120 DISSECTION OF THE DOG 



M. latissimus dorsi. — The latissimus dorsi muscle has already been partly 

 exposed in the dissection of the ventral aspect of the thorax and the axilla, 

 and its insertion into the crista tuberculi minoris of the humerus has been 

 examined. At the present stage of the dissection the origin of the muscle by a 

 tendinous expanse from the lumbo-dorsal fascia, by means of which it is con- 

 nected with the last seven thoracic and all the lumbar vertebras, is to be 

 examined. It will be found further that there is a fleshy origin from the last 

 two ribs. 



N. accessorius.- — The accessory or eleventh cerebral nerve passes towards 

 the shoulder ventral to the wing of the atlas, under cover of the brachio- 

 cephalic muscle and between this and the omo-trans verse. It then lies between 

 the cervical part of the trapezius and the cervical part of the ventral serratus 

 and supraspinous muscles, and finally disappears into the substance of the 

 thoracic part of the trapezius. During the passage of the accessory nerve down 

 the neck it is connected with the cervical nerves from the second to the fifth. 



Dissection. — Reflect the omo-transverse muscle. 



M. serratus ventralis. — During the dissection of the wall of the chest 

 the thoracic part of the ventral serratus muscle was examined. The cervical 

 portion of the muscle, arising from the transverse processes of the third, fourth, 

 fifth, sixth, and seventh cervical vertebrae, is now^exposed. 



Dissection. — After noting the presence of a small communicating vein from 

 the cephalic to the jugular on the surface of the brachio-cephalic muscle, 

 the limb may be removed by cutting through the brachio-cephalic, 

 rhomboid, latissimus dorsi, and ventral serratus muscles. Then the 

 muscles, nerves and vessels on the deep face of the scapula and arm 

 should be cleaned. . 



M. subscapulars. — The subscapular muscle is broad and fan-shaped 

 and occupies the whole of the subscapular fossa of the scapula. Its fibres are 

 separated into five or more portions by tendinous bands which converge towards 

 the shoulder-joint. The origin of the muscle is from the subscapular fossa, and 

 its insertion is into the tuberculum minus of the humerus. 



M. teres major. — A powerful muscle placed immediately aboral to the 

 foregoing, the origin of the teres major is from the axillary border of the 

 scapula, the angle separating the axillary and vertebral borders of this bone, 

 and the subscapular muscle. The insertion of the muscle is in common with 

 that of the latissimus dorsi to the crista tuberculi minoris of the humerus. 



M. biceps brachii. — The biceps muscle runs parallel to, and to the medial 

 side of, the humerus. Arising from the coracoid process of the scapula, the 

 strong tendon of origin is bound down in the intertubercular sulcus of the 



