ELBOW-JOINT. 211 



Teres minor ; and internally, by the tendon of the Subscapularis. The capsular 

 ligament usually presents three openings ; one at its inner side, below the coracoid 

 process, partially filled up by the tendon of the Subscapularis ; it establishes a 

 communication between the synovial membrane of the joint and a bursa beneath 

 the tendon of that muscle ; a second, not constant, at its outer part, where a com- 

 munication sometimes exists between the joint and a bursal sac belonging to the 

 Infra-spinatus muscle. The third is seen in the lower border of the ligament, 

 between the two tuberosities, for the passage of the tendon of the Biceps muscle. 



The Cor aco -humeral or Accessory Ligament is a broad band which strengthens 

 the upper and inner part of the capsular ligament. It arises from the outer border 

 of the coracoid process, and descends obliquely downwards and outwards to the 

 front of the great tuberosity of the humerus, being blended with the tendon of the 

 Supra-spinatus muscle. This ligament is intimately united to the capsular in the 

 greater part of its extent. 



The Glenoid Ligament is a firm fibrous band attached round the margin of 

 the glenoid cavity. It is triangular on section, the thickest portion being fixed to 

 the circumference of the cavity, the free edge being thin and sharp. It is con- 

 tinuous above with the long tendon of the Biceps muscle, which bifurcates at the 

 upper part of the cavity into two fasciculi, which encircle its margin, and unite 

 at its lower part. This ligament deepens the cavity for articulation, and protects 

 the edges of the bone. It is lined by the synovial membrane. 



The Synovial Membrane lines the margin of the glenoid cavity and the fibro- 

 cartilaginous rim surrounding it ; it is then reflected over the internal surface of the 

 capsular ligament, covers the lower part and sides of the neck of the humerus, and 

 is continued a short distance over the cartilage covering the head of this bone. The 

 long tendon of the Biceps muscle which passes through the joint is inclosed in a 

 tubular sheath of synovial membrane, which is reflected upon it at the point where 

 it perforates the capsule, and is continued around it as far as the summit of the 

 glenoid cavity. The tendon of the Biceps is thus enabled to traverse the articu- 

 lation, but is not contained in the interior of the synovial cavity. The synovial 

 membrane communicates with a large bursal sac beneath the tendon of the Sub- 

 scapularis, by an opening at the inner side of the capsular ligament; it also 

 occasionally communicates with another bursal sac, beneath the tendon of the 

 Infra-spinatus, through an orifice at its outer part. A third bursal sac, which 

 does not communicate with the joint, is placed between the under surface of the 

 deltoid and the outer surface of the capsule. 



The Muscles in relation with the joint are, above, the Supra-spinatus ; below, 

 the long head of the Triceps ; internally, the Subscapularis ; externally, the Infra- 

 spinatus, and Teres minor; within, the long tendon of the Biceps. The Deltoid 

 is placed most externally, and covers the articulation on its outer side, and in front 

 and behind. 



The Arteries supplying the joint are articular branches of the anterior and 

 posterior circumflex, and suprascapular. 



The Nerves are derived from the circumflex and suprascapular. 



Actions. The shoulder-joint is capable of movement in almost any direction, 

 forwards, backwards, abduction, adduction, circumduction, and rotation. 



5. ELBOW-JOINT. 



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

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

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

 those of flexion and extension, whilst the cup-shaped depression of the head of the 

 radius articulates with the radial tuberosity of the humerus, its circumference 

 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 superior radio-ulnar articulation. 



