These will perhaps not usually be dissected. If they are to be
dissected, proceed as follows: Make a ventral median longitudinal
incision of the skin from the cranial end of the manubrium to a point
opposite the crest of the ilium. Connect the cranial end of this
incision with the middle of the lambdoidal ridge by a similar incision
through the skin. Make another incision from the manubrium to the
spinous process of the thirteenth thoracic vertebra. Connect the caudal
end of the first incision by an oblique cut with the root of the tail.
Make another incision from the convexity of the knee-joint along the
fold of skin which connects the hind limb and body, as far as the
incision which leads to the root of the tail. Make an incision
surrounding the base of the forelimb. Now reflect these flaps one at a
time, working in general from the ventral side toward the dorsal middle
line. Take great pains not to take up the thin skin-muscle with the
skin. In this way all of one side of the body will be uncovered. The
cutaneus maximus (Fig. 62, _b_) and a part of the platysma (Fig. 62,
_a_) will be thus exposed. Read and verify the descriptions of these
muscles (pp. 93-96). The cranial portion of the platysma cannot be seen
at this stage, but should be dissected in connection with the muscles of
the face.
II. SUPERFICIAL MUSCLES OF THE FACE AND HEAD (pp. 96-107, and Figs. 63
and 64).
These will perhaps not usually be dissected by the student. They should
be studied on a well-dissected laboratory preparation, if possible. If
they are to be dissected, this should be done if possible on a fresh
specimen, as it is very difficult to dissect them on preserved material.
Proceed as follows:
The skin should be removed with care from the sides and top of the face
and head, without injury to the external ear.
1. The platysma (p. 95, and Fig. 62, _a_). Determine its cranial
attachments.