66 EQUINE ANATOMY. 



Action. Draws pelvis forward, thorax backward; flexes spine 

 and compresses abdomen. 

 Nerve. Intercostal. 



INGUINAL CANAL. 



A canal on each side and in front of the pubic bone, running 

 downward, backward and inward, which transmits the spermatic 

 cord and vessels in the male, and the external mammary vessels 

 in the female. 



Has an external or scrotal, and internal or peritoneal ring, and 

 two pillars. 



ANTERIOR EXTREMITY. 



SUPERFICIAL PECTORAL. 



Composed of two parts. 



(A) Sterno-humeralis. 



Origin. Anterior appendage and inferior border of sternum. 

 Insertion. Anterior ridge of humerus. 

 Action. Abductor of anterior limb. 

 Nerve. Inferior thoracic. 



(B) Sterno-aponeuroticus. 



Origin. Inferior surface of sternum. 

 Insertion. With preceding,' and also into fascia of limb. 

 Action. Same as preceding, and tensor of brachial fascia. 

 Nerve. Inferior thoracic. 



DEEP PECTORAL. 



Composed of two parts. 



(A) Sterno-trochineus. 



Origin. Abdominal tunic and posterior two-thirds of inferior 

 border of sternum. 



Insertion. Internal tubercle of head of humerus, fascia of 

 coraco-brachialis and coraco-radialis, and lip of bicipital groove. 



Action. Pulls limb backward. 



Nerve. Inferior thoracic. 



