ive movement of the articulation. There exist no lateral
or common ligaments jointing the scapula and humerus as in other joints,
but instead the tendinous portions of muscles perform this function. The
principal ones which are attached to the scapula and humerus that act as
ligaments are the supraspinatus (antea-spinatus), infraspinatus
(postea-spinatus) biceps-brachii (flexor brachii) and subscapularis
muscles.

Etiology and Occurrence.--Inflammation of the scapulohumeral
articulation results from injuries of various kinds, including punctures
which perforate the joint capsule, bruises from collars, metastatic
infections and involvement as a result of direct extension of infectious
conditions situated near the joint.

Classification.--Acute arthritis may be septic or aseptic, and there
seems to be a remarkable tendency for recovery in cases of septic
arthritis involving this joint in the horse.

Chronic arthritis with destruction of articular surfaces and ankylosis,
is seldom observed. It is only in cases of severe injury, where the
articular portions of the bones are damaged at the time of infliction of
the injury, and where the articulation remains exposed for weeks at a
time, together with immobility of the parts because of attending pain,
that permanent ankylosis results.

Scapulohumeral arthritis may result then from _infections_, local or
metastatic; from _injuries_, such as contusions of various kinds; from
_wounds_, which break the surface structure or perforate the joint
capsule; or from _luxations_.

Infectious Arthritis.

Infectious arthritis of the scapulohumeral joint the result of local
causes other than produced by septic wounds, seldom causes serious
inconvenience to the subject. Where such occurs, however, there is
manifested mixed lameness and complete extension of the extremity is
impossible. Local swelling is present and manifestations of pain are
evident upon palpation of the affected area.

Treatment.--During the first stage of the infection, local
applications, hot or cold, are indicated. A hot poultice of bran or
other suitable material contained within a muslin sack, may be supported
by means of cords or tapes which are passed over the withers and tied
around the opposite fore leg. Such an appliance may be held in position
more securely by attaching it to the affected member. Following the
acute stage of such an infection, any local counter-irritating
application or even a vesicant