Muscle
Brachialis
Elbow flexion regardless of palm position
High-yield
This major elbow flexor works across forearm positions. Most of its motor supply is musculocutaneous, with a frequent radial contribution laterally.
Overview
Brachialis lies under biceps and pulls the ulna toward the humerus. Because its insertion is on the ulna, it bends the elbow without directly turning the forearm palm-up or palm-down.
Reference facts
- Origin
- Anterior surface of the distal half of the humerus
- Insertion
- Ulnar tuberosity and anterior coronoid region
- Action
- Bends the elbow in pronated, neutral and supinated forearm positions
- Innervation
- Mainly musculocutaneous nerve (C5–C6), often with an additional radial nerve supply laterally
- Blood supply
- Branches of the brachial and radial recurrent arteries
Clinical correlation
A muscle injury or damage to its nerve supply can weaken elbow flexion. Its often divided nerve supply is relevant during operations near the distal humerus, where individual branches may be vulnerable.
Frequently asked questions
What does the brachialis do?
The brachialis bends the elbow in pronated, neutral and supinated forearm positions.
What nerve innervates the brachialis?
Mainly musculocutaneous nerve (C5–C6), often with an additional radial nerve supply laterally.
Where does the brachialis attach?
Origin: Anterior surface of the distal half of the humerus. Insertion: Ulnar tuberosity and anterior coronoid region.
What is the blood supply of the brachialis?
Branches of the brachial and radial recurrent arteries.