with the shaft. The inter-tubercular (bicipital) groove looks forward,
and lies in a line drawn vertically through the biceps muscle.

The subclavian artery, with its vein to the median side and the cords
of the brachial plexus to the lateral side, passes under the middle of
the clavicle, and may be compressed against the first rib immediately
above this bone.

FRACTURE OF THE CLAVICLE

Fracture of the clavicle is one of the commonest injuries met with in
practice. As about one-third of the cases occur in children, the
fracture is often of the greenstick variety. The fractures are seldom
compound or complicated, unless as a result of gun-shot injuries; but
occasionally one of the fragments pierces the skin, or comes to press
upon the subclavian vessels or the cords of the brachial plexus,
arresting the pulsation in the vessels of the limb, and causing severe
pain in the arm.

[Illustration: FIG. 13.--Oblique Fracture of Right Clavicle in Middle
Third, united.]

The most common site of fracture is in the _middle third_ (Fig. 13),
and this usually results from indirect violence, such as a fall on the
outstretched hand, the elbow, or the outer aspect of the shoulder, the
force being transmitted through the glenoid cavity to the scapula, and
thence by the coraco-clavicular ligaments to the clavicle. The
violence is therefore of a twisting character, and the bone gives way
near the junction of the lateral and middle thirds, just where the two
natural curves of the bone meet, and where the supporting muscular and
ligamentous attachments are weakest.

The fracture so produced is usually oblique from above, downwards and
inwards. The sternal fragment may be slightly drawn upwards by the
clavicular fibres of the sterno-mastoid, while the acromial fragment
falls by the weight of the arm, and the fragments usually overlap to
the extent of about half an inch. The shoulder, having lost the
buttressing support of the clavicle, falls in towards the chest wall,
narrowing the axillary space, while the weight of the arm pulls it
downward, and the muscles inserted in the region of the bicipital
groove pull it forward.

Fracture of the middle third may result also from a direct stroke,
such as the recoil of a gun, or from violent muscular contraction, the
fracture as a rule being transverse, and the displacement less marked
than in fracture by indirect violence.

_Clinical Features._--The attitude of the patient is characteris