Brachialis
Arm · Upper Limb
The Brachialis is found among the Arm muscles of the Upper Limb. Its origin is Distal half of anterior surface of humerus, and it inserts onto Coronoid process and tuberosity of ulna. Functionally, it flexion of forearm at the elbow (in all positions). It is innervated by the Musculocutaneous nerve (C5, C6); small contribution from radial nerve (C7).
Origin, Insertion, Action & Nerve
Origin
Distal half of anterior surface of humerus
Insertion
Coronoid process and tuberosity of ulna
Action
Flexion of forearm at the elbow (in all positions)
Nerve
Musculocutaneous nerve (C5, C6); small contribution from radial nerve (C7)
Attachments explained
The Brachialis is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Distal half of anterior surface of humerus
Insertion
Coronoid process and tuberosity of ulna
Action & function
When the Brachialis contracts, it produces the following movement: Flexion of forearm at the elbow (in all positions).
As part of the Arm group of the Upper Limb, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Brachialis receives its nerve supply from the Musculocutaneous nerve (C5, C6); small contribution from radial nerve (C7). This nerve carries fibres from spinal segment(s) C5, C6, C7.
Because a muscle can only contract when its nerve is intact, injury to the Musculocutaneous nerve or to its spinal roots (C5, C6, C7) can weaken or paralyse the Brachialis, impairing the movements it normally produces (flexion of forearm at the elbow (in all positions)). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Brachialis (the OIANS method)
OIANS stands for Origin, Insertion, Action and Nerve, the four facts that uniquely define every skeletal muscle. To learn the Brachialis, work through them in order: picture its origin, trace the muscle to its insertion, reason out the action that shortening between those two points must create, then add the nerve that drives it.
Most students remember the Brachialis fastest by linking its action back to its attachments rather than memorising each fact in isolation. Once the origin and insertion make sense, the action usually follows logically.
Brachialis quick facts
- Region
- Upper Limb
- Group
- Arm
- Origin
- Distal half of anterior surface of humerus
- Insertion
- Coronoid process and tuberosity of ulna
- Action
- Flexion of forearm at the elbow (in all positions)
- Nerve
- Musculocutaneous nerve (C5, C6); small contribution from radial nerve (C7)
- Spinal roots
- C5, C6, C7
Frequently asked questions
Where is the Brachialis located?
The Brachialis is a muscle of the Arm group, located in the Upper Limb.
What is the origin of the Brachialis?
Distal half of anterior surface of humerus
What is the insertion of the Brachialis?
Coronoid process and tuberosity of ulna
What movements does the Brachialis produce?
Flexion of forearm at the elbow (in all positions)
What nerve supplies the Brachialis?
Musculocutaneous nerve (C5, C6); small contribution from radial nerve (C7)
Is the Brachialis free to study in OIANS?
Yes. The Brachialis is free in OIANS: its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory, and because it belongs to the Upper Limb it is also covered by the free Quiz and Flashcard decks. The other regions, the "All Muscles" deck, and the Progress and Explore tools are unlocked with a one-time Lifetime purchase.
Related muscles
Study the Brachialis
Test yourself on Upper Limb muscles with interactive quizzes and flashcards in the free OIANS app.
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