What type of glial cell is the resident macrophage behind the blood-brain barrier?

Correct Answer: A

Rationale: Microglia are the resident macrophages of the CNS, acting as immune cells behind the blood-brain barrier. Astrocytes support neurons, Schwann cells myelinate PNS axons, and satellite cells support PNS cell bodies.

Correct Answer: D

Rationale: Acetylcholine (ACh) is released at the neuromuscular junction to stimulate skeletal muscle contraction. Norepinephrine acts at sympathetic synapses, not the neuromuscular junction.

Correct Answer: C

Rationale: The trochlear nerve (CN IV) is the smallest cranial nerve by axon count and diameter, innervating only the superior oblique muscle. The olfactory nerve (I) has many fibers, and oculomotor (III) and abducent (VI) are larger.

Correct Answer: D

Rationale: The facial nerve (CN VII) motor nucleus is in the pons, controlling facial expression muscles. The hypothalamus and midbrain are incorrect, and the third ventricle floor is unrelated.

Correct Answer: B

Rationale: The sneeze reflex’s afferent path is via the maxillary nerve (V2), sensing nasal irritation, with efferent via CN VII/X. V1 senses the cornea, V3 the jaw, and vagus (X) isn’t primary here.