Axilla

"Underarm" redirects here. For the bowling style in cricket, see Underarm bowling.

Axilla
File:Teen boy armpit.JPG Axilla
Details
Latin	Axilla
Artery	axillary artery
Vein	axillary vein
Nerve	axillary nerve, medial cord, posterior cord, lateral cord
Lymph	axillary lymph nodes
Identifiers
MeSH	A01.378.800.090
Dorlands /Elsevier	a_76/12171908
TA
TH	{{#property:P1694}}
TE	{{#property:P1693}}
FMA	{{#property:P1402}}
Anatomical terminology [[[d:|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. 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.

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
medially: serratus anterior and by the ribcage	anteriorly: by the pectoralis major, minor, and subclavius posteriorly: by the subscapularis above, and teres major and latissimus dorsi below	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 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.It can descend after weight loss.

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.It can elongate after weight loss.

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

• Axillary artery and its branches
• Axillary vein and its tributaries
• Infraclavicular part of the brachial plexus
• Five groups of axillary lymph nodes and the associated lymphatics
• The long thoracic and intercostobrachial nerves
• Axillary fat and areolar tissue in which the other contents are embedded
• lymph nodes of axilla are very important from pathological point of view because breast cancer in both males and females spread to these lymph nodes readily.

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.

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

Tickling

Main article: Tickling

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

Main article: Underarm hair

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 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. A warm, wet underarm may accommodate the growth of pathogenic bacteria, yeasts, and fungi. The condition is responsible for rash-like symptoms, pustules, or chronic itching or burning in the underarm. Axillary intertrigo is common among those who work in hot environments.

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 Axilla  Axilla Axilla  Axilla Axilla  Axilla Axilla

See also

• Deodorant
• Perspiration
• Popliteal fossa or "knee pit"
• Suspensory ligament of axilla

External links

• Step by step Video dissection of the Human Axilla showing all relevant anatomy
• 3D animated overview of axillary anatomy (rich media)
• lesson3axilla at The Anatomy Lesson by Wesley Norman (Georgetown University)
• lesson3axillarywalls at The Anatomy Lesson by Wesley Norman (Georgetown University)