Dr. Ebraheim’s educational animated video describes the anatomy of the brachialis muscle.
The brachialis muscle is a muscle in the upper arm that flexes the forearm at the elbow joint.
Origin and Insertion:
The brachialis muscle originates from the lower half of the anterior humerus, near the insertion of the deltoid muscle.
The brachialis muscle is located underneath of the biceps brachii muscle.
It is inserted into the tuberosity on the anterior surface of the coronoid process of the ulna.
Function:
Flexes the forearm at the elbow joint.
It doesn’t aid in pronation or supination.
The biceps muscle is a strong supinator.

Innervation: dual innervation of the brachialis muscle:
The musculocutaneous nerve arises from the lateral cord of the brachial plexus.\
It is the primary nerve supply to the brachialis muscle as well as the coracobrachialis and biceps muscles.
The musculocutaneous nerve lies underneath the biceps muscle and on top of the brachialis muscle.
Part of the brahialis is also innervated by the radial nerve.
The dual innervation of the brachialis allows it to be split during anterior approached to the humeral shaft.
The medial part lies in the flexor compartment with the musculocutaneous nerve.
As the limb develops, rotation of the lateral brachialis to become flexor and the lateral part brings with it the radial nerve supply.
Structures of the cubital fossa located around the brachialis muscle.
The cubital fossa is a triangular hollow area on the anterior surface of the elbow.
The brachialis muscle makes up part of the floor of the cubital fossa region.
Cubital fossa makes up four main structures from lateral to medial:
1 Radial nerve.
2 Biceps brachii tendon.
3 Brachial artery.
4 Median nerve.
Anterior approach to the humerous (splitting the brachialis:
Curved incision os made from the tip of the coracoid process along the anterolateral aspect of the humerus.
During part of theis procedure, the brachialis is split in the middle after retraction of the biceps muscle.
How to approach the radial nerve on the distal humerus?
The lower part of the humeral shaft is approached between the brachialis and the brachioradialis muscle with the brachialis retracted medially and the brachioradialis retracted laterally.
The radial nerve is identified and protected.
Because there is a dual innervation for the muscle, the brachialis is not denervated.
When the brachialis is retracted, this may endanger the nerve supply to the lateral brachialis.

Avulsion of the brachialis and coronoid process fracture:
Coronoid process fractures are usually associated with elbow dislocations and can occur from hyperflexion with avulsion of the brachialis tendon insertion or shearing off of the trochlea.



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Background music provided as a free download from YouTube Audio Library.
Song Title: Every Step