artery and is primarily distributed to the basal ganglia, hippocampus, and
choroid plexus of the lateral ventricle. The posterior communicating artery
(answer c)connects the internal carotid and vertebral arterial systems. The
ophthalmic artery (answer d)is a direct branch of the internal carotid artery
that enters the orbit along with the optic nerve. Although the anterior cere-
bral artery (answer e) has a wide distribution and anastomoses with
branches of both the middle and posterior cerebral arteries, it primarily sup-
plies medial and superior portions of the cortex.
298.The answer is d.(Moore and Dalley, pp 1143–1145.)The patient has
facial paralysis, which indicates injury to the facial nerve. A problem in the
internal auditory meatus (answer b)usually affects hearing and balance.
That the superior salivatory nucleus (answer a)is normal is indicated by
normal lacrimation. Hence, the lesion must be distal to the origin of the
greater superficial nerve at the genu of the facial nerve (answer c).How-
ever, absence of hyperacusis indicates that the branch to the stapedius
muscle is functioning normally, and this fact suggests that the lesion is
close to the stylomastoid foramen. Loss of taste and diminished salivation
locate the lesion proximal to the origin of the chorda tympani nerve. If the
lesion were distal to the stylomastoid foramen (answer e),taste and sali-
vation would have been normal, with facial paralysis as the only sign.
299.The answer is d.(Moore and Dalley, pp 923–926.)The arrow indi-
cates the cerebral aqueduct, which is the narrow canal connecting the third
and fourth ventricles. The cerebrospinal fluid produced in the lateral and
third ventricles must reach the fourth ventricle to escape into the sub-
arachnoid space through the foramina of Luschka and Magendie. Venous
blood(answer a)would be dark regions along the superior sagiatal sinus
for instance. The basilar artery (answer b)would be located for anteriorly,
along the clivus. Neuronal tacts (answers c and e)would not appear dark
in and MRI.
300.The answer is b.(Moore and Dalley, p 997.)The tensor veli palatini and
levator veli palatini, which arise from opposite sides of the auditory tube and
base of the skull, insert into the soft palate. They are innervated, respectively,
by the trigeminal nerve and the pharyngeal branch of the vagus nerve. The
anterior palatoglossal arch, or anterior faucial pillar, is formed by the
mucosa overlying the palatoglossal muscle. The posterior faucial pillar, or
Head and Neck Answers 445