Ulnar Nerve Definition
The ulnar nerve, one of the three primary nerves in the human arm, is commonly referred to as the “funny bone.” It contains both sensory and motor activities and governs the bulk of hand movements, including delicate finger movements. The ulnar nerve is often damaged as a result of compression or trauma, but most lesions are typically treatable.
Anatomy of the Ulnar Nerve
The three major nerves in the arm are the median nerve, the ulnar nerve, and the radial nerve. The ulnar nerve is named after the ulnar bone, the innermost of the two forearm bones (the second is the radial bone).
The ulnar nerve is one of five nerves that arise from the brachial plexus, a collection of nerves responsible for transmitting information from the spinal cord to the upper arm and hand. For instance, the ulnar nerve is an extension of the medial cord of the brachial plexus.
From the neck to the wrists and hands, as well as fingers, the ulnar nerve travels, passing via the upper arm and forearm. It travels along the arm’s medial side (i.e., the inner arm). It falls beyond the humerus’s medial epicondyle. Location is the region in which tendons and ligaments attach to the elbow bone. This portion of the ulnar nerve is especially susceptible to injury.
It divides into three branches as it reaches the forearm: muscle branches, palmar cutaneous branch, and dorsal cutaneous branch.
- Two forearm muscles are innervated by the muscular branches (the flexor carpi ulnaris and the flexor digitorum profundus).
- The palmar cutaneous branch is a tiny branch that innervates the palm’s centre.
- The little and ring fingers get sensation via the dorsal cutaneous branch.
At the wrist, the ulnar nerve reaches the hand via the ulnar canal, commonly known as Guyon’s canal. In the hand, it separates into two branches: the superficial branch (which serves mostly sensory functions) and the deepest branch (which serves primarily motor functions). (which serves primarily motor activities) (mainly motor functions).
The ulnar nerve is the scientific name for the “funny bone,” which is really not a bone at all. Its closeness to the humerus bone may have given it its name. Another option is the tingling sensation that occurs once the ulnar nerve gets damaged, which is accompanied by a vague ache.
Function of the Ulnar Nerve
The ulnar nerve includes a mixed nerve, meaning it possesses all sensory and motor axons. The bulk of the hand and a piece of the forearm are under its control. Sensory nerves feed the skin in the middle of the forearm, wrist, as well as two fingers.
The ulnar nerve’s motor duties include controlling the motions of the hand and portions of the forearm. It controls the tiny motions of the fingers by innervating practically all the hand’s muscles. As a consequence, it’s sometimes referred to as the musician’s nerve.
The only muscles in the hand that it does not govern are the thenar muscles (thumb muscles) as well as the two lateral lumbricals (the flexor muscles of the index and middle fingers).
The ulnar nerve always controls the movement of two forearm muscles. These muscles are the flexor carpi ulnaris, which flexes the wrist, and the medial part of the flexor digitorum profundus, which flexes the fingers.
The medial one and a half fingers, as well as the palm, are all innervated by the ulnar nerve and serve as sensory nerves. In other words, the region covering the little finger and part of the ring finger, and the palm underneath them, transmits external signals to the brain.
Damage and Injury to the Ulnar Nerve
The ulnar nerve may be damaged. This is because it is the largest nerve in the human body, that is not safeguarded by muscle or bone.
The ulnar nerve may be damaged by trauma, including a fracture or a hard force injury. The ulnar nerve is commonly damaged as a result of a ‘pinched’ nerve (also known as entrapment or nerve compression).
Ulnar Nerve Entrapment
Entrapment of the ulnar nerve (commonly termed as compression of the ulnar nerve) may cause both motor and sensory symptoms (such as muscular weakness) (for example, numbness or tingling). It might also be quite inconvenient.
Cubital tunnel syndrome would be a common complication of ulnar nerve entrapment in the elbow, particularly at the inner elbow. It may happen elsewhere along the nerve that links the wrist to the upper arm, however.
The location of the lesion across the nerve determines the severity of the injury. When the elbow is flexed, the feelings are felt more often in the hand. Symptoms include numbness within the ring as well as pinky fingers, a shaky grip, and problems maintaining fine motor skills in the fingers.
The ulnar nerve is easily identified, since it governs the movement and sensations in the hands.
The Froment’s Sign is a test that is used to diagnose ulnar nerve injury (ulnar nerve palsy). This test will be positive if the ulnar nerve is entrapped.
A piece of paper will be held between the patient’s finger and thumb during the test. The doctor will then pull out the paper. When the ulnar nerve is working properly, the individual should be able to handle the paper with ease. Patients would be reluctant to resist the doctor’s pulling and would need to drop the paper when the ulnar nerve is destroyed or compensate by squeezing it at the tip of their thumb.
An ‘ulnar claw’ may appear in more advanced forms of the condition. When the ulnar nerve is injured, it causes a malformation in the hand. This issue prevents people from completely extending their little and ring fingers.
Milder occurrences of ulnar nerve compression are frequently treated without surgery. Anti-inflammatory medications are used to reduce swelling and discomfort, while sleeping or resting, splints are utilised to straighten the joint, and activities are performed to relax the nerve into the right posture.
The ulnar nerve glide is a common exercise during which you raise an “okay” signal using your hand, bend your elbow, and raise your forearm toward your shoulder repeatedly.
Surgery may be considered if these approaches fail.
Surgical intervention may be required when non-surgical alternatives fail or the indications become too serious. These procedures may even be done with just a local anaesthetic.
Cubital tunnel release is a procedure for releasing the ulnar nerve from its entrapment at the elbow. Each and every tissue that is stiff over the nerve will be removed, allowing the pressure to be relieved.
Ulnar nerve front inversion is a surgical operation wherein the surgeon relocates the ulnar nerve to ease pressure.
The medial epicondyle, or bone bulge on the inside of your elbow, is a common source of pain and is removed during a medial epicondylectomy. The ulnar nerve is relieved of pressure as a result of this.
People with ulnar nerve entrapment frequently recover completely (or almost completely) on their own or with therapy.
Repeated elbow bending is the most common cause of ulnar nerve injury or entrapment. For example, smoking cigarettes, playing tennis, golfing, working while leaning on a desk, or constantly using a mobile phone.
Reduced ulnar nerve injury may be avoided by reducing these duties. Simply learning to lean less on your elbow and to straighten your arm as much as possible can help to relieve pressure on the nerve.
- Tubbs, R. S. (2015). Nerves and nerve injuries: First Edition. Elsevier.
- Dy, C. J., & Mackinnon, S. E. (2016). Ulnar neuropathy: evaluation and management. Current reviews in musculoskeletal medicine, 9(2), 178–184. https://doi.org/10.1007/s12178-016-9327-x
- Polatsch, D. B., Melone, C. P., Beldner, S., & Incorvaia, A. (2007). Ulnar Nerve Anatomy. Hand Clinics, 23(3), 283–289. doi: 10.1016/j.hcl.2007.05.001