Extrinsic muscles attached to the pectoral and pelvic arches,
on the dorsal aspect
In the fore-limb, the cleidomastoideus,
from the posterolateral region of the skull to the clavicle; the trapezius,
from the skull and spines of many of the vertebrae
to the scapula and clavicle; the rhomhoidei
, from the spines
of vertebrae to the vertebral edge of the scapula, beneath the
foregoing. Sometimes there is a tracheloacromialis
, from the
transverse processes of the cervical vertebrae to the scapula.
On the ventral aspect
, the subclavius
, which passes from the
anterior rib to the clavicle, may be regarded as, in part, a muscle
of the limb; the pectoralis minor
, from the ribs to the
Between the dorsal and the ventral aspects muscular fibres
arise from the cervical and dorsal ribs, and pass to the inner
aspect of the vertebral end of the scapula: anteriorly, these are
called levator anguli scapulae
posteriorly, serratus magnus.
muscle frequently connects the scapula with
the hyoidean arch.
The posterior limb does not seem to offer any muscles exactly
homologous with the foregoing. So far, however, as the recti abdominis
, the obliquus extermis
, and the fibres of the erector spince
, are attached to the pelvic girdle, they correspond
in a general way with the pre-axial, or protractor, muscles
of the pectoral arch; and the ischio-coccygeal muscles,
when they are developed, are, in relation to the pelvic arch,
retractors, though, owing to the relative fixity of the pelvis,
they act in protracting, or flexing, the caudal region.
The psoas minor
, proceeding from the under surfaces of
posterior dorsal (or lumbar) vertebrae to the ilium, or pubis,
is a protractor of the pelvis, but, as a hyposkeletal muscle,
has no homologue in the fore-limb.