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| Latin | Musculus brachialis |
|---|---|
| Origin |
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| Insertion |
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| Action |
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| Nerve | Musculocutaneous nerve (often also a branch of the radial nerve) (C5–C7) |
| Name | Latin brachium, 'arm'. |
Palpation
- Client supine with the elbow slightly bent and the forearm pronated (palm down), which relaxes the biceps.
- Find the biceps belly on the front of the lower arm, then move your fingers to either side of it, just above the elbow crease.
- Press in beside the biceps to feel a broad, flat muscle lying against the humerus.
- Ask the client to bend the elbow against light resistance with the palm still down; brachialis tightens while biceps stays fairly soft.
Brachialis is the real workhorse of elbow bending. Because it attaches to the ulna, not the radius, it does not turn the forearm, so it flexes the elbow equally well whatever the position of the hand. It lies under Biceps brachii and forms part of the floor of the elbow crease.
You can reach it at the edges of the biceps, especially on the outer side, just above the Lateral epicondyle of humerus. Keep the forearm pronated to take the biceps out of the action. Wikipedia notes that in 70–80% of people the lower outer part also gets a branch from the radial nerve (C5–C6), in addition to the musculocutaneous nerve.