310.The answer is c.(Moore and Dalley, pp 1094–1099.)The posterior
cricoarytenoid muscles rotate the arytenoids laterally, which swings the
vocal process of that cartilage outward to abduct the vocal cords and open
the glottis. These are the sole abductors of the vocal folds. The lateral
cricoarytenoid muscles (answer b)and the unpaired transverse arytenoid
muscle(answer e)adduct the vocal folds. The thyroarytenoid muscle
(answer d)and its innermost portion, the vocalis muscle, act to tense the
cords. The cricothyroid muscle (answer a)lengthens the vocal cords.
311.The answer is c.(Moore and Dalley, p 924.)Structures 8 and 9 are the
pituitary gland and infundibular stalk. You can see hints of the anterior and
posterior pituitary (answer b).The infundibular stalk is inferior to the
hypothalamus. The optic chiasm and optic tract (answer a)are partially vis-
ible slightly above the pituitary gland. The pituitary gland sits in the sella
turcica which is surrounded by the large sphenoid air sinus (black region)
just inferior to the pituitary gland (answer d).Cancers of the pituitary
gland are often removed by operating through the nose and punching
through the sphenoid air sinus, leaving the brain relatively undisturbed.
Other labeled structures are as follows: 2, frontal sinus; 7, tongue genioglos-
sus; 8, pituitary gland; 9, infundibular stalk; 10, clivus portion of the occip-
ital bone; 11, odontoid process of axis (C2); 12, anterior arch of atlas (C1);
and 13, mandible.
312.The answer is b.(Moore and Dalley, p 900.)Structure 42 is the fora-
men ovale. It transmits the mandibular division of the trigeminal cranial
nerve (CN V3), which is responsible for innervating the muscles of mastica-
tion. The patient would also likely suffer from loss of sensation along the
mandible due to loss of sensation within the mandibular division of the
trigeminal cranial nerve. Weakened facial expressions (answer a)would
result from compromising the stylomastoid foramen, which transmits part
of the facial cranial nerve (CN VII) (not on this image). Weakened ability to
turn one’s head (answer c)and shrug (answer e)would be the result of
damage to the accessory cranial nerve (CN XI), which exits the skull out the
jugular foramen (not on this image). The vagus (answer d)cranial nerve
(CN X) passesout the jugular foramen along with CN IX and XI. Structure 40
is the carotid canal. Other labeled structures are as follows: 34, condyle of
the mandible; 35, frontal process of the maxilla; 41, inferior orbital fissure;
43, foramen spinosum; and 44, external auditory canal.
450 Anatomy, Histology, and Cell Biology