Axillary sheath

Axillary Sheath is a fibrous sheath that encloses the axillary artery, the axillary vein, and the brachial plexus in the axilla. It is an extension of the prevertebral fascia of the neck.

Anatomy

The axillary sheath is a continuation of the prevertebral fascia, which is a part of the deep cervical fascia. It extends from the lateral border of the first rib to the lower border of the teres major muscle. The sheath is designed to protect the neurovascular bundle of the upper limb.

Inside the axillary sheath, there are three main structures: the axillary artery, the axillary vein, and the brachial plexus. The axillary artery and vein provide blood supply and venous return from the upper limb, respectively. The brachial plexus is a network of nerves that supply the upper limb.

Clinical Significance

The axillary sheath has clinical significance in regional anesthesia. In axillary block, local anesthetic is injected into the axillary sheath to numb the upper limb. This is commonly used in surgeries of the hand, forearm, and elbow.

In addition, the axillary sheath can be involved in certain medical conditions. For example, in Thoracic Outlet Syndrome, there can be compression of the structures within the axillary sheath, leading to symptoms such as pain, numbness, and weakness in the upper limb.

See Also

• Fascia
• Axillary artery
• Axillary vein
• Brachial plexus
• Axillary block
• Thoracic Outlet Syndrome