There are four pectoral muscles in the cat: pectoantibranchialis,
pectoralis major, pectoralis minor, and xiphihumeralis.
Pectoantibranchialis
Pectoantibranchialis
muscle is just one-half inch wide, and is the most superficial in the pectoral
muscles. Origin, manubrium of the sternum, Insertion, in a flat tendon on the
fascia of the proximal end of the ulna, Action, draws the arm towards the chest.
Pectoralis major
The pectoralis major, also called, pectoralis superficialis, is a broad
triangular portion of the pectoralis muscle which is immediately below the
pectoantibranchialis. Origin, sternum and median ventral raphe, Insertion,
Humerus, Action, draws the arm towards the chest.
Pectoralis minor
The pectoralis minor muscle is a much larger than the Pectoralis major, and
is divided into several parts. However, most of its anterior broder is covered
by the pectoralis major. Origin, Sternum, Insertion, Humerus, Action, draws the
arms towards the chest.
Xiphihumeralis
The most posterior, flat, thin, and long strip of pectoral muscle is the
Xiphihumeralis. It is a band of parallel fibers. Origin, xyphoid process of the
sternum, Insertion, proximal end of the humerus, Action, draws the arms towards
the chest.