Axilla

The axilla (or armpit, underarm, or oxter) is the area on the human body directly under the joint where the arm connects to the shoulder.

Boundaries

Anatomically, the boundaries are as follows:

	superiorly: by the outer border of first rib, superior border of scapula, and posterior border of clavicle
medially: serratus anterior and by the ribcage	anteriorly: by the pectoralis major, minor, and subclavius (see also anterior axillary fold) posteriorly: by the subscapularis above, and teres major and latissimus dorsi below (see also posterior axillary fold)	laterally: by the intertubercular sulcus (coracobrachialis and the short head of the biceps brachii are in the axilla.)
	floor/base: by the skin (visible surface of armpit)

The contents of the axilla include the axillary vein and artery, as well as the brachial plexus, lymph nodes and fat.

Medical significance

The axilla is one of the four sites (the other three being the mouth, rectum, and ear canal) in which a medical thermometer may be inserted in order to measure body temperature.

Underarm hair

Underarm hair usually grows in the underarms of both females and males, beginning in adolescence.

In modern Western culture, it is common for women to remove underarm hair for aesthetic reasons, while men tend to keep it. Throughout the feminist movement, previously in the hippie culture, and in some areas of the punk rock scene, some women choose to keep their underarm hair for a variety of reasons, from subversion to egalitarianism to comfort.

Body odor

Body odor develops in the underarms due in part to the waste products of microorganisms that feed on sebum, the fatty secretions produced by apocrine glands.

A wide variety of deodorant and antiperspirant products are sold for the purpose of mitigating this odor.

Darkening of the underarms

Sometimes, shaving, buildup of dead skin cells, antiperspirant usage, and hyper pigmentation contribute to giving the underarm a dark color. Also, a medical condition known as acanthosis nigricans may also contribute to darkened underarms, although most people with dark underarms do not have this condition.

Cultural significance

The underarms are among the locations in the human body which are most vulnerable to tickling.

The sexual attraction to the underarms is called axillism.

Terminology

The term oxter, pronounced 'ock-ster' is most often used in the United Kingdom and the Republic of Ireland. Northern Ireland generally replaces all other names of underarm for oxter.

The term "underarm" only refers to the outer surface of the axilla. However, the terms are sometimes used interchangeably in casual contexts.

Colloquially, armpit refers to an object or place which is smelly, greasy or otherwise undesirable.

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References

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