Deeper muscles of the neck and back in the cat includes the following: Rhomboideus, Rhomboideus Capitis, Splenius, Serratus Ventralis, Serratus Dorsalis, and the Intercostals.
The Rhomboideus is a thick, large muscle below the Trapezius muscles
. It extends from the vertebral border of the scapula to the mid-dorsal line. Origin, neural spines of the first four thoracic vertebrae, Insertion, vertebral border of the scapula, Action, draws the scapula to the dorsal.
Rhomboideus capitis is the most cranial of the deeper muscles. It is underneath the Clavotrapezius
. Origin, superior nuchal line, Insertion, scapula,
Splenius is the most superficical of all the deep muscles. It is a thin, broad sheet of muscle underneath the Clavotrapezius
and deflecting it. It is crossed also by the Rhomboideus capitis. Its origin is the mid-dorsal line of the neck and fasica. The insertion is the superior nuchal line and atlas. It raises or turns the head.
Serratus Ventralis is exposed by cutting the wing-like Latissimus Dorsi
. The said muscle is covered entirely by adipose tissue
. The origin is from the first nine or ten ribs, and from part of the cervical vertebrae. The insertion is the vertebral border of the scapula. It draws scapula forward, backward and against the body.
Serratus Dorsalis is medial to both the scapula and the Serratus Ventralis. Origin, apoeurosis following the length of the mid-dorsal line, Insertion, dorsal portion of the last ribs, Action, draws ribs craniad
The Intercostals is a set of muscles sandwiched between the ribs. They interconnect ribs, and are therefore the primary respiratory skeletal muscles. They are divided into the External and the Internal subscapularis. The origin and insertion are in the ribs. The intercostals pull the ribs backwards or forwards.