Practical 5

Question 1

How do cranial nerves differ from spinal nerves?

Answer 1

• Cranial nerves exit the skull; spinal nerves exit the vertebral column.
• Cranial nerves may be sensory, motor, or mixed; spinal nerves are always mixed.

Question 2

What are the five functional categories of cranial nerve fibres?

Answer 2

1. Somatosensory (SS) – skin, muscles, joints
2. Visceral Sensory (VS) – internal organs
3. Visceral Motor (VM) – parasympathetic output
4. Somatic/Branchial Motor (SM) – skeletal muscles
5. Special Sensory (SpS) – vision, hearing, taste, smell, balance

Question 3

Which cranial nerves carry only sensory information?

Answer 3

• Olfactory (I) – smell
• Optic (II) – vision
• Vestibulocochlear (VIII) – hearing and balance

Question 4

Which cranial nerves carry only motor information?

Answer 4

• Oculomotor (III) – SM, VM
• Trochlear (IV) - SM
• Abducens (VI) - SM
• Spinal Accessory (XI) – SM
• Hypoglossal (XII) – SM, VM

Question 5

Which cranial nerves carry both sensory and motor information?

Answer 5

• Trigeminal (V) – SS, SM
• Facial (VII) – SpS, SS, SM, VM
• Glossopharyngeal (IX) – SpS, SS, VS, SM, VM
• Vagus (X) – SpS, SS, VS, SM, VM

Question 6

Which cranial nerves have parasympathetic (visceral motor) output?

Answer 6

• Oculomotor (III): pupil constriction, lens accommodation
• Facial (VII): salivary and lacrimal glands
• Glossopharyngeal (IX): parotid gland
• Vagus (X): thoracic and abdominal viscera

Question 7

Which cranial nerves carry taste (gustatory) information?

Answer 7

• Facial (VII): anterior 2/3 of tongue
• Glossopharyngeal (IX): posterior 1/3 of tongue
• Vagus (X): epiglottis and oesophagus

Question 8

Which cranial nerve carries olfactory (smell) information?

Answer 8

Olfactory nerve (I)

Question 9

Which cranial nerve carries visual information?

Answer 9

Optic nerve (II)

Question 10

Which cranial nerves control eye movement?

Answer 10

• Oculomotor (III)
• Trochlear (IV)
• Abducens (VI)

Question 11

Which cranial nerve(s) enter the CNS at the cerebrum?

Answer 11

Olfactory (I)

Question 12

Which cranial nerve controls tongue movement?

Answer 12

Hypoglossal nerve (XII)

Question 13

Which cranial nerve controls muscles of mastication?

Answer 13

Trigeminal nerve (V) – mandibular branch

Question 14

Which cranial nerve controls muscles of facial expression?

Answer 14

Facial nerve (VII)

Question 15

Which cranial nerves are involved in swallowing and the gag reflex?

Answer 15

• Glossopharyngeal (IX)
• Vagus (X)