8 4 



Anatomy of Skeleton 



(Fig. 64) corresponds with the lower half or less of the attached surface of the head 

 centre, the upper part being that which is fused with the tuberosities. 

 The structures attached to the epiphysis are : 



(a) Upper two-thirds of capsule (with coraco-humeral, transverse, and upper 

 gleno-humeral ligaments). 



(b) Supraspinatus, Infraspinatus, and upper parts of insertion of Teres minor 

 and Subscapularis : the extreme upper part of upward expansion from Pectoralis 

 major. 



The bicipital groove starts as a deeply-cut notch between the upper parts of the 



tuberosities, and is bridged across here by 

 the transverse ligament. As the tuberosi- 

 ties fade away below, the groove becomes 

 shallower, but is then deepened again 

 somewhat by the increasing prominence 

 of the outer lip that marks the area of 

 Pectoralis major insertion, and of the inner 

 lip, to a lessor degree, where the Teres 

 major is attached. 



The Pectoral insertion is well marked : 

 it can be followed down into the front part 

 of the deltoid impression, showing the con- 

 nection between the two tendons. The 

 finger can usually detect a fine secondary 

 line running up from the pectoral marking 

 to the front part of the great tuberosity : 

 this indicates the line of attachment of 

 an upward expansion from the Pectoralis 

 major to the capsule, and this expansion 

 lies in front of the long tendon of the 

 Biceps in its groove and of the short head 

 further in, and between these it covers 

 part of the insertion of the Subscapularis 

 (Fig. 65). 



It is seen in the figure also that the 

 tendon and its expansion are covered by 

 the front part of the Deltoid. This muscle 

 is only in the same plane as the great 

 pectoral at its origin, becoming superficial 

 to it as it passes down. 



The long tendon of the Biceps is sur- 

 rounded by a synovial covering, the bursa 



intertubercularis, derived from the joint ; this again is enclosed in a fibrous sheath 

 thrown round it from the deep aspect of the Pectoral tendon and its upper expansion, 

 just before they are attached to the bone, and this sheath is more or less fixed to the 

 floor of the grove above and below the insertion of Latissimus dorsi. Thus the bursa 

 does not come into direct relation with the bone in the groove, but is separated from 

 it by the fibrous sheath as well as by the Latissimus dorsi and anterior circumflex 

 artery. The roughnesses generally produced by these attachments in the floor of the 

 groove are therefore more extensive than that due to the insertion of the tendon of 

 Latissimus dorsi only, though this expands a little as it reaches the bone. 



FIG. 64. The uppermost figures are to illustrate 

 schematically the meaning of the " morpho- 

 logical neck." In the first figure the head 

 is joined to the shaft along the epiphysial 

 line A., and a muscular tuberosity along the 

 line B. ; the neck is therefore along A. 

 This type is seen in the femur. In the 

 second figure, however, the tuberosity has 

 also come into relation with the head along 

 the line C. ; it is evident that C cannot be 

 regarded as part of the " neck," because it 

 does not mark the junction of head with 

 shaft, and the same remark applies to B. 

 Hence the morphological neck is represented 

 by A . only. This type is seen in the humerus. 

 The lower figure shows the five different 

 ossifications which are concerned in forming 

 the lower end of the humerus. The dotted 

 area is shaft, which reaches the end at 2 ; 

 i, 3, 4, and 5 are centres of inner condyle, 

 trochlea, capitulum, and outer condyle 

 respectively. Notice that the capitular 

 centre is also responsible for the outer part 

 of the trochlea. 



