Part 15

Below the skin is the superficial fascia, which forms a continuous covering over the whole body and serves to attach the skin to the underlying structure.

The deep fascia more densely constructed, may be attached to the skeleton, ligaments, and tendons.

When the fascia spreads out, becomes denser, and acts as a continuation of a muscle, it is called an aponeurosis.

=The Muscular Nomenclature.=—In the fowl there are 162 muscles, single or in pairs. These muscles are named from their location, as the lingualis; others from their attachments, as the dermo-temporalis; some from their form, as the rhomboideus; others from their use, as the flexor or extensor; and still others from their direction, as the transversus.

THE DERMAL MUSCLES

Birds are provided with a system of delicate muscles divided into numerous fasciculi, which harmoniously act upon the feather quills and collectively agitate the plumage. These are the dermal muscles. This group is divided into two subgroups: the true dermal muscles, that is, those that have their origin and insertion to the under surface of the skin; and the dermo-osseous, those that originate on the surface of some bone and insert to the inner surface of the skin.

TRUE DERMAL MUSCLES

Dermo-frontalis Dermo-dorsalis Dermo-tensor patagii Dermo-humeralis Dermo-pectoralis

=Dermo-frontalis.= Location.—This muscle is somewhat rudimentary and may be entirely absent. It is located in the frontal region and is about 2 or 3 centimeters long and not so wide.

Footnote 3:

The classification of Shufeldt is used.

Origin and Insertion.—Closely attached to the skin.

Shape.—Flat and rather rectangular.

Relations.—Superiorly with the skin and inferiorly with the frontal bones.

Action.—By contraction the feathers on the top of the head lie flat. Those above the eyes are elevated.

=Dermo-dorsalis.= Location.—In the median line of the neck and back.

Origin and Insertion.—Adhering closely to the skin, it generally becomes lost at the occiput; it is most highly developed in the mid-cervical region, and it gradually disappears over the caudal region.

Shape.—Delicate and ribbon-shaped.

Relations.—Superiorly it is attached to the skin. Fat sometimes surrounds the muscle.

Action.—By contraction it raises the feathers along the superior part of the neck and dorsal region.

=Dermo-tensor Patagii.= Location.—Between the root of the neck and top of the shoulder.

Origin and Insertion.—Attached to the skin in the region of the anterior part of the root of the neck, some fibers passing obliquely upward and blend with fibers of the dermo-temporalis. It blends, by a slender tendon, with that of the tensor patagii longus.

Shape.—A bundle of muscular fibers later becomes thin, delicate, and triangular in shape.

Relations.—Externally to the skin.

Action.—Auxiliary to the tensor patagii longus. A tensor of this region.

The patagii are associated with the wing fold of skin which fills the angle between the arm and forearm. This fold contains elastic tissue and muscle.

=Dermo-humeralis.= Location.—Lateral thoracic region.

Origin and Insertion.—Fan-like delicate fibers from the skin in the abdominal integument, contracting into a long narrow fasciculus of fibers, again spreading out in fan-shape to be inserted to the tendon of the pectoralis major, just below its insertion.