ascend through the transverse foramina of the sixth to the first cervical ver-
tebrae, but not the seventh. They enter the cranium through the foramen
magnum after which they join to form the basilar artery. The basilar artery
terminates by bifurcating into the posterior cerebral arteries. The hypoglossal
nerves (CN XII) leave the cranium via the anterior condylar (hypoglossal)
canals(answer b),whereas the posterior condylar canals (answer c)trans-
mit emissary veins. The vertebral arteries form the basilar artery which in
turn feeds the posterior cerebral arteries (answer e).
291.The answer is b.(Moore and Dalley, pp 919–920, 967.)The most
likely diagnosis is extracranial and epidural hematomas. The extracranial
hematoma is the growing “goose egg” that was developing on the outside of
her head. This condition is not life threatening. The physical findings of
papilledema, frontal bone skull fracture and accumulating blood inside the
cranial bones anterior to the cranial suture are all consistent with epidural
hematoma. Most likely the frontal bone fractured, lacerating the frontal
branch of the middle meningeal artery and veins which run in grooves near
the pterion. The temporal region of the skull is particularly thin in this
region and more prone to compression fractures. Subdural hematomas
(answer c)rarely present in a limited area, rather they occupy one complete
cerebral hemisphere as the arachnoid mater separates from the dura mater.
It is unlikely that a spinal tap, if performed would contain blood [indication
of subarachnid hemorrhage (answers d and e)].
292.The answer is a.(Moore and Dalley, pp 1018, 1030–1031.)A fracture
through the cribriform plate would likely cause both a leaking of cere-
brospinal fluid (CSF) out the nose (rhinorrhea) and headaches. In addition
it would likely shear off the olfactory nerves that pass through the cribriform
plate of the ethmoid bone, resulting in anosmia (inability to smell) on left
side. The lacrimal bone (answer b)surrounds the nasal lacrimal duct and if
fractured might lead to a runny nose, but this would notexplain the lack of
ability to smell. The nasal bone (answer c)froms the root of the nose is
often broken in boxers, but would notnecessary lead to a runny nose or con-
tinued headaches. Le Fort fractures (answers d and e)are fractures of the
face involving the displacement of the maxillary and nasal region (type II)
including displacement of the maxilla and zygomatic arch, thus displacing
the maxillary teeth, nose and zygomatic arch (type III). Neither of the Le
Fort fractures would fit with the symptoms.
442 Anatomy, Histology, and Cell Biology