Anatomy Exam Cranial Nerves and Foramina 4 — Questions and Answers
Question 1: Which cranial nerve is responsible for the efferent limb of the gag reflex?
- CN IX (Glossopharyngeal)
- CN X (Vagus) (Correct answer)
- CN XII (Hypoglossal)
- CN VII (Facial)
Correct answer: CN X (Vagus)
The vagus nerve (CN X) provides the motor (efferent) response of the gag reflex by elevating the palate and constricting the pharynx; CN IX is the afferent limb.
Question 2: Foramen rotundum transmits which nerve?
- V1 (Ophthalmic division)
- V2 (Maxillary division) (Correct answer)
- V3 (Mandibular division)
- CN VI (Abducens)
Correct answer: V2 (Maxillary division)
The maxillary division (V2) of the trigeminal nerve exits the middle cranial fossa through the foramen rotundum to enter the pterygopalatine fossa.
Question 3: Which cranial nerve passes through the cavernous sinus but does NOT travel within the sinus wall (it runs freely within the sinus)?
- CN III (Oculomotor)
- CN IV (Trochlear)
- CN VI (Abducens) (Correct answer)
- CN V1 (Ophthalmic)
Correct answer: CN VI (Abducens)
CN VI passes freely within the cavernous sinus, making it most vulnerable to increased intrasinus pressure; CN III, IV, V1, and V2 travel in the lateral wall.
Question 4: The spinal accessory nerve (CN XI) primarily innervates which muscles?
- Trapezius and sternocleidomastoid (Correct answer)
- Digastric and mylohyoid
- Genioglossus and hyoglossus
- Buccinator and orbicularis oris
Correct answer: Trapezius and sternocleidomastoid
The accessory nerve (CN XI) provides motor innervation to the trapezius and sternocleidomastoid muscles.
Question 5: Which foramen is the most posterior of the three foramina in the posterior cranial fossa floor?
- Jugular foramen
- Foramen magnum (Correct answer)
- Hypoglossal canal
- Internal acoustic meatus
Correct answer: Foramen magnum
The foramen magnum is the largest and most posterior foramen in the skull base, located in the posterior cranial fossa and transmitting the brainstem, vertebral arteries, and CN XI spinal roots.
Question 6: Preganglionic parasympathetic fibers for lacrimal and nasal gland secretion travel in which cranial nerve?
- CN V1 (Ophthalmic)
- CN VII (Facial) (Correct answer)
- CN IX (Glossopharyngeal)
- CN X (Vagus)
Correct answer: CN VII (Facial)
CN VII carries preganglionic parasympathetic fibers via the greater petrosal nerve to the pterygopalatine ganglion, which relays postganglionic fibers to the lacrimal and nasal glands.
Question 7: A fracture through the petrous part of the temporal bone is most likely to damage which cranial nerve(s)?
- CN II and III
- CN VII and VIII (Correct answer)
- CN IX and X
- CN V and VI
Correct answer: CN VII and VIII
The facial nerve (CN VII) and vestibulocochlear nerve (CN VIII) both traverse the petrous temporal bone through the internal acoustic meatus, making them vulnerable to petrous fractures.
Anatomy Exam Cranial Nerves and Foramina 4
Which cranial nerve is responsible for the efferent limb of the gag reflex?