subjacent to the epicranial aponeurosis. Bone (answer b)is too deep, as is
the dural mater (answer c).
280.The answer is c.(Moore and Dalley, pp 910–913.)The confluence of
sinuses is formed by the superior sagittal sinus, both transverse sinuses, the
occipital sinus, and the straight sinus. The inferior sagittal sinus (answer
b)and the great cerebral vein join to form the straight sinus. The superior
(answer e)and inferior petrosal sinuses (answer d)both drain the cav-
ernous sinuses, the former connecting with the ipsilateral transverse sinus.
The sigmoid sinus (answer a)is in between the transverse sinus and the
origin of the internal jugular vein.
281.The answer is f.(Moore and Dalley, pp 1018–1019.)You may be able
to reduce blood flow to Kiesselbach’s area by holding both sides of the
upper lip and also pressing on the incisive foramen. Kiesselbach’s area on
the nasal septum is just superior and posterior to the external nasal aper-
ture. Many nosebleeds occur in this area since it is exposed to most of the
incoming air. There are four blood vessels that supply blood to this area:
- anterior ethmoid artery (a branch off the ophthalmic artery); 2)
sphenopalatine artery (a branch off the maxillary artery that came
through the sphenopalatine foramen; 3) greaterpalatine artery (a branch
also off the maxillary artery, but has run through both the greater foramen
and the incisive foramen to get to the nose); and 4) septal branch artery (a
branch off the superior labial artery which comes off the facial artery).
While the lay press often suggests holding the bridge of the nose (answers
a and e),this would only block blood within the infratrochlear artery,
which mainly serves the exterior dorsal surface of the nose. Holding
(answer c)both sides of the nose at the junction of the nasal bones with
the lateral nasal cartilages would tend to block blood flow within the exter-
nal branch of the anterior ethmoid. This might actually increase the blood
coming from an artery in Kiesselbach’s area. Thus (answer b)holding both
sides of the upper lip between his fingers will cut off blood to the septal
branch of the superior labial artery and apply pressure from the oral cavity
over the incisive foramen (answer d)would cut off blood coming from the
greater palatine arteries. Note, it is difficult to stop blood within either the
sphenoid palatine artery or anterior ethmoid arteries by applying any
external pressure.
438 Anatomy, Histology, and Cell Biology