Anatomy and Physiology of the
Integumentary System
Definition: Integument
[L.integumentum, a covering]. A
covering consisting of the corium or
dermis, and epidermis. The
integumentary system includes the
skin and its appendages, including
the hair and nails.
Tabers Cyclopedic Medical Dictionary 14th edition
Integument
Epidermal layers
Epidermal-dermal junction: also known as the basement
membrane. At this junction there is an exchange of cells
and fluid between the dermis and epidermis. The
epidermis normally does not contain blood vessels or
nerves. The skin usually ranges from 1 1/2 to 4 mm. thick
and the epidermis makes up about 1/10 of a millimeter.
However the keratin layer can increase to about 1 mm on
the palms and soles. The epidermis and dermis are bound
together by a series of projections that grow up (dermal
papillae) and down (rete ridges), which interface with each
other.
Dermis: There are two layers - the papillary and reticular layers.
The dermis underlies the epidermis and consists of a
mucopolysaccharide matrix in which collagenic and reticular
fibers are found. The dermis contains the blood vessels and
nerves as well as the nutrient supply to the deeper living layers
of the epidermis. The blood vessels here play an important role
in the regulation of body temperature. The nerve fibers are
scattered throughout the dermis. Some of them (motor fibers)
carry impulses to dermal muscles and glands, causing these
structures to react. Others (sensory fibers) carry impulses away
from specialized sensory receptors located within the dermis.
One set of dermal receptors (Pacinian corpuscles) is stimulated
by heavy pressure, while another set (Meissner’s corpuscles) is
sensitive to light touch. Still other receptors are stimulated by
temperature changes or factors that can damage tissues.
Oil and sweat glands
Hair Structure
Nail Structure
Anatomical Structures Not Part of the Integumentary System
Fascia: Shiny or dull, usually white fibrous tissue. This is a firm tissue that separates
tissue planes. Muscle is usually just underneath the fascia. Infection can spread along
fascial planes - necrotizing fasciitis.
Muscle: Dull or beefy red in color. Highly vascular - has blood vessel supply. Fibers can
tear. Tendons are usually connected to muscle with bone underneath.
Tendon: Elastic fibers, white in color, may be shiny. Often times covered with a layer of
thin tissue- paratenon. This is the vascular layer of tendon. Otherwise, tendons are not
very vascular. Tendon attaches muscle to bone. Can cross over joints.
Bone: Hard, bright white. May however be yellowish in color depending on if it has been
exposed to air and the presence of necrotic or infected tissue. The outer layer of bone is
called the periosteum.
Joints: Cartilage is present which is a gleaming, shiny white material in healthy joints.
Joint spaces are enveloped in joint capsule which is a thin, fibrous material. Once
entered, there is synovial fluid which is typically a slightly viscous, almost straw colored
fluid. Cartilage is not vascular and has no innervations.
Blood Vessels: Tubular shaped structures which contain blood and provide nutrients for
adjacent tissues as well as return blood to the heart and lungs. May or may not be
pulsatile.
Connective tissue that cushions articular surfaces of bone. Typically clean,
white and shiny. Poor vascularity.