What is the armpit?
The armpits are on both sides of the human body, the area between the lateral chest wall and the shoulder or the medial upper arm. What the medicine understands under the armpit is different from the colloquial armpit. In the vernacular, the armpits are merely the hairy skin fold between the chest wall and the upper arm.
Medically, several arteries and one vein count the anatomical structure of the armpit. Nerves, lymph nodes and fatty tissue are also part of the underarm area. The armpit is according to this definition not only the superficial, but also the lower-lying space under the shoulder. In front, this space is bounded by the anterior axillary fold, which is formed by the great pectoralis muscle.
Behind, the rear axillary fold limits the armpit. This posterior axis of the axilla forms the large dorsal muscle, while the inside of the thorax carries out the limiting function.
Anatomy & Construction
The armpit is bordered by the first rib, the upper shoulder blade and the collarbone. A layer of muscular connective tissue and fatty tissue embeds the armpit. The posterior wall of the axilla is formed by the pectoralis major muscle together with the pectoralis minor muscle. The subscapularis muscle, together with the teres major muscle and the latissimus dorsi muscle, forms the posterior wall.
The central boundary of the anatomical structure is formed by four ribs and the intercostal muscles between them. The anterior and posterior walls of the axilla converge into a narrow surface consisting of the coracobrachialis muscle, the humerus, and the biceps brachii muscle. The blood supply to the structure is taken over by the axillary artery and its sub-branches.
The axillary vein takes over the blood drainage. The brachial plexus and its branches innervate the axilla together with the intercostal nerves of the ribs. Under the skin of the armpits are about 30 axillary lymph nodes. In addition, many sebaceous and sweat glands are located in this area.
Function & Tasks
The tasks of the armpit are versatile and consist of the individual functions of their anatomical components. In the armpits, for example, sit different glands, secrete different secretions. Some of them are apocrine glands. This means that different fragrances are released from these structures.
These fragrances are on the one hand sex attractants such as pheromones and on the other hand characterize the individual body odor. Apocrine glands thus have an influence on the sexual and social behavior of humans. This should be distinguished from pure sweat glands. Sweating is vital to the body. It regulates body temperature and cools the skin as well as the inside of the body. The glands under the armpits thus fulfill a cooling effect in addition to the scent effect. Still other functions are the axillary hair.
The armpit hair usually begins to grow during puberty. How dense the hair is is not only related to genetic factors, but has as much to do with one's origins. People from hot countries are thus usually more densely hairy than those from cooler areas. The armpit hair prevents rubbing in the armpit. In addition, the armpit hair absorbs sweat and thus plays a role in the cooling effect of Körperausdünstungen.
As well as the cooling effect, the efficiency of pheromones is also amplified by the armpit hair. The axillary lymph nodes also fulfill important tasks in the anatomical structure of the axilla. They receive inflows from the arms, the chest and the lateral trunk wall. The lymph channels of the shoulder, neck and forearm are also connected to the axillary lymph nodes. Like all other lymph nodes, the task of the axillary lymph nodes is a filtering process that swamps pollutants such as pathogens.
One of the most well-known illnesses in relation to the armpit is the underarm wetness. This refers to overproduction of sweat that occurs locally under the armpits. Excessive sweat production is mentioned when more than 100 milligrams of sweat are produced in an armpit in five minutes. Underarm wetness can be both innate and acquired.
Both hormonal, as well as mental and nervous systematic causes come as a trigger for the excessive sweat production in question. Even more frequently than underarm wetness, skin diseases occur under the armpits. Such skin diseases can be caused by shaving or a specific deodorant. Also, skin fungus under the armpits is not uncommon. The moist and warm environment of the armpit attracts parasitic mushrooms. Just as common are knots under the armpits.
These nodes do not necessarily indicate a serious illness. For example, one or more lymph nodes may be swollen, indicating an infection. If an infection is responsible for nodule formation, the swelling disappears once the body has fought bacteria, fungi or viruses.
If, instead of an infection, a cancer is responsible for the nodules under the armpits, then the nodules are usually metastases. For example, in breast cancer, a tumor often spreads to the surrounding lymph nodes. In such a case, the affected tissue is removed.