09 
THE SHOULDER-JOINT. 269 
viz. a hollow cylinder. By its upper end the capsule is attached to the circum- 
ference of the glenoid fossa, external to the glenoid ligament, and also, to a consider- 
able extent, to the glenoid ligament itself. 
By its lower end it is attached to the neck of the humerus, and therefore 
beyond the articular area of the head. The capsule is strongest on its superior 
aspect, while inferiorly, where the neck of the bone is least defined, it extends 
downwards for a short distance upon the humeral shaft. Its fibres for the most 
part run longitudinally, but a certain number of them pursue a circular direction. 
A prolongation of the capsule, the transverse humeral ligament presenting both 
longitudinal and transverse fibres, bridges that part of the bicipital groove which is 
situated between the tuberosities of the humerus. At this point an interruption 
in the capsule, beneath the transverse humeral ligament, permits the long tendon 
of the biceps to escape from its interior. In addition to the opening just referred 
to, there is another very constant deficiency in the upper and anterior part of 
_ the capsule, where the narrowing tendon of the subscapularis muscle is brought 
ee ee eee 
into contact with a bursa formed by a protrusion of the synovial membrane. This 
defect in the capsule has its long axis in the direction of the longitudinal fibres. 
Occasionally there is a similar but smaller opening under cover of the tendon of 
the infraspinatus muscle. Through the two latter openings the joint cavity 
communicates with burs situated between the capsule and the muscles re- 
ferred to. 
The tendons of the subscapularis, supraspinatus, and infraspinatus muscles 
fuse with, and so strengthen, the capsule as they approach their respective 
insertions. 
On the superior aspect of the articulation the capsule is augmented by an 
accessory structure, the ligamentum coraco-humerale (Fig.208). By its inner end, which 
is situated immediately above the glenoid fossa, but subjacent to the coraco-acromial 
ligament, it is attached to the external border of the root of the coracoid process, while 
its outer end is attached to the humeral neck close to the great tuberosity. This 
ligament forms a flattened band, having its hinder and lower border fused with 
the capsule, but 
its anterior and 
upper margin 
presents a free 
CLAVICLE 
} Coraco- Conoid 
edg e, sligh tly claviewlar (Trapezoid 
5 igamen ; 
raised above the Coraco-acromial ligament 
Y = Fi " WT Acromio- 
gy wa 
level of the cap- : = 
sule. This struc- 
ture is believed 
to represent that ' 
: Superior gleno-humeral 
portion of the ligament 
pectoralis minor 
to which refer- 
ence has already 
Coracoid process 
Bursal perforation in capsule 
: ‘Long head 
been madeincon- ; or nicens 
: : Inferior gleno-humeral | 
nex1on with the 5 ligament if ~ Capsule of 
coraco - acromial shoulder-joint 
ligament. 
Glenoid cavity: 
The coraco- 
glenoid ligament is Glenoid 
another accessory ; Epes 
structure which is ; [ 
not always present. ! 
It springs from the Fic. 209.—CapsuLAR LIGAMENT OF SHOULDER-JOINT CUT ACROSS AND 
coracoid process HUMERUS REMOVED. 
along with the 
former ligament, and extends to the upper and hinder margin of the head of the scapula. 
Gleno-humeral Ligaments (Fig. 209).—If the capsule be opened from behind, and the head of the 
humerus be removed, it will be seen that the longitudinal fibres of the anterior part of the capsule 
are specially developed in the form of thick flattened bands which extend from the anterior border 
of the glenoid fossa to the anterior aspect of the neck of the humerus. These gleno-humeral 
