Pectoralis minor
The pectoralis minor muscle is larger than the pectoralis major. However, most of its anterior border is covered by the pectoralis major. Its origins are ribs three–five, and its insertion is the coracoid process of the scapula. Its actions are the tipping of the scapula and the elevation of ribs three–five. Xiphihumeralis
The most posterior, flat, thin, and long strip of pectoral muscle is the xiphihumeralis. It is a band of parallel fibers that is found in felines but not in humans. Its origin is the xiphoid process of the sternum. The insertion is the humerus. Trapezius
In the cat there are three thin flat muscles that cover the back, and to a lesser extent, the neck. They pull the scapula toward the mid-dorsal line, anteriorly, and posteriorly. Clavotrapezius
The most anterior of the trapezius muscles, it is also the largest. Its fibers run obliquely to the ventral surface. Its origin is the superior nuchal line and median dorsal line and its insertion is the clavicle. Its action is to draw the clavicle dorsally and towards the head. Acromiotrapezius
Acromiotrapezius is the middle trapezius muscle. It covers the dorsal and lateral surfaces of the scapula. Its origin is the neural spines of the cervical vertebrae and its insertion is in the metacromion process and fascia of the clavotrapezius. Its action is to draw the scapula to the dorsal, and hold the two scapula together. Spinotrapezius
Spinotrapezius, also called thoracic trapezius, is the most posterior of the three. It is triangular shaped.
Its appearance is similar to a loose flap of skin that might occur if the cat had been overweight and had then lost weight. It provides a little extra protection against kicks, which are common during cat fights as a cat will try to rake with its rear claws. In wild cats, the ancestors of domesticated felines, this pouch appears to be present to provide extra room in case the animal has the opportunity to eat a large meal and the stomach needs to expand. This stomach pouch also allows the cat to bend and expand, allowing for faster running and higher jumping. Skeleton
Cats have seven cervical vertebrae like almost all mammals, thirteen thoracic vertebrae (humans have twelve), seven lumbar vertebrae (humans have five), three sacral vertebrae (humans have five because of their bipedal posture), and, except for Manx cats and other shorter tailed cats, twenty-two or twenty-three caudal vertebrae (humans have three to five, fused into an internal coccyx). The extra lumbar and thoracic vertebrae account for the cats enhanced spinal mobility and flexibility, compared to humans. The caudal vertebrae form the tail, used by the cat as a counterbalance to the body during quick movements. Between their vertebrae, they have elastic discs, useful for cushioning the jump landings. Unlike human arms, cat forelimbs are attached to the shoulder by free-floating clavicle bones, which allows them to pass their body through any space into which they can fit their heads.