- Scapula, coracoid and clavicle, meet to form the foramen triosseum, through which passes the tendon of the supracoracoideus, or subclavius muscle to the tuberculum superius of the humerus.
When the wing is folded the long glenoid surface of the head of the humerus is bordered above by the tuberculum externum or superius, in the middle and below by the tuberculum medium or inferius for the insertion of the coraco-brachialis posterior muscle.
From the outer tuberculum extends the large crista superior (insertion of pectoralis major and of deltoideus major muscles).
In the region of the neck lateral strands pass through the transverse canal of the cervical vertebrae; but from the thoracic region onwards, where the cardiac branch to the heart is given off, each strand is double and the basal ganglia are successively connected with the next by a branch which runs ventrally over the capitulum of the rib, and by another which passes directly through the foramen or space formed between capitulum and tuberculum.
The latter articulate with the tuberculum of the corresponding rib, while the capitulum articulates by a knob on the side of the anterior end of the centrum.