Brainstem and Cranial Nerve

Question 1

What are the three regions of the brainstem?

Answer 1

midbrain
pons
Medulla oblongata

Question 2

What are the descending brainstem tracts?

what do they affect?

Answer 2

Lateral corticospinal (muscle contraction)
Reticulospinal (inhibitory effect on muscle tone)
Vestibulospinal (maintain balance and posture)

Question 3

What does cranial nerve 1 innervate?

Answer 3

Olfactory Sensory 
Function: Detection and transmission of odors
Location: CNS
Test: Identify familiar odor
Injury: Anosmia

Question 4

What does cranial nerve 2 innervate?

Answer 4

Optic nerve sensory
Function: Detect and transmit visual information
Test: identify object or read from chart
Four point box
Injury: Inability to identify objects at a reasonable distance

Question 5

What does cranial nerve 3 innervate?

Answer 5

Oculomotor motor
Function: innervates extraocular muscles that move the eye and muscle that opens the eyelid; innervates pupillary sphincter and ciliary muscle 
Location: midbrain
Injury: tracking deficit
Test: Check pupil response w/ light 
Tracking up, down, and diagonally

Question 6

What does cranial nerve 4 innervate?

Answer 6

Trochlear motor
Function: innervates the superior oblique extraocular muscle (moves eye medially and downward)
Location: midbrain
Test: have the patient look down and in
Injury: inability to look down/in, diplopia

Question 7

What does cranial nerve 5 innervate

Answer 7

Trigeminal both
Function: 3 divisions
Location: Pons
Test: test sensation to face and ability to move mandible. Sensation of eyeball with swab.
Injury: abnormal pain in the face, lack of sensation in face and inability to move mandible.

Question 8

What does cranial nerve 6 innervate?

Answer 8

Abducens (have patient move eyes side to side) Motor
Function: Innervates lateral rectus (abducts the eyeball)
Location: Pons
Test: Abduct eyes
Injury: Inability to abduct the eyes, diplopia

Question 9

What does cranial nerve 7 innervate?

Answer 9

Facial nerve both
Function: innervates muscle s of facial expression
Location: Pons
Test: in anterior 2/3 of tongue, mimic facial expression
Injury: impaired test, facial paralysis, bells palsy

Question 10

What does cranial nerve 8 innervate?

Answer 10

Vestibulocochlear Sensory
Function: Conveys vestibular and auditory information
Location: Medulla oblongata
Test: ability to hear sound 18-24 in away

Question 11

What does cranial nerve 9 innervate?

Answer 11

Glossopharyngeal Both
Function: Sensation in and around pharynx; HR and BP control (via carotid sinus and carotid body); taste in posterior 1/3
Location: Medulla oblongata
Test: salt post 1/3 of tongue, say “Ahh” Look at uvula, have pt. swallow
Injury: Impaired regulation of BP and

Question 12

What does cranial nerve 10 innervate?

Answer 12

Vagus Both
Function: Slow HR and decrease force of heart contractions; innervates smooth muscles in trachea, bronchial tree, digestive tract, pancreas, liver, gall bladder; innervates pharyngeal muscles
Location: Medulla oblongata
Test: Have pt. swallow and quality of speech.
Injury:

Question 13

What does cranial nerve 11 innervate?

Answer 13

Spinal accessory nerve Both
Function:
Test : Have pt. shrug shoulders

Question 14

What does the cranial nerve 12 innervate?

Answer 14

Hyopglossal Motor

Test: have pt. stick tongue out and side to side

Question 15

What are the descending tracts and their effect?

Answer 15

Anterior Spinothalamic -Light touch and pressure
Lateral Spinothalamic- Pain and temperature
Dorsal column tracts- 2 point discrimination, vibration, conscious proprioception
Spinocerebellar- Unconscious proprioception

Question 16

What is the reticular formation?

Answer 16

Forms the core of the brain stem
Involved in motivation, decision making, mood, sleeping/waking, pain modification
Contains the ascending reticular activating system- sends input to thalamus from all parts of sensory system