Axilla: shape, orientation and dissection landmarks
THE CONTEXT
The axilla is a pyramidal space between the upper part of the arm and the chest wall.
Shape and orientation
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The axilla resembles a four-sided pyramid with an apex, a base, and anterior, posterior, medial and lateral walls.
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Its apex points upwards and medially towards the root of the neck, while its base points downwards.
Muscular and fascial landmarks
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The posterior axillary fold is described with subscapularis, teres major and latissimus dorsi.
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The short head of biceps brachii and coracobrachialis arise from the tip of the coracoid process; the short head lies laterally and coracobrachialis medially.
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The pectoral muscles and clavipectoral fascia form the anterior boundary.
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The dissection passage describes the upper three intercostal muscles and serratus anterior as forming the medial wall.
Dissection sequence
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The limb is abducted at right angles to the trunk for dissection.
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Fat, lymph nodes and superficial veins are removed to reach the depth of the armpit.
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The axillary vessels are identified, and the branches of the axillary artery are traced.