SKIN AND FASCIA
I. LAYERS OF SKIN
A. Epidermis - stratified squamous epithelium, keratinizing
B. Dermis - dense, irregular connective tissue
1. papillary layer: just deep to epidermis
2. reticular layer: deepest layer of the dermis
a. fibers in the reticular layer tend to run in the same direction in any area of the skin. These directional patterns are called Langer’s lines or cleavage planes. They are important since a cut across them scars more than cut paralleling them.
C. Functions
1. Sensory
2. Protective
3. Temperature regulation
4. Excretory
5. Absorptive
D. Subcutaneous connective tissue = hypodermis (rarely used term), contains fat, blood vessels, hair follicles, nerves
II. FASCIA
A. Fascia by definition, is an apparent plane of fibrous connective tissue, often adjacent to or surrounding a structure.
B. Fascial planes are not always obvious or dissectable. They are often defined by the spread of infections since intact planes can sometimes check infections, or influence the direction in which they spread
C. Superficial fascia
1. loose connective tissue between the dermis and the deep fascia or bone
2. oftentimes fat accumulates in this layer
3. other names for superficial fascia
a. hypodermis
b. tela subcutanea
c. subcutaneous tissue
d. panniculus adiposis (in locations where it accumulates fat)
4. sometimes divided into
a. fatty layer (Camper’s fascia on abdominal wall)
b. membranous layer - deep to fatty layer, called Scarpa’s fascia on abdominal wall
D. Deep fascia (muscular fascia)
1. thin, dense layer of C.T. deep to the superficial fascia and closely investing the body wall and limbs
2. sometimes named by the muscle immediately deep to it or by its general location (i.e. pectoral fascia on the chest; brachial fascia on the arm)
3. whenever it passes immediately over bone it fuses with the bone
III. SPECIALIZATIONS OF SKIN
A. Hair follicles and hair - extends slightly into hypodermis from dermis and epidermis
B. Sebaceous glands - associated with hair follicles generally
C. Sweat glands - often extend into hypodermis, open on surface of epidermis
D. Nails