What is cutaneous innervation of the upper limb?

Cutaneous innervation refers to the sensory nerve supply to the skin of the upper limb, derived from spinal segments C3 to T2. It includes somatosensory fibers for sensations like touch and pain, and autonomic sympathetic fibers for functions like sweating.

Which nerves supply the skin of the hand?

The hand is innervated by several nerves. The palm's lateral two-thirds is supplied by the median nerve and medial one-third by the ulnar nerve. The dorsum's lateral two-thirds is supplied by the radial nerve and medial one-third by the ulnar nerve.

What are dermatomes in the upper limb?

Dermatomes are skin areas innervated by a single spinal nerve, forming a spiral-like pattern in the upper limb due to embryological rotation. Key examples include C6 for the thumb and lateral forearm, C7 for the middle three fingers, and C8 for the little finger and medial forearm.

Why is sensory testing important for the upper limb?

Sensory testing, such as light touch and pinprick, is crucial for evaluating nerve and spinal cord integrity. It helps diagnose conditions like radiculopathies or brachial plexus injuries by mapping sensation loss to specific spinal segments (C3–T2).

What nerves innervate the skin of the forearm?

The forearm's skin is supplied by three main nerves: medial by the medial cutaneous nerve of forearm (C8, T1), lateral by the lateral cutaneous nerve of forearm (C5, C6; from musculocutaneous nerve), and posterior by the posterior cutaneous nerve of forearm (C6–C8; from radial nerve).

How do dermatomes help in clinical diagnosis?

Dermatomes guide the localization of nerve damage, such as in radiculopathies or spinal cord injuries. By testing sensation in specific areas (e.g., thumb for C6), clinicians can identify affected spinal segments, though overlap between dermatomes means loss is rarely complete.

Cutaneous Innervation of Upper Limb – Nerves & Dermatomes