A fascia (; plural fasciae or fascias; adjective fascial; from

Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...

: "band") is a band or sheet of

connective tissue Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tiss ...

, primarily

collagen Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whol ...

, beneath the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

that attaches to, stabilizes, encloses, and separates

muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of mus ...

s and other internal organs. Fascia is classified by layer, as superficial fascia,

deep fascia Deep fascia (or investing fascia) is a fascia, a layer of dense connective tissue that can surround individual muscles and groups of muscles to separate into fascial compartments. This fibrous connective tissue interpenetrates and surrounds the ...

, and ''visceral'' or ''parietal'' fascia, or by its function and anatomical location. Like

ligament A ligament is the fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the: * Peritoneal l ...

s, aponeuroses, and

tendon A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...

s, fascia is made up of

fibrous connective tissue Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tissue is ...

containing closely packed bundles of collagen fibers oriented in a wavy pattern parallel to the direction of pull. Fascia is consequently flexible and able to resist great unidirectional tension forces until the wavy pattern of fibers has been straightened out by the pulling force. These collagen fibers are produced by

fibroblast A fibroblast is a type of biological cell that synthesizes the extracellular matrix and collagen, produces the structural framework ( stroma) for animal tissues, and plays a critical role in wound healing. Fibroblasts are the most common cells ...

s located within the fascia. Fasciae are similar to ligaments and tendons as they have collagen as their major component. They differ in their location and function: ligaments join one

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

to another bone, tendons join muscle to bone, and fasciae surround muscles and other structures.

Structure

There exists some controversy about what structures are considered "fascia", and how types of fascia should be classified. The two most common systems are: * The one specified in the 1983 edition of

Nomina Anatomica ''Nomina Anatomica'' (''NA'') was the international standard on human anatomic terminology from 1895 until it was replaced by '' Terminologia Anatomica'' in 1998. In the late nineteenth century some 30,000 terms for various body parts were in us ...

(NA 1983) * The one specified in the 1997 edition of

Terminologia Anatomica ''Terminologia Anatomica'' is the international standard for human anatomical terminology. It is developed by the Federative International Programme on Anatomical Terminology, a program of the International Federation of Associations of Anatomi ...

(TA 1997)

Superficial fascia

Superficial fascia is the lowermost layer of the

in nearly all of the regions of the body, that blends with the reticular dermis layer. It is present on the face, over the upper portion of the

sternocleidomastoid The sternocleidomastoid muscle is one of the largest and most superficial cervical muscles. The primary actions of the muscle are rotation of the head to the opposite side and flexion of the neck. The sternocleidomastoid is innervated by the access ...

, at the nape of the

neck The neck is the part of the body on many vertebrates that connects the head with the torso. The neck supports the weight of the head and protects the nerves that carry sensory and motor information from the brain down to the rest of the body. In ...

, and overlying the breastbone. It consists mainly of loose areolar, and fatty adipose

and is the layer that primarily determines the shape of a body. In addition to its subcutaneous presence, superficial fascia surrounds organs and

glands In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream ( endocrine gland) or into cavities inside the body or its outer surface ( exocrine gland). Structure ...

neurovascular bundle A neurovascular bundle is a structure that binds nerves and veins (and in some cases arteries and lymphatics) with connective tissue so that they travel in tandem through the body. Structure There are two types of neurovascular bundles: superficia ...

s, and is found at many other locations where it fills otherwise unoccupied space. It serves as a storage medium of fat and

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...

; as a passageway for

lymph Lymph (from Latin, , meaning "water") is the fluid that flows through the lymphatic system, a system composed of lymph vessels (channels) and intervening lymph nodes whose function, like the venous system, is to return fluid from the tissues ...

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the ...

and

blood vessels The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away f ...

; and as a protective padding to cushion and insulate. Superficial fascia is present, but does not contain fat, in the eyelid, ear,

scrotum The scrotum or scrotal sac is an anatomical male reproductive structure located at the base of the penis that consists of a suspended dual-chambered sac of skin and smooth muscle. It is present in most terrestrial male mammals. The scrotum co ...

penis A penis (plural ''penises'' or ''penes'' () is the primary sexual organ that male animals use to inseminate females (or hermaphrodites) during copulation. Such organs occur in many animals, both vertebrate and invertebrate, but males d ...

and

clitoris The clitoris ( or ) is a female sex organ present in mammals, ostriches and a limited number of other animals. In humans, the visible portion – the glans – is at the front junction of the labia minora (inner lips), above the op ...

. Due to its viscoelastic properties, superficial fascia can stretch to accommodate the deposition of adipose that accompanies both ordinary and

prenatal Prenatal development () includes the development of the embryo and of the fetus during a viviparous animal's gestation. Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal devel ...

weight gain. After

pregnancy Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but ...

and weight loss, the superficial fascia slowly reverts to its original level of tension.

Visceral fascia

Visceral fascia (also called subserous fascia) suspends the organs within their cavities and wraps them in layers of connective tissue

membranes A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. Bi ...

. Each of the organs is covered in a double layer of fascia; these layers are separated by a thin serous membrane. * The outermost wall of the organ is known as the parietal layer * The skin of the organ is known as the visceral layer. The organs have specialized names for their visceral fasciae. In the brain, they are known as meninges; in the heart they are known as pericardia; in the lungs, they are known as pleurae; and in the abdomen, they are known as peritonea. Visceral fascia is less extensible than superficial fascia. Due to its suspensory role of the organs, it needs to maintain its tone rather consistently. If it is too lax, it contributes to organ prolapse, yet if it is

hypertonic In chemical biology, tonicity is a measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a partially-permeable cell membrane. Tonicity depends on the relative concentration of selective membrane- ...

, it restricts proper organ

motility Motility is the ability of an organism to move independently, using metabolic energy. Definitions Motility, the ability of an organism to move independently, using metabolic energy, can be contrasted with sessility, the state of organisms th ...

Deep fascia

Deep fascia is a layer of dense fibrous connective tissue which surrounds individual

s, and also divides groups of muscles into fascial compartments. This fascia has a high density of

elastin Elastin is a protein that in humans is encoded by the ''ELN'' gene. Elastin is a key component of the extracellular matrix in gnathostomes (jawed vertebrates). It is highly elastic and present in connective tissue allowing many tissues in the bo ...

fibre that determines its extensibility or resilience. Deep fascia was originally considered to be essentially avascular but later investigations have confirmed a rich presence of thin blood vessels. Deep fascia is also richly supplied with

sensory receptor Sensory neurons, also known as afferent neurons, are neurons in the nervous system, that convert a specific type of stimulus, via their receptors, into action potentials or graded potentials. This process is called sensory transduction. The ...

s. Examples of deep fascia are

fascia lata The fascia lata is the deep fascia of the thigh. It encloses the thigh muscles and forms the outer limit of the fascial compartments of thigh, which are internally separated by the medial intermuscular septum and the lateral intermuscular sep ...

fascia cruris The deep fascia of leg, or crural fascia forms a complete investment to the muscles, and is fused with the periosteum over the subcutaneous surfaces of the bones. The deep fascia of the leg is continuous above with the fascia lata (deep fascia o ...

brachial fascia The brachial fascia (deep fascia of the arm) is continuous with that covering the deltoideus and the pectoralis major muscle, by means of which it is attached, above, to the clavicle, acromion, and spine of the scapula; it forms a thin, loose, me ...

plantar fascia The plantar fascia is the thick connective tissue (aponeurosis) which supports the arch on the bottom (plantar side) of the foot. It runs from the tuberosity of the calcaneus (heel bone) forward to the heads of the metatarsal bones (the bone b ...

, thoracolumbar fascia and Buck's fascia.

Function

Fasciae were traditionally thought of as passive structures that transmit mechanical tension generated by muscular activities or external forces throughout the body. An important function of muscle fasciae is to reduce friction of muscular force. In doing so, fasciae provide a supportive and movable wrapping for nerves and blood vessels as they pass through and between muscles. Fascial tissues are frequently innervated by sensory nerve endings. These include myelinated as well as unmyelinated nerves. Based on this a proprioceptive, nociceptive as well as

interoceptive Interoception is contemporarily defined as the collection of senses perceiving the internal state of the body. This can be both conscious and unconscious. It encompasses the brain's process of integrating signals relayed from the body into specif ...

function of fascia has been postulated. Fascial tissues – particularly those with tendinous or aponeurotic properties – are also able to store and release elastic potential energy.

Clinical significance

Fascia becomes important clinically when it loses stiffness, becomes too stiff, or has decreased shearing ability. When inflammatory fasciitis or trauma causes fibrosis and adhesions, fascial tissue fails to differentiate the adjacent structures effectively. This can happen after surgery, where the fascia has been incised and healing includes a

scar A scar (or scar tissue) is an area of fibrous tissue that replaces normal skin after an injury. Scars result from the biological process of wound repair in the skin, as well as in other organs, and tissues of the body. Thus, scarring is a ...

that traverses the surrounding structures.

Anatomical compartments

A fascial compartment is a section within the body that contains muscles and nerves and is surrounded by fascia. In the

human body The human body is the structure of a human being. It is composed of many different types of cells that together create tissues and subsequently organ systems. They ensure homeostasis and the viability of the human body. It comprises a hea ...

, the limbs can each be divided into two segments: The

upper limb The upper limbs or upper extremities are the forelimbs of an upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digits, including all the musculatures and ligaments involved with the shou ...

can be divided into the arm and the

forearm The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is most often used to describe the entire appendage of the upper limb, but which in ...

and the sectional compartments of both of these – the fascial compartments of the arm and the fascial compartments of the forearm contain an anterior and a posterior compartment. The lower limbs can be divided into two segments – the leg and the thigh – and these contain the fascial compartments of the leg and the fascial compartments of the thigh. A

fasciotomy Fasciotomy or fasciectomy is a surgical procedure where the fascia is cut to relieve tension or pressure in order to treat the resulting loss of circulation to an area of tissue or muscle. Fasciotomy is a limb-saving procedure when used to tre ...

may be used to relieve compartment syndrome as a result of high pressure within a fascial compartment.

References

External links

Fascia Research
* {{Authority control Connective tissue