Neurology - 2 Flashcards
List the vagal nuclei.
- Nucleus solitarius
- Nucleus ambiguus
- Dorsal motor nucleus
What is the function of nucleus solitarius and which CN are involved?
Visceral sensory information (eg, taste, baroreceptors, gut distention) - CN VII, IX, X
What is the function of nucleus ambiguus?
Motor innervation of pharynx, larynx, upper esophagus (eg, swallowing palate elevation) - CN XI, X, XI (cranial portion)
What is the function of the dorsal motor nucleus?
Sends autonomic (parasympathetic) fibers to heart, lungs, upper GI - CN X
List the 5 cranial nerve reflexes.
- Corneal
- Lacrimation
- Jaw jerk
- Pupillary
- Gag
What are the afferent and efferent components of the corneal reflex?
A - V1 ophthalmic (nasociliary branch)
E - VII (temporal branch - orbicularis oculi)
What are the afferent and efferent components of the lacrimation reflex?
A - V1 (loss of reflex does not preclude emotional tears)
E - VII
What are the afferent and efferent components of the jaw jerk?
A - V3 (sensory - muscle spindle from masseter)
E - V3 (motor - masseter)
What are the afferent and efferent components of the pupillary reflex?
A - II
E - III
What are the afferent and efferent components of the gag reflex?
A - IX
E - X
What are the muscles of mastication, their function, and innervation?
3 muscles close the jaw - masseter, temporalis, medial pterygoid (M’s munch)
1 muscle opens the jaw - lateral ptyergoid (lateral lowers)
All are innervated by V3
How many pairs of spinal nerves are there?
31 pairs (8cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal)
Where do the spinal nerves exit?
C1-C7 exit above the corresponding vertebra
C8 exists below C7 and above T1
All others - exit below
Where is a lumbar puncture usually performed and why?
L3-L4 or L4-L5 (level of cauda equina)
Spinal cord ends at lower border of L1-L2; subarachnoid space (contains CSF) extends to lower border of S2
Goal - obtain CSF without damaging the spinal cord
List the ascending tracts of the spinal cord.
- Dorsal column
2. Spinothalamic
List the descending tracts of the spinal cord.
- Corticospinal tract
What is the function of the ascending tracts of the spinal cord?
- Dorsal column - pressure, vibration, fine touch, proprioception
- Spinothalamic tract (lateral) - pain, temperature
- Spinothalamic tract (anterior) - crude touch, pressure
What is the function of the descending tract of the spinal cord?
Voluntary movement
Describe the dorsal column pathway.
- Sensory nerve ending -> bypass pseudounipolar cell body in dorsal root ganglion -> enter spinal cord -> ascend ipsilaterally in the dorsal columns (fasciculus gracilis from the lower body/legs, fasciculus cuneatus from the upper body/arms)
- Synapse #1 in the nucleus gracilis or nucleus cuneatus (ipsilateral medulla)
- Decussates in the medulla -> ascends contralaterally in the medial lemniscus
- Synapse #2 in the VPL (thalamus) -> sensory cortex
Describe the spinothalamic tract.
- Sensory nerve ending (A-delta and C fibers) -> bypass pseudounipolar cell body in dorsal root ganglion -> enter spinal cord
- Synapse #1 in the ipsilateral gray matter (spinal cord)
- Decussates at the anterior white commissure -> ascends contralaterally
- Synapse #2 in the VPL (thalamus) -> sensory cortex
Describe the lateral corticospinal tract.
- UMN: cell body in the primary motor cortex -> descends ipsilaterally through the internal capsule, most fibers decussate at the caudal medulla (pyramidal decussation) -> descend contralaterally
- Synapse #1 - cell body of anterior horn (spinal cord)
- LMN: leaves spinal cord
- Synapse #2 - NMJ -> muscle fibers
List the clinical reflexes and what they test.
- Achilles reflex - S1, S2 (buckle my shoe)
- Patellar reflex - L3, L4 (kick the door)
- Biceps and brachioradialis reflexes - C5, C6 (pick up sticks)
- Triceps reflex - C7, C8 (lay them straight)
- Cremasteric reflex - L1, L2 (testicles move)
- Anal wink reflex - S3, S4 (winks galor)
Why might primitive reflexes re-emerge in adults?
Frontal lobe lesion (frontal lobe normally inhibits them)
What is the moro reflex?
Abduct/extend arms when started, and then draw together (“Han on for life”)