598 



THE VASCULAR SY8TKMX 



only as high as the angle of the mouth or nose. The deficiency is then supplied by enlargement 

 of one of the neighboring arteries. 



Applied Anatomy. The passage of the facial artery over the body of the mandible would 

 appear to afford a favorable position for the application of pressure in case of hemorrhage from the 

 lips, the result either of an accidental wound or during an operation; but its application is useless, 

 except for a very short time, on account of the free communication of this vessel with its fellow 

 and with numerous branches from different sources. In a wound involving the lip it is better 

 to seize the part between the fingers, and evert it, when the bleeding vessel may be at once secured 

 with pressure forceps. In order to prevent hemorrhage in cases of removal of diseased growths 

 from the part, the lip should be compressed on each side between the fingers and thumb or bv 

 a pair of specially devised clamp forceps, while the surgeon excises the diseased part. In order 

 to stop hemorrhage where the lip has been divided in an operation, it is necessary, in uniting 

 the edges of the wound, to pass the sutures through the cut edges from the skin almost as deep 

 as the mucous surface; by these means not only are the cut surfaces more neatly and securelv 

 adapted to each other, but the possibility of hemorrhage is prevented by including in the suture 



the divided artery. If the suture is, on the contrary, 

 passed through merely the cutaneous portion of the wound, 

 hemorrhage occurs into the cavity of the mouth. Lastlv, 

 the relation of the angular artery to the lacrimal sac should 

 be observed, and it will be seen that, as the vessel passes up 

 along the inner margin of the orbit, it ascends on the 

 nasal side. In operating ior fistula lacrimalis the sac should 

 always be opened on its outer side, in order that this vessel 

 may be avoided. 



4. The occipital artery (a. occipitalis} (Figs. 

 438 and 443) arises from the posterior part of the 

 external carotid, opposite the facial, near the lower 

 margin of the Digastric muscle. 



Relations. At its origin it is covered by the posterior 

 belly of the Digastric muscle and the Stylohyoid muscle, 

 and the hypoglossal nerve winds around it from behind 

 forward; higher up, it passes across the internal carotid 

 artery, the internal jugular vein, and the vagus and spinal 

 accessory nerves ; it then ascends to the interval between the 

 transverse process of the atlas and the mastoid process of 

 the temporal bone, and passes horizontally backward in the 

 occipital groove on the mastoid portion of the temporal, 

 being covered by the Sternomastoid, Splenius, Trachelo- 

 mastoid, and Digastric muscles, and resting upon the 

 Rectus lateralis, the Superior oblique, and Complexus 

 muscles; it then changes its course and passes vertically 

 upward, pierces the fascia which connects the cranial 

 attachment of the Trapezius with the Sternomastoid, and 



ascends in a tortuous course over the occiput, as high as the vertex, where it divides into 

 numerous branches. It is accompanied in the latter part of its course by the great occipital 

 nerve, and occasionally by a cutaneous filament from the suboccipital nerve. 



Branches. The branches given off from this vessel are: 



Muscular. Meningeal or dural. 



Sternomastoid. Mastoid. 



Auricular. Arteria princeps cervicis. 



Cranial branches. 



The muscular branches (rami musctdares) supply the Digastric, Stylohyoid, 

 Splenius, and Trachelomastoid muscles. 



The Sternomastoid (a. sternocleidomastoidca) is a large and constant branch, 

 generally arising from the artery close to its commencement, but sometimes spring- 

 ing directly from the external carotid. It first passes downward and backward 

 over the hypoglossal nerve, and enters the substance of the muscle in company 

 with the spinal accessory nerve. 



DESCENDING 



BRANCH OF 



HYPOGLOSSAL 



NERVE 



FIG. 443. The loop of the hypo- 

 glossal nerve and the branches of the 

 external carotid artery. 



