326 



THE MUSCLES OF THE DOG 



MUSCLES OF THE ABDOMEN 

 The abdominal tunic is practically absent. 



The obliquus abdominis externus has an extensive fleshy portion. It arises 

 from the last eight or nine ribs and the lumbo-dorsal fascia. 



The obliquus abdominis internus arises from the external angle of the ilium 

 and the lumbo-dorsal fascia. The fibers have an almost vertical direction, and 

 there is a fleshy attachment to the last rib. 



The rectus abdominis is attached by a long tendon on the first five or six costal 

 cartilages, and l)y fleshy fibers on the xiphoid cartilage. It has three to six indis- 

 tinct tendinous inscriptions. 



The transversus abdominis presents no special features except that the poste- 

 rior part of its aponeurosis 

 3 splits into two layers which 



6 h ^ _—]-—■ include the rectus between 



them. 



muscles of the pelvic 

 Limb 

 The psoas minor arises 

 on the last thoracic and first 

 four or five lumbar vertebrae, 

 and is inserted into the ilio- 

 pectineal line. 



The psoas major is 

 short, arising from the last 

 four lumbar vertebra?. 



The outer head of the 

 iliacus is small, while the 

 inner head is large and fuses 

 with the psoas major. 



The quadratus lumbor- 

 um is well developed, and 

 extends laterally beyond the 

 outer edge of the ilio-psoas. 

 It arises from the last four 

 ribs and the lumbar transverse processes, and ends on the pelvic surface of the 

 wing of the ilium. 



The tensor fasciae latae consists of two parts. The anterior part is long and 

 rounded; the posterior is shorter and fan-like. 



The gluteus superficialis is small. It arises on the sacrum, first coccygeal 

 vertebra), and sacro-sciatic ligament. It is inserted below and behintl the tro- 

 chanter major of the femur, on the outer branch of the linea aspera. 



The gluteus medius has no lumlxir portion. It is inserted into the trochanter 

 major l)y a strong tendon. 



The gluteus profundus is broad and fan-shaped. It arises on the superior 

 ischiatic spine and on the ilium as far forward as the gluteal line, and is inserted 

 into the trochanter major below the medius. 



The pyriformis is not ])lended with the gluteus medius. It arises from the 

 border of the sacrum and from the sacro-sciatic ligament, and ends on the tro- 

 chanter major. 



The biceps femoris has two heads of origin which soon fuse. The larger head 

 arises from the sacro-sciatic ligament and tuber ischii, the smaller one from the tuber 



Fig. 235. — Muscles of Tail, Anus, and Genital Organs of Dog. 

 1, Ilium; 2, femur; 3, tuber ischii; 4, sacro-sciatic lig.; 5, sacral 

 region; 6, tail; 7, penis; 8, anus; 9, rectum; a, sacro-coccygeus supe- 

 rior; b, sacro-coccygeus accessorius; c, coccygeus; d, sacro-coccygeus 

 inferior; e, retractor ani; /, /', sphincter ani externus; g, retractor 

 penis; h, bulbo-cavernosus; (', transversus perinei (?); k, m, ischio- 

 urethrales; /, ischio-cavernosus; n, tendon of obturator internus; o, 

 gemellus; p, urethral muscle, (.\fter Ellenberger, in Leisering's Atlas.) 



