MUSCLES 33 



Pectoralis major : superiorly, sternal half of clavicle(p) ; in- 

 ternally, front of sternum, cartilages of upper six ribs(F) ; in- 

 fer iorly aponeurosis of external oblique muscle of abdomen (F) 

 outer ridge of bicipital groove of humerus(T) (External 

 and internal anterior thoracic). [A adducts humerus, flexes 

 shoulder; B raises ribs in forced inspiration.] Anterior 

 boundary of axilla, separated front the deltoid above by cephalic vein 

 and branch of acromio - thoracic artery. 



Pectoralis minor : 3rd, 4th, and 5th ribs outside cartilages, 

 aponeurosis over intercostal muscles(F) anterior* of superior 

 surface and inner border of coracoid process of scapula(x) 

 (Internal anterior thoracic). [Draws scapula forwards and 

 depresses it.] Forms middle of anterior axillary boundary, and 

 conceals 2nd part of axillary artery. 



Subclavius : ist rib at junction of bone and cartilage(x) 

 groove on under surface of clavicle between the two tubercles(F) 

 (Branch from 5th and 6th cervical). [Depresses clavicle.] 

 Encased by costo-coracoid sheath. 



LATERAL THORACIC REGION. 



Serratus magnus : eight or nine digitations from as many 

 ribs, the ist digitation being attached to ist and 2nd ribs; 

 aponeurosis over intercostal muscles ; lower four slips digitate 

 with external oblique muscle of abdomen(F) vertebral border 

 of ventral surface of scapula; viz., ist digitation from ist 

 and 2nd ribs to upper angle, from 2nd and 3rd ribs to base ; 

 the rest to inferior angle(p) (Posterior thoracic). [Draws 

 scapula forwards, and by rotating inferior angle forwards 

 and upwards, raises arm.] 



ACROMIAL REGION. 



The deep fascia over the shoulder conceals the back part of 

 the deltoid and the infra-spinatus muscle, and is attached to 

 the clavicle, acromion, and spine of scapula. 



Deltoid : outer anterior border of clavicle, anterior edge 

 of acromion, all lower edge of spine of scapula(F) rough 

 deltoid impression on outer surface of humerus just above the 

 middle(T) (Circumflex). [Abducts arm; anterior fibres flex 

 shoulder, posterior extend.] 



Parts covered by deltoid : head and neck of humerus ; bursa 

 between head of humerus and muscle; tendons of insertion 

 of subscapularis, pectorales major and minor, teretes naajor 

 and minor, latissimus dorsi, supra- spinatus, infra-spinatus. 

 Origins of coraco-brachialis, biceps (two heads), triceps (long 



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