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TENDON

They are tough whitish cords/straps varying in length and thickness, and are almost inextensible. They comprise numerous parallel Fascicles (bundles) of collagen fibres and tendon cells surrounded by firbo-areolar tissue which helps to bind them together. This fibro-areolar tissue is called interfascicular tissue or endo-tenon.

At the surface of the tendon the fibro-areolar tissue is condensed into a thin fibro-elastic sheath called Epitendineum.

The point where a tendon leaves the muscle, the connective tissue coverings of the muscles and tendon are continuous.

At the point of attachment to the bone the various components of tendon are attached to the bone in following ways:-

Endotenon (Inter fascicular tissue): It blends with the periosteum.

Collagen fibre component: They pass through the cortical bone as perforating fibres of Sharpey.
Tendons show limited elasticity and viscosity. Their tensile strength is half that of steel which is very much high for routine functions. A tendon having I cm2 area will support about 1000 Kg.

BLOOD SUPPLY:

It is derived from number of longitudinally running small arterioles which are continued down from the perimysium and course for the most part in the inter-fascicular grooves. These little vessels communicate freely with one another and each is accompanied by: two venae comitans
four lymph vessels.

The density of vascular network is low in tendons, SO they look whitish cords. Metabolic turnover is low in tendons, but it is increased in response to injury or infection. Repair is only due to cells associated with collagen fibres.

NERVE SUPPLY:

Nerves supplying the tendons end in what are known as neurotendinous endings (afferent receptors). Vasomotor fibres are not clearly defined.

FUNCTIONS:

1. They connect the muscles with bones and cartilages.
2.Due to their slight flexibility they can bend around the bones and retinacula and in this manner help in movements.

APONEUROSES (S-aponeurosis)

They are flattened or expanded sheets of white fibrous tissue often glistening and sparingly supplied with blood vessels. The C.T. is arranged in fascidles or bundles which are parallel within a layer but inclined in different directions in adjacent layers.

It is found immediately beneath the skin over the inner surface of the body.
It is usually a single lamina but in fatty people in the region of groin it may be divided into two laminae. Beneath the fatty layer there is generally another layer of superfacial fascia which is almost devoid of fat. This stratification is also seen in the anterior abdominal wall, perineum and upper most part of thigh.

This layer contains:-

i)Trunks of subcutaneous vessels.

ii)Trunks of subcutaneous nerves.

iii) Superficial lymph nodes.

VARIATIONS IN DENSITY:

It is most distinct in the following regions:
1.Lower part of anterior abdominal wall (numerous elastin fibres).
2.Perineum
3.Limbs
It is very dense in following regions:
i) Scalp

ii)Palm of the hand

iii)Sole of the foot

In these regions it forms a fibro-fatty layer which binds the skin
firmly to underlying structures.

• It is very thin in the following regions:

i) Dorsal aspect of hands and feet.
ii)On the side of the neck.
iii)In face (No deep fascia at all).
iv) Around the arms.

CONTENTS:

1.Subcutaneous vessels going to the skin.
2.Subcutaneous nerves going to the skin.
3.Certain muscles, e.g.,Platysma in the neck.
4.Muscles of facial expression.
5.Superficial lymph vessels and lymph nodes.

FAT DISTRIBUTION:

1.The distribution is more uniform and thick in females than in the males.
2.It is absent in:
i)Penis
ii)Scrotum
iii)External Ear
iv) Eye lids.
3.It is seen in large quantities at following places:
i) Buttocks
ii)Flanks
iii) Mammary Glands
iv)Anterior abdominal wall below the umbilicus
v) Cervico-thoracic region
vi)Post deltoid region

FUNCTIONS:

1.It binds the skin with deeper structures.
2.It serves as a soft bed for the passage of vessels and nerves to the skin.
3.It retains the warmth since it contains fat which is a bad conductor of heat.
4.It facilitates the movements of the skin.


They help to connect the muscles with bones and cartilages which are to be moved, e.g., aponeurosis of external oblique muscle of abdomen, bicipital aponeurosis of biceps brachii muscle of the upper limb.

FASCIAE:

These are fibro-areolar membranous laminae or sheets of variable thickness and strength found in all regions of the body investing the softer and more delicate structures.

DEVELOPMENT:

Mesoderm differentiates to form the bones, muscles and vessels. The cells of the mesoderm which are spared are utilized for the formation of following structures :-
i)Investment of bones.
ii)Investment of muscles.
iii)Investment of blood vessels.
iv)Fasciae
v)Dermis of skin.

TYPES:

• Superficial fascia.
• Deep Fascia.