Anatomy/Physiology Flashcards
(211 cards)
1
Q
Within the pain pathway how many orders of neurones are there?
A
3
2
Q
What type of neurones are first order neurones?
A
Pseudounipolar
3
Q
Where are the cell bodies of first order neurones?
A
dorsal root ganglion
4
Q
How many branches do first order neurones have?
A
two branches, a peripheral branch (which extends towards the peripheries) and a central branch (which extends centrally into the spinal cord/brainstem).
5
Q
Where are the cell bodies of second order neurones found?
A
Rexed laminae of the spinal cord or the nuclei of cranial nerves in the brainstem.
6
Q
Where do second order neurones decussate?
A
anterior white commissure of the spinal cord
7
Q
Which tract do second order neurones of the pain pathway travel through?
A
Spinothalamic tract
8
Q
Where to second order neurones travel to in the brain?
A
ventral posterolateral (VPL) nucleus of the thalamus
9
Q
Where are the cell bodies of third order neurones?
A
ventral posterolateral (VPL) nucleus of the thalamus
10
Q
Where do third order neurones terminate?
A
ipsilateral postcentral gyrus (primary somatosensory cortex)
11
Q
What receptors on first order neurones detect pain?
A
Nociceptors
12
Q
What do unencapsulated cutaneous receptors detect?
A
Pain
13
Q
What do encapsulated cutaneous receptors detect?
A
Vibration and skin stretching as well as other sensory modalities.
14
Q
Give an example of encapsulated cutaneous receptors.
A
Merkel’s discs
15
Q
What does it mean that each nociceptor has its own receptive field?
A
one nociceptor will transduce the signal of pain when a particular region is skin is stimulated
16
Q
What allows for a greater acuity in detecting sensory stimulus?
A
Larger density of free nerve endings with a smaller receptive field
17
Q
Do the fingertips have a relatively large or small size of cortical representation in the somatosensory cortex?
A
larger due to small receptive fields
18
Q
What are the 4 different types of nociceptors?
A
Mechanical, Thermal, Chemical and polymodal
19
Q
What do mechanical nociceptors detect?
A
Stretch and pressure which elicit sharp, prickling pain
20
Q
What do chemical nociceptors detect?
A
exogenous and endogenous chemical agents
21
Q
What do thermal nociceptors detect?
A
Thermal sensation that elicit slow, burning or cold and sharp pain
22
Q
Through what fibres do nociceptors transmit their signals to the spinal cord?
A
A delta fibres
23
Q
To which pat of the spinla cord do nociceptors transmit their signals through?
A
Dorsal horn
24
Q
Why are A delta fibres responsible for transmitting first pain felt?
A
These myelinated fibres have a low threshold for firing and a fast conduction speed
25
What do A delta fibres mainly terminate?
Rexed laminae I
26
What neurotransmitter do A delta fibres mainly release?
Glutamate
27
Through what fibres do polymodal nociceptors transmit their signals through?
C fibres
28
Why are C fibres responsible for secondary pain?
They are unmyelinated so have a slow conduction speed
29
What does is mean that C fibres have a large receptive field?
They have poor localisation of pain
30
Where do C fibres mainly terminate?
Rexed laminae II (known as substantia gelatinosa)
31
What neurotransmitter do C fibres release?
Substance P
32
What factors are released in response to tissue damage that can activate nociceptors?
Arachidonic acid
Potassium
5-HT
Histamine
Bradykinin
Lactic acid
ATP
33
What is the name for enhanced sensation of pain at normal threshold?
Hyperalgesia
34
What is allodynia?
a sensation of pain experienced in response to a stimulus that was previously not painful
35
What are the three types of opiod receptors that that regulate the neurotransmission of pain signals?
Mu, delta and kappa
36
What is the collective name for the Mu, delta and kappa receptors?
G protein coupled receptors
37
What does the activation of opioid receptors lead to?
a reduction in neurotransmitter release and cell hyperpolarisation, reducing cell excitability.
38
Give an example of an exogenous opioid.
Morphine
39
What are the three types of endogenous opioid?
B-endorphins, Dynorphins, Enkephalins
40
What receptors do B-endorphins predominantly bind to?
mu opioid receptors
41
What receptors do dynorphins predominantly bind to?
kappa opioid receptors
42
What receptors do enkephalins predominantly bind to?
delta opioid receptors
43
Which opioid neurotransmitters act in the spinal cord?
Dynorphins and enkephalins
44
Which synapses in the neurones have opioid receptors on them?
Post synaptic of second order neurones and pre synaptic ends of first order neurones.
45
Where does the cell body of Upper Motor Neurones originate?
Cerebral cortex or brainstem
46
Where do UMNs terminate?
Brainstem or spinal cord
47
What neurones give rise to the descending motor tracts?
UMNs
48
Which neurones synapse onto the nuclei of the extrapyramidal tracts?
UMNs
49
Which neurones are used to describe descending motor neurones within the corticospinal and corticobulbar tracts?
UMNs
50
Where do the corticospinal and corticobulbar tracts arise from?
Pre-central gyrus
51
Where do the corticospinal tracts terminate?
ventral horn of the brainstem
52
Where do the corticobulbar tracts terminate?
motor nuclei of cranial nerves
53
Which neurotransmitter is typically involved in transmission from UMN to LMN
Glutamate
54
What is the pre-central gyrus also known as?
M1 (primary motor cortex)
55
What is the general function of the corticospinal tract?
To facilitate voluntary movement
56
What signs can you get if there is damage to an UMN?
mono/hemiparesis or mono/hemiplegia, hypertonia, hyperreflexia, clonus, Spasticity, positive babinski sign
57
What is the first cranial nerve?
Olfactory nerve
58
What is the shortest cranial nerve?
Olfactory nerve
59
Embryologically, what is the olfactory nerve derived from?
the olfactory placode
60
What is the olfactory placode?
a thickening of the ectoderm layer
61
What cells does the olfactory placode also give rise to which support the olfactory nerve?
Glial cells
62
Where are olfactory receptors located?
nasal epithelium
63
Where do olfactory nerve bundles enter the cranial cavity?
Through the small foramina in the cribriform plate of the ethmoid bone
64
Where does the olfactory bulb lie?
Olfactory groove in the anterior cranial fossa
65
What specialised neurones does the olfactory bulb contain?
Mitral cells
66
What are the collections formed when the olfactory nerve fibres synapse with with mitral cells?
Synaptic glomeruli
67
How does the olfactory tract travel to the anterior perforated substance?
Posteriorly on the inferior surface of the frontal lobe
68
Where does the olfactory tract divide?
Anterior perforated substance
69
What does the olfactory tract divide into?
Lateral stria and medial stria
70
What does the lateral stria of the olfactory tract do?
carries the axons to the primary olfactory cortex
71
Where does the primary olfactory cortex lie?
uncus of temporal lobe
72
What does the medial stria of the olfactory tract do?
carries the axons across the medial plane of the anterior commissure, where they meet the olfactory bulb of the opposite side
73
Where does the primary olfactory cortex send nerve fibres to?
piriform cortex, amygdala, olfactory tubercle and the secondary olfactory cortex
74
Where is the olfactory mucosa located?
located in the roof of the nasal cavity
75
What kind of epithelium is the olfactory mucosa made of?
pseudostratified columnar epithelium
76
What kind of cells is the epithelium of the olfactory mucosa made up of?
Basal cells, sustentacular cells, olfactory receptor cells
77
What do basal cells in the olfactory mucosa do?
form the new stem cells from which the new olfactory cells can develop
78
What do sustentacular cells in the olfactory mucosa do?
they are tall cells for structural support. These are analogous to the glial cells located in the CNS.
79
What are the two processes of the bipolar olfactory cells in the olfactory mucosa?
Dendritic process projects to the surface of the epithelium, where they project a number of short cilia, the olfactory hairs, into the mucous membrane. These cilia react to odours in the air and stimulate the olfactory cells.
Central process projects in the opposite direction through the basement membrane.
80
What glands in the olfactory mucosa secrete mucus?
Bowman's glands
81
What is anosmia?
Absence of sense of smell
82
What can temporary anosmia be caused by?
Infection or local disorders of the nose (common cold)
83
What can permanent anosmia be caused by?
Head injury or tumours which occur in the olfactory groove (meningiomas) and neurodegenerative disorders
84
What genetic conditions is anosmia a feature of?
Kallmann syndrome and primary ciliary dyskinesia
85
What is the second cranial nerve?
The optic nerve
86
Embryologically, where is the optic nerve derived from?
Optic vesicle, an outpocketing of the forebrain
87
What surrounds the optic nerve?
Cranial meninges
88
What are the cells that converge to form the axons of the optic nerve?
Retinal ganglion cells
89
What impulses do the retinal ganglion cells recieve?
Impulses from the photoreceptors of the eye (rods and cones)
90
Through what bone does the optic canal travel through?
Sphenoid bone
91
What surface of the cranial fossa does the optic nerve travel along?
Middle cranial fossa
92
Where do the fibres of the medial half of each retina cross over?
Optic chiasm
93
What fibres does the left optic tract contain?
left temporal (lateral) retina and the right nasal (medial) retina
94
What fibres does the right optic tract contain?
right temporal retina and left nasal retina
95
Where does each optic tract travel to in the thalamus?
Lateral geniculate nucleus
96
What pathway carries the visual information after the lateral geniculate nucleus?
Optic radiation pathway
97
What information travels along the upper optic radiation pathway?
Fibres from the superior retinal quadrants
98
What information travels along the lower optic radiation pathway?
Fibres from the inferior retinal quadrants
99
Where does the upper optic radiation pathway travel through?
Parietal lobe to reach the visual cortex
100
Where does the lower optic radiation pathway travel through?
Temporal lobe via Meyer's loop to reach the visual cortex
101
What kind of adenoma occurs in close proximity to the optic chiasm?
Pituitary adenoma
102
What symptom tends to occur when the optic chiasm gets compressed?
Bitemporal hemianopia
103
What is the third cranial nerve?
The oculomotor nerve
104
What muscles are innervated by the oculomotor nerve?
levator palpebrae superioris, superior rectus, inferior rectus, medial rectus and inferior oblique
105
What is the parasympathetic function of the oculomotor nerve?
Supplies the sphincter pupillae and ciliary muscles of the eye
106
What is the sympathetic function of the oculomotor nerve?
Innervates superior tarsal muscles (helps to raise the eyelid)
107
Where does the oculomotor nerve originate from?
oculomotor nuclues
108
Where is the oculomotor nerve located?
within the midbrain of the brainstem, ventral to the cerebral aqueduct. It emerges from the anterior aspect of the midbrain, passing inferiorly to the posterior cerebral artery and superiorly to the superior cerebellar artery.
109
Where does the oculomotor nerve travel after it pierced the dura mater?
It enters the lateral aspect of the cavernous sinus
110
What fibres travel within the sheath of the oculomotor nerve?
sympathetic branches from the internal carotid plexus
111
Through what does the oculomotor nerve leave the cranial cavity?
The superior orbital fissure
112
Where does the oculomotor nerve split into its two branches?
The superior orbital fissure
113
What does the superior branch of oculomotor nerve do?
provides motor innervation to the superior rectus and levator palpabrae superioris. Sympathetic fibres run with the superior branch to innervate the superior tarsal muscle.
114
What does the inferior branch of the oculomotor nerve do?
provides motor innervation to the inferior rectus, medial rectus and inferior oblique. Also supplies pre-ganglionic parasympathetic fibres to the ciliary ganglion, which ultimately innervates the sphincter pupillae and ciliary muscles
115
What does the superior rectus muscle do?
Elevates the eyeball
116
What does the levator palpabrae superioris muscle do?
Raises the upper eyelid
117
What does the inferior rectus muscle do?
Depresses the eyeball
118
What does the medial rectus muscle do?
Adducts the eyeball
119
What does the inferior oblique muscle do?
Elevates, abducts and laterally rotates the eyeball
120
What are the two structures in the eye that receive parasympathetic innervation from the oculomotor nerve?
Sphincter pupillae and ciliary muscles
121
What does the sphincter pupillae do?
Constricts the pupil, reducing the amount of light entering the eye
122
What do the ciliary muscles do?
contracts, causes the lens to become more spherical, and thus more adapted to short range vision
123
Do the pre-ganglionic parasympathetic fibres travel in the superior or inferior branch of the oculomotor nerve?
Inferior branch
124
Where do the pre-ganglionic fibres of the oculomotor nerve synapse?
ciliary ganglion
125
What are the most common structural causes of oculomotor nerve palsy?
Raised ICP
Posterior communicating artery aneurysm
Cavernous sinus infection or trauma
126
What are the clinical features of CN III injury?
Ptosis
Down and out position of the eye
Dilated pupil
127
What is the fourth cranial nerve?
The trochlear nerve
128
What is the smallest cranial nerve by number of axons?
The trochlear nerve
129
Which cranial nerve has the longest intracranial course?
The trochlear nerve
130
Where does the trochlear nerve arise from?
The trochlear nucleus
131
Which cranial nerve is the only one to exit from the posterior midbrain?
The trochlear nerve
132
How does the the trochlear nerve travel before it pierces the dura mater?
Anteriorly and inferiorly within the subarachnoid space
133
Where does the trochlear nerve pierce the dura mater?
Adjacent to the posterior clinoid process of the sphenoid bone?
134
Which sinus does the trochlear nerve pass along after piercing the dura mater?
Cavernous sinus
135
Which nerves and arteries travel in the cavernous sinus?
Oculomotor nerve, abducens nerve, ophthalmic and maxillary branches of the trigeminal nerve and the internal carotid artery
136
Through what fissure does the trochlear nerve enter the orbit of the eye?
Superior orbital fissure
137
What muscle does the trochlear nerve innervate?
Superior oblique
138
The fibres of the trochlear nerve from the trochlear nucleus cross in the midbrain before they exit. What does this mean for its innervation?
Trochlear neurones innervate the contralateral superior oblique
139
What is the tendon that tethers the superior oblique called?
Trochlea
140
What does the superior oblique do?
Depresses and intorts the eyeball
141
What does trochlear nerve palsy present with?
Vertical diplopia
142
What are trochlear nerve palsies commonly caused by?
DM or HTN
143
What is the fifth cranial nerve?
The trigeminal nerve
144
What is the largest cranial nerve?
The trigeminal nerve
145
Which pharyngeal branch is the trigeminal nerve associated with?
1st
146
What is the sensory function of the trigeminal nerve?
They innervate the skin, mucous membranes and sinuses of the face
147
Which branch of the trigeminal nerve has motor function?
Mandibular branch
148
What is the motor function of the mandibular branch of the trigeminal nerve?
Innervates the muscles of mastication
149
What are the muscles of mastication?
Medial pterygoid, masseter and temporalis
150
What is the motor function of the mandibular branch of the trigeminal nerve do as well as innervating the muscles of mastication?
Supplies other 1st pharyngeal arch derivatives; anterior belly of digastric, mylohyoid, tensor veli palatini and tensor tympani
151
Where does the trigeminal nerve originate?
From three sensory nuclei and one motor nucleus
152
At what level do the sensory nuclei of the trigeminal nerve merge to form a sensory root?
At the level of the pons
153
Where does the sensory root of the trigeminal nerve expand into the trigeminal ganglion?
middle cranial fossa
154
Where is the trigeminal ganglion found?
the cavernous sinus, in a depression of the temporal bone. This depression is known as the trigeminal cave.
155
What are the 3 divisions that the trigeminal nerve gives rise to?
ophthalmic (V1), maxillary (V2) and mandibular (V3)
156
Which is the only division of the trigeminal nerve to have a motor root?
mandibular division
157
Through what does the ophthalmic branch of the trigeminal nerve leave the cranial fossa?
superior orbital fissure
158
Through what does the maxillary branch of the trigeminal nerve leave the cranial fossa?
foramen rotundum
159
Through what does the mandibular branch of the trigeminal nerve leave the cranial fossa?
foramen ovale
160
What are the three terminal branches of the ophthalmic branch of the trigeminal nerve?
frontal, lacrimal and nasociliary
161
What does the ophthalmic branch of the trigeminal nerve supply?
Forehead and scalp
Frontal and ethmoidal sinus
Upper eyelid and its conjunctiva
Cornea (see clinical relevance)
Dorsum of the nose
162
What is the job of the parasympathetic component of the ophthalmic branch of the trigeminal nerve?
To innervate the lacrimal gland
163
What nerve is the afferent limb of the corneal reflex that detects stimuli?
Ophthalmic nerve
164
What nerve is the efferent limb of the corneal reflex that innervates movement?
The facial nerve
165
An absent corneal reflex is a sign of damage to which nerve?
trigeminal/ophthalmic nerve, or the facial nerve
166
How many branches does the maxillary branch of the trigeminal nerve give rise to?
14
167
What does the maxillary nerve innervate?
derivatives of the maxillary prominence of the 1st pharyngeal arch:
Lower eyelid and its conjunctiva
Cheeks and maxillary sinus
Nasal cavity and lateral nose
Upper lip
Upper molar, incisor and canine teeth and the associated gingiva
Superior palate
168
What is the job of the parasympathetic supply of the maxillary nerve?
Innervates lacrimal gland and the nasal glands
169
What are the terminal branches of the mandibular nerve?
buccal nerve, inferior alveolar nerve, auriculotemporal nerve and lingual nerve.
170
What does the sensory supply of the mandibular nerve innervate?
Mucous membranes and floor of the oral cavity
External ear
Lower lip
Chin
Anterior 2/3 of the tongue (only general sensation; special taste sensation supplied by the chorda tympani, a branch of the facial nerve)
Lower molar, incisor and canine teeth and the associated gingiva
171
What dies the motor supply of the mandibular nerve innervate?
Muscles of mastication; medial pterygoid, lateral pterygoid, masseter, temporalis
Anterior belly of the digastric muscle and the mylohyoid muscle (these are suprahyoid muscles)
Tensor veli palatini
Tensor tympani
172
What is the job of the parasympathetic supply of the mandibular nerve?
To innervate the Submandibular and Sublingual glands and the parotid glands
173
What is the sixth cranial nerve?
The Abducens nerve
174
What muscle does the abducens nerve innervate?
the lateral rectus muscle
175
Where does the abducens nerve arise from?
abducens nucleus in the pons of the brainstem
176
What area does the abducens nerve travel through after it has entered the subarachnoid space?
Dorello's canal
177
Where does the abducens nerve travel after it leaves dorello's canal at the tip of the temporal bone?
Through the cavernous sinus
178
Through what does the abducens nerve enter the bony orbit?
Through the superior orbital fissure
179
What does the lateral rectus muscle do?
abduct the eyeball
180
What is a clinical features of abducens nerve palsy?
diplopia, the affected eye resting in adduction (due to unopposed activity of the medial rectus), and inability to abduct the eye. The patient may attempt to compensate by rotating their head to allow the eye to look sideways.
By TeachMeSeries Ltd (2023)
181
What is the seventh cranial nerve?
The facial nerve
182
Which pharyngeal branch is the facial nerve associated with?
2nd
183
Where does the facial nerve arise from?
The pons
184
How many roots does the facial nerve have and which is the biggest?
a large motor root, and a small sensory root
185
Where does the facial nerve travel through after it has left the pons?
the internal acoustic meatus, a 1cm long opening in the petrous part of the temporal bone. Here, they are in very close proximity to the inner ear
186
After leaving the internal acoustic meatus but still in the temporal bone, through wheat does the facial nerve travel?
The facial canal
187
After the two roots of the facial nerve fuse in the facial canal, what does the nerve form?
the geniculate ganglion
188
After forming the geniculate ganglion in the facial canal, what does the facial nerve give rise to?
Greater petrosal nerve, Nerve to stapedius, Chorda tympani
189
Through what does the facial nerve exit the facial canal and cranium?
Via the stylomastoid foramen
190
What is the first extracranial branch of the facial nerve?
posterior auricular nerve
191
Which nerve innervates the parotid gland?
Glossopharyngeal nerve
192
Even through it does not innervate this gland, where does the facial nerve split into it's 5 branches?
In the parotid gland
193
What are the 5 terminal branches of the facial nerve?
Temporal branch
Zygomatic branch
Buccal branch
Marginal mandibular branch
Cervical branch
194
Between the stylomastoid foramen, and the parotid gland, what are the three motor branches that the facial nerve gives off?
Posterior auricular nerve, Nerve to the posterior belly of the digastric muscle, Nerve to the stylohyoid muscle
195
What does the posterior auricular nerve do?
Ascends in front of the mastoid process, and innervates the intrinsic and extrinsic muscles of the outer ear. It also supplies the occipital part of the occipitofrontalis muscle.
196
What dies the nerve to the posterior belly of the digastric muscle do?
Innervates the posterior belly of the digastric muscle (a suprahyoid muscle of the neck). It is responsible for raising the hyoid bone.
197
What does the nerve to the stylohyoid muscle do?
Innervates the stylohyoid muscle (a suprahyoid muscle of the neck). It is responsible for raising the hyoid bone.
198
What does the temporal branch of the facial nerve do?
Innervates the frontalis, orbicularis oculi and corrugator supercilii.
199
What does the zygomatic branch of the facial nerve do?
Innervates the orbicularis oculi
200
What does the buccal branch of the facial nerve do?
Innervates the orbicularis oris, buccinator and zygomaticus
201
What does the marginal mandibular branch of the facial nerve do?
Innervates the depressor labii inferioris, depressor anguli oris and mentalis
202
What does the cervical branch of the facial nerve do?
Innervates the platysma
203
What nerve does the chorda tympani branch off?
The facial nerve
204
What does the chorda tympani do?
responsible for innervating the anterior 2/3 of the tongue with the special sense of taste.
205
Which nerve does the chorda tympani travel with in the infratemporal fossa?
The lingual nerve
206
Through what fissure does the chorda tympani exit from the facial canal?
Petrotympanic fissure
207
What branches of the facial nerve carry the parasympathetic fibres of the facial nerve?
the greater petrosal and chorda tympani branches
208
Where does the greater petroseal nerve arise from?
Immediately distal to the geniculate ganglion within the facial canal
209
Where does the greater petroseal nerve exit the cranium?
the temporal bone into the middle cranial fossa
210
What is the function of the greater petroseal nerve?
parasympathetic innervation to the mucous glands of the oral cavity, nose and pharynx, and the lacrimal gland
211
What is formed when the chorda tympani combines with the lingual nerve?
Submandibular ganglion
