Axilla

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Axilla
File:Teen boy armpit.JPG
Axilla
Details
Latin Axilla
axillary artery
axillary vein
axillary nerve, medial cord, posterior cord, lateral cord
axillary lymph nodes
Identifiers
MeSH A01.378.800.090
Dorlands
/Elsevier
a_76/12171908
TA Lua error in Module:Wikidata at line 744: attempt to index field 'wikibase' (a nil value).
TH {{#property:P1694}}
TE {{#property:P1693}}
FMA {{#property:P1402}}
Anatomical terminology
[[[d:Lua error in Module:Wikidata at line 863: attempt to index field 'wikibase' (a nil value).|edit on Wikidata]]]

The axilla (or underarm, or oxter) is the area on the human body directly under the joint where the arm connects to the shoulder. It also provides the under-arm sweat gland.

In humans, the formation of body odor happens mostly in the axillary region.[1] These odorant substances serve as pheromones which play a role related to mating. The underarm regions seem more important than the genital region for body odor which may be related to human bipedalism.[2]

Structure

Boundaries

Anatomically, the boundaries of the axilla are:

superiorly: by the outer border of first rib, superior border of scapula, and posterior border of clavicle[3]
medially: serratus anterior[4] and by the ribcage anteriorly: by the pectoralis major, minor,[5] and subclavius[4]

posteriorly: by the subscapularis above, and teres major and latissimus dorsi below[4]

laterally: by the intertubercular sulcus[5] (coracobrachialis and the short head of the biceps brachii are in the axilla.)[4]
floor/base: by the skin[3] (visible surface of axilla)

The lower posterior boundary is called the posterior axillary fold and this is a compound structure consisting of the latissimus dorsi and teres major muscles.[6]It can descend after weight loss.[7]

The anterior boundary is called the anterior axillary fold and this is rounded in shape and formed by the lower border of the pectoralis major. Some sources also include the pectoralis minor.[8]It can elongate after weight loss.[7]

The contents of the axilla include the axillary vein and artery, as well as the brachial plexus, lymph nodes and fat. The axilla is the space between the side of the thorax and the upper arm.

Contents

Society and culture

The term "underarm" typically refers to the outer surface of the axilla. However, the terms are sometimes used interchangeably in casual contexts. Colloquially, underarm refers to the hollow beneath the junction of the arm and shoulder.[9]

The term oxter is used in the Scots language instead of "axilla".[10]

Tickling

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The underarm can be a ticklish area, possibly due to the number of nerves it contains. Some people find this area to be particularly unpleasant when tickled.

Underarm hair

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

In some modern Western cultures, it is common for women to remove underarm hair. Some view this practice as an aesthetic matter, while others view its removal as a possible effect of health related concerns. As underarm hair grows quickly, shaving must be performed frequently, or else stubble will appear in the axilla.

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. Conversely, some men choose to remove their underarm hair for similar aesthetic reasons or to reduce friction in some sports, such as swimming.

Male shaved underarm 
Female hairy underarm 

Clinical significance

Axillary intertrigo

Excessive perspiration can result in axillary intertrigo. Intertrigo is an inflamed skin condition caused by heat, friction, and moisture.[11] A warm, wet underarm may accommodate the growth of pathogenic bacteria, yeasts, and fungi.[12] The condition is responsible for rash-like symptoms, pustules, or chronic itching or burning in the underarm.[11] Axillary intertrigo is common among those who work in hot environments.[12]

Additional images

Anatomy of the axilla
Superficial muscles of the chest and front of the arm. 
Axillary artery and its branches - anterior view of right upper limb and thorax. 
The veins of the right axilla, viewed from in front. 
The right brachial plexus (infraclavicular portion) in the axillary fossa; viewed from below and in front. 
The left side of the thorax. 
Axilla 
Axilla 
Axilla 
Axilla 
Axilla 
Axilla 
Axilla 

See also


Notes

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  2. The Oxford Handbook of Evolutionary Psychology, Edited by Robin Dunbar and Louise Barret, Oxford University Press, 2007, Chapter 22 Body odours and body odour preferences in humans by Claus Wedekind
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  6. lesson3axilla at The Anatomy Lesson by Wesley Norman (Georgetown University)
  7. 7.0 7.1 Lua error in package.lua at line 80: module 'strict' not found.
  8. lesson3axilla at The Anatomy Lesson by Wesley Norman (Georgetown University)
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  11. 11.0 11.1 Selden, Samuel, MD. Intertrigo. emedicine, WebMD. March 9, 2007. Accessed May 21, 2009.
  12. 12.0 12.1 Occupational Dermatoses - A Program for Physicians. National Institute for Occupational Safety and Health. April 17, 2001. Accessed May 21, 2009.

External links