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The brachialis is a muscle in the upper arm that flexes the elbow. It lies beneath the biceps brachii and makes up part of the floor of the cubital fossa (elbow pit). Traditionally, the brachialis has been described as a single-head muscle, but cadaver assessment has demonstrated that it may have two heads: one superficial and one deep. The superficial head forms the major head, which originates from the anterior mid-shaft humerus and the lateral intermuscular septum and inserts onto the ulnar tuberosity.
| Characteristics | Values |
|---|---|
| Number of heads | Traditionally described as single-head, but cadaver assessment has shown it may have 2 heads: 1 superficial and 1 deep |
| Origin | Anterior mid-shaft humerus and the lateral intermuscular septum |
| Insertion | Ulnar tuberosity |
| Innervation | Musculocutaneous nerve, with additional innervation from the radial nerve in 70-80% of people |
| Function | Flexes the elbow, generating about 50% more power than the biceps |
| Location | Upper arm, beneath the biceps brachii |
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What You'll Learn
The brachialis is a muscle in the upper arm
The brachialis lies beneath the biceps brachii and makes up part of the floor of the region known as the cubital fossa (elbow pit). It originates from the anterior aspect of the distal humerus and inserts onto the tuberosity of the ulna. It is innervated by the musculocutaneous nerve and commonly also receives additional innervation from the radial nerve. The brachialis is the prime mover of elbow flexion, generating about 50% more power than the biceps.
Traditionally, the brachialis has been described as a single-head muscle. However, cadaver assessment has demonstrated that the brachialis muscle may have two heads, one superficial and one deep. The superficial head forms the major head, which originates from the anterior mid-shaft humerus and the lateral intermuscular septum and inserts onto the ulnar tuberosity. In detail, the insertion of the deep head has three portions: medial and lateral aponeurosis and muscular contractile fibres that attach directly to the ulna. The deep head forms a smaller muscle that originates from the anterior humerus and the medial intermuscular septum and inserts mainly into an aponeurosis that branches to the ulna.
The brachialis is occasionally doubled; additional muscle slips to the supinator, pronator teres, biceps brachii, lacertus fibrosus, or radius are more rarely found. The muscle is innervated by the musculocutaneous nerve, which runs on its superficial surface, between it and the biceps brachii. However, in 70-80% of people, the muscle has double innervation with the radial nerve.
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It lies beneath the biceps brachii
The brachialis is a muscle in the upper arm that flexes the elbow. It lies beneath the biceps brachii, and makes up part of the floor of the region known as the cubital fossa (elbow pit). It originates from the anterior aspect of the distal humerus; it inserts onto the tuberosity of the ulna. It is innervated by the musculocutaneous nerve, and commonly also receives additional innervation from the radial nerve. The brachialis is the prime mover of elbow flexion, generating about 50% more power than the biceps. The brachialis originates from the anterior surface of the distal half of the humerus, near the insertion of the deltoid muscle, which it embraces by two angular processes.
The brachialis is an important flexor muscle of the forearm at the elbow. It lies in the anteroinferior area of the arm and is deeper than the biceps brachii muscle. Brachialis contributes to the upper part of the anatomically important antecubital fossa of the elbow joint. The brachialis is an elbow flexor that originates from the distal anterior humerus and inserts onto the ulnar tuberosity. The brachialis is one of the largest elbow flexors and provides pure forearm flexion at the elbow.
The brachialis works closely with the biceps brachii and brachioradialis muscles to ensure that the elbow bends appropriately. Injury to the brachialis muscle may cause pain and limit your ability to use your arm normally.
Traditionally, the brachialis has been described as a single-head muscle, although cadaver assessment has demonstrated that the brachialis muscle may have two heads, one superficial and one deep. The superficial head forms the major head, which originates from the anterior mid-shaft humerus and the lateral intermuscular septum and inserts onto the ulnar tuberosity. In detail, the insertion of the deep head has three portions: medial and lateral aponeurosis and muscular contractile fibres that attach directly to the ulna. The deep head forms a smaller muscle that originates from the anterior humerus and the medial intermuscular septum and inserts mainly into an aponeurosis that branches to the ulna.
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It is innervated by the musculocutaneous nerve
The brachialis is a muscle in the upper arm that flexes the elbow. It lies beneath the biceps brachii and makes up part of the floor of the cubital fossa (elbow pit). It is innervated by the musculocutaneous nerve, which runs on its superficial surface, between it and the biceps brachii. In 70-80% of people, the muscle has double innervation with the radial nerve (C5-T1). The divide between the two innervations is at the insertion of the deltoid.
The musculocutaneous nerve is a branch of the brachial plexus, which is a network of nerves that supply the arm and hand. The brachial plexus is formed by the ventral rami of the lower four cervical nerves and the first thoracic nerve. The musculocutaneous nerve arises from the lateral cord of the brachial plexus and runs down the arm, supplying the muscles that flex the elbow.
The brachialis is a "pure flexor" of the forearm at the elbow. It is one of the largest elbow flexors and provides about 50% more power than the biceps. It originates from the anterior surface of the distal half of the humerus and inserts onto the ulnar tuberosity. The brachialis works closely with the biceps brachii and brachioradialis muscles to ensure that the elbow bends appropriately.
Traditionally, the brachialis has been described as a single-head muscle. However, cadaver assessments have demonstrated that it may have two heads: one superficial and one deep. The superficial head forms the major head, which originates from the anterior mid-shaft humerus and the lateral intermuscular septum. The deep head forms a smaller muscle that originates from the anterior humerus and the medial intermuscular septum.
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It is occasionally doubled
The brachialis is a muscle in the upper arm that flexes the elbow. It lies beneath the biceps brachii, and makes up part of the floor of the region known as the cubital fossa (elbow pit). It is innervated by the musculocutaneous nerve, and commonly also receives additional innervation from the radial nerve. In 70-80% of people, the muscle has double innervation with the radial nerve. The brachialis is occasionally doubled; additional muscle slips to the supinator, pronator teres, biceps brachii, lacertus fibrosus, or radius are more rarely found.
Traditionally, the brachialis has been described as a single-head muscle, although cadaver assessment has demonstrated that the brachialis muscle may have two heads, one superficial and one deep. The superficial head forms the major head, which originates from the anterior mid-shaft humerus and the lateral intermuscular septum and inserts onto the ulnar tuberosity. The deep head forms a smaller muscle that originates from the anterior humerus and the medial intermuscular septum and inserts mainly into an aponeurosis that branches to the ulna.
The brachialis is the prime mover of elbow flexion, generating about 50% more power than the biceps. It is considered a 'pure flexor' of the forearm at the elbow. It works closely with the biceps brachii and brachioradialis muscles to ensure that the elbow bends appropriately. Injury to the brachialis muscle may cause pain and limit the ability to use the arm normally.
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It is considered a 'pure flexor' of the forearm at the elbow
The brachialis is a muscle in the upper arm that flexes the elbow. It is considered a pure flexor of the forearm at the elbow. It lies beneath the biceps brachii, and makes up part of the floor of the region known as the cubital fossa (elbow pit). It is the prime mover of elbow flexion, generating about 50% more power than the biceps.
Traditionally, the brachialis has been described as a single-head muscle. However, cadaver assessment has demonstrated that the brachialis muscle may have two heads: one superficial and one deep. The superficial head forms the major head, which originates from the anterior mid-shaft humerus and the lateral intermuscular septum and inserts onto the ulnar tuberosity. The deep head forms a smaller muscle that originates from the anterior humerus and the medial intermuscular septum and inserts mainly into an aponeurosis that branches to the ulna.
The brachialis is innervated by the musculocutaneous nerve, which runs on its superficial surface, between it and the biceps brachii. However, in 70-80% of people, the muscle has double innervation with the radial nerve. The brachialis is supplied by muscular branches of the brachial artery and by the recurrent radial artery. The muscle is occasionally doubled, with additional muscle slips to the supinator, pronator teres, biceps brachii, lacertus fibrosus, or radius more rarely found.
The brachialis works closely with the biceps brachii and brachioradialis muscles to ensure that the elbow bends appropriately. Unlike the biceps, the brachialis does not insert on the radius and does not participate in pronation and supination of the forearm.
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Frequently asked questions
There is one brachialis muscle, but it may have two heads, one superficial and one deep.
The brachialis is a muscle in the upper arm that flexes the elbow.
The brachialis is located in the upper arm, near the crook of the elbow.
The brachialis flexes the arm at the elbow joint.
The brachialis is an important flexor muscle of the forearm at the elbow. It provides elbow flexion at all physiologic positions and is considered a "pure flexor" of the forearm at the elbow.
