The Axillary Region

Original Editor - Alyssa Brooks-Wells

Top Contributors - Alyssa Brooks-Wells and Kim Jackson  

Description:

The axillary region (also known as the arm pit) is a pyramid-shaped area located between the shoulder girdle and thorax. It serves as a space for neurovascular and lymphatic structures to travel through to reach the upper extremity from the neck.

Structure/Borders:

• Apex: (also known as cervicoaxillary margin, axillary inlet) region of entrance/exit of the axillary neurovascular bundle
  • 1st rib (lateral)
  • Scapula (superior portion and coracoid process)
  • Clavicle (posterior)
• Base:
  • Axillary skin
  • Fascia Axillaris
• Anterior Wall:
  • Pectoralis major
  • Pectoralis minor
• Posterior Wall:
  • Subscapularis
  • Latissimus dorsi
  • Teres major
• Medial Wall:
  • Ribs 1-4
  • Intercostal muscles of ribs 1-4
  • Serratus anterior
• Lateral Wall:
  • Intertubercular groove of the humerus

The structure of the axilla is dependent upon the position of the upper extremity - an expansive region when the arm is elevated and minimized when adducted.

Contents:

The axillary artery is an extension of the subclavian artery, and is called so after passing the first rib. It is renamed and considered the brachial artery after passing the teres major and exiting the axilla. The artery is encompassed by the axillary sheath and the brachial plexus cords and branches. The axillary artery is divided into three parts with arterial branches associated with each section. The branches of the axillary artery include the superior thoracic, thoracoacromial, lateral thoracic, subscapular, anterior humeral circumflex and posterior humeral circumflex. The scapular and humeral anastomoses created by these branches are important factors to compensate if there are any occlusions of the axillary artery.

Axillary vein

Brachial plexus

Axillary lymph vessels and nodes Adipose tissue

Mammary tissue possible

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