4 THE UPPER EXTREMITY 



superior surface of the acromion of the scapula. By moving 

 the limb, however, the joint can easily be detected. In strong 

 contrast to this is the sternoclavicular joint, where the medial 

 end of the clavicle can be felt as a marked projection, 

 although this is masked to the eye by the sternal part of 

 the sterno-cleido-mastoid muscle. The incisura jugularis 

 (suprasternal notch), on the upper border of the manubrium 

 sterni between the clavicles, should next be felt, and then 

 the finger can be carried downwards, in the middle line, 

 along the anterior aspect of the sternum. A prominent 

 ridge, crossing the bone transversely at the level of the second 

 costal cartilages, indicates the junction between the corpus 

 sterni and the manubrium. The portion of the sternum 

 uncovered by the two greater pectoral muscles is narrow 

 above, but it widens out below, and suddenly, at the lower 

 end of the corpus sterni, the finger sinks into a depression, 

 between the cartilages of the seventh pair of ribs, and rests 

 upon the xiphoid process. The depression is termed the in- 

 frasternal fossa, or pit of the stomach. The costal arches below 

 the first are easily recognised, but the first rib lies deeply under 

 the clavicle, and can only be felt in front at its junction with 

 the manubrium sterni. The arm should now be abducted 

 (i.e. carried laterally from the trunk), when the hollow of 

 the armpit will be brought into view, as well as the two 

 rounded folds which bound it in front and behind. The 

 anterior fold of the axilla is formed by the lower border of 

 the pectoralis major, and to a small extent also by the lower 

 border of the pectoralis minor. The posterior fold, which is 

 formed by the latissimus dorsi, as it winds round the teres 

 major muscle, is carried downwards to a lower level than the 

 anterior fold. This, as will be seen later on, is an important 

 point in connection with the anatomy of the axilla. If the 

 finger be pushed upwards into the axilla the globular head of 

 the humerus can be felt, when the arm is rotated. One other 

 point demands the attention of the student before the dis- 

 section is commenced, and that is, the position of the nipple. 

 As a rule it lies superficial to the interspace between the 

 fourth and fifth ribs, and it is situated rather more than four 

 inches from the middle line. 



The student should examine these various landmarks not 

 only upon the body but upon himself and his friends until he 

 is perfectly familiar with them, both by touch and sight, and 



