Anatomy Exam Cranial Nerves and Foramina 5 — Questions and Answers
Question 1: Which cranial nerve carries general somatic afferent (GSA) fibers from the skin of the external ear and external auditory meatus?
- CN VIII (Vestibulocochlear)
- CN X (Vagus) via auricular branch (Correct answer)
- CN VII (Facial)
- CN IX (Glossopharyngeal)
Correct answer: CN X (Vagus) via auricular branch
The auricular branch of the vagus nerve (Arnold's nerve) provides GSA innervation to the skin of the external ear and posterior external auditory meatus.
Question 2: Which functional fiber type is carried exclusively by CN II (Optic nerve)?
- General somatic afferent (GSA)
- Special somatic afferent (SSA) (Correct answer)
- Special visceral afferent (SVA)
- General visceral afferent (GVA)
Correct answer: Special somatic afferent (SSA)
The optic nerve carries only special somatic afferent (SSA) fibers conveying vision from the retina.
Question 3: The tympanic nerve, a branch of CN IX, carries preganglionic parasympathetic fibers that eventually synapse in which ganglion?
- Pterygopalatine ganglion
- Ciliary ganglion
- Otic ganglion (Correct answer)
- Submandibular ganglion
Correct answer: Otic ganglion
The tympanic nerve (Jacobson's nerve) forms the tympanic plexus, which becomes the lesser petrosal nerve synapsing in the otic ganglion to provide secretomotor innervation to the parotid gland.
Question 4: Which cranial nerve is tested by asking a patient to look toward the tip of their nose (extreme adduction) to detect a superior oblique palsy?
- CN III (Oculomotor)
- CN IV (Trochlear) (Correct answer)
- CN VI (Abducens)
- CN II (Optic)
Correct answer: CN IV (Trochlear)
The trochlear nerve (CN IV) innervates the superior oblique muscle; in adduction, the superior oblique acts as an intorter/depressor, revealing CN IV palsy as vertical diplopia.
Question 5: The superior orbital fissure transmits all of the following EXCEPT:
- CN III (Oculomotor)
- CN VI (Abducens)
- CN II (Optic nerve) (Correct answer)
- CN V1 (Ophthalmic division)
Correct answer: CN II (Optic nerve)
The optic nerve passes through the optic canal, not the superior orbital fissure; CN III, IV, V1, VI, and the ophthalmic veins pass through the superior orbital fissure.
Question 6: Parasympathetic stimulation via CN III produces which two effects on the eye?
- Mydriasis and accommodation
- Miosis and cycloplegia (loss of accommodation)
- Miosis and accommodation (Correct answer)
- Mydriasis and cycloplegia
Correct answer: Miosis and accommodation
Parasympathetic fibers from CN III via the ciliary ganglion stimulate the sphincter pupillae (causing miosis) and the ciliary muscle (causing accommodation for near vision).
Question 7: Which cranial nerve foramen is found in the middle cranial fossa and transmits the middle meningeal artery?
- Foramen ovale
- Foramen rotundum
- Foramen spinosum (Correct answer)
- Foramen lacerum
Correct answer: Foramen spinosum
The foramen spinosum transmits the middle meningeal artery (and vein), which runs in grooves on the inner surface of the temporal bone; rupture causes epidural hematoma.
Anatomy Exam Cranial Nerves and Foramina 5
Which cranial nerve carries general somatic afferent (GSA) fibers from the skin of the external ear and external auditory meatus?