THE ARTERIES * 635 



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

 the digastricus, gives oti' tlie 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 upjx'r liorder of the digastricus 

 and continues between the niylo-hyoideus and the ramus 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 l)orders 

 of the external ear. 



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

 a small transverse facial artery, turns forward under the tenii)oral fascia toward the 

 eye, and divides iiit(^ uj^per and lower l)ranches which su])ply 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 m(>ntal branches of the inferior alveolar (or dental) artery are of consideral:>lo 

 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 buccinator; it gives off 

 the middle meningeal, which .sends a branch 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 retina. The superficial branches of the 

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

 the small siz(> of the superior lal)ial. 



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

 the ellK)w it jiass'.'s between the bice])s 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 suliscapularis 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 circimiflex, which often arises with the posterior circumflex. 

 Its other branches resemble 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. (-i) 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 carjii dorsale. It often supplies the bicipital 

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

 small. (7) The common interosseous artery is given off a little Ijelow the elbow. 

 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 artery, which descends 

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

 and the fifth volar metacarpal artery, and terminates by joining the volar branch 

 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 flexor 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 

 border of the radius, and divides near the carpus into dorsal and volar branches. 



