302 THE MUSCLES OF THE OX 



The transversus abdominis presents no striking differential features. The 

 transversalis fascia is strong and distinct except over the diaphragm. 



Muscles of the Thoracic Limb 

 i. muscles of the shoulder girdle 



The trapezius is much thicker and broader than in the horse, and is undivided. 

 It arises on the hgamentum nuchse and supraspinous hgament, from the atlas to 

 the twelfth thoracic vertebra. 



The omo-transversarius is a muscle (not present in the horse) which arises 

 on the wing of the atlas, and, inconstantly, the transverse process of the second 

 cervical vertebra, and is inserted into the scapular spine and fascia. 



The rhomboideus is clearly divided into cervical and dorsal portions, the latter 

 extending further than in the horse. 



The latissimus dorsi has a broad tendon of origin, which blends with the 

 lumbo-dorsal fascia; it is also attached to the eleventh and twelfth ribs, the fascia 

 over the external intercostal and oblique abdominal muscles, and by a tendinous 

 slip to the deep pectoral muscle. 



The mastoido-humeralis has two distinct parts. The dorsal division (M. 

 cleido-occipitalis) arises on the occipital bone and the ligamentum nuchse. The 

 ventral part (M. cleido-mastoideus) is smaller and arises by a round tendon on 

 the mastoid process and the rectus capitis anterior major, and by a thin tendon on 

 the mandible. At the shoulder a small muscle which arises on the first rib blends 

 with the deep face of the mastoido-humeralis.^ 



The superficial pectoral muscle does not present any striking difference. 



The deep pectoral arises as far forward as the second rib and is undivided. 

 However, the scapular portion may be considered to be represented by a small 

 branch extending over the lower part of the supraspinatus. A tendon is detached 

 from the dorsal edge, which blends with the latissimus dorsi and coraco-brachialis. 



The serratus magnus is clearly divided into cervical and thoracic portions. 

 The former is large and extends from the third (or second) cervical vertebra to 

 the fifth rib, being overlapped behind by the thoracic part. The thoracic part is 

 relatively thin and is covered by a very strong aponeurosis; it is attached to the 

 fourth to the ninth ribs by six digitations, and is inserted by a flat tendon into the 

 inner face of the dorsal angle of the scapula. 



IL MUSCLES OF THE SHOULDER 



The deltoid is clearly divided into acromial and scapular portions. The former 

 arises on the acromion, the latter on the posterior border of the scapula and the 

 aponeurotic covering of the infraspinatus. The scapular part of the muscle is 

 largely inserted into the fascia covering the triceps. 



The supraspinatus, infraspinatus, and teres minor do not differ materially 

 from those of the horse. 



The subscapularis consists of three portions with a common tendon of inser- 

 tion. 



The teres major and coraco-brachialis resemble those of the horse. 



III. MUSCLES OF THE ARM 

 The biceps is smaller and less tendinous, and is situated more internally than 

 in the horse. The tendon of origin is flat, and is bound down in the bicipital groove 



1 This is probably the homologue of the subclavius of man. 



