Exam 4 - Part 1 Flashcards
1
Q
The nervous system develops from the ___ (ectoderm, mesoderm, endoderm).
A
Ectoderm
2
Q
What triggers development of the neural plate? From what is this structure derived (ectoderm, mesoderm, endoderm)?
A
The notochord triggers development of the neural plate (via cell proliferation); Mesoderm
3
Q
What is the first step in nervous system development?
A
The anterior portion of the notochord thickens, forming the neural plate.
4
Q
As the neural plate widens, it forms the ___, which deepens; cells in the lateral margin and separate and migrate to a dorsal position to become the ___.
A
Neural groove; neural crest
5
Q
How is the neural tube formed?
A
Fusion of the neural folds in the midline
6
Q
What structures are formed via cell proliferation triggered by the notochord?
A
Neural Plate, Neural Groove, Neural Crest, Neural Tube
7
Q
What four types of neurons do neural crest cells differentiate into?
A
- Cranial nerve sensory cells
- Dorsal root ganglion cells
- Postganglionic autonomic ganglion cells
- Schwann cells
8
Q
Mesodermal cells alongside the neural tube begin to form ___, which will form skeletal muscle, vertebrae, and dermis.
A
Somites
9
Q
The anterior aspect of the neural tube forms three distinct vesicles. What are they?
A
- Prosencephalon (forebrain)
- Mesencephalon (midbrain)
- Rhombencephalon (hindbrain)
10
Q
What are the 5 secondary vesicles and from what do they form?
A
- Telencephalon (from forebrain)
- Diencephalon (from forebrain)
- Mesencephalon (from midbrain)
- Metencphalon (from hindbrain)
- Myelencephalon (from hindbrain)
11
Q
What are the 4 regions of the telencephalon?
A
- Cerebral cortex
- Basal ganglia
- Amygdala
- Hippocampus
12
Q
What are the 4 regions of the diencephalon?
A
- Thalamus
- Hypothalamus
- Pituitary
- Pineal Gland
13
Q
What is the 1 region of the mesencephalon?
A
- Midbrain
14
Q
What are the 2 regions of the metencephalon?
A
- Pons
2. Cerebellum
15
Q
What is the 1 region of myelencephalon?
A
- Medulla
16
Q
What ventricle/component originates from the telencephalon?
A
Lateral ventricle
17
Q
What ventricle/component originates from the diencephalon?
A
3rd ventricle
18
Q
What ventricle/component originates from the mesencephalon?
A
Cerebral aqueduct
19
Q
What ventricle/component originates from the metencephalon?
A
4th ventricle
20
Q
During proliferation, grooves appear at the midpoints of the neural canal. What are these grooves known as?
A
Sulcus limitans
21
Q
Neurocytes migrating dorsal to the sulcus form the ___ plate; those migrating ventral to it form the ___ plate. Those that lie in the intermediate position will form the ___ cell column.
A
Alar; basal; intermediolateral
22
Q
Which type of pathways are found in the alar plate? The basal plate? The intermediolateral cell column?
A
Alar plate: sensory pathways
Basil plate: motor pathways
Intermediolateral cell column: Autonomic neurons
23
Q
Describe the order of the functional components in the spinal cord from dorsal to ventral.
A
GSA - GVA - GVE - GSE
24
Q
In the brainstem, the alar plate is found ___ to the basal plate.
A
Lateral
25
What defect arises when the posterior neuropore fails to close (manifests by a failure of the vertebral canal to close properly)?
Spina bifida (myeloschisis; lower neural tube defect)
26
What type of spina bifida involves a defect in vertebral arches that is covered by skin and does not usually involve neural tissue?
Spina bifida occulta
27
What is the classic mark of spina bifida occulta?
Patch of hair over the affected region
28
What type of spina bifida involves neural tissue and/or meninges protruding through the defect in the arches and skin, forming a cyst-like sac?
Spina bifida cystica
29
What are the two types of spina bifida cystica?
Meningomyelocele (neural tissue + meninges protrude)
| Meningocele (meninges protrude)
30
What defect occurs when the neural tube becomes necrotic or fails to form? How can this be reduced?
Rachischisis; taking folic acid during pregnancy
31
True or false - development of the nervous system occurs before the formation of the skull.
True
32
What are three types of ossification defects?
Meningocele - protruding meninges
Meningoencephalocele - protruding brain tissue
Meningohydroencephalocele - protruding ventricles
33
What is the Arnold-Chiari malformation?
Caudal displacement and herniation of the posterior cranial fossa structures through the foramen magnum
34
What is a microcephaly?
Cranial vault is smaller than normal due to lack of brain development
35
What can cause microcephaly?
Zika virus
36
What is hydrocephalus?
Abnormal accumulation of CSF within the ventricular system
37
What typically causes hydrocephalus?
Blockage or narrowing (stenosis) of the aqueduct of Sylvius
38
What occurs with failure to close the anterior neuropore (upper NTD)?
Anencephaly (not compatible with life)
39
From what are the ventricles formed?
Lumen of the neural tube
40
What ventricle/component originates from the myelencephalon?
Central canal
41
What are the two layers of the cranial dura? Which layer is continuous with the spinal meninges?
1. Outer layer - periosteum
| 2. Inner layer - meningeal; continuous with spinal dura
42
List the meningeal spaces.
1. Cranial epidural space (potential space between periosteum and calvaria)
2. Spinal epidural space (real space between dura and vertebral periosteum)
3. Subdural space (space between dura and arachnoid)
4. Subarachnoid space (space between arachnoid and pia)
43
What are the four ventricles of the brain?
1/2. Lateral ventricles in telencephalon
3. Third ventricle in diencephalon
4. Fourth ventricle in rhombenecphalon
44
Describe the flow of CSF through the ventricles.
1. Two lateral ventricles
2. Two foramen of Monro
3. Third ventricle
4. Cerebral aqueduct of Silvius
5. Fourth ventricle
6a. Foramen of Magendie to median aperture
6b. Foramen of Luschka to lateral aperture
7. Cisterna magna
45
What happens to the CSF after it enters the cisterna magna?
Spinal subarachnoid space -> Basal part of brain/Dural sinuses -> Arachnoid villi -> Venous system
46
What are 5 functions of the CSF?
1. Cushion
2. Remove metabolites
3. Reduce traction on nerves/blood vessels
4. Maintain intracranial pressure
5. Spread neuroactive hormones
47
Describe the composition of the CSF.
1. Little protein
2. Less glucose, calcium, and potassium than serum
3. More sodium, chloride, magnesium than serum
48
What are the two types of hydrocephalus and how are they different?
1. Noncommunicating: obstruction cuts off communication between ventricles and subarachnoid space
2. Communicating: obstruction of tentorial notch or arachnoid villi
49
What are structures in the CNS that lack a blood-brain barrier and consist of neurons, glia, ependymal cells, leptomeningeal, and vascular elements?
Circumventricular organs
50
What are the two categories of circumventricular organs?
1. Sensory
| 2. Secretory
51
What are the three sensory circumventricular organs?
1. Subfornical organ
2. Vascular organ of the lamina terminalis
3. Area postrema
52
What are the three secretory circumventricular organs?
1. Median eminence of hypothalamus
2. Neurohypophysis (posterior pituitary gland)
3. Pineal gland
53
What causes an epidural hematoma?
Torn meningeal artery (or cerebral vein from dural venous sinus)
54
What causes a subdural hematoma?
Torn cerebral vein from dural venous sinus or vein at attachment to sinus
55
What causes a subarachnoid hemorrhage?
Ruptured cerebral artery or vein
56
Broadly, what supplies the cerebrum?
Internal carotid arteries
57
Broadly, what supplies the brainstem, cerebellum, and spinal cord?
Vetebrobasilar arteries
58
What are the branches of the internal carotid arteries?
Ophthalmic artery, anterior choroidal artery, posterior communicating artery
59
What does the ICA bifurcate into?
Anterior and middle cerebral arteries
60
What are the branches of the vertebrobasilar arteries?
Posterior and anterior spinal arteries, posterior inferior cerebellar artery (PICA)
61
The vertebral arteries fuse to form the ___ artery.
Basilar
62
What are the branches of the basilar artery?
Anterior inferior cerebellar artery (AIC), superior cerebellar artery
63
What does the basilar artery bifurcate into?
Posterior cerebral arteries
64
Describe the circulation of blood in the brain, beginning with the vertebral arteries.
1. 2 vertebral arteries (Branch: 2 PICA)
2. 1 basilar artery (Branches: 2 AICA, 2 SCA, 2 PCA)
3. 2 posterior communicating arteries
4. ICA (2 MCA, 2 ACA)
5. 1 anterior communicating artery
65
What are small perforated arteries that supply deep cerebral structures?
Ganglionic arteries
66
What are visible entry points of perforating arteries on the base of the brain?
Perforated substances
67
What makes up the Circle of Willis?
Basilar artery branches into 2 PCA, 2 posterior communicating arteries connect to the ICA, which gives 2 MCA and ACA; the ACA are connecting by the anterior communicating artery
68
Describe the drainage pattern of cerebral veins (deep and superficial groups).
Superficial veins -> Superior sagital sinus -> Confluence of sinuses
Deep veins -> Internal cerebral veins -> Great vein (of Galen) -> Straight sinus -> Confluence of sinuses
Confluence of sinus -> Transverse sinuses
69
What are three mechanisms of regulation of cerebral blood flow?
1. Autoregulation
2. Metabolic
3. Neural control
70
Describe metabolic regulation of cerebral blood flow.
Increased neuronal activity leads to glutamate release. This activates astrocyte end feet receptors. Vasodilator factors are released and applied to vessels.
71
What are the 4 components of the BBB?
1. Capillary endothelial cells
2. Pericytes
3. Astrocytes
4. Neuronal processes
72
What are the three divisions of the gray matter in the spinal cord?
1. Dorsal horn
2. Intermediate gray
3. Ventral horn
73
What nuclei are found in the dorsal horn of the SC?
1. Substantia gelatinosa
| 2. Nucleus proprius
74
What nuclei are found in the intermediate gray of the SC?
1. Clarke's nucleus (nucleus dorsalis)
2. IML
3. IMM
75
What nuclei are found in the ventral horn of the SC?
1. Lateral motor neurons
| 2. Medial motor neurons
76
What are the divisions of the white matter in the SC?
1. Dorsal funiculus
2. Dorsolateral fasciculus
3. Lateral funiculus
77
What is found in the dorsal funiculus?
Fasciculus gracilis and cuneatus
78
What is found in the lateral funiculus?
DSCT, VSCT, STT
79
Where are the spinal enlargements found?
Cervical and lumbar levels
80
What is unique about the thoracic spinal cord cross section?
Distinct lateral horn
81
What are the 3 non-encapsulated receptors?
1. Free nerve endings
2. Merkel's disk
3. Hair follicle
82
What are the 6 encapsulated receptors?
1. Meissner's corpuscle
2. Pacinian corpuscle
3. Ruffini ending
4. Joint receptor
5. Neuromuscular spindle
6. Golgi tendon organs
83
What is the function of free nerve endings?
Pain and temperature
84
What is the function of Merkel's disks and hair follicles?
Touch
85
What is the function of Meissner's corpuscles?
2-point discrimination
86
What is the function of Pacinian corpuscles?
Vibration
87
What is the function of Ruffini endings?
Stretch and pressure
88
What is the function of joint receptors?
Joint position
89
What is the function of neuromuscular spindles?
Limb muscle, stretch/length
90
What is the function of Golgi Tendon Organs?
Muscle tension
91
The lateral division of dorsal root afferents is made up of ___ (lightly, heavily) myelinated fibers; what does this division communicate?
Lightly (communication is slower); pain and temperature, light touch, visceral afferenets
92
The medial division of dorsal root afferents is made up of ___ (lightly, heavily) myelinated fibers; what does this division communicate?
Heavily (communication is faster); 2-point touch, limb position, muscle stretch
93
The medial division of dorsal root afferents also sends collaterals to what part of the brain?
Medulla
94
Describe the difference between a muscle spindle and a Golgi tendon organ.
Muscle spindles fire only in response to stretching of a muscle. Golgi tendon organs fire only in response to an increase in muscle tension during an isometric contraction.
95
Describe the stretch reflex arc.
1. Muscles stretch.
2. Spindle afferents fire
3. Alpha motor neurons fire
4. The muscle shortens and the spindle gets saggy
5. Gamma motor neurons fire
6. Spindle shortens/resets
96
Describe the Dorsal Column Pathway (DCP).
Receptors send information to the spinal cord/DRG through the medial division of dorsal root afferents. If the information comes from the lower body (T6-S5), fasciculus gracilis is used. If the information comes from the upper body (C1-T5), fasciculus cuneatus is used. Information ascends to the caudal medulla and a synapse occurs at nucleus cuneatus/gracilis. The information continues as internal arcuate fibers, DECUSSATES in the caudal medulla, ascending as the medial lemniscus. A synapse occurs in the VPL of the thalamus. Information then travels in the internal capsule the sensorimotor cortex (312, post-central gyrus)
97
What information does the DCP communicate?
2-point discrimination, vibration, proprioception (consciousness)
98
Where does the DCP decussate?
Caudal medulla
99
What receptors are involved in the DCP?
1. Pacinian corpuscles
2. Meissner's corpuscles
3. Merkel's discs
4. Ruffini corpuscles
5. Joint receptors
100
What is a positive Romberg sign and what causes it to occur?
Patient requires vision to stand steadily; dorsal columns destroyed, often as a result of tabes dorsalis
101
What is an ascending bundle of heavily myelinated axons that decussate in the medulla?
Medial lemniscus
102
What forms the medial lemniscus?
Crossing of internal arcuate fibers
103
What makes up internal arcuate fibers?
Axons of nucleus gracilis and nucleus cuneatus
104
Describe the Spinothalamic Tract (STT).
Receptors send information to the spinal cord/DRG through the lateral division of the dorsal root afferents (for pain and temperature) and medial division of the dorsal root afferents (for simple tactile sensations). A synapse occurs in the spinal cord at nucleus proprius. DECUSSATION occurs in the spinal cord and then the fibers ascend via the lateral funiculus to the thalamus, where they synapse on the VPL. Finally, the fibers travel to the primary sensory cortex (312).
105
What information does the STT communicate?
Pain, temperature, simple tactile sensations
106
Where does the STT decussate?
Spinal cord
107
What is the origin of STT?
Nucleus proprius
108
Lesions of the STT and DCP in the brain stem or higher lead to deficits of pain perception, touch sensation, and proprioception ___ (ipsilateral, contralateral) to the lesion.
Contralateral
109
Lesions of the STT and DCP in the spinal cord lead to deficits of pain and temperature perception ___ (ipsilateral, contralateral) to the lesion and proprioception deficits (ipsilateral, contralateral) to the lesion.
Contralateral; ipsilateral
110
In the event that syringomyelia trasects the spinal cord, how are STT and DCP inputs affected?
STT input is destroyed on the contralateral side below the lesion. DCP input is destroyed on the ipsilateral side below the lesion.
111
Describe the Dorsal Spinocerebellar Tract (DSCT).
Information from Golgi tendon organs, muscle spindles, and joint receptors enters the spinal cord (C8-L2) and synapse in Clarke's nucleus in the spinal cord. The fibers ascend in the lateral funiculus as the posterior spinocerebellar tract and enter the inferior cerebellar peduncle. Finally, the information is delivered to the cerebellum.
112
Describe the Ventral Spinocerebellar Tract (VSCT).
Interneuronal information from the intermediate gray DECUSSATES in the spinal cord. Fibers ascend to the superior cerebellar peduncle where it DECUSSATES again. Finally, the information is delivered to the cerebellum.
113
Where does the DSCT decussate?
It doesn't.
114
How does information below L2 participate in the DSCT?
Uses fasciculus gracilis to get to Clarke's nucleus
115
Where does the VSCT decussate?
First the spinal cord, then the pons
116
Describe the Cuneocerebellar Tract.
Information from muscle spindles and Golgi tendon organs enters the spinal cord and ascends in the fasciculus cuneatus. Information synapses in the accessory cuneate nucleus of the pons, passes through the inferior cerebellar peduncle, and travels in the cuneocerebellar tract to the cerebellum.
117
Where does the Cuneocerebellar tract decussate?
It doesn't.
118
What information is transmited in the DSCT and VSCT?
Generally, both SCTs relay unconscious proprioception. DSCT relays muscle stretch and VSCT relays information of the spinal motor centers.
119
Which SCT uses the inferior cerebellar peduncles and which use the superior cerebellar peduncles?
Inferior: SCT and Cuneocerebellar
Superior: VSCT
120
Describe the Corticospinal Tract (CST).
Information travels from the motor cortex (precentral gyrus, area 4) via the corona radiata. Information travels through the internal capsule and the cerebral peduncles. Then, the majority of fibers DECUSSATE in the medulla. Those that do not decussate form the Anterior CST. Those that do form the Lateral CST.
121
Where does the CST decussate?
Lateral CST fibers decussate in the caudal medulla. Anterior CST fibers do not decussate.
122
What are neurons that directly innervate skeletal muscles?
Lower motor neurons
123
What are cortical neurons that innervate lower motor neurons (directly or via local interneurons)?
Upper motor neurons
124
Where are lower motor neuron cell bodies located?
Ventral horns of the spinal cord and within brainstem motor nuclei
125
Where are upper motor neuron axons located?
Pyramidal system (corticospinal and corticobulbar tracts)
126
Describe the cellular anatomy of a pyramidal cell.
- Triangle-shaped soma
- Single axon
- Large apical dendrite
- Multiple basal dendrites
- Dendritic spines
127
A stroke in the primary motor cortex impairs motor function on the ___ (ipsilateral, contralateral) side of the body.
Contralateral
128
Damage to the lateral spinal cord (where lateral CST axons are located) causes motor deficit in the limbs on the ___ (ipsilateral, contralateral) side of the body.
Ipsilateral
129
List the symptoms of CST damage.
Spasticity, hyper-reflexivity, positive Babinski sign, hemiplegia
130
List the symptoms of damage to ventral horn cells or their axons
Hypo-reflexivity, atrophy, fasiculations, flaccid paralysis
131
Common lesions of the CST include...
...stroke, tumor, MS, ALS.
132
Common lesions of lower motor neurons include...
...spinal stroke or bleed, ALS, tumor, polio, trauma to the nerve or cord
133
What are the three components of the brainstem from caudal to rostral?
1. Medulla
2. Pons
3. Midbrain
134
What are the 3 unique structures of the caudal medulla?
1. Central canal
2. Nucleus cuneatus
3. Nucleus gracilis
135
What 2 tracts have consistent locations throughout the brainstem?
CST and STT
136
In which parts of the brainstem are the spinal trigeminal nucleus/tract located?
1. Caudal medulla
2. Rostral medulla
3. Caudal pons
137
In which parts of the brainstem are the pyramids located?
1. Caudal medulla
| 2. Rostral medulla
138
Where does the medial lemniscus form?
Caudal medulla
139
In which parts of the brainstem are the internal arcuate fibers located?
1. Caudal medulla
| 2. Rostral medulla
140
What are the unique structures of the rostral medulla?
1. Inferior olive
| 2. Inferior cerebellar peduncle
141
In which parts of the brainstem is the fourth ventricle found?
1. Rostral medulla
2. Caudal pons
3. Rostral pons
142
In which parts of the brainstem is the medial longitudinal fasciculus (MLF) found?
All EXCEPT the caudal medulla
143
What causes the lateral medullary syndrome of Wallenberg?
Stroke of PICA
144
What are the symptoms of the lateral medullary syndrome of Wallenberg?
Loss of cerebellar function, STT, nucleus ambiguous
145
Describe the location of the symptoms of the lateral medullary syndrome of Wallenberg?
Ipsilateral ataxia
| Contralateral loss of pain and temperature in the body
146
What are the unique structures of the caudal pons?
1. Middle cerebellar peduncle
147
In which parts of the brainstem are the pontine nuclei found?
1. Caudal pons
| 2. Caudal midbrain
148
What are the unique structures of the rostral pons?
There are none.
149
What are the unique structures of the caudal midbrain?
There are none.
150
In which parts of the brainstem is the cerebral peduncle found?
1. Caudal midbrain
| 2. Rostral midbrain
151
In which parts of the brainstem is the periaqueductal gray found?
1. Caudal midbrain
| 2. Rostral midbrain
152
Where does the decussation of the superior cerebellar peduncles occur?
Caudal midbrain
153
What are the unique structures of the rostral midbrain?
1. Red nucleus
| 2. Substantia nigra
154
What neurotransmitter is contained in each of the following nuclei: Raphe, Locus ceruleus, Substantia nigra, Ventral tegmental area (VTA), nucleus basalis of Meynert, septal nuclei
Raphe: Serotonin
Locus ceruleus: Noradrenaline
Dopamine: substantia nigra, VTA
Acetylcholine: Nucleus basalis of Meynert, septal nuclei
SE Raphe's Substantial Dopey Blue NEs
155
List the functional components of the cranial nerves.
```
GVA: 7, 9, 10
SVA: 1, 7, 9, 10
GVE: 3, 7, 9, 10
GSA: 5, 7, 9, 10
SVE: 5, 7, 9, 10, 11
SSA: 2, 8
GSE: 3, 4, 6, 12
```
156
Where do the 10 true cranial nerves emerge/enter approximately?
Midbrain: 3, 4
Pons: 5, 6, 7, 8
Medulla: 9, 10, 11, 12
157
What is the attachment of CN 1?
Olfactory bulb
158
What is the foramen of CN 1?
Cribriform plate
159
What is the component(s) of CN 1?
SVA (taste)
160
What is the afferent nucleus of termination of CN 1?
Olfactory mucosa
161
What are the main structures innervated by CN 1?
Olfactory nasal mucosa
162
What is the attachment of CN 2?
Optic chiasma
163
What is the foramen of CN 2?
Optic foramen (canal)
164
What is the component(s) of CN 2?
SSA (vision)
165
What is the afferent nucleus of termination of CN 2?
Lateral geniculate body
166
What are the main structures innervated by CN 2?
Retina
167
What is the attachment of CN 3?
Sulcus on walls of interpeduncular fossa
168
What is the foramen of CN 3?
Superior orbital fissure
169
What is the component(s) of CN 3?
GVE and GSE
170
What is the efferent nucleus of origin of CN 3 for each of its components?
1. GVE: Edinger-Westphal (midbrain)
| 2. GSE: Oculomotor nucleus (midbrain)
171
What are the main structures innervated by CN 3 for each of the its components?
GVE: Sphincter pupillae and ciliary muscles
GSE: All eye muscles except LR & SO
172
What is the attachment of CN 4?
Superior medullary velum
173
What is the foramen of CN 4?
Superior orbital fissure
174
What is the component(s) of CN 4?
GSE
175
What is the efferent nucleus of origin of CN 4?
Trochlear nucleus (midbrain)
176
What are the main structures innervated by CN 4?
Superior oblique
177
What are 3 interesting facts about the trochlear nerve?
1. Longest intracranial exposure
2. Only nerve to originate from the dorsal brainstem
3. Only nerve to cross
178
What is the attachment of CN 5?
Lateral part of pons
179
What is the foramen of CN V1, V2, and V3?
V1 - superior orbital fissure
V2 - foramen rotundum
V3 - foramen ovale
180
What is the component(s) of CN 5?
GSA and SVE
181
What are the nuclei of origin (efferent) and termination (afferent) for each of the components of CN 5?
GSA (pain and temperature from face): spinal trigeminal nucleus
GSA (conscious proprioception): chief sensory nucleus
GSA (unconscious proprioception from jaw): mesencephalic nucleus
SVE: motor nucleus of nerve 5
182
What are the main structures innervated by CN 5 for each of the its components?
GSA, V1: skin of upper part of face
GSA, V2: skin of middle face, upper teeth, nasal and palatal mucosa
GSA, V3: skin of lower face/jaw, floor of mouth, mucosa of anterior 2/3 of tongue, lower teeth and gums, ear pinna and canal
SVE: muscles of mastication, anterior belly of digastric, tensor tympani, mylohyoid tensor palatini
183
Axons from the principle sensory nucleus and the spinal nucleus end up in the ___ of the thalamus.
VPM
184
What is the spinal correlate of the principle sensory nucleus of 5?
Nucleus cuneatus/gracilis
185
What is the spinal correlate of the spinal trigeminal nucleus?
Nucleus proprius
186
What is the attachment of CN 6?
Sulcus between pons and medulla on anterior surface
187
What is the foramen of CN 6?
Superior orbital fissure
188
What is the component(s) of CN 6?
GSE
189
What is the nucleus of origin (efferent) of CN 6?
Abducens nucleus (pons)
190
What is the main structure innervated by CN 6?
Lateral rectus
191
What is the facial colliculus?
Bump created when CN 7 courses over CN 6
192
What is the attachment of CN 7?
Cerebellomedullary pontine angle
193
What is the foramen of CN 7?
Internal auditory meatus
194
What are the components of CN 7?
GVA, SVA, GSA, GVE, SVE
195
What are the nuclei of origin (efferent) and termination (afferent) for CN 7?
GVA and SVA: nucleus solitarius (pons)
GSA: spinal nucleus of CN 5 (medulla)
GVE: superior salivatory nucleus (pons)
SVE: motor nucleus of CN 7 (pons)
196
What are the main structures innervated by CN 7 for each of its components?
GVA: deep sensation from soft palate
SVA: taste buds from the anterior 2/3 of the tongue
GSA: sensory from the small part of the ear pinna
GVE: submandibular and sublingual glands, glands in nasal mucosa
SVE: muscles of facial expression, posterior belly of digastric, stylohyoid, stapedius
197
What is the internal genu?
Bend of CN 7
198
The facial motor nucleus contains neurons that innervate both the upper face and neurons that innervate the lower face. Those doing the upper face receive ___ (bilateral, unilateral) cortical input; those doing the lower face receive ___ (bilateral, unilateral) cortical input.
Bilateral; unilateral (contralateral)
199
What is the result of a left cortical stroke?
Lower right face is paralyzed
200
What is the result of a severed right facial nerve/Bell's palsy?
Entire right face is paralyzed
201
What nucleus does the internal genu of CN 7 loop around?
Abducent nucleus
202
What is the attachment of CN 8?
Cerebellomedullary pontine angle
203
What is the foramen of CN 8?
Internal auditory meatus
204
What are the components of CN 8?
SSA (cochlear and vestibular)
205
What are the nuclei of termination (afferent) of CN 8?
SSA, cochlear - cochlear nuclei (medulla)
| SSA, vestibular - vestibular nuclei (medulla)
206
What are the main structures innervated by CN 8?
SSA, cochlear - organ of Corti in cochlear duct
| SSA, vestibular - semicircular canals, utricle, saccule
207
Why is hearing hard to knock out with lesions?
Hearing is bilateral
208
What is the attachment of CN 9?
Posterior lateral (olivary) sulcus
209
What is the foramen of CN 9, 10, and 11?
Jugular foramen
210
What are the components of CN 9?
GVA, SVA, GSA, GVE, SVE
211
What are the nuclei of origin (efferent) and termination (afferent) of CN 9?
GVA and SVA: nucleus solitarius (pons)
GSA: spinal nucleus of CN 5 (medulla)
GVE: inferior salivatory nucleus (medulla)
SVE: nucleus ambiguous (medulla)
212
What are the main structures innervated by the components of CN 9?
GVA: deep sensory from posterior tongue, soft palate, pharynx, mucosa of tympanic cavity, posterior auditory tube, carotid body and sinus
SVA: taste buds in posterior 1/3 of tongue and adjacent pharynx
GSA: general sensory from small part of ear pinna and canal
GVE: parotid salivary gland
SVE: stylopharyngeus
213
What is the attachment of CN 10?
Posterior lateral (olivary) sulcus
214
What are the components of CN 10?
GVA, SVA, GSA, GVE, SVE
215
What are the nuclei of origin (efferent) and termination (afferent) of CN 10?
GVA and SVA: nucleus solitarius (medulla)
GSA: spinal nucleus of CN 5 (medulla)
GVE: dorsal motor nucleus of CN 10 (medulla)
SVE: nucleus ambiguous
216
What are the main structures innervated by CN 10?
GVA: visceral sensory from pharynx, esophagus, trachea, larynx, and abdominal viscera
SVA: taste buds in epiglottis and glottis
GSA: sensory from small part of ear pinna, canal, and tympanic membrane
GVE: thoracic and abdominal viscera
SVE: muscles of pharynx and larynx, levator palatini, and cricothyroid
217
What is the attachment of CN 11?
Upper cervical spine between posterior and anterior roots
218
What are the components of CN 11?
SVE
219
What is the nucleus of origin (efferent) for CN 11?
Accessory nucleus
220
What are the main structures innervated by CN 11?
Trapezius and SCM
221
What is the attachment of CN 12?
Anterior lateral (olivary) sulcus
222
What are the components of CN 12?
GSE
223
What is the nucleus of origin (efferent) of CN 12?
Hypoglossal nucleus (medulla)
224
What are the main structures innervated by CN 12?
Intrinsic and extrinsic muscles of the tongue (except palatoglossus)
225
A lesion in CN 12 causes the tongue to deviate to which side?
Ipsilateral side
226
Nucleus ambiguous provides SVE innervation for what 2 cranial nerves?
9, 10
227
The solitary nucleus provides what two types of innervation for CN 7, 9, and 10?
GVA and SVA
228
Spinal nucleus of CN 5 provides GSA innervation for what 4 cranial nerves?
5, 7, 9, 10
229
Which three nuclei provide innervation for multiple cranial nerves?
1. Nucleus ambiguous
2. Solitary nucleus
3. Spinal nucleus of 5
230
What innervates stapedius?
CN 7
231
What innervates tensor tympani?
CN 5
232
What is the function of stapedius?
Prevents excess movement of stapes, protects inner ear from sudden loud noises
233
What is the function of tensor tympani?
Tightens ear drum and dampens sound (in loud environment)
234
The bony portion of the inner ear is filled with ___; the membranous portion is filled with ___.
Perilymph; endolymph
235
Describe the composition of endolymph.
Concentration of potassium is much greater than the concentration of sodium
236
Describe the tonotopic tuning of the basilar membrane.
The membrane is widest at the helicotrema and stiffest at the base (corresponds to low pitches and high pitches respectively)
237
What is the site of transduction of pressure waves in the hair cells and where is it found?
Organ of Corti; sits on basilar membrane
238
Describe the mechanism of sound conduction through the middle and inner ears.
1. Pressure wave strikes tympanic membrane
2. Lifts handle of malleus
3. Head of malleus moves laterally
4. Pulls head of incus laterally
5. Drives lenticular process medially
6. Drives stapes medially into oval window
7. Displaces perilymph in inner ear
8. Fluid moves through the cochlear duct
9. Fluid returns and hits the round window
239
What are the three types of air conduction?
1. Air conduction
2. Bone conduction
3. Ossicular conduction
240
Outer hair cells are ___ sensitive; inner hair cells are ___ sensitive.
Displacement; velocity
241
What happens when hair cells bend toward the kinocilium? Away from the kinocilium?
Potassium channels open, depolarization occurs, NT release increased
Potassium channels closed, hyperpolarization, NT release decreased
242
What is the basic auditory pathway?
1. Cochlea
2. Cochlea Nuclei
3. Inferior Colliculus
4. Medial Geniculate Body
5. Cortex
243
What is hyperacusis?
Paralysis of stapedius allows wider oscillations of stapes, causing normal sounds to be perceived as overly loud
244
Where is Wernicke's area? Broca's area?
22/temporal lobe; 45/frontal lobe
245
What happens when there are lesions in Wernicke's area? Broca's area?
A lesion in Wernicke's area leads to failure to comprehend audio signals; one cannot understand visual or spoken language. A lesion in Broca's area disrupts speech output
246
Lesions of the arcuate fasciculus can also disrupt ___.
Vocal output
247
A lesion in the cochlear, cochlear nerve, or cochlear nuclei leads to a ___ (ipsilateral, contralateral) lesion. After that, what happens?
Ipsilateral; after that, the information is pretty much bilateral and thus hard to knock out.
248
What are the three divisions of the vestibular apparatus?
1. Semicircular canals (anterior, posterior, horizontal)
2. Utricle
3. Saccule
249
What do the utricle and saccule sense?
Gravity and acceleration
250
What do semicircular canals sense?
Angular motion
251
Where are the hair cells of the semicircular canals located?
Ampulla (swelling) in each canal; consists of the ampullary crest (nerve) and the cupola (gelatinous substance that covers the hair cells)
252
Describe what happens in the vestibular system when the head is rotated to the left.
Rotation of the head to the left causes an inertial displacement of the fluid and cupola. On the left, the hair cells bend toward the kinocilium, causing depolarization and increased NT. On the right, the hair cells bend away from the kinocilium, causing hyperpolarization and decreased NT. The bigger the difference, the faster one is moving; the brain compares the left and the right.
253
The horizontal canals are oriented ___ the utricle; the anterior and posterior canals are oriented ___ the utricle.
Toward; away from
254
The cupola in the saccule and utricle contain ___ and respond to ___.
Otolithic granules; gravity
255
What does the utricle detect? The saccule?
The utricle detects upright position and head tilt, gravity (primary gravity sensor), horizontal linear acceleration. The saccule detects general orientation and vertical linear acceleration.
256
In the vestibular system, ascending fibers (MLF) control ___.
Eye movement
257
Describe how ascending fibers (MLF) control eye movement.
Inputs from the vestibular apparatus synapse in the vestibular nuclei. Some information goes directly to the cerebellum. Other information travels to the abducens nucleus, trochlear nucleus, and oculomotor nuclear complex, which communicate to the extraocular muscles.
258
In the vestibular system, descending fibers control ___.
Head and neck movements
259
Primary afferents of the vestibular pathways travel to what two locations?
1. Vestibular nuclei
| 2. Flucculonodular lobe
260
What are some of the secondary vestibular connections?
1. Cerebellum
2. Spinal cord (Lateral and Medial Vestibulospinal Tract)
3. Brainstem
4. Thalamic and cortical areas
261
What is the vestibulo-ocular reflex (VOR)?
Stabilizes the image on the retina during a rotation of the head; as the head rotates, the VOR rotates the eyes with the same speed, but in the opposite direction
262
Describe the VOR.
1. Head rotates right.
2. Right horizontal canal activated
3. Right vestibular nucleus activated
4. Left 6th nucleus activated via PPRF
5. Left lateral rectus muscle contracts
6. Left PPRF activates neurons in right third nucleus
7. Right medial rectus contracts
8. Both eyes begin to move to the left
263
What happens to the VOR over time?
Attenuates with tonic stimulation (turns itself off)
264
What is nystagmus?
Rhythmic back and forth movement of the eyes (slow in one direction - smooth, fast in other direction - saccadic)
265
How is nystagmus tested?
Carolic test: COWS - cold water, opposite direction
| warm water, same direction
266
Describe the pathway from the retina to the brain.
1. Optic nerve
2. Optic chiasm
3. Optic tract
4. Lateral geniculate nucleus (thalamus)
5. Optic radiations (geniculocalcarine tract)
6. Visual cortex
267
___ (temporal, nasal) portions of the retina do not cross; ___ (temporal, nasal) portions of the retina do cross.
Temporal does not cross; nasal does cross
268
Describe the movement of information through the visual system.
Information from the right visual field ends up in the left visual cortex. Information from the left visual field ends up in the right visual cortex.
269
What are the two types of ganglion cells?
M-type, P-type
270
Describe M-type ganglion cells.
1. Large (Massive) cell bodies
2. Large receptive fields
3. Rapidly adapting
3. Found in rods
271
Describe P-type ganglion cells.
1. Small (Petite) cell bodies
2. Small receptive fields
3. High acuity
4. Found in color
272
Where do visual perceptions begin?
Primary visual cortex (area 17, striate cortex, V1)
273
Some visual information enters the brainstem via what two other pathways?
1. Pretectal area (pupillary reflexes)
| 2. Superior colliculus (head and eye movements)
274
Optic radiations reach the primary visual cortex through upper fibers via the ___ lobe and lower fibers via the ___ lobe. Which forms Meyer's loop?
Parietal; temporal; lower fibers
275
What causes a blind right eye?
Lesion in the right optic nerve
276
What is bitemporal hemianopia and what causes it?
"Tunnel vision," blindness in left half of left eye, right half of right eye; caused by lesion at optic chiasm (of nasal fibers)
277
What is left homonymous hemianopia and what causes it?
Blindness in left half of each eye, lesion in optic tract
278
What is left homonymous upper quadrantanopia and what causes it?
"Pie in the Sky," blindness in left upper 1/4 of each eye, lesion in temporal lobe
279
What is left homonymous hemianopia and what causes it?
Blindness in left half of each eye, lesion in LG
280
What is left homonymous lower quadrantanopia and what causes it?
Blindness in left lower third, lesion in parietal lobe
281
What is left homonymous hemianopia with macular sparing and what causes it?
Blindness in left half of each eye + macular sparing; stroke in primary visual cortex
282
How is the optic nerve tested?
Pupillary light reflex
283
What happens when the pupillary light reflex is normal?
A light is shone through one pupil and both pupils contract equally.
284
The response of the illuminated eye is the __ reflex, the response of the unilluminated eye is the ___ response.
Direct; consensual
285
Why do both pupils constrict in the pupillary light reflex?
Bilateral connections to the Edinger-Westphal nucleus by the optic fibers traveling through the brachium of the superior colliculus to the pretectal area.
286
What happens in optic nerve damage vis a vis the pupillary light reflex?
Produces equal pupils, neither of which respond to light shone in the eye ipsilateral to the lesion; both eyes respond normally to light shone in the contralateral eye
287
What happens in oculomotor nerve damage vis a vis the pupillary light reflex?
Causes a dilated ipsilateral pupil that does not respond to light shone into either eye.
288
What causes the accommodation reflex?
Changing gaze to focus on a nearby object
289
What is the accommodation reflex?
1. Vergence of the eyes (contraction of both medial recti)
2. Ciliary muscle constriction, lens thickening
3. Constriction of both pupils
290
What are the two basic ways to detect motion of an object?
1. Image moves temporally across the retina while the eye remains stationary
2. Head and eyes move to fix the image of the object on the fovea
291
Where are movements represented best?
1. Middle Temporal area of V5
| 2. Medial Superior Temporal area of V5a
