Exam 2: Cranial Nerves

Question 1

Anatomy of the Brainstem

Answer 1

• Medulla
• Pons
• Midbrain
• Cranial Nerves and their nuclei arise from the brainstem and basic bodily functions of life are maintained here

Question 2

Brainstem Parts

Answer 2

• Midbrain – most superior portion
• Pons – middle portion
• Medulla – lowest portion

Question 3

Brainstem Functions

Answer 3

• Regulating major life functions (e.g., heart beat, respiration)
• Mediating head and neck reflexes (e.g., gag) via cranial nerves
• Regulating alertness and wakefulness.

Question 4

Medulla Oblongata

Answer 4

A portion of the hindbrain that controls
autonomic functions
- Digestion
- Heart and blood vessel function
- Swallowing
- Sneezing
◦ Motor and sensory neurons from midbrain and forebrain
◦ Relay of nerve signals between the brain and
spinal cord
◦ Coordination of body movements.

Question 5

Pons

Answer 5

◦ Connects the cerebral cortex with the medulla oblongata
◦ Communication and coordination center between the two cerebral hemispheres
◦ Helps in transferring of messages between brain and spinal cord

Question 6

Midbrain

Answer 6

• Midbrain and hindbrain make up the brainstem
• Connects the hindbrain and the forebrain
• Involved in auditory and visual responses as well as motor function

Question 7

Cranial Nerves

Answer 7

• Cranial nerves I through IV stem from
  midbrain
• Cranial nerves V through VIII stem from pons
• Cranial nerves IX through XII stem from
  medulla
• Cranial nerves can be efferent, afferent or
  mixed
• Cranial nerves always referred to with
  Roman Numerals.

Question 8

I. Olfactory Nerve

Answer 8

• Origin = Olfactory bulb
• Function(s) = Smell
• Problem(s) = Anosmia

Question 9

II. Optic Nerve

Answer 9

• Origin = Thalamus
• Function(s) = Vision
• Problem(s) = Visual
  disturbances; loss of vision

Question 10

III. Oculomotor Nerve

Answer 10

• Origin = Midbrain
• Function(s) =
  ◦ GSE: Moves eyes left and right; controls eyelid
  ◦ GVE: pupil constrictor
• Problem(s) = Loss of pupillary light reflex; ptosis

Question 11

IV. Trochlear Nerve

Answer 11

• Origin = Midbrain
• Function(s) = Moves eyes up and down
• Problem(s) =Diplopia; nystagmus; difficulty moving eyes up and down

Question 12

V. Trigeminal Nerve

Answer 12

• Origin = Pons
• Function(s) =
  ◦ GSA: touch, pain, temp. and vibration for face, mouth, ant. 2/3
  of tongue
  ◦ GVE: Chewing muscles
• Problem(s) = Loss of above sensations; difficulty chewing; abnormal jaw-jerk reflex

Question 13

VI. Abducens Nerve

Answer 13

• Origin = Pons
• Function(s) = Rotates eyes out
• Problem(s) = eye rotates in (strabismus) and diplopia; nystagmus

Question 14

VII. Facial Nerve

Answer 14

• Origin = Pons
• Functional Category = SVE, GVE, GSA, SVA
• Function(s) =
  ◦ SVE: Muscles of face
  ◦ GSA: Sensation near ears
  ◦ SVA: Taste in ant. 2/3 of tongue
  ◦ GVE: Salivary glands
• Problem(s) = Facial paralysis/paresis; taste loss

Question 15

VIII. Vestibulocochlear Nerve

Answer 15

• Also known as auditory nerve
• Origin = Pons/medulla junction
• Function(s) = Hearing and balance
• Problem(s) = Hearing loss; balance problems

Question 16

IX. Glossopharyngeal Nerve

Answer 16

• Origin = Pons/medulla junction
• Fiber type = SVE, GVE, GVA, SVA
• Function(s) =
  ◦ SVE: Pharyngeal movement
  ◦ GVE: Parotid gland (salivation)
  ◦ GVA: Middle ear, pharynx, post. 1/3 of tongue
  ◦ SVA: Taste on post. 1/3 of tongue
• Problem(s) = Absent gag and swallow reflex; loss of taste; loss of pharyngeal movement

Question 17

X. Vagus Nerve

Answer 17

• Origin = Medulla
• Fiber type = SVE, GVE, GSA, GVA, SVA
• Function(s) =
  ◦ SVE: Pharyngeal and laryngeal muscles
  ◦ GVE: Heart, lungs; digestive tract
  ◦ GSA: Tactile sensation to external ear canal
  ◦ GVA: Pain from mucous membranes
  ◦ SVA: Taste from epiglottis and pharynx
• Problem(s) = Absent gag and swallow reflex; loss of velar movement; loss of voice

Question 18

XI. Spinal Accessory Nerve

Answer 18

• Origin = Medulla, spinal cord
• Fiber type = SVE
• Function(s) = Neck and shoulder muscles
• Problem(s) = Droopy shoulder; movement of neck

Question 19

XII. Hypoglossal Nerve

Answer 19

• Origin = Medulla
• Fiber type = GSE
• Function(s) = Muscles of tongue
• Problem(s) = Loss of tongue movement; tongue fasciculations, tongue atrophy

Question 20

Cranial Nerves (where they stem from)

Answer 20

• Cranial nerves I through IV stem from
  midbrain
• Cranial nerves V though VIII stem from pons
• Cranial nerves IX through XII stem from
  medulla
• Cranial nerves can be efferent, afferent or
  mixed

Question 21

All Cranial Nerves (their order + sensory/motor/both)

Answer 21

I. Olfactory (S)
II. Optic (S)
III. Oculomotor (M)
IV. Trochlear (M)
V. Trigeminal (B)
VI. Abducens (M)
VII. Facial (B)
VIII. Vestibulocochlear (S)
IX. Glossopharyngeal (B)
X. Vagus (B)
XI. Spinal Accessory (M)
XII. Hypoglossal (M)