The soft skin covering the lateral axilla contains many hair and sweat glands. In humans, the formation of body odor happens mostly in the axilla.[1] These odorant substances have been suggested by some to serve as pheromones, which play a role related to mate selection, although this is a controversial topic within the scientific community.[2] The underarms seem more important than the pubic area for emitting body odor, which may be related to human bipedalism.[3]
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[4]
floor/base: by the skin[4] (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.[8] It can descend after weight loss.[9]
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.[9]
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.
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.
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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.[10]
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 for health-related concerns.[11] As underarm hair grows quickly, removal must be performed frequently, or stubble will appear in the axilla.
In the feminist movement, the hippie culture, and in the punk rock scene, some women retain their underarm hair for a variety of reasons, from subversion to egalitarianism to comfort.[12] Conversely but uncommonly, some men choose to remove their underarm hair for aesthetic reasons or to reduce friction in sports such as swimming.
Shaved underarm
Natural underarm
Clinical significance
Like other flexion surfaces of large joints (groin, popliteal fossa, cubital fossa and essentially the anterior part of the neck), it is an area where blood vessels and nerves pass relatively superficially, and with an increased amount of lymph nodes.
Lymphogenic spread of breast cancer
Breast cancer typically spreads via lymphatic vessels to the lymph nodes found in the axilla.
Axillary intertrigo
Excessive perspiration without adequate air circulation can result in axillary intertrigo. Intertrigo is an inflammatory skin condition of skin folds exposed to friction or maceration in the presence of heat and moisture.[13] Intertrigo is worsened by infection, usually fungal (Candida yeast species), but also bacterial or viral; warm, wet underarms promote those growths. The condition results in rash-like symptoms, pustules, or chronic itching or burning in the underarm.[13] Intertrigo (in any site) has no racial or sexual predilection.[13] Axillary intertrigo is common among those who work in hot environments where air circulation is restricted by necessary clothing or safety equipment.[14]
↑ Turkington, Carol; Dover, Jeffrey S. (2007). The encyclopedia of skin and skin disorders (3rded.). New York: Facts on File. p.363. ISBN978-0-8160-6403-8.
↑ 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
In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint and the elbow joint. The distal part of the upper limb between the elbow and the radiocarpal joint is known as the forearm or "lower" arm, and the extremity beyond the wrist is the hand.
Articles related to anatomy include:
The radial nerve is a nerve in the human body that supplies the posterior portion of the upper limb. It innervates the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm and the associated joints and overlying skin.
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 comes from Latin and means "broadest [muscle] of the back", from "latissimus" and "dorsum". The pair of muscles are commonly known as "lats", especially among bodybuilders. The latissimus dorsi is the largest muscle in the upper body.
The brachial artery is the major blood vessel of the (upper) arm. It is the continuation of the axillary artery beyond the lower margin of teres major muscle. It continues down the ventral surface of the arm until it reaches the cubital fossa at the elbow. It then divides into the radial and ulnar arteries which run down the forearm. In some individuals, the bifurcation occurs much earlier and the ulnar and radial arteries extend through the upper arm. The pulse of the brachial artery is palpable on the anterior aspect of the elbow, medial to the tendon of the biceps, and, with the use of a stethoscope and sphygmomanometer, often used to measure the blood pressure.
The brachial plexus is a network of nerves formed by the anterior rami of the lower four cervical nerves and first thoracic nerve. This plexus extends from the spinal cord, through the cervicoaxillary canal in the neck, over the first rib, and into the armpit, it supplies afferent and efferent nerve fibers to the chest, shoulder, arm, forearm, and hand.
The axillary nerve or the circumflex nerve is a nerve of the human body, that originates from the brachial plexus at the level of the axilla (armpit) and carries nerve fibers from C5 and C6. The axillary nerve travels through the quadrangular space with the posterior circumflex humeral artery and vein to innervate the deltoid and teres minor.
The long thoracic nerve is a branch of the brachial plexus derived from cervical nerves C5-C7 that innervates the serratus anterior muscle.
The cubital fossa, chelidon or inside of elbow is the area on the anterior side of the upper part between the arm and forearm of a human or other hormid animals. It lies anteriorly to the elbow when in standard anatomical position.
In human anatomy, the axillary artery is a large blood vessel that conveys oxygenated blood to the lateral aspect of the thorax, the axilla (armpit) and the upper limb. Its origin is at the lateral margin of the first rib, before which it is called the subclavian artery.
In human anatomy, the axillary vein is a large blood vessel that conveys blood from the lateral aspect of the thorax, axilla (armpit) and upper limb toward the heart. There is one axillary vein on each side of the body.
The subclavius is a small triangular muscle, placed between the clavicle and the first rib. Along with the pectoralis major and pectoralis minor muscles, the subclavius muscle makes up the anterior axioappendicular muscles, also known as anterior wall of the axilla.
The thoracodorsal nerve is a nerve present in humans and other animals, also known as the middle subscapular nerve or the long subscapular nerve. It supplies the latissimus dorsi muscle.
The intercostobrachial nerve is the name applied to the lateral cutaneous branch of the second intercostal nerve. It arises anterior to the long thoracic nerve. It provides sensory innervation to the skin of the axilla, and a variable region of the medial side of the upper arm.
The pectoral fascia is a thin lamina, covering the surface of the pectoralis major, and sending numerous prolongations between its fasciculi: it is attached, in the middle line, to the front of the sternum; above, to the clavicle; laterally and below it is continuous with the fascia of the shoulder, axilla, and thorax.
The axillary lymph nodes or armpit lymph nodes are lymph nodes in the human armpit. Between 20 and 49 in number, they drain lymph vessels from the lateral quadrants of the breast, the superficial lymph vessels from thin walls of the chest and the abdomen above the level of the navel, and the vessels from the upper limb. They are divided in several groups according to their location in the armpit. These lymph nodes are clinically significant in breast cancer, and metastases from the breast to the axillary lymph nodes are considered in the staging of the disease.
The axillary spaces are anatomic spaces. through which axillary contents leave the axilla. They consist of the quadrangular space, triangular space, and triangular interval. It is bounded by teres major, teres minor, medial border of the humerus, and long head of triceps brachii.
The following outline is provided as an overview of and topical guide to human anatomy:
Brachial plexus block is a regional anesthesia technique that is sometimes employed as an alternative or as an adjunct to general anesthesia for surgery of the upper extremity. This technique involves the injection of local anesthetic agents in close proximity to the brachial plexus, temporarily blocking the sensation and ability to move the upper extremity. The subject can remain awake during the ensuing surgical procedure, or they can be sedated or even fully anesthetized if necessary.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
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.
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