Buttocks

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Buttocks
Human buttocks.jpg
Buttocks of a human female (upper) and a human male (lower)
Details
Artery Superior gluteal artery, inferior gluteal artery
Nerve Superior gluteal nerve, inferior gluteal nerve, superior cluneal nerves, medial cluneal nerves, inferior cluneal nerves
Identifiers
Latin clunis
MeSH D002081
TA98 A01.1.00.033
A01.2.08.002
TA2 157
FMA 76446
Anatomical terminology

The buttocks (SG: 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 of a layer of exterior skin and underlying subcutaneous fat superimposed on a left and right gluteus maximus and gluteus medius muscles. The two gluteus maximus muscles are the largest muscles in the human body. They are responsible for movements such as straightening the body into the upright (standing) posture when it is bent at the waist; maintaining the body in the upright posture by keeping the hip joints extended; and propelling the body forward via further leg (hip) extension when walking or running. [1]

Contents

In many cultures, the buttocks play a role in sexual attraction. [2] Many cultures have also used the buttocks as a primary target for corporal punishment, [3] as the buttocks' layer of subcutaneous fat offers protection against injury while still allowing for the infliction of pain.

Anatomy

The buttocks are formed by the masses of the gluteal muscles or "glutes" (the gluteus maximus muscle and the gluteus medius muscle) superimposed by a layer of fat. The superior aspect of the buttock ends at the iliac crest, and the lower aspect is outlined by the horizontal gluteal crease. The gluteus maximus has two insertion points: 13 superior portion of the linea aspera of the femur, and the superior portion of the iliotibial tractus. The masses of the gluteus maximus muscle are separated by an intermediate intergluteal cleft or "crack" in which the anus is situated.

The buttocks allow primates to sit upright without resting their weight on their feet as four-legged animals do. Females of certain species of baboon have red buttocks that blush to attract males. In the case of humans, females tend to have proportionally wider and thicker buttocks due to higher subcutaneous fat and proportionally wider hips. In humans they also have a role in propelling the body in a forward motion and aiding bowel movement. [4] [5]

Some baboons and all gibbons, though otherwise fur-covered, have characteristic naked callosities on their buttocks. While human children generally have smooth buttocks, mature males and females have varying degrees of hair growth, as on other parts of their body. Females may have hair growth in the gluteal cleft (including around the anus), sometimes extending laterally onto the lower aspect of the cheeks. Males may have hair growth over some or all of the buttocks.

Names

A burlesque stage show with three men in Las Vegas Stage Door Johnnies.jpg
A burlesque stage show with three men in Las Vegas
Seattle's nudist cyclists with painted buttocks Fremont naked cyclists 2007 - 59.jpg
Seattle's nudist cyclists with painted buttocks
Japanese man in a traditional swimwear Fundoshi-rokushaku Japanese traditional swimwear FUNDOSHI red rokushaku back photomodel fthong 1.jpg
Japanese man in a traditional swimwear Fundoshi-rokushaku
Posterior view of human female and male to show the comparison of their buttocks Posterior view of human female and male, without labels.jpg
Posterior view of human female and male to show the comparison of their buttocks
Some female clothing, such as the bikini or panties, show part of the female buttocks (woman on left). Thongs, in particular, leave almost all of the buttocks exposed (woman on right). Photo is of a beach in Holland, 1999. Bikini girls Holland beach 1999.jpg
Some female clothing, such as the bikini or panties, show part of the female buttocks (woman on left). Thongs, in particular, leave almost all of the buttocks exposed (woman on right). Photo is of a beach in Holland, 1999.

The Latin name for the buttocks is nates (English pronunciation /ˈntz/ NAY-teez, [6] classical pronunciation nătes [ˈnateːs] [7] ) which is plural; the singular, natis (buttock), is rarely used. There are many colloquial terms for them.

Georges Seurat's 1884 painting A Sunday Afternoon on the Island of La Grande Jatte depicts a woman on the right with a prominent bustle under her dress. Georges Seurat - A Sunday on La Grande Jatte -- 1884 - Google Art Project.jpg
Georges Seurat's 1884 painting A Sunday Afternoon on the Island of La Grande Jatte depicts a woman on the right with a prominent bustle under her dress.
Models participate in "got ass?", a competition to judge the woman with best buttocks, at AVN Adult Entertainment Expo, Las Vegas, 2014. D6B 1320 - Got Ass%3F Girls (12079087053).jpg
Models participate in "got ass?", a competition to judge the woman with best buttocks, at AVN Adult Entertainment Expo, Las Vegas, 2014.

See also

Related Research Articles

<span class="mw-page-title-main">Gluteus maximus</span> Largest and most superficial of the three gluteal muscles

The gluteus maximus is the main extensor muscle of the hip in humans. It is the largest and outermost of the three gluteal muscles and makes up a large part of the shape and appearance of each side of the hips. It is the single largest muscle in the human body. Its thick fleshy mass, in a quadrilateral shape, forms the prominence of the buttocks. The other gluteal muscles are the medius and minimus, and sometimes informally these are collectively referred to as the glutes.

<span class="mw-page-title-main">Gluteus medius</span> One of the three gluteal muscles

The gluteus medius, one of the three gluteal muscles, is a broad, thick, radiating muscle. It is situated on the outer surface of the pelvis.

<span class="mw-page-title-main">Gluteus minimus</span> Smallest of the three gluteal muscles

The gluteus minimus, or glutæus minimus, the smallest of the three gluteal muscles, is situated immediately beneath the gluteus medius.

<span class="mw-page-title-main">Greater trochanter</span> Quadrilateral part of the thigh bone

The greater trochanter of the femur is a large, irregular, quadrilateral eminence and a part of the skeletal system.

<span class="mw-page-title-main">Piriformis muscle</span> One of six small hip muscles in the lateral rotator group

The piriformis muscle is a flat, pyramidally-shaped muscle in the gluteal region of the lower limbs. It is one of the six muscles in the lateral rotator group.

<span class="mw-page-title-main">Hip</span> Anatomical region between the torso and the legs, holding the buttocks and genital region

In vertebrate anatomy, hip refers to either an anatomical region or a joint.

<span class="mw-page-title-main">Buttock augmentation</span> Cosmetic and corrective surgery

Gluteoplasty denotes the plastic surgery and the liposuction procedures for the correction of the congenital, traumatic, and acquired defects and deformities of the buttocks and the anatomy of the gluteal region; and for the aesthetic enhancement of the contour of the buttocks.

<span class="mw-page-title-main">Intergluteal cleft</span> Crack between buttocks

The intergluteal cleft or just gluteal cleft, also known by a number of synonyms, including natal cleft, butt crack, ass crack and cluneal cleft, is the groove between the buttocks that runs from just below the sacrum to the perineum, so named because it forms the visible border between the external rounded protrusions of the gluteus maximus muscles. Other names are the anal cleft, crena analis, crena interglutealis, and rima ani. Colloquially the intergluteal cleft is known as bum crack (UK) or butt crack (US). The intergluteal cleft is located superior to the anus.

<span class="mw-page-title-main">Gluteal sulcus</span> Fold separating the thigh from the buttock

The gluteal sulcus is an area of the body of humans and anthropoid apes, described by a horizontal crease formed by the inferior aspect of the buttocks and the posterior upper thigh. The gluteal sulcus is formed by the posterior horizontal skin crease of the hip joint and overlying fat and is not formed by the lower border of the gluteus maximus muscle, which crosses the fold obliquely. It is one of the major defining features of the buttocks. Children with developmental dysplasia of the hips are born with uneven gluteal folds and can be diagnosed with a physical examination and sonogram.

<span class="mw-page-title-main">Tensor fasciae latae muscle</span> Muscle of the thigh

The tensor fasciae latae is a muscle of the thigh. Together with the gluteus maximus, it acts on the iliotibial band and is continuous with the iliotibial tract, which attaches to the tibia. The muscle assists in keeping the balance of the pelvis while standing, walking, or running.

<span class="mw-page-title-main">Gluteal muscles</span> Group of three muscles which make up the buttocks

The gluteal muscles, often called glutes, are a group of three muscles which make up the gluteal region commonly known as the buttocks: the gluteus maximus, gluteus medius and gluteus minimus. The three muscles originate from the ilium and sacrum and insert on the femur. The functions of the muscles include extension, abduction, external rotation, and internal rotation of the hip joint.

<span class="mw-page-title-main">Muscles of the hip</span> Causes movement in the hip

In human anatomy, the muscles of the hip joint are those muscles that cause movement in the hip. Most modern anatomists define 17 of these muscles, although some additional muscles may sometimes be considered. These are often divided into four groups according to their orientation around the hip joint: the gluteal group; the lateral rotator group; the adductor group; and the iliopsoas group.

<span class="mw-page-title-main">Posterior cutaneous nerve of thigh</span> Sensory nerve that supplies the back of the thigh, leg, buttock, and perineum

The posterior cutaneous nerve of the thigh is a sensory nerve of the thigh. It is a branch of the sacral plexus. It supplies the skin of the posterior surface of the thigh, leg, buttock, and also the perineum.

<span class="mw-page-title-main">Inferior gluteal nerve</span>

The inferior gluteal nerve is the main motor neuron that innervates the gluteus maximus muscle. It is responsible for the movement of the gluteus maximus in activities requiring the hip to extend the thigh, such as climbing stairs. Injury to this nerve is rare but often occurs as a complication of posterior approach to the hip during hip replacement. When damaged, one would develop gluteus maximus lurch, which is a gait abnormality which causes the individual to 'lurch' backwards to compensate lack in hip extension.

<span class="mw-page-title-main">Superior gluteal nerve</span> Nerve on the pelvis and leg

The superior gluteal nerve is a mixed nerve of the sacral plexus that originates in the pelvis. It provides motor innervation to the gluteus medius, gluteus minimus, tensor fasciae latae, and piriformis muscles; it also has a cutaneous branch.

<span class="mw-page-title-main">Sacrotuberous ligament</span>

The sacrotuberous ligament is situated at the lower and back part of the pelvis. It is flat, and triangular in form; narrower in the middle than at the ends.

<span class="mw-page-title-main">Superior gluteal artery</span>

The superior gluteal artery is the terminal branch of the posterior division of the internal iliac artery. It exits the pelvis through the greater sciatic foramen before splitting into a superficial branch and a deep branch.

<span class="mw-page-title-main">Inferior gluteal artery</span>

The inferior gluteal artery is a terminal branch of the anterior trunk of the internal iliac artery. It exits the pelvis through the greater sciatic foramen. It is distributed chiefly to the buttock and the back of the thigh.

<span class="mw-page-title-main">Hip bone</span> Bone of the pelvis

The hip bone is a large flat bone, constricted in the center and expanded above and below. In some vertebrates it is composed of three parts: the ilium, ischium, and the pubis.

<span class="mw-page-title-main">Gluteal lines</span> Lines of the human ilium

The gluteal lines are three curved lines outlined from three bony ridges on the exterior surface of the ilium in the gluteal region. They are the anterior gluteal line; the inferior gluteal line, and the posterior gluteal line.

References

  1. Norman Eizenberg et al., General Anatomy: Principles and Applications (2008), p. 17.
  2. Hennig, Jean-Luc (1995). The rear view: A brief and elegant history of bottoms through the ages. London: Souvenir. ISBN   0-285-63303-1.
  3. "Police". The Times. London. 22 March 1894. Archived from the original on 1 July 2014. Retrieved 5 December 2010. Mr. Curtis Bennett deprecated caning on the hands and boxing the ears, and said they were exceedingly dangerous forms of punishment. Nature provided a special place for boys to be punished upon and it should be used.
  4. Foundations of Osteopathic Medicine, Page 586, Anthony G. Chila – 2010
  5. Recent Advances in Pediatrics, 2013 Suraj Gupte, p 141
  6. "Nates Definitions & Meanings | Dictionary.com". www.dictionary.com. Retrieved 10 June 2022.
  7. A New Dictionary of the Latin and English Languages, published Ward, Lock & Co., London, 1908