Forearm & Thumb Pain – Musculocutaneous Nerve Impingement

Pain into the outer forearm and Thumb region may not be a tendon injury but instead a Nerve impingement one, namely impingement of the Musculocutaneous Nerve. The Musculocutaneous Nerve comes from the vertebra of the cervical spine which we know as the Neck, it originates from the C5, C6, and C7 vertebra. Restriction on the nerve roots at these vertebra levels or along the nerve in the bicep muscle, or outer forearm can cause pain down the arm and into the Thumb. Musculocutaneous Nerve Impingement and DeQuervain’s Tenosynovitis condition of the thumb and wrist have similar symptoms. Hence it really important to correctly diagnose if there is nerve involvement through Neurodynamic testing.

Signs & Symptoms:

  • Tenderness or Pain along the outside area of elbow & forearm, along the Biceps Tendon

  • Pain radiating into the thumb

  • Aggravated by constant sideways bending of the wrist, such as when using a Hammer

DeQuervain’s tenosynovitis

DeQuervain’s tenosynovitis which causes pain and tenderness into the palm of the hand at the base the thumb. It affects the tendons called Extensor Pollicis Longus and Abductor Pollicis Brevis which are used to grip an object such as a towel your hand. With constant repetitive movements of the wrist and thumb, inflammation develops in the synovial sheath that covers these two tendons as they pass through the wrist joint. The synovial sheath’s function is to protect the tendons from friction from surrounding bones in the wrist, when the sheath becomes inflamed; the following symptoms can be felt;

  • Pain and swelling will be noted in the palm of the hand at the base of the Thumb.

  • Activities involving movement of the thumb & Thumb

  • Muscle weakness in the Thumb is often noted overtime.

  • Numbness may also be felt in the back of the thumb and index finger.

Treatment of Musculocutaneous Nerve Impingement

Firstly it is easily diagnosed with Neurodynamic testing in the clinic. A gentle treatment technique of identifying where there is tension or restriction on the nerve and then using nerve slider technique to mobilise the nerve. In tandem with this, manual soft tissue stretching of the tight muscles that overlap the nerve are important to in helping to release the nerve compression. Avoiding aggravating wrist movements and homecare nerve slider exercises is important also.

Tomás Ryan is a Registered Physical Therapist with The Irish Association of Physical Therapy and is based in Thurles.Contact Number: 0504 26672 Email your queries to:

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Physiotherapy & Injury Rehabilitation Clinic in Tipperary

0504 26672


The Surgery, Fianna Road, Thurles


Riverside Medical Centre, 7 Upper

Irishtown, Clonmel

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