Armpit

Armpit

The armpit, also known as the axilla, is a complex anatomical region located beneath the shoulder joint, where the arm connects to the shoulder. It serves as a passageway for important neurovascular structures and contains several lymph nodes that are crucial for the immune response. The armpit is also a site of sweat production and plays a role in thermoregulation and pheromone release.

Anatomy

The armpit is bordered by several muscles and bones:

• The superior boundary is formed by the clavicle (collarbone).
• The medial boundary is the lateral edge of the rib cage.
• The lateral boundary is the medial aspect of the humerus (upper arm bone).
• The posterior boundary is formed by the scapula (shoulder blade) and associated muscles.

Muscles

Several muscles contribute to the structure and function of the armpit:

• The pectoralis major and pectoralis minor muscles form the anterior wall.
• The latissimus dorsi and teres major muscles form the posterior wall.
• The serratus anterior muscle lies along the medial wall.

Neurovascular Structures

The armpit contains important neurovascular structures, including:

• The brachial plexus, a network of nerves that innervates the upper limb.
• The axillary artery and its branches, which supply blood to the shoulder and upper limb.
• The axillary vein, which drains blood from the upper limb.

Lymphatic System

The armpit contains numerous lymph nodes, which are part of the body's immune system. These nodes filter lymphatic fluid and can become enlarged in response to infection or cancer. The axillary lymph nodes are clinically significant in the staging and treatment of breast cancer.

Sweat Glands

The armpit is home to two types of sweat glands:

• Eccrine sweat glands, which are involved in thermoregulation and are found throughout the body.
• Apocrine sweat glands, which are concentrated in the armpits and are responsible for body odor due to bacterial breakdown of sweat.

Clinical Significance

The armpit is a common site for various medical conditions, including:

• Hidradenitis suppurativa, a chronic skin condition characterized by painful lumps and abscesses.
• Hyperhidrosis, excessive sweating that can affect the armpits.
• Lymphadenopathy, enlargement of the lymph nodes, which can indicate infection or malignancy.

Cultural and Social Aspects

The armpit has cultural significance in terms of hygiene and grooming. Practices such as shaving and the use of deodorants and antiperspirants are common in many societies to manage sweat and body odor.

See Also

• Sweat gland
• Lymph node
• Brachial plexus

References

• Gray's Anatomy: The Anatomical Basis of Clinical Practice.
• Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2013). Clinically Oriented Anatomy.