206 



MUSCLES OF THE UPPER LIMB. 



run the cephalic vein and the humeral branch of the acromio-thoracic artery. The 

 anterior surface is subcutaneous in the greater part of its extent, being covered only 

 by some of the fibres of the platysma myoides and by the mamma. The posterior 

 surface rests chiefly on the pectoralis minor, and externally and internally to that 

 muscle forms the anterior wall of the axilla. 



The tendinous fibres of origin of opposite sides sometimes decussate in front of the 

 sternum, and occasionally the fleshy fibres also of opposite sides come into contact. 

 In some instances additional muscular slips take origin from the aponeurosis of the 

 external oblique muscle, and in others the lower part of the muscle presents consider- 

 able deficiency. 



The pectoralis minor arises from the upper margins and external surfaces 

 of three ribs near their cartilages usually the third, fourth and fifth and 

 from the neighbouring parts of the intercostal aponeurosis. Its fibres 

 converge to a narrow tendon, which is inserted into the anterior half of the 

 inner border and upper surface of the coracoid process, in contact with the 

 conjoined origin of the coraco-brachialis and biceps muscles. 



This muscle is covered by the pectoralis major, and forms a part of the anterior 

 wall of the axilla. When the arm is much raised a portion of the muscle is seen 

 below the outer margin of the pectoralis major. 



The subclavius muscle arises by a short thick tendon from the first costal 

 arch at the junction of the rib and cartilage, close to the costo-clavicular 

 ligament. From this tendon its fibres pass outwards and upwards, forming 



Fig. 174. 



Fig. 174. LATERAL VIEW 

 OP THE TRUNK, snow- 



INO IN A DEEP DIS- 

 SECTION A VIEW OF 

 THE SERRATUS MAGNUS 

 MUSCLE. 



a, coracoid process of 

 the scapula ; 6, glenoid 

 cavity; c, lower angle; 

 d, first dorsal vertebra ; 1, 

 VI, XII, the first, sixth, 

 and twelfth ribs ; 1, upper 

 portion of the serratus 

 magnus attached to the 

 first and second ribs ; 2, 

 second or middle portion 

 attached chiefly to the 

 third rib ; 3, lower or fan- 

 shaped portion attached to 

 the ribs from the fourth 

 to the ninth ; 4, external 

 intercostal muscles marked 

 in the third and ninth 

 spaces ; 5, upper costal 

 origins of the transver- 

 salis abdominis ; x , sca- 

 pular extremities of the 

 levator scapulae and omo- 

 hyoid muscles. 



a rounded belly, which is inserted into the groove along the inferior surface 

 of the clavicle, extending as far as the recess between the conoid and 



