Anatomy - Neurology Flashcards
(350 cards)
1
Q
Medial plane
A
implies towards the sagittal plane/midline
2
Q
Lateral plane
A
implies away from the sagittal plane/midline
3
Q
Superior
A
- towards the uppermost part of the cerebral hemisphere
4
Q
Inferior
A
- towards the base of the brain
5
Q
Rostral
A
- refers to the direction towards the front (literally the beak)
6
Q
Caudal
A
- refers to the direction towards the tail
7
Q
Anterior/posterior (in brainstem and spinal cord)
A
- towards anterior/posterior surfaces of the body respectively
- synonymous with VENTRAL (anterior) and DORSAL (posterior)
8
Q
Terminology in cerebral hemisphere
A
- dorsal = superior
- ventral = inferior
- rostral = anterior
- caudal = posterior
9
Q
Terminology in referring to sections of the brain
A
- coronal = vertical plane (perpendicular to the sagittal plane)
- frontal = parallel (perpendicular to the sagittal plane)
10
Q
Transverse plane
A
- denote a plane at right angles to the long axis of a structure
- divides the body at the waist (top and bottom halves of the body)
11
Q
What are the three main parts of the brain?
A
- hindbrain
- midbrain
- forebrain
12
Q
What is the Hindbrain also known as?
A
rhombencephalon
13
Q
Divisions of the hindbrain
A
- medulla oblongata
- pons
- cerebellum
14
Q
What is the medulla oblongata derived from?
A
myelencephalon
15
Q
What is the pons derived from?
A
metencephalon
16
Q
What is the cerebellum derived from?
A
metencephalon
17
Q
What is the forebrain also known as?
A
prosencephalon (forms the majority of the brain)
18
Q
What are the divisions of the Forebrain?
A
- diencephalon
- telencephalon
19
Q
What is the diencephalon derived from?
A
- anterior part of the developing neural tube
- comprises the thalamus and hypothalamus
20
Q
What is the telecephalon derived from?
A
- cerebral vesicle of each side
- consisting of an outer layer of grey matter, cerebral cortex, the basal ganglia (deep nuclei) which grows into the vesicle
- cerebral hemisphere (description word)
21
Q
What are the meninges?
A
- three separate tubular sheaths of membrane
- surround and enclose entire CNS
- regional differences in detail of distribution and attachment exist but their basic composition is the same throughout
22
Q
What are the three tubular sheaths of the meninges?
A
- dura mater
- arachnoid mater
- pia mater
23
Q
Dura mater
A
- fibrous sheet
- white collagen fibres and a few elastic fibres arranged in dense laminae (often parallel fibres)
- wide angle between direction of fibres in adjacent laminae (latticed appearance)
- cranial dura mater has two layers: outer endosteal layer and inner meningeal layer (second is dura mater proper)
24
Q
What is the dura mater proper?
A
the second inner meningeal layer of the dura mater
25
Arachnoid mater
- named for spider-web appearance
- poorly vascularised membrane of loose connective tissue (has collagen, elastin and reticulin fibres)
- loosley covers brain without following the gyral and sulcal undulations
26
Pia mater
- intimately adherent to entire surface of CNS (including gyrul and sulcal folds)
- innermost layer of pial cells lies on the surface of the CNS (formed by underlying end-feet of astrocytes with their covering basement membrane
27
How is the pia mater separated from the arachnoid mater?
- by the Subarachnoid space
- contains cerebrospinal fluid (CSF)
28
White matter
- formed by collections of nerve fibres (axons)
- wrapped in fatty myelin sheaths
- few/no neuronal somata (cell bodies)
29
Grey matter
- formed by aggregations of neuronal cell bodies and their local processes
30
Neuropil
- network of interconnected neuronal processes
- occupies space between neuronal bodies
31
Difference in appearance of fatty myelin sheaths in fresh/not fresh brain
- fresh: white
- not fresh: greyish
32
Cortex
- outer surface of the brain
- formed by flatter sheets neurones
33
What shape is the grey matter in the spinal cord?
a butterfly shape
34
Frontal lobes- what key areas are found here?
- primary motor cortex
- prefrontal cortex
35
Temporal lobes- key features
- primary auditory cortex
- auditory association cortex (Wernicke's area)
- hippocampus
- amygdala
36
Parietal lobes- what key areas are found here?
- primary somatosensory cortex
- association cortex
37
Occipital lobes- what key areas are found here?
- primary visual
- visual association cortex
38
Cerebellum- function
- motor control of equilibrium, posture and muscle tone
- movement co-ordination
39
Brainstem- key features
- ascending and descending tracts
- cranial nerve nuclei
- reticular formation
40
What are the Gyri?
the rolls of cerebral cortex
41
What are the Sulci?
the grooves between the gyri
42
What is the central sulcus?
- a large fissure separating the frontal from the parietal lobes
43
What is the lateral sulcus?
- a large fissure that separates the temporal lobe from the parietal and frontal lobes
44
What are occipital poles?
- the posterior most part of the occipital lobes
45
What is the insula?
- forms the floor of the lateral sulcus
46
What is the opercula (lips)
- the parts of the temporal, frontal and parietal lobes that overlie the insula
47
What is the Deep, interhemispheric median longitudinal fissure?
- long fissure going down the midpoint of the brain
- separates the right and left
- sagittal
48
Corpus callosum
- a large bundle of white matter connecting the two hemispheres
49
Olfactory tracts
- run on the inferior surface of the frontal lobes
(turn the brain upside down to see)
50
Optic nerves, optic chiasma, optic tracts
- OPTIC NERVES are seen passing backwards and medially
- converge in midline to form OPTIC CHIASMA
- then pass backwards and laterally as the OPTIC TRACTS
51
Mamillary bodies
- two rounded eminences behind optic chiasma
52
Hypothalamus- location
- behind the optic chiasma up to and including the mamillary bodies
53
True or false? The only part of the diencephalon visible on the outside of the brain is the hypothalamus
true
54
Crus cerebri/crura cerebri of cerebral penducles
- two large masses of white matter emerging behind mamillary bodies on each side
- from cerebral hemisphere
- pass backwards
- converge in the midline at upper border of pons
55
Interpeduncular fossa
- space between the crura roofed over by arachnoid
56
Pons
- situated immediately behind the point where the crura meet in midline
- forms bridge of neural tissue between the midbrain and medulla oblongata
57
Cerebellum (little brain) - general structure + location
- two lobes
- either side of medulla
- central vermis joining the two hemispheres
58
Medulla oblongata- location
- runs from caudal border of pons to where the spinal cord was cut off when brain removed
59
How many parietal lobes are there?
two, left and right
60
Which parietal lobe is dominant and what is it important for?
- normally left
- important for perception, interpretation of sensory information and formation of idea of complex, meaningful motor response
61
What is the supramarginal and angular gyrus of the dominant parietal lobe concerned with?
- language
- mathematical operations
62
What is the non-dominant parietal lobe and what is it important for?
- usually the right lobes
- important for visuospatial functions
63
What is the frontal lobe generally concerned with?
- motor function
- problem solving
- spontaneity
- memory
- language
- judgement
- personality
- impulse control
- social and sexual behaviour
64
What is the anterior portion of the frontal lobe (prefrontal cortex) important for?
- higher cognitive functions
- determination of personality
65
What does the posterior portion of the frontal lobe contain?
the motor and premotor areas
66
Where is broca's area found and what is it important for?
- left inferior frontal gyrus
- important for language production and comprehension
67
What does the temporal lobe contain?
- primary auditory cortex
- hippocampus
- amygdala
- Wernicke's area
68
Where is the auditory cortex found?
around the lateral (sylvian) fissure in the temporal lobe
69
Where is the Wernicke's area, what is it concerned with?
- located in the superior temporal gyrus of left hemisphere
- understanding spoken word
70
Where is the occipital lobe and what is it concerned with?
- posterior aspect of brain
- contains primary visual and visual association cortex
71
What is the limbic system?
- limbic lobes surrounds medial margin of hemisphere
- includes hippocampus, fornix, amygdala
- involved in emotion, memory behaviour and olfaction
- operates by influencing the endocrine system and autonomic nervous system
- it is highly interconnected with the brains pleasure centre
72
What is the role of the hippocampus?
- involved in long term memory formation
73
What is the role of the amygdala?
- important in motivationally significant stimuli e.g. related to reward and fear
74
Nuclus accumbens
- role in sexual arousal and the high experienced with recreational drugs
75
Describe the inner meningeal layer of the dura mater
- envelopes the central nervous system
- continues as tube of dura seen around the spinal cord
- provides tubular sheaths for the cranial nerves
76
Why does the inner layer of the dura mater separate from the skull?
- to form dural folds which support the subdivisions of the brain
- partially divide the brain into three areas: right and left hemispheres and posterior cranial fossa (where cerebellum lies)
77
The dural venous sinuses
- system of communicating blood filled spaces where the DURAL FOLDS ARE ATTACHED TO THE SKULL
78
Falx cerebri
- arched crescent of dura lying in longitudinal fissure between the cerebral hemispheres
79
Superior sagittal sinus
- where the falx cerebri attaches to the cranium
80
Inferior sagittal sinus
- at free border of falx cerebri
81
Tentorium cerebelli
- dura forming a thick fibrous roof over the posterior cranial fossa and cerebellum
82
Straight sinus
- within tentorium cerebelli (at its attachment) to falx cerebri
83
Tentorial inscisure
- a horseshoe-shaped space between the free concave border of tentorium and the dorsal sellae of the sphenoid
84
Transverse sinuses
- along line of attachment of
- tentorium cerebelli - occipital bone
85
Cavernous sinus position
- lateral to the body of the sphenoid
86
Trigeminal cave
- next to apex of petrous part of temporal bone
- envelops the roots of the trigeminal nerve
87
Diaphragma sellae
- small, circular, horizontal fold of dura mater which forms the roof of the pituitary fossa
88
Falx cerebelli
- small, vertical, sickle-shaped reflection of dura
- separates the two lobes of cerebellum
89
Subarachnoid cisterns
- spaces between the arachnoid and pia mater
- found where the arachnoid spans the gyri of the brain
- full of CSF
90
Foramen of magendie
- midline communication between the IVth ventricle and the subarachnoid space
91
Foramen of Luschka
- lateral communication between the IVth ventricle and the subarachnoid space
92
What are the 6 cisterns of the subarachnoid cisterns?
1. cerebellomedullary cistern
2. pontine cistern
3. interpeduncular cistern
4. cistern of the lateral fissure
5. superior cistern
6. cisterna ambiens
93
Cerebellomedullary cistern
- lies in angle formed by dorsal surface of medulla and inferior surface of cerebellum
94
Pontine cistern
- on the ventral surface of the pons
95
Interpeduncular cistern
- contains the circle of willis
96
Cistern of lateral fissure- what does it contain
- contains the middle cerebral artery and bridges the lateral sulcus on each side
97
Superior cistern
- contains the great cerebral vein (of Galen)
- and the pineal gland
- found between the posterior end (selenium) of the corpus callosum and the superior surface of the cerebellum
98
Cisterna Ambiens
- group of subarachnoid cisterns which completely encircle the midbrain
99
What is the choroid plexus?
a network of blood vessels and cells in the ventricles (fluid-filled spaces) of the brain
100
True or false? The pia mater is indishtinguishable from the underlying nervous tissue with the naked eye
true - it also forms the blood brain barrier (acts as a barrier between the blood vessels and the neurological tissue)
101
Describe the blood brain barrier
- on surface of brain the arteries lie in subarachnoid space
- as vessels pass into the substance of the brain they take with them prolongations of pia mater and some of subarachnoid space
- this forms a layer around the vessel
- as it penetrates deeps into the brain tissue, tunica media thins and prolongation of subarachnoid space narrows
- at level of capillary, basement membrans of endothelial cells and of pia fuse
102
What are the features unique to the brain and spinal cord in the blood brain barrier that limit the ability of molecules to pass between the blood and CNS?
(protects tissue from toxic substances)
1. edges of adjacent endothelial cells that line blood vessel are bonded closely together by 'tight junctions' to prevent molecules passing between them
2. basement membrane of CNS blood vessels lack 'fenestrations' (small holes) that are present elsewhere in the body
3. pericytes are cells that are embedded in basement membrane and wrap around endothelial cells (regulate capillary blood flow, immunity and vascular permeability)
4. astrocytes extend processes called end feet that envelop C|NS capillaries and restrict the flow of molecules into the CNS parenchyma
103
What is the cribiform plate of the ethmoid?
the portion of the ethmoid bone that forms the roof of the nasal cavity
104
What does the anterior cranial fossa contain?
- frontal lobe of the brain
- orbital part of frontal bone
- ethmoid bone (cribriform plates and crista Galli)
- lesser wing of the sphenoid bone
105
What does the middle cranial fossa contain?
- temporal, parietal and occipital lobes of the brain
- much deeper than the anterior cranial fossa
106
What does the posterior cranial fossa contain?
- cerebellum, pons and medulla oblongata
- deepest of three fossae
107
Where do the arteries and veins on the surface of the brain lie within?
- the subarachnoid space, partially hidden by the arachnoid mater
108
How are the superficial cerebral veins easily distinguished?
- darker in colour
- fixed coagulated blood visible through thin fragile walls
109
How do the superficial cerebral arteries look compared to the veins?
- arteries look paler
- thicker, muscular walls and are not so easily torn
110
What are the three anatomical elements that contribute to the blood brain barrier?
1. endothelial cells of capillaries
2. basement membrane, which lies between the endothelial cells and astrocytic end feet and is formed from the true basement membrane and the pia
3. the astrocyteic end feet themselves
111
What are the two pairs of vessels that supply arteriole blood to the brain?
- internal carotid arteries (80% - of P CB + anterior + medial + diencephalon)
- vertebral arteries (20% - of posterior cerebrum)
112
Where in the arterial blood supply to the brain is the weakest point?
- at branches
113
At what level does the common carotid bifurcate into the internal and external carotid?
- level of upper border of thyroid cartilage
114
Where does the internal carotid artery enter the brain from?
- base of the skull
- temporal bone
- lies in the carotid canal
115
Describe the course of the internal carotid artery in the brain
- temporal bone > carotid canal
- > pierces the dura forming the roof of cavernous sinus to enter the cranial cavity > anterior perforated substance at medial end of lateral sulcus > divides into terminal branches (anterior and middle cerebral arteries)
116
Terminal branches off the internal caroitd artery
- anterior cerebral artery
- middle cerebral artery
117
What does the anterior cerebral artery supply?
- the corpus callosum and medial aspects of the hemispheres
118
What does the middle cerebral artery supply?
- largest of the terminal branches of the internal carotid artery
- supplies majority of lateral surface of the hemisphere and deep structures of the anterior part of the cerebral hemisphere via its ANTERIOR PERFORATING BRANCHES
119
Purpose of the anterior communicating artery
- connects together the two anterior cerebral arteries
- provides anterior perforating branches
120
Purpose of the posterior communicating artery
- connects the internal carotid and vertebra-basilar systems
- via the posterior cerebral artery
121
Branches of the internal carotid artery NOT TERMINAL
Do we need to know this?
- central artery
- precentral artery
- anterior cerebral artery
- prefrontal artery
- middle cerebral artery
- anterior temporal artery
- middle temporal artery
- basilar artery
- vertebral artery
- posterior inferior cerebellar artery
- anterior inferior cerebellar artery
- superior cerebellar artery
- angular artery
- parietal artery
- postcentral artery
- temporo-occipital artery
122
What are the deep structures of the hemisphere, including the internal capsule supplied by?
- central branches from the circle of willis
123
True or false? there is no functional anastomosis between the capillary beds and the circle of willis
true (clinically important as infarction of one area does not automatically mean that supply will be taken up by other vessels
124
Where does the vertebral artery arise from?
the subclavian artery
125
True or false? the two sides of vertebral arteries have different diameters?
true
126
Where do the vertebral arteries enter the skull from?
through the foramen magnum
127
Basilar artery
- at the lower border of the pons, the two vertebral arteries unite in the midline
- lying in the anterior median fissure on the pons
128
What is referred to as the posterior circulation?
- vertebral and basilar arteries
- branches from them
- posterior cerebral artery
129
What is referred to as the anterior circulation?
- right and left internal carotid arteries and their branches
130
True or false? the anterior and posterior circulations are linked via the circle of willis
true
131
Branches of the vertebro-basilar system
- anterior spinal artery
- posterior spinal arteries
- posterior inferior cerebellar arteries
- pontine arteries
- labrinthine artery
- anterior inferior cerebellar artery
- superior cerebellar artery
- posterior cerebellar artery
132
True or false? cerebral veins first drain into the dural venous sinuses before draining back towards the heart
true - they are channels formed between the two layers of dura mater
133
What are the two groups of cerebral veins?
Internal cerebral veins:
- run within the substance of the brain tissue and end when they reach the surface of the brain where they become external cerebral veins
External cerebral veins:
- run on the surface of the brain
- cross the subarachnoid space to drain the dural venous sinuses
- there are four named groups which drain into different dural sinuses
134
Great Cerebral vein (of Galen)
- drains the deep structures of the brain
- drains into the straight sinus
135
What do the sinuses connect?
- they connect the major cerebral veins to the internal jugular veins
136
Name the 8 sinuses
1. inferior sagittal sinus
2. superior sagittal sinus
3. straight sinus
4. transverse sinus
5. sigmoid sinus
6. cavernous sinus
7. superior petrosal sinus
8. inferior petrosal sinus
137
Where can you find the inferior sagittal sinus?
at the inferior margin of the falx cerebri
138
Where can you find the superior sagittal sinus?
at the superior border of the falx cerebri
139
Where can you find the straight sinus?
in the midline of the tentorium cerebelli
140
Where can you find the transverse sinus?
in the posterior fixed margin of the tentorium cerebelli
141
Where can you find the sigmoid sinus?
a deep groove in the mastoid part of the temporal bone
142
Where can you find the cavernous sinus?
beside the body of the sphenoid bone (contains five cranial nerves and the internal carotid artery)
143
Where can you find the superior petrosal sinus?
in the attached lateral margin of the tentorium cerebelli
144
Where can you find the inferior petrosal sinus?
in the groove between the petrous temporal bone and the basal part of the occipital bone
145
Why does the cavernous sinus have an important clinical relevance?
- houses five cranial nerves and the internal carotid artery
- also very close to the pituitary gland
146
Intracranial venous sinuses and the veins outside the skull communicate via...
a variable number of EMISSARY VEINS
147
Why are emissary veins important?
- they represent a possible route for infection or inflammation to spread into the cranial cavity from outside the skull
- difficult to find but 'grooves' can be found on inside of skull that demonstrate where these veins run
148
What does the brain develop from?
- the hollow neural tube
- it remains hollow
- central spaces form the ventricles
149
Why are the ventricles in the brain important?
- involved in formation and circulation of CEREBROSPINAL FLUID (CSF)
- the largest aggregation of choroid plexus is in the lateral ventricles
150
Where is the majority of CSF formed?
- in the choroid plexus in the ventricle of the brain
151
How does the CSF travel after it has been made in the choroid plexus?
- passes through the interventricular foramen into the IIIrd ventricle
- then travels backwards through the cerebral aqueduct into the IVth ventricle
- IVth ventricle communicates with the subarachnoid space via the median foramen of magendie and lateral foramen of Luschka
- through these openings CSF passes out to occupy the subarachnoid space around the brain and the spinal cord
152
The Choroid Process
- invagination of vessels into the ventricles produces a vascular fold of pia mater
- covered by an epithelium derived from ependymal lining of the ventricle
153
What prevents passage of fluid from the extracellular space of the choroid plexus into the ventricle except via choroid cells themselves?
What does this enable?
- tight junctions
- enables close control over the volume and composition of the CSF
154
Arachnoid granulations
- projections of the arachnoid membrane (villi) into the dural sinuses
- allow CSF to pass from the subarachnoid space into the venous space
155
Ependyma
- constitutes the CSF brain barrier
156
Function of the arachnoid villi (tufts of arachnoid mater)
- resorption of the CSF into the venous drainage of the brain
157
What happens to arachnoid villi as you age?
- these villi tend to calcify
- will form arachnoid granulations
158
What does the presence of arachnoid granulation cause occurrence of?
- cause bone to be resorbed along the internal surface of the cranial vault near the midline
- causing a pit-like structure
159
Magendie foramen is the...
medial aperture
160
Luschka foramen is the...
Lateral aperture
161
Sella turcica
- saddle shaped depression in the body of the sphenoid bone
- holds the pituitary gland
162
Foramen rotunda
- greater wing of sphenoid bone
- posterior to medial end of the superior orbital fissure
163
Foramen lacerum
- internal carotid artery emerges from here
164
Foramen ovale
- the mandibular nerve passes through here
165
Foramen spinosum
- middle meningeal artery
- middle meningeal vein
- meningeal branch of the mandibular nerve
166
Internal acoustic (auditory) meatus
- temporal bone
- between inner ear and posterior cranial fossa
167
what is cranial nerve 6
Abducens nerve
168
What is the supra-orbital nerve?
a branch of the frontal nerve
169
What is cranial nerve 5?
Trigeminal nerve
V1 - maxillary
V2 - ophthalmic
V3 - mandibular
170
Levator palpebrae superioris
- muscle in the eyelid
- originates: posterior of orbit at the common tendinous ring
- inserts: into the upper eyelid
171
What is the common tendinous ring?
- ring of fibrous tissue surrounding the optic nerve at its entrance at the apex of the orbit
172
Lacrimal gland
- inside lateral margin of orbit
- adjacent to lateral margin of levator palpebrae superioris
173
Superior rectus
- originates: common tendinous ring
- inserts: behind conjunctival sac
174
What is cranial nerve 4?
- trochlear nerve
- at medial edge of superior orbital fissure passing forward from cavernous sinus
- terminates on superior oblique muscle
175
Lateral rectus muscle
- running along the length of lateral walls of the orbit on a deeper plane to the lacrimal gland
176
What is cranial nerve 3?
- oculomotor nerve
- deep to levator palpebral superioris
177
Superior oblique
- originates at the posterior of the orbit
- runs forawrd to pass through the trochlear
- inserts onto the posterior part of the eyeball
178
Trochlea
- structure that the superior oblique muscle passes through
179
Medial rectus muscle
- running along the length of the medial aspect of the orbit on a deeper plane than the superior oblique muscle
180
What is cranial nerve 2?
the optic nerve
181
Ophthalmic artery
- first branch from internal carotid
182
Nasociliary nerve
- sensory nerve to the eye
- attached to the ciliary ganglion
183
What is cranial nerve 3?
- Oculomotor nerve
- supplies both medial and inferior rectus muscles
184
What is cranial nerve 6?
- Abducens nerve
- supplies lateral rectus muscle
185
Where is the inferior oblique muscle?
- deepest plane
- passing from the medial aspect of the orbit postereolaterally to insert onto the sclera behind the equator of the eyeball
186
Where is the lacrimal puncti?
- small medial holes in the upper and lower eyelids
187
What is the medial palpebral ligament?
- a ligament of the face
- attaches to frontal process of maxilla, lacrimal groove and tarsus of each eyelid
188
What is the tarsus of the eyelid?
- dense connective tissue
- contain eyelash follicles
189
What is the nasolacrimal duct?
- drains the inferior part of the lacrimal sac to the nasal cavity
190
Which cranial nerves are responsible for parasympathetic outflow from the CNS?
- CN III
- CN VII
- CN IX
- CN X
(+ sacral spinal segments 2, 3 and 4)
191
True or false? Cranial nerves III and VII have branches to the orbit
true
192
Where do the parasympathetic fibres in the oculomotor nerve (CN III) originate from?
- Edinger-westphal nucleus in the mid-brain
- travels into the branch to the inferior oblique muscle
- leave the nerve to inferior oblique and enter a small ganglion (ciliary ganglion)
- gives fibres that innervate the ciliary muscle (accommodation) and the sphincter papillae
193
Where do the parasympathetic fibres in the facial nerve (CN VII) leave the nerve?
- in the middle ear to synapse in a ganglion in the pterygopalatine fossa and supply the lacrimal gland
194
Sympathetic outflow from the CNS is from the spinal segments...
T1 - L2
(these fibres pass into the sympathetic trunks which run from the base of the skull to the bottom of the sacrum)
195
Where do the sympathetic fibres to the orbit arise from and where do they go from there?
- segment T1
- pass up the sympathetic trunk through the stellate ganglion to the base of the skull
- leave the superior cervical ganglion of the sympathetic trunk to supply the dilator papillae muscle and blood vessels
196
What do extraocular muscles do?
- move the front of an eye in a specific direction or directions
197
Movement of the medial rectus
- move eye inwards towards the nose (adduction)
198
What is the medial rectus innervated by?
- oculomotor nerve (CN III)
199
Movement of the lateral rectus
- moves eye outwards away from the nose (abduction)
200
What is the lateral rectus innervated by?
- abducens nerve (CN VI)
201
Movement of superior rectus
Elevation
201
What is the superior rectus innervated by?
- oculomotor nerve (CN III)
202
Movement of inferior rectus
- primarily moves the eye downward (depression)
- secondarily rotates the top of the eye away from the nose (extorsion)
- tertiarily moves the eye inward (adduction)
203
What is the inferior rectus innervated by?
- oculomotor nerve (CN III)
204
Movement of the superior oblique
- primarily rotates the top of the eye toward the nose (intorsion)
- secondarily moves the eye downward (depression)
- tertiarily moves the eye outward (abduction)
205
What is the superior oblique innervated by?
- trochlear nerve (CN IV)
206
Movements of the inferior oblique
- primarily rotates the top of the eye away from the nose
- secondarily moves the eye upward (elevation)
- tertiarily moves the eye outward (abduction)
207
What is the inferior oblique innervated by?
- oculomotor nerve (CN III)
208
Mnemonic to explain action of the superior and inferior muscles in the eye
- RAD SIN
- Rectus ADucts (therefore oblique abducts)
- Superior INtorts (inferior extorts)
209
Mnemonic to explain innervation of the extraocular muscles
- LR6 SO43
- Lateral Rectus is innervated by the abducens nerve (CN VI)
- Superior Oblique is innervated by the trochlear nerve (CN IV)
- all other extraocular muscles are innervated by oculomotor nerve (CN III)
210
Petrous temporal bone
in floor of middle cranial fossa
211
Greater petrosal nerve
parasympathetic branch of the facial nerve CN VII emerges from the petrous temporal bone and passes anteromedially
212
Tegmen tympani
lies lateral and posterior to the greater petrosal nerve
213
Tympanic membrane
malleus is attached to it and articulates with the incus
214
Chorda tympani nerve
branch of the facial nerve CN VII crossing the tympanic membrane
215
Internal acoustic meatus
transmits the facial CN VII and vestibulocochlear CN VIII nerves
216
What is the midbrain divided into?
- dorsal tectum
- ventral tegmentum
217
What is the medulla oblongata limited by?
- the caudal border of the pons and the bulbopontine sulcus
218
What is the bulbopontine sulcus?
- transverse groove at the caudal border of the pons
219
What is the basilar sulcus?
- a shallow sulcus in which thr basilar artery runs
- through the midline of the pons
220
What are middle cerebellar peduncles?
- lateral extensions of neural tissue from the pons to the cerebellum
221
Ventrolateral suclus on medulla
- on lateral border of the pyramid on each side continuous with the same groove in the spinal cord
222
Olive
- lateral to ventrolateral sulcus
- caused by presence of underlying structure inferior olivary nucleus
223
Inferior olivary nucleus
- concerned with control of movement
224
Inferior cerebellar peduncle
- forms posterolateral margin of the medulla
- a thick bundle of white matter passing into the cerebellar
225
Superior colliculi
- part of visual system
- concerned with visual reflexes
226
Inferior colliculi
- part of auditory system
- concerned with reflex of looking towards a loud noise
227
Superior cerebellar peduncle
- fibre bundle passing from the cerebellum to the midbrain
228
Pineal gland
- endocrine gland that synthesises melatonin which modulates sleep patterns in both circadian and seasonal cycles
229
What are the two important nerve pathways hat lie just deep to the surface in the midbrain?
- inferior brachium
- superior brachium
230
Inferior brachium
- conveys auditory information from the medial geniculate body (nucleus) to the inferior colliculi
231
Superior brachium
- conveys visual information from the lateral geniculate body (nucleus) to the superior colliculi
232
What does the tegmentum of the pons contain?
- nuclei of CN VI
- nuceli of CN VII
- nuclei of CN V
233
What is the gracile tubercle?
- round swelling on either side of the midline in the medulla
- overlying the gracile fasciculus
234
Gracile fasciculus
- carries fine touch, vibration, two-point discrimination and proprioception from the lower limb
235
What does the tegmentum of the medulla contain?
- nuceli of CN: IX, X, XI and XII
236
Dorsal column medial lemniscal system DCMLS
- nuclei underlying the gracile and cuneate tubercles
- major relay site for the dorsal column sensory pathway
237
True or false? The cerebellum is the largest part of the hindbrain?
true
238
Describe the cerebellum
- two ovoid hemispheres
- joined by midline by the narrow median VERMIS
- consists of outer layer of grey matter, cortex and inner core of white matter
239
What is the folia of the cerebellar cortex?
the curves and ridges on the outside
240
Red nucleus
- circular mass of grey matter
- ventro-lateral to the cerebral aqueduct
241
Substantia nigra
- black band of nerve cells overlying the crus cerebri (cerebral peduncles)
- ventro-lateral to the red-nucleus on each side
242
Primary fissure of the cerebellum
- deeper
- marks the division betweent the anterior and posterior lobes of each cerebellar hemisphere
243
Tonsil (cerebellum)
- a prominent rounded swelling of the cerebellar cortex anteriorly on either side of the vermis
244
Flocculus (cerebellum)
- approximately ovoid in shape with a crinkled edge
- posterior to the lateral foramen of 4th ventricle on each side partly covered by choroid plexus
- caudal to entry point of CN VIII and crossed anteriorly by emerging CN X and XII
245
Nodule (cerebellum)
- continuous with the flocculus via a peduncle of white matter
246
Flocculo-nodular lobe (cerebellum)
- the flocculus and nodule together
- primarily concerned with vestibular information
247
Corticopontocerebellar pathway/tract
- information from the primary motor cortex of the motor plan
- same information goes to the spine
248
Vestibulocerebellar tract
- vestibular impulses from labryrinths, directly and via the vestibular nucleus
249
Vestibulocerebellar tract
- vestibular impulses from labryrinths, directly and via the vestibular nucleusk
250
Spinocerebellar tracts
- sensory input for balance and position sense
251
Dentate nucleus
- largest and most lateral of the deep cerebellar nuclei
- zig-zag edged oval mass with its major fibre bundles passing into the superior cerebellar peduncle
252
Rhomboid fossa
- diamond shaped floor of 4th ventricle
- limited laterally by cerebellar peduncles
- posteriorly by the gracile and cuneat tubercles
253
Median sulcus
- divides the rhomboid fossa into triangular left and right halves
254
Facial colliculus
- rounded swelling caused by fibres of facial nerve
- in substance of the pons curving around the nucleus of the abducens nerve at level of superior fovea
255
Medullary striae
- aberrant ponto-cerebellar fibres passing from the pons to the cerebellum
- they divide the floor of the ventricle into a rostral pontine half and a caudal medullary half
256
Locus coeruleus
- bluish-grey pigmented noradrenergic cells
- under the ependyma at the rostral half of the sulcus limitans
- small brainstem nucleus
257
Hypoglossal trigone
- medial triangular area overlying the hypoglossal nerve nucleus
258
Vagal trigone
- intermediate triangular area overlying the vagus nerve nucleus
259
Vestibular trigone
- lateral triangular area overlying the vestibulocochlear nerve nucleus
260
Obex
- inferior apex of the rhomboid fossa
261
Area postrema
- a small tongue-shaped area immediately rostra-lateral to the obex
- site commonly associated with nausea control
- chemoreceptive trigger zone for emetic response and lies outside the blood-brain barrier
262
Area postrema
- a small tongue-shaped area immediately rostra-lateral to the obex
- site commonly associated with nausea control
- chemoreceptive trigger zone for emetic response and lies outside the blood-brain barrier
263
Splenium
- posterior end of the corpus callosum
264
Septum pellucidum
- thing triangular double membrane
- separating the frontal horns of the right and left lateral ventricles of the brain
265
Paracentral lobule
- U-shaped gyrus surrounding the medial extenion of central gyrus
- contains representations of lower limb within the primary motor and somatic sensory areas of the cortex which on the lateral surface occupy the pre-central and post-central gyri respectively
266
Cingulate sulcus
- separates cingulate gyrus
- runs above corpus callosum from rest of hemisphere
267
Calcarine sulcus
- roughly at right angles to parieto-occipital sulcus
- runs posteriorly to reach the occipital lobe
- primary visual cortex lies in the walls of the calcarine sulcus
268
Pre-occipital notch
- lies posteriorly on the inferolateral border of the hemisphere, vertically below and slightly in front of the point where the Pareto-occipital sulcus reaches the supero-lateral margin
269
Striae of genari
- white band in primary visual cortex running parallel with the pial surface in the mid-depth of the grey matter
- this prominent feature gives the name striate cortex to the primary visual area
270
Genu
anteiror curved end of the brain
271
Splenium
rounded posterior end
272
Fornix
- bundle of white matter beneath the body of the corpus callosum
- connects the hippocampus with the diencephalon and precommisural septum
273
Commisure of the fornix
- fibres from one hippocampus cross to the opposite fornix and so back to the opposite hippocampus
274
Columns of the fornix
- anterior and posterior extensions of the fornix
- anteriorly they extend vertically downwards to the mamillary bodies
275
Anterior commissure
- thick bundle of white matter crossing the midline horizontally between the lamina terminals and the fornix
- crosses to interconnect the temporal lobes and olfactory structures of each side
276
Septum pellucidum
- two thin vertical sheets made primarily of glia with a few white fibres
- sparse grey matter and a covering of ependyma at the anterior inferior border of the corpus callosum from the fornices
277
Lamina terminalis
- thin sheet of ependyma and pia which extend downwards
- from the rostrum of the callosum and fornix to the anterior wall of the IIIrd ventricle
278
Interthalamic adhesion
- flattened grey disc joining the thalami of each side
- behind the interventricular foramen
- may be absent
279
Hypothalamic sulcus
- shallow groove on lateral wall of IIIrd ventricle
- extending from the cerebral aqueduct to the interventricular foramen
- divides diencephalon into dorsal and ventral part
280
Medial geniculate nucleus/body
- relays auditory information from midbrain to auditory cortex
- passes some fibres via the inferior brachium to the inferior colliculi
281
Lateral geniculate nucleus/body
- relays visual information from the optic nerve to both the visual cortex via the optic radiation (for vision) and the superior colliculi via the superior brachium (for pupillary reflexes)
282
Hypothalamus
- a ventral part of the diencephalon that extends from the lamina terminals in front to a vertical plane immediately behind the mamillary bodies
- the hypothalamus is an important centre contributing to body homeostasis and to autonomic nervous and neuroendocrine systems control
283
Subthalamus
- a ventral part of the dienchephalon below thalamus and lateral to the hypothalamus merging posteriorly with the tegmentum
- functionally this region is closely associated with the basal ganglia
284
Preoptic area
- adjacent to the lamina terminalis and in front of the optic chiasma
- should be included as part of the hypothalamus on functional grounds
285
Association fibres
- link cortical regions within one cerebral hemisphere
286
Commissural fibres
- link similar functional areas of the two hemisphere
- e.g. corpus callosum
- upper and lower limb representations in somatic sensory cortex neither send nor receive commissural fibres due to it containing representations of either one half or the body of one hemi-visual field
287
Projection fibres
- these link the cortex the subcortical structures such as the thalamus and spinal cord via the internal capsule and the corona radiata
288
True or false? the callosal connections are restricted to those parts containing the representation of the vertical midline of the retina while the periphery has no such connections
true
289
True or false? The olfactory system is intimately related to the limbic system
true
290
What connects the structures in the limbic system?
the papez system
291
Parahippocampal gyrus
- continuity with cingulate gyrus around splenium of corpus callosum
- part of the temporal lobe
292
UNCUS
- hook shaped region of cortex at anterior end of temporal lobe
- plays a role in olfaction, emotions and memory
293
Olfactory tract
- runs on the orbitofrontal surface of the brain
294
Olfactory striae
- medial and lateral (most of the fibres)
- the olfactory tract divides into these along the anterior border of the anterior perforated substance
- lateral striae run to the uncus
295
Cingulum bundle
- one of the many association fibre bundles
296
What are association fibres?
- axons interconnecting different areas of the cerebral cortex of one hemisphere
297
What is the largest bundle of association fibres?
- superior longitudinal fasciculus
298
Corona radiata
- white matter sheet
- contains ascending and descending tracts
299
choroid fissure
- c shaped site of attachment for the choroid plexus in the lateral ventricles
300
Caudate nucleus
- head, body and tail
- forms a large bulge into the infero-lateral aspect of the anterior horn of the ventricle
301
stria terminalis
- slender bundle of white fibres
- accompany the curve of the caudate around into the temporal horn of the ventricle
- connect the amygdala with the septum and hypothalamus
302
Amygdaloid body
- continuation of tail of caudate and stria terminalis at tip of inferior horn
303
Amygdala (amygdaloid body)
- shaped like an almond
- overlies on medial side of tip of inferior horn deep to uncus
- continuous medially with cortex of temporal lobe and posteriorly with tail of caudate nucleus
304
Fimbria
- efferent fibres from the hippocampus heading to the fornix forming a flattened, longitudinal bundle of white matter of medial argin of ventricular surface of hippocampus
305
extreme capsule
- white matter
306
Claustrum
- forms part of basal ganglia being subcortical nucleus derived from telencephalon
- recieves from and projects to cerebral cortex in a topographically organised manner
- known to have cells within it which respond to visual, auditory and sensory stimuli
307
external capsule
- white matter separating putamen from claustrum
308
lentiform nucleus
- comprised of putamen and medial globus pallidus
309
lateral medullary lamina
- white matter between putamen and medial globus pallidus
310
lateral globus pallidus
grey matter
311
medial medullary lamina
- white matter between lateral and medial globus pallidus
312
medial globus pallidus
grey matter
313
internal capsule
- convergence and concentration of white matter projection fibres which carries all motor and sensory fibres from and to the cortex
314
Corona radiata
- white matter fibres radiating from internal capsule
- deep to lentiform
315
Forceps major
- posterior curve of corpus callosum fibres into parietal and occipital lobes
- form ~2/3rds of a circle with the opposite side
316
Forceps minor
- anterior curve of corpus callosum fibres into the frontal lobe forming 2/3rds of a cricle with the opposite side
317
Lacunar stroke
- occlusion of a deep perforating artery
- risk factors: hypertension, smoking and diabetes mellitus
- lesions occur in deep nuclei pons or internal capsule
318
What can happen due to a stroke in the internal capsule?
- hemiparesis typically affecting half the face, one arm or leg
- ataxic hemiparesis most commonly affecting the leg (combination of cerebellar and motor symptoms)
- mixed sensorimotor stroke if thalamus is also affected, causing hemiparesis with ipsilateral sensory impairment
319
Describe how many vertebrae there are in the spinal cord?
- cervical: 7
- thoracic: 12
- lumbar: 5
- sacrum: 5 fused vertebrae
- coccyx: 4 fused (rudimentary) vertebrae
320
Sacroilliac joints
- link between pelvis and lower spine
- they support the weight of the upper body whilst standing
321
What is the highest point of the iliac crest in line with?
L3/4
322
True or false? the sinusoidal shape of the vertebral column is developed after birth
true
- secondary curvatures with convexity develop in the cervical region when she child holds their head up
- also in the lumbar region when the legs start weight bearing
323
Describe the shape of the spine in a foetus
- vertebral body is a c shape with concavity facing anteriorly
324
Movements of the vertebral column
- forward flexion (40 degrees)
- extension (15 degrees)
- lateral flexion (30 degrees)
- rotation (40 degrees)
325
Where is the maximum rotation possible in the spinal cord?
thoracic region
326
Where in the spinal cord is the least flexion and extension?
- thoracic (due to presence of rib cage)
327
Intervertebral discs
- strong fibrocartilaginous structures
- can withstand compression forces
- flexible enough to allow movements between vertebrae
- made of: nucleus pulposus surrounded by annulus fibrosis
328
Nucleus pulposus
- a well hydrated gel having proteoglycan, collagen and cartilage cells
329
Annulus fibrosis
- made up of 10-12 concentric layers of collagen (oblique arrangment alters in successive layers)
- peripherally it is attached to vertebral bodies and to posterior longitudinal ligament
330
Herniation of intervertebral disc
- narrows intervertebral foramen
- cause compression of nerve root
- more common in lumbar region
- nucleus pulposus bulges out into spinal canal/intervertebral foramina
- straight posterior herniation is prevented by firm attachment of disc to posterior longitudinal ligament
- herniation into intervertebral foramina is more common
331
Arthiritis of facet joints/bony irregularities in pedicle or vertebral body
- can narrow intervertebral foramen and cause nerve root compression
332
Radiculopathy
- nerve root pathology
- most commonly compression due to prolapsed intervertebral disc
- most common: L5/S1 or C6/7
333
Sciatica
- compression or irritation of sciatic nerve L5
- signs and symptoms: pain radiating down buttoc into leg down to calf, weakness in dorsiflexion causes foot drop, abnormal gait
334
Epidural space (spinal cord)
- space between vertebrae and dura mater
- contains small arteries which supplies spinal cord and vertebral venous plexuses
- veins in these plexuses (batson's veins) contain no valves and communicate freely with intercostal veins and pelvic veins including veins draining the prostrate
335
Cauda equina syndrome
- compression of nerve roots below spinal cord termination (L1-S5)
- most commonly caused by disc prolapse at L4/5 or L5/S1
- signs: low back pain, perineal paraesthesia, decreased anal tone, bladder dysfunction, faecal incontinence, sciatica, variable lower extremity motor and sensory loss, sexual dysfunction
336
How many spinal nerves do we have?
- total: 31
- cervical: 8
- thoracic: 12
- lumbar: 5
- sacral: 5
- coccygeal: 1
337
Dorsal root
sensory and posterior
338
Ventral root
motor and anterior
339
Spinal nerve is formed by?...
- anterior and posterior roots joining together at intervertebral foramen
340
What occurs when the spinal nerve emerges from the intervertebral foramen?
- it divides immediately into anterior and posterior rami
- each containing both motor and sensory fibres
341
True or false? the length of the nerve roots increases progressively from above downwards
true
342
What forms the cauda equina?
- lumbar and sacral nerve roots below the termination of the cord
343
From where do the spinal nerves leave the vertebral canal?
- through intervertebral foramen
344
Anteriorly, the intervertebral foramen is bounded by?...
bodies of adjoining vertebrae and intervening intervertebral disc
345
Posteriorly, the intervertebral formane is bounded by?...
synovial joints between two superior and two inferior articular processes
346
Conus medullaris
- tapering end of cord
347
Filum terminale
- fibrous strand extending from conus medullaris to coccyx
348
Where in the spinal cord do the subarachnoid space and CSF extend into?
upper half of the sacrum
349
mnemonic for spinocerebellar tracts
COVID
- contralateral is ventral
- ipsilateral is dorsal
