THE ELBOW-JOINT. 349 



and rarely it passes backward and remains in the infraspinatous fossa, beneath the spine (sub- 

 spinous). 



The shoulder-joint is sometimes the seat of all those inflammatory affections, both acute and 

 chronic, which attack joints, though perhaps less frequently than some other joints of equal size 

 and importance. Acute synovitis may result from injury, rheumatism, or pyaemia, or may fol- 

 low secondarily on the so-called acute epiphysitis of infants. It is attended with effusion into 

 the joint, and when this occurs the capsule is evenly distended and the contour of the joint 

 rounded. Special projections may occur at the site of the openings in the capsular ligament. 

 Thus a swelling may appear just in front of the joint, internal to the lesser tuberosity, from effu- 

 sion into the bursa beneath the Subscapularis muscle ; or, again, a swelling which is sometimes 

 bilobed may be seen in the interval between the Deltoid and Pectoralis major muscles, from effu- 

 sion into the diverticulum, which runs down the bicipital groove with the tendon of the biceps. 

 The effusion into the synovial membrane can be best ascertained by examination from the axilla, 

 where a soft, elastic, fluctuating swelling can usually be felt. 



Tubercular arthritis not unfrequently attacks the shoulder-joint, and may lead to total de- 

 struction of the articulation, when ankylosis may result or long-protracted suppuration may 

 necessitate excision. This joint is also one of those which is most liable to be the seat of osteo- 

 arthritis. and may also be affected in gout and rheumatism ; or in locomotor ataxy, when it 

 becomes the seat of Charcot's disease. 



Excision of the shoulder-joint may be required in cases of arthritis (especially the tuber- 

 cular form ) which have gone on to destruction of the articulation : in compound dislocations and 

 fractures, particularly those arising from gunshot injuries, in which there has been extensive 

 injury to the head of the bone ; in some cases of old unreduced dislocation, where there is much 

 pain ; and possibly in some few cases of growth connected with the upper end of the bone. The 

 operation is best performed by making an incision from the middle of the coraco-acromial liga- 

 ment down the arm for about three inches : this will expose the bicipital groove and the tendon 

 of the Biceps, which may be either divided or hooked out of the way, according as to whether it 

 is implicated in the disease or not. The capsule is then freely opened, and the muscles attached 

 to the greater and lesser tuberosities of the humerus divided. The head of the bone can 

 then be thrust out of the wound and sawn off, or divided with a narrow saw in situ and 

 subsequently removed. The section should be made, if possible, just below the articular surface, 

 so as to leave the bone as long as possible. The glenoid cavity must then be examined, and 

 gouged if carious. 



V. Elbow-Joint. 



The Elbow is a ginglymus or hinge-joint. The bones entering into its forma- 

 tion are the trochlear surface of the humerus, which is received into the greater 

 sigmoid cavity of the ulna, and admits of the movements peculiar to this joint viz. 

 flexion and extension ; whilst the lesser, or radial, head of the humerus articulates 

 with the cup-shaped depression on the head of the radius ; the circumference of the 

 head of the radius articulates with the lesser sigmoid cavity of the ulna, allowing of 

 the movement of rotation of the radius on the ulna, the chief action of the supe- 

 rior radio-ulnar articulation. The articular surfaces are covered with a thin layer 

 of cartilage, and connected together by a capsular ligament of unequal thickness, 

 being especially thickened on its two sides and, to a less extent, in front and 

 behind. These thickened portions are usually described as distinct ligaments 

 under the following names: 



Anterior. Internal Lateral. 



Posterior. External Lateral. 



The orbicular ligament of the upper radio-ulnar articulation must also be 

 reckoned among the ligaments of the elbow. 



The Anterior Ligament (Fig. 245) is a broad and thin fibrous layer which 

 covers the anterior surface of the joint. It is attached to the front of the internal 

 condyle and to the front of the humerus immediately above the coronoid fossa ; 

 below, to the anterior surface of the coronoid process of the ulna and orbicular 

 ligament, being continuous on each side with the lateral ligaments. Its superficial 

 fibres pass obliquely from the inner condyle of the humerus outward to the 

 orbicular ligament. The middle fibres, vertical in direction, pass from the upper 

 part of the coronoid depression and become partly blended with the preceding, but 

 mainly inserted into the anterior surface of the coronoid process. The deep or 

 transverse set intersects these at right angles. This ligament is in relation, in 

 front. Avith the Brachialis anticus, except at its outermost part ; behind, with the 

 svnovial membrane. 



