Superior lateral cutaneous nerve of arm

Superior Lateral Cutaneous Nerve of Arm

The superior lateral cutaneous nerve of the arm (SLCNA) is a sensory nerve that provides innervation to the skin on the lateral aspect of the upper arm. It is a branch of the axillary nerve, which arises from the posterior cord of the brachial plexus.

Anatomy

The SLCNA originates from the axillary nerve near the quadrangular space, which is formed by the teres major muscle, teres minor muscle, long head of the triceps brachii muscle, and the surgical neck of the humerus. After its origin, the nerve courses along the posterior aspect of the deltoid muscle, running parallel to the axillary artery.

As it travels distally, the SLCNA pierces the deep fascia and divides into multiple branches that supply the skin on the lateral aspect of the upper arm. These branches innervate the skin overlying the deltoid muscle, extending from the shoulder to the mid-arm region.

Function

The main function of the SLCNA is to provide sensory innervation to the lateral aspect of the upper arm. It carries sensory information from the skin back to the central nervous system, allowing for the perception of touch, temperature, and pain in this region.

Clinical Significance

Injury or compression of the SLCNA can result in sensory disturbances in the lateral aspect of the upper arm. This can manifest as numbness, tingling, or a loss of sensation in the affected area. Common causes of SLCNA injury include trauma, such as fractures or dislocations of the shoulder or humerus, as well as compression due to tight clothing or repetitive activities.

Related Nerves

The SLCNA is closely related to other nerves in the brachial plexus and upper extremity. These include:

- Axillary Nerve: The SLCNA is a branch of the axillary nerve, which also provides motor innervation to the deltoid muscle and teres minor muscle.

- Radial Nerve: The radial nerve runs alongside the axillary nerve and gives rise to branches that innervate the posterior aspect of the arm, forearm, and hand.

- Musculocutaneous Nerve: The musculocutaneous nerve arises from the lateral cord of the brachial plexus and provides motor innervation to the muscles in the anterior compartment of the arm, as well as sensory innervation to the lateral forearm.

Conclusion

The superior lateral cutaneous nerve of the arm is an important sensory nerve that provides innervation to the skin on the lateral aspect of the upper arm. Understanding its anatomy and function is crucial for diagnosing and managing sensory disturbances in this region.

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