axillaire

Axillaire is a French adjective meaning relating to the axilla, or armpit, and more broadly to the axillary region of the body or of a plant. In English, the corresponding term is axillary. The word is used in anatomy to describe structures in the armpit and in botany to describe features located in the leaf axil.

Anatomical sense: The axilla is a pyramidal space between the upper limb and the thorax. Its boundaries include the clavicle, first rib, and scapula at the apex; anteriorly by the pectoralis major and minor; posteriorly by the subscapularis, latissimus dorsi, and teres major; medially by the upper thoracic wall and serratus anterior; laterally by the intertubercular sulcus of the humerus. Contents typically include the brachial plexus cords, the axillary artery and vein with branches, lymph nodes, and adipose tissue. The region serves as a conduit for neurovascular structures to the upper limb and as a lymphatic drainage area for the arm and breast.

Clinical relevance: The axillary region is central to breast cancer staging because axillary lymph nodes are common sites of metastasis. The axillary nerve can be injured during surgical procedures or trauma, causing weakness of shoulder abduction and sensory loss over the lateral deltoid area. Vascular injuries or compression in this area can affect blood flow to the arm. Axillary infections and hidradenitis suppurativa are other clinical considerations in this region.

Botanical sense: In botany, axillary describes structures located in the leaf axil, the angle between a leaf and its stem. An axillary bud forms there and may develop into a lateral shoot or a flower cluster, contributing to plant branching and flowering patterns. Axillary meristems regulate growth in many species.