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AREOLAR TISSUE, TENDONS, AND MUSCLES. 155
is enclosed in its own vesicle. In health this tissue is moistened and
lubricated by a transparent fluid of the nature of lymph.
Fascia is divided into two varieties, superficial and deep.
Superficial or Subcutaneous Fascia connects the skin with the deeper
its
and firmer parts beneath by numerous delicate bands or trabeculae ;
structure is more open than that of the deep fascia, and its bands run
more irregularly. It varies in thickness and density in different parts,
and is found distributed throughout nearly the entire surface of the
body. Within the meshes of this tissue is found the subcutaneous fat,
which forms a blanket of adipose tissue and serves to keep the body
warm, fat being a poor conductor of heat. No adipose tissue is found
upon the eyelids, the penis, and the scrotum. In animals, such as the
cow, the horse, and the dog, the superficial fascia contains within its
structure a muscle known as the panniculus carnosus, which extends
over almost the entire body. In man a muscle corresponding to this,
known as the platysma myoides, is found in the region of the head and
neck.
In some portions of the body the superficial fascia is separable into
several layers ; this is especially true in the region of the groin. In
health the superficial fascia often becomes loaded with fat, this tissue in
corpulent people being much thicker. The opposite is the case with
emaciated people, the superficial fascia becoming extremely thin its
;
fibrous bands are closely approximated, and the skin appears wrinkled
or in folds. Also on the soles of the feet and in the palms of the hands
it is very thin and closely attached to the skin. It is generally divided
into two or more layers, between which are the glands, and through
Mdiich pass the superficial blood-vessels, nerves, and lymphatics, these
structures having free communication with each other.
The Deep or Aponeurotic Fascia is immediately beneath the super-
ficial fascia. The course of its fibres is not so irregular as that of the
superficial fascia, inclining more to an arrangement in layers or bands,
with much less adipose tissue confined within its meshes; this forma-
tion makes it denser and stronger than the superficial fascia.
Like the superficial, the deep fascia extends over nearly the entire
surface of the body, forming an envelope which holds the muscles to
their shape and in their proper position. Numerous septa are given off
from it which dip down between the muscles, dividing and enclosing
their bands, subdividing and enclosing their fibres, and forming a sheath
which enwraps the vessels and nerves wherever met. It encloses the
tendinous structures in the same manner as the muscular. That portion
of the fascia which invests a tendon is called its theca or vagina.
This fascia also assists in forming intermuscular connections and
septa, as those between the two bellies of the digastric and the occipito-
frontalis muscle. When the fascia is broad and well defined it is
called an aponeurosis. The deep fascia, in different forms, serves to
attach muscles and tendons to osseous and other structures, and throws
off stout fibrous bands wdiich form various ligaments, such as those sur-
rounding the joints, the annular and the bicipital, the palmar and the
plantar fascia, etc.
The deep fascia likewise forms pulley-like apertures through which