Exam 1 (Lecture 6) - Medulla 1

Question 1

What neural tube region is the medulla oblongata derived from?

Answer 1

Myelencephalon

Question 2

Which medulla structures are visible on the dorsal view?

Answer 2

1) Fasciculus cuneatus
2) Spinal tract of the trigeminal nerve (V)

Question 3

Describe the spinal tract in the fasciculus cuneatus.

Answer 3

1) Ascending sensory tract (afferent)
- origin: spinal cord C1 - T5
- termination: thalamus

Question 4

What is the function of the fasciculus cuneatus?

Answer 4

Proprioception (where the limbs are in space)
- cervical area
- upper trunk
- thoracic limb

Question 5

Describe the spinal tract of the trigeminal nerve (spinal tract of V).

Answer 5

Runs through the medulla and terminates in the nucleus of the spinal tract of V.

Question 6

What is the function of the spinal tract of V?

Answer 6

Responsible for facial pain and facial temperature.

Question 7

Which medulla structures are visible on the ventral medulla oblongata?

Answer 7

1) Trapezoid body
2) Pyramid
3) Pyramidal decussation (where they cross)

Question 8

Describe the pyramid including origin, termination and function.

Answer 8

1) origin: cerebral motor cortex
2) termination: brain stem, spinal cord
3) function: motor

Question 9

How many cranial nerves emerge at the level of the medulla?

Answer 9

Seven (VI - XII)

Question 10

Name those cranial nerves!

Answer 10

1) Abducent (VI)
2) Facial (VII)
3) Vestibulocochlear (VII)
4) Glossopharyngeal (IX)
5) Vagus (X)
6) Accessory (XI) (has 2 roots; cranial and spinal)
7) Hypoglossal (XII)

Question 11

Describe the abducent nerve including origin, termination, and function.

Answer 11

1) origin: motor nucleus of VI
2) termination: lateral rectus and retractor bulbi
3) function: somatic motor

Question 12

Describe the facial nerve including origin and functions.

Answer 12

1) origin: trapezoid body
2) somatic motor
- muscles of facial expression and blinking (closing eyelid)
visceral motor
- lacrimal gland and salivary glands
sensory
- taste (some tastebuds)

Question 13

What clinical signs would you expect with a lesion of the facial nerve?

Answer 13

1) Somatic = loss of facial tone, unable to blink or a decrease in blinking

2) Visceral = decreased tear production (less tear film = dry eye/infection); decreased salivation

3) Sensory = decreased taste

Question 14

Which central nuclei are involved with the facial nerve?

Answer 14

1) Motor nuclei
- motor nucleus of VII (somatic)
- parasympathetic nucleus of VII (visceral)

2) Sensory nuclei
- nucleus of the solitary tract

Question 15

If you touch the medial canthus and the animal doesn’t blink, which nerves are potentially affected?

Answer 15

Ophthalmic and facial.

Question 16

If the animal doesn’t blink (previous question), but the 3rd eyelid response is present, what information does this tell you?

Answer 16

This tells you that the ophthalmic and abducent nerve are in tact, so the problem is with the facial nerve.

Question 17

Which nerves does the corneal reflex test? And what are they responsible for?

Answer 17

1) Ophthalmic branch of trigeminal (sensory)
2) Abducent and Facial (motor)

Responsible for blinking and 3rd eyelid

Question 18

Which nerves does the palpebral reflex test? And what are they responsible for?

Answer 18

1) Trigeminal (sensory)
2) Facial (motor)

Responsible for blinking