Intrinsic muscles proceeding from the pectoral / pelvic arches to the humerus or femur
Intrinsic muscles proceeding from the pectoral or pelvic arches to the humerus or femur, on the dorsal aspectIn the fore-limb, the deltoides proceeds from the clavicle and scapula to the humerus. This superficial shouldei-muscle continues the direction of the fibres of the trapezius; and, when the clavicle is rudimentary, the adjacent portions of the two muscles coalesce into a cephalo-humeralis muscle. Beneath the deltoid the supra-spinatus, on the pre-axial side of the spine of the scapula; the infra-spinatus, and the teres major and minor, on its post-axial side, run from the dorsal aspect of the scapula to that of the head of the humerus.
In the hind-limb, the tensor vaginal femoris, which passes from that part of the ilium which corresponds with the spine and acromion of the scapula, to the femur, appears to answer better to the deltoid than does the glutaeus maximus, which, at first sight, would seem to be the homologue of that muscle.
The iliacus, proceeding from the inner surface of the crest of the ilium to the smaller trochanter, answers to the supraspinatus; the glutaeus medius and minimus, which arise from the outer surface of the ilium, to the infra-spinatus and teres.
In the fore-limb, a muscle, the subscapularis, is attached to the inner face of the scapula, and is inserted into the humerus. No muscle exactly corresponding with this appears to exist in the hind-limb.
On the ventral aspect in the fore-limb, the coracobrachialis passes from the coracoid to the humerus. In the hind-limb, a number of muscles proceed from the corresponding (ischiopubic) part of the pelvic arch to the femur. These are, from the outer surface of the pubis, the pectineus, and the great abductors of the femur; with the obturator externus, from the outer side of the ischiopubic fontanelle, or obturator membrane. The gemelli and the quatadratus femoris take their origin fiom the ischium.
No muscle is attached to the proper inner surface of the ilium, so that there is no homologue of the subscapularis in the hind-limb. On the other hand, a muscle, the obturator intenus, attached to the inner surface of the ischiopubic fontanelle, and winding round to the femur, has no homologue in the upper extremity of the higher Vertebrata, unless it be the so-called coracobrachialis, which arises from the inner surface of the coracoid in many Sauropsida.