124 MUSCLE TISSUE 



skin and fascia. They are not supplied by nerves, and 

 possess a meager blood-supply. 



Fasciae. When the skin is removed the structure 

 beneath will appear as a silvery-white layer through 

 which are seen the muscles, and contained superficial 

 nerves and bloodvessels. This is known as the fascia 

 which covers the muscles as a sheath, also forms 

 support and coverings for the various organs. It 

 consists of layers of fibro-areolar connective tissue. 

 In certain parts of the body the fascia is found in 

 two layers superficial and deep and often three, as 

 the thigh. Certain muscles are lodged in the layers 

 of fasciae, as the platysma muscle in the neck, and 

 the orbicularis palpebrarum muscle around the eye- 

 lids. The deep fascia usually forms sheaths for the 

 individual muscles of an extremity, as in the thigh, 

 where the membrane encloses it as a stocking; this 

 arrangement increases the tension and pressure, thus 

 assisting the muscles in their action. In addition the 

 deep fascia gives off septa or walls which separate 

 the muscles of the limbs, and are deeply attached to 

 the periosteum of the bone; these are called intermuscu- 

 lar septa. Near the wrist-joint the deep fascia becomes 

 thickened and reinforced by transverse fibers to assist 

 in holding in firm position (front and back) the tendons 

 passing to the hand and fingers; also near the ankle- 

 joint is a similar arrangement for the tendons passing 

 to the foot and toes. They are called annular ligaments. 



Description. 1 The description of a muscle includes: 

 the location, origin, insertion, relations, action, nerve, 

 and blood-supply. 



THE MUSCLES OF THE HEAD AND NECK 



The Cranial Region or Scalp. The scalp consists, 

 from without inward, of the skin, a layer of adipose 



1 The most important muscles only will be described. 



