital fissure

159

Consider CNVII: What is the site of nerve attachment and the site of exit from the skull?

Lateral edge of pontomedullary sulcus; internal acoustic meatus

160

Consider CNVIII: What is the site of nerve attachment and the site of exit from the skull?

Lateral edge of pontomedullary sulcus (lateral to CN VII); internal acoustic meatus

161

Consider CNIX: What is the site of nerve attachment and the site of exit from the skull?

Lateral to the olive of the medulla; jugular foramen

162

Consider CNX: What is the site of nerve attachment and the site of exit from the skull?

Lateral to the olive of the medulla; jugular foramen

163

Consider CNXI: What is the site of nerve attachment and the site of exit from the skull?

Lateral surface of the upper vercial spinal cord; jugular foramen

164

Consider CNXII: What is the site of nerve attachment and the site of exit from the skull?

Between pyramid and olive of medulla; hypoglossa canal

165

Which 3 CNs exit the skull through the superior orbital fissure?

III, IV and V1

166

Which 2 CNs exit the skull thorugh the interal acoustic meatus?

VII and VIII

167

Which 3 CNs exit the skull through the jugular foramen?

IX, X, XI

168

Describe where the first, second and third order neurons of themedial lemniscal pathway (dorsal column system) arise and synapse

First-order neurons reside in dorsal root ganglia and send their axons through theÊfasciculusÊgracilis andÊcuneatous. The first-order axons make contact with second order neurons at the gracilis and cuneate nuclei in the lowerÊ(closed) medulla. The second-order neurons send their axons to theÊthalamus. The third order neurons arise from thalamus to the postcentral gyrus

169

Fibres from which other nerve join with the dorsal column system information is it travels upwards as the medial lemniscus?

Fibres from the trigeminal nerve

170

Describe where the first, second and third order neurons of the spinothalamic pathways arise and synapse

First order have cell bodies in dorsal root ganglion and synapses in dorsal root of spinal cord on the ipsilateral side. Second order neurons cross the cord and send fibres upward to synpase in the thalamus. Third order neurons are sent up to the somatosensory cortex in the post-central gyrus

171

What information do the spinocerebellar tracts convey?

information to the cerebellum about length and tension of muscle fibers (i.e., unconscious proprioceptive sensation)

172

The dorsal spinocerebellar tracts carries information from which receptor types?

Muscle spindles and golgi tendon organs (i.e., information about skeletal muscle and joint proprioception)

173

Briefly describe the dorsal spinocerebellar tract

Proprioceptive information is taken to the spinal cord via dorsal root gangliaÊ(first order neurons). Central processes travel through theÊdorsal horn, where they synapse with second order neurons ofÊClarke's nucleus. Fibres from Clarke's Nucleus convey information in the spinal cord in the peripheral region of theÊfuniculus posteriorÊipsilaterally. The fibers continue to course through the medulla oblongataÊand theÊponsÊof theÊbrainstem, at which point they pass through theÊinferior cerebellar peduncleÊand into the cerebellum. This tract involves twoÊneuronsÊand ends up on the same side of the body

174

What information do the dorsal spinocerebellar and cuneocerebellar tracts relay?

Both relay proprioceptive information, but the former is more concerned with forearm, trunk and lower limb, which cuneate is concerned with the arm

175

Vry briefly describe the ventral spinocerebellar tract

The ventral spinocerebellar tract will cross to the opposite side of the body first in the spinal cord as part of theÊanterior white commissureÊand then cross again to end in the cerebellum (referred to as a "double cross")

176

CSF is produced by the ____ lexuses, located in the ___ and ___ ventricles

Choroid, lateral and fourth

177

The anterior choroidal artery is a branch of the ____ artery, and enters the ____ horn of the lateral ventricle

Internal carotid, inferior horn

178

The anterior choroidal artery supplies the optic tract as far as which structure?

Dorsal lateral geniculate nulceus

179

The plexuses of each lateral ventricle are continuous with each other via which structure?

Intraventricular foramen (of Munro)

180

From the 4th ventricle, most CSF leaves the ventricular system via which 2 foramen? Where does the CSF then flow?

Luschka (lateral) and Magendie (medial). CSF then enters the subarachnoid cisterns that surround the cerebellum

181

List the 4 places that CSF flows after entering the cerebello-medullary cistern

1. Down and around the spinal cord 2. Anteriorly and up into the pontine and interpeduncular cisterns 3. Upwards and backwards around the cerebellum and into a cistern posterior to the midbrain 4. Around the tentorium cerebelli into the subarachnoid space of the middle and anterior cranial fossa

182

Briefly describe how the CSF is resorbed into the venous system

Arachnoid granulations (outpuchings of arachnoid meninges) pass through small openings in fibrous dura later and endothelial linin of superior sagittal sinus. CSF is pumped up towards this sinus under hydrostatic pressure, where is diffuses through the granulations into the venous blood

183

What are tracts?

Bundles of axons of neurons in the CNS (white matter)

184

What name are given to bundles of axons that connect the anterior part with the posterior part of the brain?

Association fibres

185

What name are given to bundles of axons that connect right and left sides of the brain?

Commissures

186

Give an example of a white matter commissure in the brain

Corpus callosum

187

What are neurological receptors?

Biological transducers - convert one type of energy to another (i.e., mechanical stimulus to Aps)

188

Motor neurons exit the spinal cord _____, whilst sensory informatio is taken into the ___ horn

Ventrally, dorsal

189

The ventral and dorsal root of the spinal cord combine to form the spinal _____, which then divides into an anterior and posterior _____

Trunk; ramus

190

The anterior ramus of a spinal nerve innervates structures in which part of the body?

Anterolateral wall of the body

191

The dorsal ramus of a spinal nerve innervates structures in which part of the body?

Back of the body

192

Dorsal columns of the spinal column are also known what what other name?

Dorsal funiculus

193

Which is the only white matter column that sends ONLY ascending tracts?

Dorsal columns (funiliculi)

194

Which ascending tracts of the spinal cord are most modern/advanced? What sort of information do they carry?

Dorsal columns. More heavily myelinated than anterolateral tracts, so carries faster information > very fine touch, proprioception, vibration and position and is highly specialised (rather than crude temperature, pain, etc. in anterolateral tracts)

195

List 4 types of receptors that transmit information regarding fine touch, proprioception, pressures, vibrations into the ascending dorsal tract

Meissner receptors, Pacinian receptors, goldi tendon organs and muscle spindles

196

The dorsal root ganglion contains which neural structure?

Cell body of first order neuron (first in chain of sensory system)

197

Within the dorsal column, sensations from the lower body are located ____, while caudal structures are added in ____

Medially, laterally

198

If there is a lesion impinging on the medial part of dorsal tract of the spinal cord, sensations from which structures will be lost? What if the lesion were affecting the lateral part of the dorsal tract only?

Those from the lower limbs (as lowest structures are carried most medially). If the lesion were in the lateral part of the dorsal tract, upper limb sensation would be lost.

199

All sensory fibres from the lower limb that enter the dorsal column (up to level of C6) make a special medial ascending bundle called ____?

Facisculus Gracillis

200

All sensory fibres from the upper limb, abdomen and thorax that enter the dorsal column make a special lateral ascending bundle called _____?

Fasisculus Cuneatous

201

If a section of the spinal cord is viewed from the level of L1, comment on which dorsal column bundles will be seen

Only 1 fasisculus gracillis on each side (no fasisculis cutaneous at this point because it only carries sensation from the upper limbs)

202

The dorsal columns are made up of the ____ processes of which neurons?

Central processes of first order neurons whose cell bodies lie in the dorsal root ganglion (and whose peripheral processes bring sensory information into the spinal cord)

203

Dorsal columns carry sensory information from which side of the body?

The same side as the column (i.e., information does not cross)

204

What is the name of the bundle of fibres connecting medulla with cerebellum?

Inferior cerebellar peduncle

205

The fibres from the dorsal columns terminate in which nuclei?

Nucleus gracillis and nucleus cuneatous/cuneate in lower medulla

206

The cell bodies present in the nucleus cuneatous and gracillis are what sort of neurons?

Second order (first order was in dorsal root ganglion)

207

Describe the trajectory of axons from the cell bodies of second order neurons in the nucleus graccilis and cuneatous

Cross to contralateral side at level of nuclei (in lower medulla) and move upward

208

What is the name given to the fibres from the nucleus gracillis and cuneatous that cross in the lower medulla before moving upward?

Internal arcuate fibres

209

What is the name given to the ascending group of second order neurons of the nucleus graccilis and cuneatous, after they have decussated in the lower medulla?

Medial lemniscus (there is a right and left - and each carries sensory information from the opposite side of the body)

210

The dorsal column medial lemniscus system is comprised of which structures?

Fasisculus graccilis and cuneatous, nuclei gracillis and cuneatous, internal arcuate fibres and right/left medial lemnisci

211

What is the name given to axons/fibres in the CNS that form a circular bundle? What if they form a flattened bundle?

Fasisculus; lemniscus

212

Where do the second order neurons of the medial lemniscus system (dorsal ascending system) terminate?

In the thalamus

213

If sections of the brainstem are taken, comment on where the medial lemnisci will be seen and why

Upper medulla and passing through pons and midbrain. Will not be seen in lower medulla, as this is where the fibres from the second order neurons are decussating before forming the ascending medial lemnisci (right and left)

214

VPL nucleus receives what sort of information?

Most of the sensation from most of the body (touch, pain ,temperature, position)

215

VPM nucleus receives what sort of information?

Sensation from taste fibres and head/neck fibres

216

The second-order neurons in the medial lemnisci reach the thalamus and terminate in which nucleus?

VPL (ventroposterolateral): second order neurons terminate and third order neurons originate here

217

In which nucleus do the third order neurons of the dorsal ascending system originate?

VPL of the thalamus

218

Which nuclei are present on the lateral sides of the thalami?

Lentiform nuclei

219

Which arc-shaped nucleus stretches over the thalami and connects to the lentiform nucleus?

Caudate nucleus

220

Between the thalamus and lentiform nucleus is which white matter bundle?

Internal capsule

221

In between the right and left thalami is which fluid-filled cavity?

Third ventricle

222

Third order neurons from the dorsal column sensory system originate from VPN of the thalamus and travel upward through which structure? What happens to these fibres once they pass through the capsule?

Posterior limb of internal capsule. After passing through, fibres radiate outward to cerebral cortex (corona radiata) and eventually connect to cortex in post central gyrus (sensory cortex)

223

From which structure does the corona radiata originate?

Posterior limb of the internal capsule

224

What are the receptors in the skin for pain and temperature?

Free nerve endings for pain and thernal receptors for temperature sense

225

The pain pathway has which 2 distinct fibre types carrying information to the CNS?

A delta (sharp/fast pain) and C fibre (dull, diffuse pain) pathways

226

The thermal sensory pathway follows the same pattern as which other pathway?

Pain pathway

227

What is the stimulus for fast pain?

Mechanical or thermal pain (usually from the skin)

228

What is the stimulus for slow pain?

Mechanical or thermal pain, and chemical pain (can be from skin or deeper structures)

229

Which chemical substances originate from tissue damage and can stimulate the nerve endings for pain?

5-HT, histamine, bradykinin, acids (and potassium from injured cells)

230

Which 2 chemical substances cannot cause pain, but can reduce the threshold for pain if present in tissue?

Substance P and prostaglandins

231

The first order neurons for the pain (and temperature) pathway have their cell bodies in which location?

Dorsal root ganglion

232

First order neurons in the pain pathway terminate in which location?

In the substantia gelatinosa in the dorsal grey horn of the spinal cord

233

Describe the origin and pathway of second order neurons in the pain (and temp) pathway (anterolateral pathway)

Originate in the substantia gelatinosa in the dorsal horn of the spinal cord and cross to the contralateral side at the same level of the spinal cord.

234

As sensory pain/temp fibres enter the spinal cord, they give off which branches to form which tract?

Ascending and descending branches, which form their own local vertical tract (dorsolateral tract of Lissauer) within the spinal cord

235

The dorsolateral tract of Lissauer is made up of what structures?

Ascending and decending branches of first order neuron central prcesses as they enter into the spinal cord

236

Cell bodies of the second order neurons fom the pain/temp (anterolateral) pathway exist where?

Within the dorsal horn of the spinal cord (at the level of entry) in the substantial gelatinosa

237

The lateral part of the lateral spinothalamic tract carries pain and temperature information from the ____ lower part of the body, and the medial part of the tract carries information from the _____ part of the body.

Lower; upper

238

Describe the path that the second order neurons of the pain/thermal pathway take

Originate in substantial gelatinosa and decussate the spinal cord the the level of entry before ascending as the lateral spinothalamic tract.

239

Compare and contrast the information carried by the lateral spinothalamic and anterior spinothalamic tracts

Lateral carries pain and temperature information, anterior carries information about crude touch

240

The tectum is part of which brain strcture?

posterior midbrain

241

What is the name of the swellings on the posterior midbrain?

Superior and inferior colliculus (= tectum)

242

The tectum of the midbrain is made up of which 2 strucutres?

Superior and inferior colliculus

243

Which 3 ascending spinal pathways fuse together in the medulla and then run anatomically as a single bundle up to the thalamus? What is the name of the bundle?

Lateral and anterior spinothalamic tracts and spinotectal tract. Form the spinal lemniscus

244

What is the spinotectal pathway responsible for?

Spinovisual reflexes

245

The medial lemniscus is formed from the ____ tract, whilst the spinal lemniscus is formed from the _____

edial formed form dorsal column system, spinal lemniscus is formed from the anterolateral tract (combination fo anterior and lateral spinothalamic tracts and spinotectal traact)

246

Where do the anterior and lateral spinothalamic tracts and spinotectal tracts terminate? (after they have fused to form the spinal lemniscus in the medulla)

Anterior and lateral spinothalamic tracts terminate in the VPL nucleus of the thalamus, whilst the spinotectal tract terminates in the superior tectum/colliculus (note that slow/diffuse pain fibres also terminate in the internal thalamic lamina)

247

Compare and contrast where the fast vs slow pain second order neurons from the pain pathway terminate

Fast pain all terminate in VPL nucleus of the thalamus. Slow/diffuse/dull pain fibres terminate in the VPL as well as the internal.intra lemina nuclei of the thalamus

248

Slow pain fibres intensely stimulate the _____ _____ before terminating the the VPL nucleus and internal lamina nucleus of the thalamus

Reticular formation

249

What is the reticular formation?

Mixture of grey and white matter entending throughout the brainstem

250

What is the main function of the reticular formation?

Main switch of the brain: keeps all cerebral cortex active during the day but decreases activity night so no longer has ability to stimulate cortex - regulates sleep/wake cycles

251

The reticular formation has heavy connections with which nuclei of the thalamus?

Internal lamina nucleus/intra lamina nucleus

252

All ascending sensory pathways give collaterals to which structure of the brainstem?

Reticular formation

253

What is the clinical significance of ascending slow pain fibres stimulating the reticular formation and intra laminal nucleus of the thalamus?

Painful stimuli from slow fibres irritates reticular formation to keep the CNS on and active to eliminate the source of pain (i.e., can't sleep)

254

Compare the information passed on to the cortex from sharp pain vs slow/dull pain fibres after passing through their respective nuclei in the thalamus

Fast pain fibres from the VPL nucleus provide the cortex with information about the characteristic and location of the pain. Slow/dull pain fibres from the intra lamina nucleus alert the whole cortex to the pain in general

255

What is the insula?

A portion of the cerebral cortex folded deep within the lateral sulcus (the fissure separating the temporal lobe from the parietal and frontal lobes)

256

Describe the passageway of the pain pathway after travelling through the thalamus

Pass through poterior limb of internal capsule and fan out to postcentral gyrus

257

Some pain fibres are connected with which nucleus, which is responsible for the emotional response to pain?

Cingulate gyrus

258

The cingulate gyrus is concerned with what information?

Emotion (and emotional response to pain)

259

Some slow pain fibres travel to which part fo the cortex, which is responsible for autonomic responses to pain?

Insula cortex

260

Explain why slow pain is diffuse and difficult to localise, while fast pain is easily located

When fast pain fibres enter the spinal cord (from A delta fibres which are myelinated), they synapse immediately with second order neuron before decussating and travelling straight up the lateral spinothalamic tract to the brain. On the other hand, slow pain fibres (C fibres, non myelinated) enter the spinal cord and then synapse with many, many neurons before decussating. In this way, the cortex finds it much more difficult to localise where the dull pain started/came from.

261

Which NTs are produced by pain nerve endings to stimulate second order neurons in the substantia gelatinos of the spinal cord?

Glutamate and substance P

262

Explain why massaging/stimulating areas of skin that are not painful can decrease the pain of another area of the body

Gate control theory: some sensory neurons have the ability to give off APs to collateral connector neurons that are connected with the second order neurons of the pain pathway and ican release NTs that inhibit them

263

What substances are released by the descending analgesia system in the spinal cord to reduce pain?

Enkephalins and endorphins (morphine-like)

264

Comment generally on areas where fibres from the descending analgesic fibres come from

Periventricular area, periaqueductal area and other midline nuclei in the brainstem

265

Spinocerebellar pathways carry information from the right side of the body to which side of the cerebellum?

Right - i.e., the spinocerebellar pathways are the only acending pathways that carry ipsilateral information

266

What are the 2 main spinocerebellar pathways?

1. Dorsal spinocerebellar pathway (cuneocerebellar pathway included) 2.

267

Describe the dorsal spinocerebellar pathway

Fibres enter dorsal horn spinal cord and terminate in Clark's nucleus, giving rise to second order neurons which turn laterally and enter the white matter lateral column on the ipsilateral side before ascending. They enter the ipsilateral cerebellar cortex via the inferior cerebellar peduncles

268

Information from which 3 receptor types contributes to the dorsal spinocerebellar pathway?

Goldi tendon organs, muscle spindles and pressure receptors

269

The cell bodies of the second order neurons of the dorsal spinocerebellar pathway make which vertical nucleus in the spinal cord?

Dorsolateral nucleus of clarke (Clark's nucleus)

270

The pons is connected to the cerebellum via what strcutures?

Middle cerebellar peduncles

271

The midbrain is connected to the cerebellum via what strcutures?

Superior cerebellar peduncles

272

What are peduncles?

Bundles of white matter which connect the brain stem with the cerebellum

273

The cell bodies of the first order neurons in the dorsal spinocerebellar system exist in which spinal levels. What about Clark's nucleus? What is the significance of this arrangement?

Dorsal root ganglion from C8 to S3. Clark's nucleus extends from C8 to L3 (not to lower lumbar and sacral levels). Therefore fibres which enter through lower levels must first ascend upwards to connect with Clarks nucleus

274

Clark's nucleus receives information from which parts of the body? What about the accessory cuneate nucleus?

Trunk and lower limb; upper limb sensory

275

What is the cuneocerebellar pathway?

Counter-part of dorsal spinocerebellar pathway but providing informationf rom the upper limbs via the accessory cutaneous nucleus

276

What is the most significant difference between the dorsal spinocerebellar pathway and the anterior spinocerebellar pathway?

Second order neurons cross the spinal cord to the contralateral side before ascending

277

Describe the anterior/ventral spinocerebellar pathway

Enter dorsal spinal cord and synapse, giving rise to second order neurons which decussate at the level of entry to the spinal cord and then ascend. Enter the superior cerebellar peduncle on contralateral side, and then they turn back and re-decussate across the cerebellum so they end up back on the ipsilateral side.

278

Briefly describe the spinotectal pathway

Enters spinal cord and second order neuron decussates before ascending to the tectum (also joins with anterior and lateral spinothalamic pathways at the level of the medulla)

279

Briefly describe the spino-olivary pathway

Enters spinal cord second order neuron decussates before ascending to the olive of medulla and then through the inferior cerebellar peduncles into the cerebellum

280

What sort of information is carried by the spino-olivary pathway?

Prioprioception, touch, pressure and sense of position (movement and posture)

281

Briefly describe the spino-reticular pathway

Enters spinal cord and ascends directly upward to the reticular formation

282

What name is given to the cortex located in the precentral gyrus?

Primary motor cortex = M1

283

What functions is the pre-motor area responsible for?

Planning the motor activity (programming) - i.e., where the body is located in space and what program must be executed to complete a particular movement (therefore all proprioceptive information passes to this area) - basically decides which neurons in the primary motor area need to be stimulated to carry out the movement

284

What is the supplementary motor area responsible for?

Bilateral primitive movement planning, such as primitive movement of hips and axial skeleton

285

Why is the primary motor cortex unable to function without the pre-motor area?

Because the pre-motor area decides what program must be carried out and stimuluates specific neurons in the primary area as required. I.e., the primary area cannot make decisions and needs the input from the pre-motor area, which has made the plan

286

Which area in the pre-motor cortex is responsible for programming patterns and neurons in the primary motor area for meaningful speech

Broca's area

287

Describe, in terms of neuroanatomy, why a baby can make sounds but not meaningful words

Speech area (Broca's area) of pre-motor cortex is not functional yet

288

Suppose a patient has had a stroke, and knows what he wants to say but cannot make meaningful words. What part of the area is liklely to have damaged?

Speech area (Broca's area) of pre-motor cortex (i.e., nothing is wrong with the neurons in the primary motor cortex that work the required muscles, but damage to the pre-motor area means that no program can be given to the primary area)

289

Describe the difference in outcome if the primary motor cortex was stimulated, vs if the pre-motor area was stimulated

Primary motor area would elicit random movements of some muscles, but stimulation of the pre-motor area would result in whole patterns of pre-programmed movement

290

Above Broca's area is which part of the pre-motor area concerned with eye movement?

Frontal eye field

291

What is the purpose of the frontal eye field in the pre-motor area?

Plan how eyes should be deviated and to what degree (stimulation on one side of the field will result in conjugate eye movement toward the opposite side)

292

Explain why a tumour in the pre-motor area may cause the eyes to deviate toward the contralateral side (i.e., away from the tumour) initially, but then cause the eyes to swing back toward the tumour after some time

Tumour irritating front eye field in pre-motor side causes neurons to overperform/hyperfunction. At a point where the tumour actually destroys the eye field, it is unable to program the eyes to look toward the contralateral side. However, the eye field on the other side (not affected by the tumour) is now unbalanced, so the eyes deviate toward the tumour

293

List the areas of the motor homunculus, from lateral to medial (within the primary motor cortex)

Pharynx, tongue, facial expression etc (speech - large area), head and neck, hand (large area), shoulder through to foot (most medially)

294

Describe the important areas in the pre-motor cortex, from most lateral

Brocas area, frontal eye fields, neck movement, hand movement

295

Where do the fibres of the descending corticospinal tracts found?

30% from primary motor area, 30% from supplementary + pre-motor area and 40% from sensory cortex (post central gyrus)

296

The cerebral motor cortex contains how many layers of neurons?

6

297

In which layer of the cerebral cortex are the cell bodies of the neurons that contribute to the corticospinal tracts?

5th layer/lamina

298

What is the name of the large neuronal cell bodies that are present ONLY in the primary motor cortex? What is special about these neurons?

Cells of Batz: very large cells with very thick and heavily myelinated descending axons

299

Cells of Batz directly stimulate which motor neurons?

Alpha lower motor neurons

300

All decending fibres in the corticospinal region pass firstly through the _____ ____, and then converge in the ________

Corona radiata; posterior limb of internal capsule

301

Explain why a small lesion or infarct near/on the posterior limb of the internal capsule can destroy so much motor activity in the cerebrum and even lead to hemiplegia

Due to arrangement of motor fibres being so compact - i.e., lots of information in a small space as they pass through the posterior limb of the internal capsule. This posterior limb is supplied only by 1 small artery, which can commonly become blocked in old age > many fibres destroyed > equivalent of destroying all cerebral cortex > all motor movements on the contralateral side become impaired > hemiplegia (note that sensory information travelling upward would also be affected, so sensation on the contralateral side would also be impaired)

302

Describe the passage of the corticospinal tract fibes after passing through the internal capsule until they reach the midbrain

Pass through midbrain and converge on central 3/5ths of crus cerebri. Pass through pons and are scattered/dispersed (due to density of pontine nuclei and corticopontine/corticocerebellar fibres). Once they have reached the medulla, the re-converge to pass through the pyramids

303

Which structures lie beneath the cerebral adqueduct and are known to be implicated in Parkinson's disease?

Substantia nigra

304

What is the name given to the area of the midbrain that lies between the substantia nigra and the tectum?

Tegmentum

305

What is the name given to the area of the midbrain between the substantia nigra and cerebral peduncles, where the corticospinal tracts pass thorugh?

Crus cerebri

306

How many segments of the crus cerebri are there? Through which sections do the corticospinal tracts pass through?

5; tracts pass thorugh central 3/5ths

307

What is the name given to the white matter fibres connecting the brainstem to the cerebrum?

Cerebral peduncles

308

What are pontine nuclei and what are they responsible for?

Groups of grey matter/cell bodies surround by white matter in the pons. Special fibres from the cortex terminate on these nuclei (corticopontine fibres), and from here, fibres travel through medial cerebellar peduncle into the cerebellum to give constant updates about body position

309

Explain why a small lesion near the corticospinal tracts as they pass throught he internal capsule is worse than a small lesion affecting the motor fibres in the pons

Because the tract is densely packed in the cerebrum but all the fibres become scattered in the pons

310

The pyramids of the medulla are made from what stuctures?

Fibres from coricospinal motor tracts

311

Describe the passage of the corticospinal tract once they have passed through the pyramids of the medulla

At the lower end of the pyramid, 90% of fibres cross and continue to descend in the contralateral side of the spinal cord (pyramidal decussation) while 10% remain on the ipsilateral side. The fibres that have crossed continue to descend through the spinal cord as the lateral corticospinal tracts, whilst the uncrossed 10% of fibres from each side run to form the anterior corticospinal tract. The lateral tracts continue down and synapse onto motor neurons in the lateral ventral horn (or via interneurons). The anterior tract fibres decussate in the spinal cord and synapse onto medial ventral horn.

312

Describe the location of the pyramidal decussation of the corticospinal tract

Junction of medulla and spinal cord

313

Describe the resultant effects on the motor system if there is a lesion above vs a lesions below the pyramidal decussion

Lesions above the decussation result in contralateral motor dysfunction, while lesions below the decussation produce motor deficits on the ipsilateral side (as the lesion is occuring after the decussation has occurred)

314

The fibres from the anterior corticospinal tract are concerned with what types of movements? Where does this information originate from in the cortex?

Primitive movements of the trunk/axial skeleton. Information comes from supplementary motor area

315

The fibres from the lateral corticospinal tract are concerned with what types of movements?

Skilled and voluntary movements (especially fine movements in the hands)

316

Compare the points of decussation for the anterior vs lateral corticospinal tracts

Lateral tract decussates in the pyramidal decussation (90% of fibres), and anterior (remaining 10%) decussate at the level of the spinal cord for which they are needed

317

List all of the areas that the corticospinal tract sends collateral information to on its descending pathway through the brain and brainstem

Feeds back to cortex, to basal ganglia (lentiform nucleus), red nucleus, vestibular nuclei and olivary nuclei

318

What is a lower motor neuron?

Neurons coming out of CNS (brainstem or spinal cord) and connecting to NMJs

319

What is an upper motor neuron?

Group of all neurons that originate at high cortical level and decend to lower motor neurons (directly or indirectly) to moderate the activity of the LMN

320

List the types of neurons that leave the CNS

Preganglionic parasympathetic, preganglionic sympathetic and lower motor neurons (connecting to NMJs)

321

What is the name given to the tract that sends descending fibres to stimulate lower motor neurons of the brainstem?

Corticoneuclear fibres

322

Corticonuclear fibres are synonymous with which other tract?

Corticospinal tract

323

Those corticonuclear fibres that are specifically connected with lower motor neurons in medulla are called ____?

Corticobulbar fibres

324

The superior and inferior colliculi are specifically concerned with which reflexes?

Superficial = Visual reflexes; Inferior = Auditory reflexes

325

Lower motor neurons receive input from which descending tracts?

Corticospinal (or corticonuclear in the brainstem), tectospinalÉ

326

Fibres that decending from the red nucleus and cross before descending on the contralateral side are part of what tract?

Rubrospinal tract

327

List the 5 descending tracts that originate from subcortical areas

Tectospinal, reticulospinal, rubrospinal, vestibulospinal, olivospinal tracts

328

What is the name of the nuclei present at the junction between the medulla and the pons?

Vestibular nuclear complex

329

Decending tracts that take information to cranial nerve LMNs come from the _______tract, whilst tracts that take information to the spinal nerves are carried in the _____ tract

Corticonuclear tract; corticospinal tract

330

What is meant by the pyramidal tracts? Which fibres are included?

Any descending tracts which pass through pyramids of medulla = corticospinal (also called pyramidal tracts) and sometimes the corticonuclear tracts are also included (because origin is the same)

331

Extensor musles are also known by what other name?

Anti-gravity muscles

332

Which pathway (and assistant pathway) is responsible for providing input to the extensor muscles?

Vestibulospinal (and assisted by pontine reticulospinal)

333

Which pathway is an assisting pathway to the vestibulo spinal pathway? Which nucleus do these fibres come from?

Ponto-reticulospinal (from pontine nucleus in reticular formation)

334

Which pathway (and assistant pathway) is responsible for providing input to the flexor muscles?

Rubrospinal and assisted by medullary reticulospinal

335

Describe the vestibulospinal and ponto-reticulo spinal tracts

Begin at vestibular nuclear system and pontine reticular nuclei and decend UNCROSSED to spinal cord anterior white matter to control extensor/anti-gravity muscles

336

Describe the rubrospinal tract

Begin in red nucleus, cross in the brainstem and descend to the lateral white matter of the spinal cord to control the flexor muscles

337

What are the 2 main functions of the rubrospinal tract?

1. Enhances flexor tone; 2. Acts an accessory pathway from the cortex to spinal neurons (corticorubral fibres)

338

Which tract is assistant to the rubrospinal tract in controling flexor muscle tone?

Medullary-reticulospinal tract (from medullary reticular nuclei)

339

Sympathetic fibres originate in the ____ part of the hypothalamus, whilst parasympathetic fibres originate in the ____ part

Posterior; anterior

340

Sympathetic fibres from the posterior part of the hypothalamus descend down the spinal tract and stimulate pre-ganglionic sympathetic neurons in which spinal levels?

T1-L2

341

If there is any interruption to the thoracic sympathetic outflow from fibres suppying T1 and T2, what is the resultant pathology? Why?

Horner's syndrome - because T1 and T2 have some sympathetic supply to head and neck. So if there is damage, there will be ptosis, anhydrosis (lack of sweating), constriction of pupil and other symptoms of Horner's

342

Parasympathetic outflow is from which cranial nerves?

3, 7, 9 and 10 (III, VII, IX and X)

343

Comment on where there is/is no parasympathetic outflow from the spinal cord

CN III, VII, IX and X. No parasympathetic outflow from cervical, thoracic or lumbar regions. S2-S4 have parasympathetic outflow (i.e., cranial sacral outflow)

344

Which fibres of a muscle are connected to Golgi tendons?

Extrafusal

345

Alpha motor neurons connect the anterior horn of the spinal cord with which muscle fibres?

Extrafusal fibres

346

Alpha motor neurons release which neurotransmitter at the NMJ?

Cholinergic fibres (NT is ACh)

347

What sort of receptors are present at the NMJ and allow binding of the NT released by alpha motor neurons?

Nicotinic receptors (for ACh)

348

Nicotinic receptors at the NMJ are coupled with what sort of channels?

Cationic channels

349

Very briefly describe the interactino between alpha motor neurons and muscle contraction

AP travels along alpha motor neuron and releases ACh into the NMJ. This binds to nicotinic receptors which are coupled to cationic channels. This causes depolarisation, and AP travels along surface of extrafusal muscle fibres and into T tubules, then they stimulate release of calcium in the cell, which leads to actin-myosin interaction (calcium bids to toponin, which moves toposiosin away so that actin and myosin can interact and contract the muscle)

350

The sensitivity of muscle contraction is dependent on what?

Muscle spindles (degree of stretch sensed by afferent neurons and relayed to spinal cord)

351

What will be the result of stimulating muscle spindles?

Stimulates increase in AP traffic in sensory stretch receptor afferents toward the spinal cord > stimulates alpha motor neurons in spinal cord > causes extrafusal muscle fibres to contract

352

Gamma motor neurons give motor supply to what part of the muscle?

Spindle

353

Alpha motor neurons supply ______ muscle fibres, whilst gamma motor neurons supply ______ muscle fibres

Extrafusal; intrafusal

354

If a gamma motor neuron is stimulated, what will be the result?

Contraction of muscle spindles > not enough to contract whole muscle but enough to produce stretch at the end of muscle spindles > more APs thrown toward spinal cord > leads to stimulation of alpha motor neuron > leads to contraction of extrafusal muscle > increased muscle tone

355

What sort of fibres take stretch information from muscle spindles toward the spinal cord?

Ia

356

Describe the pathway of a deep tendon reflex

Hammer hits tendon > produces brisk, transient stretch on whole muscle > extrafusal fibres stretched > stretches intrafusal fibres > stretch receptors increase information (APs) travelling through Ia fibres to spinal cord/CNS > transient overstimulation of alpha motor neurons > produces increased transient AP traffic to NMJ of the same muscle which was stretched > slightly increase NMJ at a very short time > transient contraction/reflex/jerk

357

Why is the terminology 'deep tendon reflex' a misnomer?

Because the hitting of the tendon does not target deep golgi tendon organs, but the stretch of the whole muscle

358

List the 5 things that can be tested in a stretch reflex

1. Intrafusal stretch receptors working 2. Sensory afferent Ia fibres working 3. Integration in spinal cord working 4. Alpha motor neuron transmission working 5. NMJ at the muscle working (i.e., in a particular spinal cord level, that input and output are working)

359

When are golgi tendon organs stimulated?

When there is too much tension on the muscle and it threatens the integrity of the locomotor system

360

Explain how golgi tendon organs are responsible for maintaining the integrity of the locomotor system

When there is undue tension on a muscle/tendon (to the point where stress would cause damage), golgi tendon organs (receptors) are stimulated > send APs to spinal cord via Ib fibres > stimulate interneurons in the spinal cord > interneurons release inhibitory NT which act on alpha motor neurons > alpha motor neuron inhibited > muscle relaxes > this is the golgi tendon reflex

361

Explain the difference between muscle stretch reflex and golgi tendon reflex

Stretch reflex (stimulus = stretch, response = contraction); Golgi tendon reflex (stimulus = tension, response = relaxation). When a muscle spindle is stimulated, the end result is contraction of the muscle. When a goldi tendon organ is stimulated, the end result is relaxation of the muscle (due to inhibition)

362

Which spinal nerve supplies the biceps?

Musculoskeletal

363

Presume there has been a LMN lesion affecting the biceps. After 3 months, comment on the changes seen in the muscle

1. Mass is lost (due to lack of trophic action due to lack of ACh released at NMJ) 2. Power is totally lost 3. Tone reduced = flaccid (gamma motor neurons denervated, resulting in relaxation of msucle spindles > no signal to spinal cord or alpha motor neuron action) 4. Related tendon reflexes are lost (because muscle stretch cannot stimulate the motor reflex) 5. Babinski reflex should be normal (plantar flexion)

364

Explain why there is more atrophy of muscles in a LMN lesions compared with an UMN lesion

Because in LMN, there is loss of mass due to loss of ACh release at the NMJ, which causes lack of tonicity and muscle atrophy (complete termination of trophic action). In an UMN lesion, the UMN loses inhibitory control of the LMNs, leading to over-firing of the LMN and tonicity of the muscle. There is still atrophy due to lack of use, but not as marked as the atrophy due to neuro degeneration (i.e., there is disuse atrophy but not denervation atrophy)

365

Which 2 factors lead to atrophy of muscle?

1. Trophic action (denervation) 2. Disuse

366

Maintenance of tone of a muscle is primary dependent on acitivty of?

Gamma motor neuron

367

Explain why there is muscle rigitidy in a UMN lesion

UMN lesion = over-firing of LMN > over firing of gamma motor neurons > muscle spindle becomes stretched > give more sensory input to spinal cord > excessive stimulation of alpha motor neurons (i.e., alpha motor neurons are overstimulated by stretch reflex but also via disinhibition of gamma motor neurons)

368

Explain why there is hyperreflexia in UMN lesions

UMN inhibitory control is lose > gamma and motor neurons over-fire > hammer tap will cause excessive overfiring and excessive stimualtion of alph amotor neurons > produce a lot of ACh and reflex becomes exaggerated

369

Describe the location of the exit point of CN III (occulomotor) in the brainstem

At the level of the superior colliculus in the front of the midbrain, on the medial side of cerebral peduncle and moves anteriorly

370

Describe the location of the exit point of CN IV (trochlear) in the brainstem

At the level of the inferior colliculus in the midbrain at the back (this is the only spinal/cranial nerve exiting dorsally) and wraps around to cerebral peduncle more laterally than CN III

371

Which is the only cranial nerve which exists from the back of the CNS?

CN IV (trochlear)

372

The pineal gland is located at the back of which ventricle?

3rd

373

CN V (trigeminal) exits the brainstem at what location?

Anterolateral side of the pons

374

Describe the exit of cranial nerves in the pontine medullary sulcus from medial to lateral

Most medial is CN VI, then VII more laterally and CN VIII

375

Which cranial nerves exit the brainstem at the inferior cerebellar peduncle (from superior to inferior)

CN IX, X and XI (cranial part of XI)

376

Where does CN XII exit the brainstem?

In the medulla between the pyramid and olive

377

What sort of fibres are attached to the cell bodies of neurons in the anterior grey horn of the spinal cord?

General somatic efferents

378

What sort of fibres are attached to the cell bodies of neurons in the posterior grey horn of the spinal cord?

General somatic afferents

379

What sort of fibres are attached to the cell bodies of neurons in the transverse grey horn of the spinal cord?

General visceral efferents and general visceral afferents (sensory fibres are more posterior)

380

Generally speaking, compare the locations of sensory vs motor nuclei in the brainstem

Sensory are more lateral and motor are more medial (results from opening of spinal cord around the central canal to form the 4th ventricle)

381

Describe the location of the trigeminal sensory ganglion

Posterior-most part of middle cranial fossa at the tip of the temporal bone

382

Describe the pathway of the sensory root of the trigeminal ganglion

Lateral part of mid-pons > enters CNS at anterilateral part of mid-pontine area

383

The motor root of the trigeminal nerve is responsible for which functions?

Muscles of mastication (NOT connected with ganglion)

384

Where does the motor root of the trigeminal nerve exit the skull? Which other structure exits at this point?

Foramen ovale with the mandibular division of the trigeminal nerve (that has originated from the trigeminal ganglion)

385

Which is the largest cranial nerve?

Trigeminal

386

Where are the trigeminal nuclei located and what are they called?

Midbrain (mesencephalic nucleus), pons (prinicpal sensory pontine nucleus) and floor of medulla to upper spinal cord (spinal nucleus of V)

387

What are the names of the fibres coming from the trigminal sensory root and projecting to spinal nucleus of the trigeminal nerve?

Trigeminal spinal tract

388

Fibres from the trigeminal nuclei end up in what structure? What are these ascending fibres called?

Ventro-postero medial nucleus of thalamus; trigeminal lemniscus (or trigeminothalamic tract)

389

List the 6 components of the trigeminal system

1. Divisions 2. Ganglion 3. Motor and sensory root 4. Tracts (especially spinal) 5. Nuclei 6. lemnisci

390

Describe the pathway of the trigeminal lemniscus after travelling through the VPM nucleus of the thalamus

Ascend through posterior limb of internal capsule and end up in posterior central gyrus

391

General somatic afferents of the trigeminl system carry what sorts of information?

Fine touch (and 2 point discrimination), pain, temperature and proprioception

392

General somatic afferents of the trigeminl system supply which structures?

Half of head, full face, cranial cavity (anterior and medial cranial fossa), eye, nose and paranasal sinuses, oral cavity, anterior 2/3 tongue and external ear

393

What is very unique about the myelination of the sensory root of the trigeminal system? What is significant about this?

For about 7mm, the part of the trigeminal root connected with the pons, the myelination is provided by oligodendrocytes (which are usually only present within the CNS). Significance is that diseases which affect myelination in CNS can also effect the sensory root of the trigeminal system.

394

The external ear is supplied by which 4 nerves?

V, VII, IX, X

395

What motor supply is the trigeminal nerve responsible for?

Muscles of mastication (temporalis, masseter, lateral and medial pterygoids), tensor tympani (pulls ear drum medially), tensor vali palatini, myelohyoid and anterior belly of digastric muscle

396

What % of CO goes to CNS?

15%

397

Vertebral arteries take orogin from which major blood vessel?

Subclavian

398

Which 2 major systems are responsible for delivering blood to the brain?

Vertebral arteries (basillar/posterior system) and internal carotid arteries (anterior system)

399

Vertebral arteries travel through which foramina?

Foramina of transverse processes of cervical vertebrae

400

Describe the pathway of the vertebral arteries supplying the brain, from their origin

Originate from subclavian system, travel upwards and medially and pass through foramina of cervical vertebrae transverse processes. Enter cranial cavity through foramen magnum > must pierce dura mater and arachnoid mater to end up in subarachnoid space. R and L meet at ponto medullary junction to become basilar artery, which travels upward before giving off terminal posterior cerebral arteries at the top of the brainstem (just above level of 3rd cranial nerve region)

401

All major arteries supplying the brain (carotid system, vertebral system and circle of willis) are present in which area?

Subarachnoid space (and floating in CSF)

402

Where do the R and L vertebral arteries meet?

Ponto-medullary junction (i.e., after they have entered through foramen magnum)

403

Once the R and L vertebral arteries meet at the ponto-medullary junction, they move upwards as which large artery?

Basilar artery

404

The basilar artery divides into which terminal branches at the top of the brainstem?

R and L posterior cerebral arteries (PCAs)

405

The right and left posterior cerebral arteries supply which areas of the brain?

Midbrain, posterior part of cerebral hemispheres

406

Where does the anterior spinal artery originate?

In front of the medulla from the contributary branches of the R and L vertebral arteries. Moves inferio-medially and combine to form anterior spinal artery which descends in the anterior medial fissure of the spinal cord

407

What is the origin of the posterior inferior cerebellar artery?

Vertebral arteries

408

How much of the spinal cord is supplied by the anterior spinal artery?

Anterior 2/3 of the spinal cord

409

If anterior spinal artery is blocked, what will be the result?

Loses blood supply and undergoes infarction to the anterior 2/3 of the spinal cord at that level

410

Which arteries carry blood toward the spinal cord to reinforce the anterior spinal artery?

Segmental arteries

411

Segmental arteries move medially toward the spinal cord and divide into which divisions?

Anterior reticular artery (reinforce blood flow in anterior spinal artery) and Posterior reticular artery (reinforce blood flow in 2 posterior spinal arteries)

412

What is the origin of the posterior spinal arteries?

Vertebral artery (either directly or indirectly from posterior inferior cerebellar arteries)

413

List 3 major arteries that give segmental arteries to reinforce the blood in the spinal arterial system

1. Deep cervical arteries 2. Intercostal arteries 3. Lumbar arteries

414

What is the most important artery that provides a segmental artery to reinforce the spinal arteries?

Direct supply from aorta > great medullary artery of ADAM niewicz

415

Which 2 levels of the spinal cord is the weakest area of blood supply in the territory of anterior spinal artery? Why is this clinically significant?

T4 and L1 (this is because main reinforcing arteries are located just below these points). This is clinically significant because these areas are most likley to develop infarction with reduced blood flow to the anterior spinal artery

416

Which levels of the spinal cord is the weakest area of blood supply in the territory of the posterior spinal arteries?

T1, 2 and 3

417

What areas are supplied by the posterior inferior cerebellar artery?

Cerebellum and lateral part of medulla

418

Which artery may originate from beginning of basillar artery or from the vertebral artery in other people?

Anterior inferior cerebellar artery

419

What areas are supplied by the anterior inferior cerebellar artery?

Lateral part of pons as well as under side of cerebellum

420

Which long artery may originate from the basilar artery or from the anterior inferior cerebellar artery in others, and goes to supply the inner ear?

Labyrinthine arteries

421

Which 2 nerves accompany the labyrinthine artery?

Facial nerve and vestibulocochlear nerve (through internal acoustic meatus to supply inner ear)

422

Which arteries originate from the basilar artery just below the level of the occulomotor cranial nerve exit?

Superior cerebellar artery

423

What structures are supplied by the superior cerebellar artery?

Some midbrain and superior cerebellum

424

The internal carotid artery enters through the ____ canal, moves forward and then turns upward to exit through the foramen ______, reaching the ____ cranial fossa

Carotid; foramen lacerum; medial

425

Which dural venous sinus is located in the middle cranial fossa? Which important structure runs through this sinus?

Cavernous sinus; internal carotid artery

426

Describe the pathway of the internal carotid artery, from it's origin

Originates at common carotid artery (where the division of internal and external carotid arteries occurs at the carotid sinus). Moves upward, enters into carotid canal, moves forward (anterior part of carotid canal opens into the foramen lacerum) and arteries moved through the foramen lacerum, then upwards, pierces the dura mater and enters the cavernous sinus. Then moves upward from here (medial to the anterior clenoid process) and then pierces mater again and comes into subarachnoid space

427

Which branch of the internal carotid artery passes into the orbital cavity through the optic canal?

Ophthalmic artery

428

Which important branch of the ophthalmic artery supplies the retina?

Central retinal artery

429

What is the origin of the central retinal artery?

Internal carotid artery > ophthalmic artery > central retinal artery

430

Name one of the signs of anterior carotdi circulation failure

Blindness in one eye due to occlusion of central retinal artery

431

Which 2 branches of the internal carotid artery travel backward from the internal carotid artery after it has entered the subarachnoid space?

Posterior communicating artery and anterior choroidal artery

432

Which arterry forms a connection between the the carotid system and vertebral basillar systems?

Posterior communicating artery

433

What is supplied by the anterior choroidal artery?

Supply choroid plexus of lateral ventricle

434

What are the 2 terminal arteries of the internal carotid artery?

After giving off posterior communicating artery, ophthalmic artery and anterior choroidal artery, internal carotid artery divides into 2 terminal branches: lateral terminal branch = middle cerebral artery; and anterior terminal branch = anterior cerebral artery

435

The anterior communicating artery forms a connection between which vessels?

R and L anterior cerebral arteries

436

Which structures border the circle of willis?

R and L internal carotid arteries, anterior communicating artery, posterior communicating arteries, posterior cerebral arteries

437

Which structure of the arachnoid mater anchors it to the pia matter?

Connective tissue reticuli

438

Which cranial meningeal layer is highly vascular?

Pia mater

439

Name the 2 layers of the dura mater

Periosteal layer and meningeal layer

440

What is clinically relevant about the periosteal layer of dura mater?

Periosteal layer can become pathologically separated from the skull bone. Meningeal vessels run through this area (between periosteal and meningeal dura meter), and so haemorrhage can occur.

441

The periosteal layer of the dura mater is tightly connected to the skull bone except for at which normal anatomical structures?

Venous dural sinuses

442

Within which 2 layers of the meninges do the meningeal arteries and veins run?

Between the meningeal and periosteal layers of the dura mater

443

Why does an epidural haemorrhage appear as a 'lens' shape on CT?

Because the ligaments between the sutures in the skull will stop the bleed from pogressing part that point (due to tension), so bleed appears long and thin, with distinct end points at the sutures

444

Describe the appearance of a subdural haemorrhage on CT

Crescent shape (tracks around the skull between dura and arachnoid mater, with little resistance and little pressure = even distribution)

445

Rupture of bridging/cerebral veins as they approach the dural sinuses causes what sort of haemorrhage?

Subdural

446

Bleeding of meningeal arteries and veins causes what sort of haemorrhage?

Epidural

447

What is an aneurysm?

Abnormal, irreversible dilation of arterial wall

448

Why is subarachnoid haemorrhage so diffuse and widespread?

Because the space is full of CSF, so blood can move easily and throughout entire space

449

Which form of haemorrhage will result in apperance of RBCs in a LP sample?

Subarachoid

450

Which basal ganglia strucutres are considered to be in the clinical slassification?

Caudate nucleus, lentiform nucleus (putamen + globus pallidus), substantia nigra and subthalami

451

The globus pallidus is divided into which 2 parts?

1. Globus pallidus interna (medial) 2. Globus pallidus externa (lateral)

452

Which 3 structures make up the corpus striatum?

Caudate nucleus, putamen and globus pallidus (lentiform nucleus)

453

Which structures make up the striatum/neostriatum

Caudate nucleus plus only the putamen part of the lentiform nucleus

454

What are the corticonuclear fibres?

Fibres originating in the cortex that serve motor neurons which are present in the brain stem

455

The cerebellum is embryonically derived from which structure?

Mesencephalon portion of rhomboncephalon (part of the hindbrain)

456

Which lobe of the cerebellum is most primitive? What is the functional significance of this?

Flocculonodular - most primitive functions - balance of head and eyes

457

What is the main function of the anterior lobe of the cerebellum?

Tone

458

What is the main function of the posterior lobe of the cerebellum?

Coordination of movement

459

What is the name given to the longitudinal depression on the posterior surface of the cerebellum?

Vermis

460

Cerebellum controlls functions on the ______ side of the body

Ipsilateral

461

The area just lateral to the vermis of the cerebellum is given what name?

Intermediate zone or para-vermal area

462

What is significant about the vermis and paravermal area of the cerebellum?

They are topographically mapped with the head and neck in the centre and the trunk and limbs are represented more . The trunk and axial body is represented in the actual vermis, whilst the limbs extend into the paravermal area. This is significant because if there is a lesion in the centre of the vermis, the motor control in the trunk will be affected (ataxia od axial muscles) but limbs will be spared

463

The brainstem is related posteriorly to the ____ and ____ ventricle of the brain

Cerebellum; fourth ventricle

464

The pons rests on which strucure of the occipital bone?

Clivus

465

The brainstem is continuous rostralling with the cerebral ____ and _____

Peducles; forebrain (thalamus)

466

How long is the brainstem?

7.6cm

467

The trigeminal system information converges on which 3 nuclei?

Spinal trigenimal, principal trigeminal and mesencephalic nuclei

468

Auditory fibres from the cochlear nerve synapse in the ___ nucleus, which then projects to the opposite )____ ____

Cochlear; inferior colliculus

469

In which part of the brainstem is the auditory field spatially mapped?

In the inferior colliculi (opposite side to cochelar nerve providing input)

470

Discuss visual field mapping in the superior colliculus and which layers receive which input

Direct retinal projects to superior colliculus are mapped onto the superficial layers of the superior colliculus. Deeper layers get somatosensory as well as auditory inputs from the inferior colliculus.

471

What is the purpose of auditory and visual field mapping?

Coordinates eye movements and head/neck movements to accommodate reflex-like responses to external events

472

Which nucleus is known as the 'gatekeeper' of cardiovscular and cardiorespiratory control?

Solitary nucleus

473

Where is the solitary nucleus located?

Dorsolateral medulla

474

What information is mapped onto the solotary nucleus?

Nerves carrying afferent info (chemoreceptors) about internal environemnt (taste VII, IX; blood chemistry IX and X, gut sensations X)

475

The solitary nucleus + reticular formation + periaqueductal grey influence what feelings?

Wellbeing, satisfaction, attention and sleep cycles

476

Circuits in the dorsolateral open medulla regulate what functions?

Cardiovascular control - through HR and arteriolar paripheral resistance (note there are also cells in this area that regulate sympathetic activity in the lateral horn neurons)

477

What features can be seen on a cross section at the pyramidal decussation?

Crossing of pyramidal fibres, spinal trigeminal nucleus. Dorsal columns still look like the do in the spinal cord, but the nucleus gracillis can now be seen

478

Where are the medul lary cardiovasular and repiratory control centres located?

Dorsolateral medulla

479

What features can be seen on a cross section at the closed medulla?

Axons of neurons coming from the nucleus gracilis and cuneatus sweep ventrally and medially as the internal arcuate fibres - they cross the midline and form the medial lemniscus. Can now see the inferior olivary nucleus and the spinal trigeminal nucleus which appeared in the pyramidal decussation is still visible

480

What features can be seen on a cross section at the open medulla?

All dorsal column system migrated into medial lemnicus by this point - nothing remains dorsal to the central canal, which open to form the 4th ventricle. Can now see inferior cerebralle peduncles and can still see the inferior olivary nucleus, which arose at the lower level of the closed medulla

481

Where do the inferior cerebela peduncles takes fibres from?

Dorsal cerebellar and nuneo-cerebellar tracts and from the C/L inferior olivary nucleus to the cerebellum

482

What is the cerebromedullary bottleneck? Why is it clinically significant?

Many fibres in the pons squeezed into a small space - this is vulnerable due to the way the blood supply is arranged. A lesions in the basillar artery can interrupt supply to almost the entire pons

483

How is 'locked in syndrome' diagnosed?

Presence of eye movements

484

Where do the axons from pointine cells go?

Cross the midline and enter the C/L cerebellum via the middle cerebellar meduncle

485

What features can be seen on a cross section at the pons?

Fibres of the superior cerebellar peduncles can be seen dorsolateral to the 4thventricle

486

What features can be seen on a cross section at inferior colliculus?

Substantial bigra and cerebral penduncles prominent ventrally. Main feature is the crossing of the superior cerebellar peduncles centrally. The cerebral aqueduct can now also be seen (and the superior cerebellar penuncles are still visible)

487

Which CN features prominently in the inerpeduncular fossa of the inferior colliculus?

III

488

What features can be seen on a cross section at the superior colliculus?

Superior cerebral peduncles have crossed and enter the red nucleus at this level. Fibres of CN III cross thorugh the red nucleus and SCP fibres.

489

The cerebral peduncles are seen ventrallly in the midbrain and are separated by the ______

Interpeduncular fossa

490

Which structures of the ventral midbrain contain all of the descending tracts that originate in the cerebral cortex?

The cerebral peduncles

491

List at least 4 of the regulatory functions of the reticular formation

1. Respiratory and cardiovascular control 2. Arousal and sleep-wake cycle 3. Control of gait 4. Autonomic

492

Explain briefly how the reticular formation has a greater range of influence and can effect hundreds of thousands of neurons

Transmitter released into extracellular space, not confined to post-cynaptic cleft > therefore more diffuse

493

List the 3 distinct groups of cells in the reticular formation and comment on their fucntions

1. Median/raphe - seratonergic 2. Paramedial: magnocellular (upper) and gigantocellular (lower) - motor 3. Lateral: parvocellular - sensory

494

Describe the inputs and outputs of the solitary nulceus and tract that function as respiratory control

Inputs from CNs carrying information from chemoreceptors (VII, IX and X), also from carotid body (IX) and arotic arch (X); outputs to reticular formation, hypothelamus, thalamus (taste - cortex), parasympathetic and sympathetic nuclei

495

The respiratory control centre of the brainstem (solitary N and tract) integrates activity of the dorsal respiratory nucleus to influence which respiratory function?

Inspiration

496

The cventral respiratory nucleus (dorsal to the nucleus ambiguous) regulates which function of respiration?

Expiration

497

Which nucleus is the pacemaker of respiration? Where does it get it's input from and what functions does this regulate?

uParabrachial nucleus > input from amygdala and periaqueductal grey matter > increased breathin rate in anxiety states (including fear and pain

498

Circuit through DMNX (parasympathetics) have what effect on heart rate? What is the name of this response?

Slows heart rate = barovagal response

499

Circuit through lateral reticular nucleus has what effect on heart rate? What is the name of this response?

Decreases sympathetic tone in arteriolar smooth muscle > decreases peripheral resistance = barosympathetic response