Brachialis muscle
Musculus brachialis
Brachialis is a broad muscle on the front of the lower arm, lying under the biceps and acting as the main flexor of the elbow.
At a glance
- English
- Brachialis muscle
- Latin (TA2)
- Musculus brachialis
- System
- Muscle
- Region
- Upper limb
- Side
- Paired, left and right
About the brachialis muscle
The brachialis is a broad, flat flexor in the front of the arm. It sits beneath the biceps brachii, so most of it is hidden from view, and its lower part helps form the floor of the cubital fossa at the front of the elbow. It is sometimes called brachialis anticus or Teichmann's muscle.
Its fleshy origin covers the front of the lower half of the humeral shaft. At the top, two pointed slips reach up on either side of the deltoid's attachment, gripping it between them, and at the bottom the fibres start only a short way above the elbow joint surface. The fibres gather into a stout tendon that crosses the front of the joint and fixes to the ulna, on the coronoid process and the ulnar tuberosity just below it.
Because it attaches to the ulna rather than the radius, the brachialis bends the elbow whatever position the forearm is in, and it takes no part in turning the palm up or down. That makes it the main flexor of the elbow, with biceps and brachioradialis assisting. The musculocutaneous nerve runs across its front surface, lying between it and the biceps, and supplies it; in many people the lateral part also gets a twig from the radial nerve.
Clinically the muscle matters at the elbow. It lies directly in front of the joint capsule, so it is at risk in supracondylar fractures of the humerus and in elbow dislocation, and bleeding into it after such injuries is a recognised cause of myositis ossificans. Occasionally the muscle is doubled, or sends small slips to nearby forearm muscles or the radius.
Attachments, action and supply
- Origin
- Front of the lower half of the humeral shaft, from around the deltoid's attachment, which it embraces with two slips, down to just above the elbow joint.
- Insertion
- Coronoid process of the ulna and the ulnar tuberosity, by a thick tendon.
- Action
- Flexes the elbow in every forearm position; it does not pronate or supinate because it has no hold on the radius.
- Nerve supply
- Musculocutaneous nerve (C5, C6); the lateral part usually also receives a branch of the radial nerve.
- Blood supply
- Muscular branches of the brachial artery and the radial recurrent artery.
Anthromica
See the brachialis muscle where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
