(3) Connective tissues. Connective tissue (figure 1-6) primarily binds and
supports, is highly vascular, and has a rich blood supply. An exception is cartilage that
is avascular (no blood vessels). Cells in connective tissue are widely scattered rather
than closely packed, and there is a lot of intercellular material. The general functions of
connective tissue are protection, support, and the binding together of various organs.
These tissues anchor and support organs and cover bone and cartilage. Two types of
connective tissue will be explored in this lesson: skeletal connective tissue and fascial
(fibrous) connective tissue.
Figure 1-6. Connective tissue.
(a) Skeletal connective tissue. Synovial membranes line the joint
cavities. Like serous membranes, these membranes do not open to the exterior. They
cover tendons and secrete a thin lubricant fluid. Synovial membranes are composed of
loose connective tissue with elastic fibers and varying amounts of fat. Synovial fluid is
secreted by synovial membranes. This fluid lubricates the ends of bones as they move
at joints and nourishes the articular cartilage covering the bones that form the joints.
Periosteum is a connective membrane classified as synovial connective membrane.
Periosteum covers bone, and perichondrium covers cartilage.
(b) Fascial (fibrous) connective tissue. The term fascia refers to a
sheet or a broad band of fibrous connective tissue that is under the skin or around
muscles and other organs of the body. There are three types of fascia: superficial
fascia or subcutaneous layer (immediately deep in the skin); deep fascia (the most
extensive of the three types); and subserous (visceral) fascia (located between the
internal layer of deep fascia and a serous membrane).
1 Superficial fascia (subcutaneous layer). This type of connective
tissue covers the entire body and varies in thickness in different regions. It is quite thin
on the back of the hand but quite thick on the abdominal wall. The functions of this
tissue include serving as a storehouse for water and for fat; forming an insulating layer
to protect the body from loss of heat; providing a layer of protection from blows to the
body; and providing a pathway for nerves and vessels.