Human Anatomy

Axillary nerve

A crucial nerve responsible for innervating the deltoid and teres minor muscles, as well as providing sensory function to the skin over the lateral aspect of the shoulder.

The axillary nerve is a major peripheral nerve arising from the brachial plexus, specifically from the posterior cord. It primarily innervates the deltoid and teres minor muscles, which play a significant role in shoulder movement. Additionally, it provides sensory innervation to the skin overlying the deltoid muscle and part of the upper arm.

Terminologia Anatomica

nervus axillaris

System

Nervous system

Function

The primary function of the axillary nerve lies in facilitating movement and sensation in the shoulder region. By innervating the deltoid muscle, the nerve enables the arm to be lifted away from the body, an essential movement for reaching and throwing. The teres minor muscle, also innervated by the axillary nerve, contributes to the rotation of the arm, thereby assisting in various activities such as sports and manual tasks. Additionally, the sensory fibers of the axillary nerve serve an important role by transmitting touch and pain sensations from the skin on the lateral side of the shoulder, enhancing the sensory feedback that is vital for coordinated arm movements.

Location

The axillary nerve is located in the upper limb, situated in the axillary region, specifically around the shoulder. It originates from the brachial plexus, emerging from fibers C5 and C6 of the spinal nerves. After branching off, the axillary nerve travels posteriorly around the humerus, specifically in the quadrangular space, which is defined by the teres minor muscle, the teres major muscle, and the long head of the triceps brachii muscle. This pathway allows the nerve to safely innervate the deltoid muscle while providing sensory innervation to the skin over the shoulder area.

Did You Know?

The axillary nerve is susceptible to injury during shoulder dislocations, which can lead to weakness in arm abduction.
Despite being a small nerve, the axillary nerve plays a significant role in the function of the shoulder joint, making it essential for athletes.
The sensory area of the axillary nerve covers approximately 15% of the shoulder's surface, highlighting its importance in shoulder sensation.