The pectoral girdle is composed of two similar halves one lying on either side of the T-shaped interclavicle and sternum. Each half of the pectoral girdle consists of scapula, suprascapula, coracoid and epicoracoid.
Scapula is bony, oblong and flat plate which is narrow in the middle. Its outer broader end articulates with the suprascapula, while its inner narrow end unites with the coracoid.
Its lower posterior end forms a part of the glenoid cavity and its dorsal anterior end gives out an ossified process, the mesoscapula.
Suprascapula is more or less rectangular thin plate of calcified cartilage with a free distal border. It articulates proximally with the scapula and its distal border is free.
Coracoid is large, flat and fenestrated bone. It is partly ossified and partly cartilaginous. Two large fenestrae divide the coracoid into outer procoracoid, middle mesocoracoid and inner coracoid proper.
Inner anterior part of coracoid is cartilaginous forming the epicoracoid. It lies above the two fenestrae. Epicoracoid meet with the posterior long arm of interclavicle and sternum.
Interclavicle or Episternum
It is a T-shaped bone located in between the two halves of pectoral girdle. Its lateral curved limbs lie anterior to the scapulae and the posterior long limb is closely set to the mid-ventral surface of sternum.
It is a small curved narrow bone attached to the anterior side of lateral limb of interclavicle. Its outer distal end articulates with the union of scapula and suprascapula, while its inner limb does not reach up to the middle of interclavicle.
At the joint of scapula and coracoid along the ventral side is present a glenoid cavity for the articulation of head of humerus.