THE ARTERIES 635 



The external maxillary, smaller than the lingual, passes along the upper border of 

 the digastricus, gives off the sublingual, gains the anterior border of the masseter, 

 and divides into superior and inferior labial and the angularis oris. The last-named 

 vessel passes forward on the cheek between the labials to the angle of the mouth. 

 The sublingual artery passes at first along the upper border of the digastricus 

 and continues between the mylo-hyoideus and the ranuis of the mandible. The 

 posterior auricular artery arises at the anterior border of the digastricus, gives 

 branches to the salivary glands and the adjacent muscles, and ascends on the convex 

 face of the concha. It divides into two branches which return along the ])orders 

 of the external car. 



The superficial temporal artery, after giving off the anterior auricular artery and 

 a small transverse facial artery, turns forward under the temporal fascia toward th(^ 

 eye, and divides into upper and lower branches which supply the frontal region and 

 the eyelids. It also supplies branches to the parotid gland and the masseter and 

 temporalis muscles. 



The internal maxillary artery pursues a course similar to that of the horse. 

 The mental branches of the inferior alveolar (or dental) artery are of considerable 

 size and are distributed in the lower lip and gums. Two or three deep temporal 

 arteries are present. The anterior one may arise from the l;)Uccinator; it gives off 

 the middle meningeal, which sends a liranch to the carotid plexus. The ophthalmic 

 artery gives off a branch which enters the cranium through the foramen lacerum 

 orbitale and connects with the internal carotid; this is termed the internal ophthal- 

 mic and gives off the arteria centralis retinse. The superficial branches of the 

 infraorbital artery replace the dorsal and lateral nasal arteries, and compensate for 

 the small size of the superior lal)ial. 



The brachial artery in its course in the arm presents no special features. At 

 the elbow it passes between the biceps and the pronator teres, descends (as the 

 median) under the flexor carpi radialis about a third of the way down the forearm, 

 and divides into radial and ulnar arteries. Among its collateral branches are: 

 (1) The subscapular artery, which passes up between the subscapularis and teres 

 major, turns around the posterior angle of the scapula and terminates in the supra- 

 spinatus, deltoid, trapezius, and mastoido-humeralis. In about half the cases it 

 gives off the anterior circumflex, which often arises with the posterior circumflex. 

 Its other branches resem1)le those of the horse. (2) The anterior circumflex artery 

 (in about half the cases). (3) The deep brachial arises about a third of the way 

 down the arm. (4) The bicipital artery (for the biceps) is given off at the lower part 

 of the arm, (5) The proximal collateral radial artery (not present in the horse) 

 arises at the lower fourth of the arm, crosses over the terminal part of the biceps, 

 descends on the extensor carpi radialis, and concurs with a branch of the volar 

 interosseous in forming the rete carpi dorsale. It often supplies the bicipital 

 artery. (6) The anterior radial artery (A. collateralis radialis distalis) is verj- 

 small. (7) The common interosseous artery is given off a little below the (>lbow. 

 It supplies branches to the flexor muscles and the dorsal interosseous artery, 

 which passes through the interosseous space, gives branches to the extensor muscles, 

 and by its terminal twigs concurs in the formation of the rete carpi dorsale. The 

 direct continuation of the trunk is the volar interosseous arter}^, which descends 

 under cover of the pronator ciuadratus, gives off a branch to the rete carpi dorsale 

 and the fifth volar metacarpal artery, and terminates by joining the volar l)ranch 

 of the radial artery to form the deep volar arch. (8) The volar antibrachial artery 

 (Ramus volaris antibrachii) arises below the interosseous and descends at first 

 under the fiexor carpi radialis, then between the heads of the deep flexor, and divides 

 into ascending and descending branches. 



The radial artery, the smaller terminal of the brachial, descends along the inner 

 ])order of the radius, and divides near the carpus into dorsal and volar branches. 



