Human Anatomy Lecture 3: Skin

Study Notes

Divided into two parts: epidermis (superficial) and dermis (deep)
Epidermis is a stratified epithelium; thick on palms and soles to withstand wear and tear
Dermis is composed of dense connective tissue containing blood vessels, lymphatic vessels, and nerves
Connected to underlying deep fascia or bones by superficial fascia (subcutaneous tissue)
Appendages of skin include nails, hair follicles, sebaceous glands, and sweat glands

Two types: superficial and deep
Superficial fascia (subcutaneous tissue) is a mixture of loose areolar and adipose tissue
Deep fascia is a membranous layer of connective tissue investing muscles and other deep structures
In neck, forms well-defined layers; in thorax and abdomen, a thin film of areolar tissue covering muscles and aponeuroses

Produce movements of skeleton; sometimes called voluntary muscles
Made up of striped muscle fibers
A skeletal muscle has two or more attachments: origin (moves least) and insertion (moves most)
Attachments may be reversed; terms origin and insertion are interchangeable
Fleshy part of muscle is referred to as its belly
Ends of a muscle are attached to bones, cartilage, or ligaments by tendons or aponeurosis
Raphe is an interdigitation of tendinous ends of fibers of flat muscles
Skeletal muscle action:
- Prime mover: chief muscle or member of a chief group of muscles responsible for a particular movement
- Antagonist: opposes the action of the prime mover
- Fixator: contracts isometrically to stabilize the origin of the prime mover
- Synergist: contracts to stabilize intermediate joints, allowing prime mover to act on main joint

Consists of long, spindle-shaped cells closely arranged in bundles or sheets
Provides motive power for propelling contents through lumen in tubes of the body
Causes ingested food to be thoroughly mixed with digestive juices in digestive system
Fibers are irregularly arranged and interlaced; contraction is slow and sustained
Found in walls of blood vessels, serving to modify the caliber of the lumen

Consists of striated muscle fibers that branch and unite with each other
Forms the myocardium of the heart
Fibers tend to be arranged in whorls and spirals, with property of spontaneous and rhythmic contraction

A site where two or more bones come together, whether or not movement occurs between them
Classified according to tissues between bones: fibrous, cartilaginous, and synovial joints

Articulating surfaces of bones joined by fibrous tissue, allowing very little movement
Example: sutures of the vault of the skull

Bones united by a plate of fibrocartilage; articular surfaces covered by a thin layer of hyaline cartilage
Small amount of movement is possible
Example: joints between vertebral bodies

Articular surfaces of bones covered by a thin layer of hyaline cartilage, separated by a joint cavity
Allows a great degree of freedom of movement
Cavity of joint is lined by synovial membrane, which extends from margins of one articular surface to those of the other
Protected on the outside by a tough fibrous membrane referred to as the capsule of the joint
Articular surfaces lubricated by synovial fluid, produced by synovial membrane
Discs or wedges of fibrocartilage (articular discs) may be interposed between articular surfaces of bones

A cord or band of connective tissue uniting two structures
Commonly found in association with joints
Two types: dense bundles of collagen fibers (unstretchable) and elastic tissues (can regain original length after stretching)

A lubricating device consisting of a closed fibrous sac lined with a smooth membrane
Walls separated by a film of viscous fluid
Found wherever tendons rub against bones, ligaments, or other tendons
Commonly found close to joints where skin rubs against underlying bony structures