Brachialis: Pain Pattern and Treatment
The brachialis lies under the biceps on the front of the upper arm and attaches directly to the ulna. It bends the elbow whatever the position of the hand, and it is the workhorse elbow flexor. Its documented pattern is pain at the base of the thumb, on the back of the hand, from a trigger point in the upper arm. The thumb is examined and imaged and the upper arm is not, which is why it is missed. It relates to the biceps brachii page.
Attachments and action
Origin: The lower half of the front of the humerus.
Insertion: The coronoid process and tuberosity of the ulna.
Action: Flexion of the elbow in every forearm position; it works whether the palm faces up, down, or sideways.
Where the pain is felt: At the base of the thumb, on the back of the hand and in the web. At the front of the elbow crease. Over the front of the upper arm. A numb or tingling patch on the back of the thumb.
Common causes: Carrying groceries or a child with the elbow bent; a heavy bag over the forearm; curls and pull-ups; holding a phone up for long calls; guitar and violin playing; a cast that held the elbow bent for weeks.
Patients say: "My thumb hurts and the hand X-ray was normal." "The back of my thumb goes numb." An ache at the front of the elbow after carrying bags. "I cannot straighten my arm all the way in the morning."
When to get evaluated: Thumb-base pain after a fall on the hand needs an X-ray for a scaphoid fracture before anything else. Upper arm pain with sudden weakness, a visible bulge, or bruising after a heavy lift needs medical assessment for a tendon rupture.
How this muscle is examined and treated
Examination tests elbow flexion against resistance with the palm down, which takes the biceps out of the picture, then presses the muscle on either side of the biceps in the lower upper arm for the point that reproduces the thumb-base pain, and checks the back of the thumb for numbness. Needling here addresses the muscle deep to the biceps, from the outer side of the arm, with the radial nerve's course respected. Assessment and treatment happen in the same visit.
Related conditions
TendinitisChronic Pain PatternsSports & Performance Injuries
This page is educational. It describes muscle referral patterns commonly associated with pain; it does not diagnose your condition. Individual patterns vary. For evaluation of your specific pain, see a licensed clinician. Seek immediate medical care for emergencies. Eugene Baek, L.Ac. · New Jersey License 25MZ00080600