Ulnar nerve

The ulnar nerve is a crucial nerve responsible for movement and sensation in the forearm and hand.

The ulnar nerve is one of the major peripheral nerves in the upper limb. It originates from the brachial plexus, a network of nerve fibers that emerges from the spinal cord in the neck region. This nerve travels down the arm and into the hand, where it innervates several muscles responsible for fine motor control as well as providing sensory feedback from the skin on the palm, particularly along the little finger and half of the ring finger.

Terminologia Anatomica

nervus ulnaris

System

Nervous system

Function

The primary function of the ulnar nerve is to provide motor innervation to intrinsic muscles of the hand, which are essential for performing delicate movements and grip strength. Specifically, it controls muscles such as the hypothenar muscles, which aid in the movement of the little finger, and the interossei muscles that enable finger abduction and adduction. Additionally, the ulnar nerve is responsible for sensory perception in the skin of the hand, allowing individuals to feel sensations such as touch, temperature, and pain in its designated areas. Damage or compression to the ulnar nerve can lead to conditions such as 'cubital tunnel syndrome,' often resulting in symptoms such as tingling, numbness, and muscle weakness, particularly noticeable when the elbow is bent.

Location

The ulnar nerve has a distinct and complex pathway through the upper limb. It originates from the medial cord of the brachial plexus, composed of roots from the lower cervical and upper thoracic spinal nerves (C8 and T1). From there, it travels down the arm, running posterior to the medial epicondyle of the humerus—this area is commonly referred to as the 'funny bone' due to the tingling sensation experienced when the nerve is bumped. As it continues its journey, the ulnar nerve enters the forearm, where it lies between the flexor carpi ulnaris and flexor digitorum profundus muscles. Finally, it travels into the hand through the Guyon's canal (located at the wrist) before branching out to innervate muscles and skin in the palm and fingers.

Did You Know?

The ulnar nerve is one of three main nerves that innervate the hand, alongside the median and radial nerves.
The ulnar nerve is responsible for the 'ulnar grasp,' enabling the body to hold and manipulate objects more effectively.
People may experience hand symptoms when leaning on their elbows for an extended period, which can compress the ulnar nerve.
The ulnar nerve is uniquely positioned to be subjected to injuries in activities that involve repetitive elbow flexion, like certain sports or work-related tasks.