4.4 Midbrain and CN

Question 1

What are the substantia nigra? Where?

Answer 1

Midbrain

dopamine production for movement and emotion

Question 2

What is the red nucleus? Where?

Answer 2

Midbrain

posture control

Question 3

What is the superior colliculus? Where?`

Answer 3

Midbrain

visual tracking of objects, visual reflexes

Question 4

What is the inferior colliculus?

Answer 4

auditory reflex, orient to loud sounds

Question 5

What are the cerebral peducles?

Answer 5

large white matter tract from cerebrum to spinal cord in midbrain

Question 6

What are the cerebellar peduncles?

Answer 6

large white matter tract to cerebellum in the midbrain

Question 7

What is the pons? Fx? CNs?

Answer 7

bulging region between midbrain and medulla, anterior to cerebellum
cranial nerve nuclei (CN V, VI, VII, VIII)
Pneumotaxic respiratory center – works with medulla to maintain rhythmic breathing
cerebellar peduncle white matter tract pons to cerebellum

Question 8

What are the pyramids of the medulla?

Answer 8

contains corticospinal motor tracts that cross over (decussation) before they continue down the spinal cord

Question 9

What are the nucleus gracilis and cuneatus? Where?

Answer 9

Medulla

sensory information from limbs to thalamus

Question 10

What are the olives? Where?

Answer 10

sensory information to cerebellum

Question 11

What does the medulla control?

Answer 11

cardiac center: heart rate and force of contraction
vasomotor center: blood pressure
respiratory center: respiratory rate, coordination with pons
Vomiting, swallowing, coughing, sneezing, hiccups

Question 12

What CN nuclei are in the medulla?

Answer 12

IX, XI, XII

Question 13

What is a diffuse axonal injury?

Answer 13

DAI- widespread white matter damage, diffuse swelling of axons, hemorrhage or damage to corpus callosum, brainstem
rapid stretch of axons, loss of elasticity, axonal swelling and disconnection, calcium entry cell death
loss of consciousness, persistent coma, severe impairment likely
rule out cervical spinal injury

Question 14

What is a concussion?

Answer 14

mild TBI, traumatic force with or without loss of consciousness, changes in the brain with no evidence of structural abnormality
metabolic dysfunction of neurons, excessive glutamate accumulation, swelling of neurons that resolves over time
confusion, headache, dizziness, flat affect, lack of coordination, imbalance, brief amnesia

Question 15

What is a cerebral contusion?

sx?

Answer 15

bruise” of the brain, scattered bleeding on surface of brain
vascular and tissue damage, swelling of tissue, increased intracrranial pressure, loss of consciousness
severe headache, dizziness, vomiting, change in one pupil, restlessness, agitation, irritability, memory loss, drowsiness, confusion, decreased respiration, decreased heart rate, hypertension

Question 16

What is a cerebral hematoma? Sx?

Answer 16

bleeding in epidural or subdural spaces most severe TBI complication and major cause of death
fracture lacerates arteries or veins in meninges region
severe headache, vomiting, seizure, may or may not lose consciousness, can be progressive, fluctuating, dilated, sluggish or fixed pupils, positive Babinksi sign, hypertension, bradycardia, bradypnea

Question 17

What is CN I?

Answer 17

sensory smell
group of neurons from nasal cavity to olfactory bulb
through cribiform plate of ethmoid bone
damage: anosmia (lack of smell)

Question 18

What is CN II?

Answer 18

sensory vision
from retina of eye to optic chiasm
through optic canal of sphenoid bone
damage: anopsia (lack of vision)

Question 19

What is CN III?

Answer 19

motor: upper eyelid, 4/6 eye muscles (inferior rectus, superior rectus, medial rectus, inferior oblique)
autonomic motor: sphincter pupillae muscle of iris (constricts pupil), ciliary muscle of lens (near vision)
superior orbital fissure of sphenoid bone
damage: ptosis (eyelid droop), strabismus (eyes not parallel), diplopia (double vision), difficulty focusing

Question 20

What is CN IV?

Answer 20

motor: superior oblique eye muscle, moves eye inferior/laterally (pulls back of eyeball up)
superior orbital fissure of sphenoid bone
damage: strabismus (eyes not parallel), diplopia (double vision

Question 21

What is CN V?

Answer 21

Trochlear
Opthalmic (V1):
sensory anterior scalp, forehead, cornea, meninges
superior orbital fissure
Maxillary (V2):
sensory nasal mucosa, hard palate, gums, cheeks, meninges
foramen rotundum
Mandibular (V3):
sensory anterior 2/3 tongue, chin, jaw, teeth, ear & motor (chewing, swallowing) masseter, pterygoids, mylohyoid, digastric, tensor tympani, tensor veli palatini muscles
foramen ovale
damage: loss of facial sensation, loss of corneal reflex, weakening of jaw muscles, trigeminal neuralgia (intense, pulsating pain)

Question 22

What is CN VI?

Answer 22

Abducens
motor: lateral rectus eye muscle
superior orbital fissure
damage: limited lateral movement of eye, diplopia (double vision)

Question 23

What is CN VII?

Answer 23

motor: 5 motor branches to muscles of facial expression, digastric, stylohyoid, stapedius muscles
stylomastoid foramen
autonomic: lacrimal and salivary glands
internal acoustic meatus
sensory: taste, anterior 2/3 tongue
damage: dry eye, dry mouth, decreased taste, facial paralysis, difficulty closing eyelid, sagging corner of mouth

Question 24

What is Cn VIII?

Answer 24

. Vestibulocochlear
sensory: hearing and equilibrium
from cochlea, semicircular canals to internal acoustic meatus
damage: loss of hearing, loss of balance, nausea, vomiting, dizziness

Question 25

What is CN IX?

Answer 25

. Glossopharyngeal

sensory: taste and sensation of posterior 1/3 tongue
motor: swallowing, pharynx muscle
autonomic: parotid salivary gland
damage: dry mouth, decreased taste

Question 26

What is CN X?

Answer 26

Vagus
sensory: heart, lungs, abdominal organs, eardrum, external acoustic meatus larynx, laryngopharynx
motor: pharynx, larynx
autonomic: heart, lungs, pharynx, larynx, trachea, abdominal organs
jugular foramen
damage: loss of voice, hoarse voice, difficulty swallowing, decreased GI motility

Question 27

What is CN XI?

Answer 27

motor: trapezius and sternocleidomastoid, travels with CNX to pharynx
jugular foramen
damage: difficulty elevating shoulder, difficulty turning head

Question 28

What is CN XII?

Answer 28

Hypoglossal
muscles of the tongue
hypoglossal canal
damage: impaired tongue movement, difficulty swallowing, difficulty speaking, deviation of tongue to one side