FISTULA. 
523 
muscles downward and backward. The arterial supply, in 
the anterior cervical region, is through the occipital, and its 
main nerve is the spinal accessory. It is covered by the 
subcutaneous muscles, parotid gland and cervico-auricularis 
muscles. It, in turn, covers portions of the splenius, small 
complexus, both oblique, omo-hyoid, digastric, the great pos¬ 
terior straight, angularis, scalenius, small pectoral, both 
spinatus muscles, long abductor of the arm and coraco- 
radial. 
The arterial supply of the entire cervical region comes 
mainly through the dorsals, superior cervicals, vertebrals and 
occipitals, first being collateral branches of the axillary 
arteries and the occipitals, terminal branches of the common 
carotids. The dorsal is given off opposite the second'inter¬ 
costal space, the superior cervical opposite the head of second 
rib, and the vertebral leaves the parent trunk nearly under the 
upper portion of the first intercostal space and passes forward 
under the transverse process of the seventh cervical and 
thence into the vertebral foramen of sixth cervical vertebras. 
The occipital leaves the common carotid trunk on a line 
drawn from the auricular base to the posterior portion of the 
larynx. From this point it passes forward, upward, backward 
and forward again, like a letter S, and goes under the trans¬ 
verse process of atlas, back to the guttural pouch, beneath 
the small lateral straight muscle, thence through the anterior 
foramen of the atlas, where its terminal division occurs. The 
dorsal and its larger branches may be readily located as 
follows : draw one line to the highest point of the withers 
from the head of first rib. Draw a second from the same 
point directly upward to the cervical cord. Intersect this 
second line midway and draw a third line two-thirds of the 
distance toward the base of ear. 
The superior cervical may be located, for surgical purposes, 
by drawing a line from the head of first rib to highest point 
of withers (which point also locates the superior spinous 
processes of the fourth and fifth dorsal vertebrae). Intersect 
this line midway and draw another toward the auricular 
base, to a point opposite the third cervdcal vertebrae. Both 
