Muscles of the Back
Latissimus Dorsi
Originates from the dorsal surface, and is also prominent on lateral and ventral surfaces. Inserts on proximal end of the humerus on its medial surface. This muscle moves the forelimb dorsally and posteriorly, and gives the forelimb great power.
Trapezius
Originates from the occipital bone, cervical vertebrae, and thoracic vertebrae. Inserts on the spine of the scapula. This muscle retracts the scapula toward the spine, and helps to stabilize the scapula (and shoulder girdle during forelimb movement).
Brachiocephalic
Originates from the back of the neck. Inserts on humerus. This muscle moves the forelimb anteriorly.
Rhomboideus cervicis
Originates from mid-dorsal line together with the cervical part of the trapezius. Inserts on the dorsal or vertebral edge of the scapula. This muscle acts on the scapula to hold it in place, and pull it cranially or caudally.
Rhomboideus capitis
Originates from the occipital area of cranium. Inserts on scapula at vertebral border. This muscle draws the scapula foreward.
Deltoid
Originates from the scapula. Inserts on the proximal end of the humerus. This muscle raises the humerus. Often not fully developed in fetal pigs.
Splenius
Originates from the first 2 thoracic (chest) vertebrae. Inserts on the occipital bone of the head. This muscle extends the head and flexes it to the side.