PHYSIOLOGY, AND PATHOLOGY OF THK CHIMPANZEE. 391 



and deep divisions. The former continues as digital branches 

 to the outer two digits ; the latter passes between the heads of 

 adductor halliicis and supplies the interossei, tarso-metatarsal 

 joints, and anastomoses with the vessel corresponding to the 

 dorsalis pedis to form the plantar arterial arch. The medial 

 plantar artery gives oflF medial calcanean branches to the skin 

 of the inner side of the sole of the foot and muscular branches 

 to the abductor hallucis and flexor brevis hallucis and digital 

 arteries to the inner three toes. 



Veins of the Thorax. 



Innominate Veins (text-fig. 42 B) : — The left vein runs as in 

 Man and unites with the more vertical right one to form the 

 superior vena cava. It receives inferior thyroid (I.T.V), thymic 

 (T.V), internal mammary (I.M.V) and superior intercostal 

 (L.I.Y) veins. The short right vein only receives the forma- 

 tive vessels. 



The superior vena catKi (S.V.C) is large, vertical, and enters 

 the upper part of the right auricular appendix. It receives the 

 vena azygos major as in Man. The thoracic part of the inferior 

 vena cava is 2"6 cm. long. 



The azygos veins drain the lower nine spaces, the first three 

 being drained by the superior intercostal vein. All are small. 

 No ascending lumbar veins were found. The vena azygos 

 major entex-s the supeinor vena cava at the level of the fifth 

 dorsal vertebra. 



Veins of the Head and Neck (text-fig. 42 A). 



The intra-cranial blood sinuses have the same general arrange- 

 ment as in Man. The chief difference lies in the union of the 

 inferior petrosal and lateral sinuses within the jugular foramen 

 to form the internal jugular vein. The groove in the skull for 

 the right lateral sinus is much larger than that for the left, and 

 a very shallow bony groove connects the two. 



The anterior facial vein (A.F.V) begins by the confluence of 

 palpebral and lateral nasal veins. It runs downwards and back- 

 wards and crosses the mandible at the anterior border of the 

 masseter. It crosses the levator anguli oris and buccinator, and 

 it is covered by the zygomaticus, risorius, and platysma. It runs 

 between the mandible and sub-maxillary gland, and then under 

 the stylo-hyoid and posterior belly of the digastric. Finally it 

 unites with the tempoi-o-maxillary vein to form the external 

 jugular vein. It receives the following tributaries: — (1) Pal- 

 pebral veins (P.V) from both eyelids. (2) Lateral nasal veins 

 (L.N.V). (3) Masseteric veins (M.Y). (4) Deep facial vein 

 (D.F.V), which runs under the malar bone and buccal pad of 

 fat to the pterygoid region. (5) Sithmaxillary glandidar vein 

 (S.M.G). (6) Lingual vein (L.V). (7) Laryngeal and sicperior 



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