The human back, also called the dorsum, is the large posterior area of the

human body The human body is the structure of a Human, human being. It is composed of many different types of Cell (biology), cells that together create Tissue (biology), tissues and subsequently organ systems. They ensure homeostasis and the life, viabi ...

, rising from the top of the

buttock The buttocks (singular: buttock) are two rounded portions of the exterior anatomy of most mammals, located on the posterior of the pelvic region. In humans, the buttocks are located between the lower back and the perineum. They are composed ...

s to the back 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 ...

. It is the

surface A surface, as the term is most generally used, is the outermost or uppermost layer of a physical object or space. It is the portion or region of the object that can first be perceived by an observer using the senses of sight and touch, and is t ...

of the body opposite from the

chest The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the crea ...

and the

abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...

. The

vertebral column The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordata, ...

runs the length of the back and creates a central area of recession. The breadth of the back is created by the

shoulder The human shoulder is made up of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone) as well as associated muscles, ligaments and tendons. The articulations between the bones of the shoulder mak ...

s at the top and the

pelvis The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The ...

at the bottom.

Back pain Back pain is pain felt in the back. It may be classified as neck pain (cervical), middle back pain (thoracic), lower back pain (lumbar) or coccydynia (tailbone or sacral pain) based on the segment affected. The lumbar area is the most common area ...

is a common medical condition, generally benign in origin.

Structure

The central feature of the human back is the

, specifically the length from the top of the

thoracic vertebrae In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebra (anatomy), vertebrae and they are intermediate in size b ...

to the bottom of the

lumbar vertebrae The lumbar vertebrae are, in human anatomy, the five vertebrae between the rib cage and the pelvis. They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse p ...

, which houses the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spi ...

in its

spinal canal The spinal canal (or vertebral canal or spinal cavity) is the canal that contains the spinal cord within the vertebral column. The spinal canal is formed by the vertebrae through which the spinal cord passes. It is a process of the dorsal body ca ...

, and which generally has some curvature that gives shape to the back. The ribcage extends from the spine at the top of the back (with the top of the ribcage corresponding to the T1

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

), more than halfway down the length of the back, leaving an area with less protection between the bottom of the ribcage and the hips. The width of the back at the top is defined by the

scapula The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on eithe ...

, the broad, flat bones of the shoulders. Gray204.png, View of the bones of the thorax and shoulders from behind. Back Muscles.jpg, Posterior view of muscles connecting the upper extremity to the vertebral column.
A Trapezius
B Teres Major
C Teres Minor
D Latissimus Dorsi
E Levator Scapulae
F Rhomboid Major Gray798-back crop.png, Distribution of

cutaneous nerve A cutaneous nerve is a nerve that provides nerve supply to the skin. Human anatomy In human anatomy, cutaneous nerves are primarily responsible for providing sensory innervation to the skin. In addition to sympathetic and autonomic afferent (sens ...

s, dorsal aspect. Dorsal and lateral cutaneous branches labeled at center right.

Muscles

The muscles of the back can be divided into three distinct groups; a superficial group, an intermediate group and a deep group.

Superficial group

The superficial group, also known as the appendicular group, is primarily associated with movement of the appendicular skeleton. It is composed of

trapezius The trapezius is a large paired trapezoid-shaped surface muscle that extends longitudinally from the occipital bone to the lower thoracic vertebrae of the spine and laterally to the spine of the scapula. It moves the scapula and supports the ...

latissimus dorsi The latissimus dorsi () is a large, flat muscle on the back that stretches to the sides, behind the arm, and is partly covered by the trapezius on the back near the midline. The word latissimus dorsi (plural: ''latissimi dorsorum'') comes from L ...

rhomboid major The rhomboid major is a skeletal muscle on the back that connects the scapula with the vertebrae of the spinal column. In human anatomy, it acts together with the rhomboid minor to keep the scapula pressed against thoracic wall and to retract the ...

rhomboid minor In human anatomy, the rhomboid minor is a small skeletal muscle on the back that connects the scapula with the vertebrae of the spinal column. Located inferior to levator scapulae and superior to rhomboid major, it acts together with the latter ...

and

levator scapulae The levator scapulae is a slender skeletal muscle situated at the back and side of the neck. As the Latin name suggests, its main function is to lift the scapula. Anatomy Attachments The muscle descends diagonally from its origin to its inserti ...

. It is innervated by anterior rami of spinal nerves, reflecting its embryological origin outside the back.

Intermediate group

The intermediate group is also known as respiratory group as it may serve a respiratory function. It is composed of

serratus posterior superior The serratus posterior superior muscle is a thin, quadrilateral muscle. It is situated at the upper back part of the thorax, deep to the rhomboid muscles. Structure The serratus posterior superior muscle arises by an aponeurosis from the l ...

and

serratus posterior inferior The serratus posterior inferior muscle, also known as the posterior serratus muscle, is a muscle of the human body. Structure The muscle is situated at the junction of the thoracic and lumbar regions. It has an irregularly quadrilateral form, b ...

. Like the superficial group, it is innervated by anterior rami of spinal nerves.

Deep group

The deep group, also known as the intrinsic group due to its embryological origin in the back, can be further subdivided into four groups: * Spinotransversales - composed of

splenius capitis The splenius capitis () () is a broad, straplike muscle in the back of the neck. It pulls on the base of the skull from the vertebrae in the neck and upper thorax. It is involved in movements such as shaking the head. Structure It arises from th ...

and splenius cervicis. *

Erector spinae The erector spinae ( ) or spinal erectors is a set of muscles that straighten and rotate the back. The spinal erectors work together with the glutes (gluteus maximus, gluteus medius and gluteus minimus) to maintain stable posture standing or sittin ...

- composed of

iliocostalis Iliocostalis muscle is the muscle immediately lateral to the longissimus that is the nearest to the furrow that separates the epaxial muscles from the hypaxial. It lies very deep to the fleshy portion of the serratus posterior muscle. It lateral ...

, longissismus and

spinalis The spinalis is a portion of the erector spinae, a bundle of muscles and tendons, located nearest to the spine. It is divided into three parts: Spinalis dorsi, spinalis cervicis, and spinalis capitis. Spinalis dorsi Spinalis dorsi, the medial co ...

Transversospinales The transversospinales are a group of muscles of the human back. Their combined action is rotation and extension of the vertebral column. These muscles are small and have a poor mechanical advantage for contributing to motion. They include: * the ...

- composed of semispinalis,

multifidus The multifidus (multifidus spinae : ''pl. multifidi'' ) muscle consists of a number of fleshy and tendinous fasciculi, which fill up the groove on either side of the spinous processes of the vertebrae, from the sacrum to the axis. While very thin ...

and rotatores * Segmental muscles - composed of

levatores costarum The ''Levatores costarum'' (), twelve in number on either side, are small tendinous and fleshy bundles, which arise from the ends of the transverse processes of the seventh cervical and upper eleven thoracic vertebrae They pass obliquely downward ...

, interspinales and

intertransversarii The intertransversarii are small muscles placed between the transverse processes of the vertebrae. Structure Cervical In the cervical region they are best developed, consisting of rounded muscular and tendinous fasciculi, and are placed in pairs, ...

The deep group is innervated by the posterior rami of spinal nerves.

Organs near the back

The

lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...

s are within the ribcage, and extend to the back of the ribcage making it possible for them to be listened into through the back. The

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...

s are situated beneath the muscles in the area below the end of the ribcage, loosely connected to the

peritoneum The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesoth ...

. A strike to the lower back can damage the kidneys of the person being hit.

Surface of the back

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 cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...

of the human back is thicker and has fewer nerve endings than the skin on any other part of the torso. With some notable exceptions (see, e.g.

George "The Animal" Steele William James Myers (April 16, 1937 – February 16, 2017), better known by his ring name George "The Animal" Steele, was an American professional wrestler, school teacher, author, and actor. His career lasted from 1967 until 1988, though he mad ...

), it tends to have less hair than the chest on men. The upper-middle back is also the one area of the body which a typical human under normal conditions might be unable to physically touch. The skin of the back is innervated by the ''dorsal cutaneous

branches A branch, sometimes called a ramus in botany, is a woody structural member connected to the central trunk of a tree (or sometimes a shrub). Large branches are known as boughs and small branches are known as twigs. The term ''twig'' usually ...

'', as well as the ''lateral abdominal cutaneous branches of

intercostal nerve The intercostal nerves are part of the somatic nervous system, and arise from the anterior rami of the thoracic spinal nerves from T1 to T11. The intercostal nerves are distributed chiefly to the thoracic pleura and abdominal peritoneum, and diffe ...

s''.

Movement

The intricate anatomy of the back provides support for the head and trunk of the body, strength in the trunk of the body, as well as a great deal of flexibility and movement. The upper back has the most structural support, with the ribs attached firmly to each level of the thoracic spine and very limited movement. The lower back (lumbar vertebrae) allows for flexibility and movement in back bending (extension) and forward bending (flexion). It does not permit twisting.

Clinical significance

Back pain

The back comprises interconnecting nerves, bones, muscles, ligaments, and tendons, all of which can be a source of pain.

is the second most common type of pain in adults (the most common being headaches). By far the most common cause of back pain is muscle strain. The back muscles can usually heal themselves within a couple of weeks, but the pain can be intense and debilitating. Other common sources of back pain include disc problems, such as

degenerative disc disease Degenerative disc disease (DDD) is a medical condition typically brought on by the normal aging process in which there are anatomic changes and possibly a loss of function of one or more intervertebral discs of the spine. DDD can take place with ...

or a

lumbar In tetrapod anatomy, lumbar is an adjective that means ''of or pertaining to the abdominal segment of the torso, between the diaphragm and the sacrum.'' The lumbar region is sometimes referred to as the lower spine, or as an area of the back i ...

disc herniation Spinal disc herniation is an injury to the cushioning and connective tissue between vertebrae, usually caused by excessive strain or trauma to the spine. It may result in back pain, pain or sensation in different parts of the body, and physical ...

, many types of fractures, such as

spondylolisthesis Spondylolisthesis is the displacement of one spinal vertebra compared to another. While some medical dictionaries define spondylolisthesis specifically as the forward or anterior displacement of a vertebra over the vertebra inferior to it (or t ...

or an osteoporotic fracture, or

osteoarthritis Osteoarthritis (OA) is a type of degenerative joint disease that results from breakdown of joint cartilage and underlying bone which affects 1 in 7 adults in the United States. It is believed to be the fourth leading cause of disability in the w ...

Society and culture

Cicatrices de flagellation sur un esclave

The curvature of the female back is a frequent theme in paintings, because the sensibilities of many cultures permit the back to be shown nude - implying full nudity without actually displaying it. Indeed, the practice of showing explicitness on the lower back has been performed for centuries. Certain articles of clothing, such as the

haltertop Halterneck is a style of women's clothing strap that runs from the front of the garment around the back of the neck, generally leaving the upper back uncovered. The name comes from livestock halters. The word "halter" derives from the Germanic w ...

and the

backless dress A backless dress is a style of women’s clothing designed to expose the wearer's human back, back. The back may be either partially exposed with a low cut or fully exposed with the use of strings. A backless dress is most commonly worn on formal ...

, are designed to expose the back in this manner. The lower back is typically exposed frequently by many types of shirts in woman's fashion, and even the more conservative shirts and blouses will reveal the lower back. This happens for a variety of reasons- the lower waist area is a pivot point for the body and lengthens and arches as a person sits or bends. Secondly, woman's fashion typically favors tops that are waist length, allowing the back to be left bare during slight movement, bending or sitting. The back also serves as the largest

canvas Canvas is an extremely durable plain-woven fabric used for making sails, tents, marquees, backpacks, shelters, as a support for oil painting and for other items for which sturdiness is required, as well as in such fashion objects as handbags ...

for

body art Body art is art made on, with, or consisting of, the human body. Body art covers a wide spectrum including tattoos, body piercings, scarification, and body painting. Body art may include performance art, body art is likewise utilized for investiga ...

on the human body. Because of its size and the relative lack of hair, the back presents an ideal canvas on the human body for

lower back tattoo Tattoos on the lower back became popular in the first decade of the 21st century, and gained a reputation for their erotic appeal. The tattoos were sometimes accentuated by low-rise jeans or crop tops. Their popularity was in part due to the i ...

s, mostly among young women. Indeed, some individuals have

tattoo A tattoo is a form of body modification made by inserting tattoo ink, dyes, and/or pigments, either indelible or temporary, into the dermis layer of the skin to form a design. Tattoo artists create these designs using several Process of tatt ...

s that cover the entirety of the back. Others have smaller tattoos at significant locations, such as the shoulder blade or the bottom of the back. Many

English English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national ide ...

idiom An idiom is a phrase or expression that typically presents a figurative, non-literal meaning attached to the phrase; but some phrases become figurative idioms while retaining the literal meaning of the phrase. Categorized as formulaic language, ...

s mention the back, usually highlighting it as an area of vulnerability; one must "watch one's back", or one may end up "with one's back up against the wall"; worse yet, someone may "stab one in the back", but hopefully a friend "has got one's back". The back is also a symbol of strength and hard work, with those seeking physical labor looking for "strong backs", and workers being implored to "put their back into it". Historically,

flagellation Flagellation (Latin , 'whip'), flogging or whipping is the act of beating the human body with special implements such as whips, rods, switches, the cat o' nine tails, the sjambok, the knout, etc. Typically, flogging has been imposed on ...

of a person across the back with a whip was both a common form of

punishment Punishment, commonly, is the imposition of an undesirable or unpleasant outcome upon a group or individual, meted out by an authority—in contexts ranging from child discipline to criminal law—as a response and deterrent to a particular acti ...

of criminals, and a common means of forcing slaves to work. As well, self-flagellation, as in self punishment, may include the use of whipping oneself. This is one method of mortification, the practice of inflicting physical suffering on oneself with the religious belief that it will serve as penance for one's own sins or those of others. While more moderate forms of mortification are widely practiced—particularly in the Catholic Church—self flagellation is not encouraged by mainstream religions or religious leaders. A well-known instrument used for flagellations is the infamous

Cat 'o Nine Tails The cat o' nine tails, commonly shortened to the cat, is a type of multi-tailed whip or flail that originated as an implement for severe physical punishment, notably in the Royal Navy and British Army, and as a judicial punishment in Britain ...

, a nine-corded whip with one handle enabling a much more effective whipping than would be possible with only one lashing at a time.

References

{{DEFAULTSORT:Back, human

Back The human back, also called the dorsum, is the large posterior area of the human body, rising from the top of the buttocks to the back of the neck. It is the surface of the body opposite from the chest and the abdomen. The vertebral column run ...