Anatomy for MRCEM primary exam

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Upper limb Anatomy

Brachialis muscle

Actions & innervation of Brachialis.

Knowledge of origins & insertions is NOT required but an appreciation of the surface topography is required.

OriginAnteriorly from distal half of Humerus
InsertionTuberosity of Ulna and coronoid process of Ulna
Nerve supplyMusculocutaneous nerve
ActionsFlexion of forearm

Though the curriculum says origin and insertion not required, we’ve included them as that knowledge will help you understand the movements better based on muscle orientation.

Brachialis muscle Origin and Insertions – Image modified from BodyParts3D, © The Database Center for Life Science licensed under CC Attribution-Share Alike 2.1 Japan

The orange colored muscle is coracobrachialis and the wider brownish muscle is the Brachialis in the image.

When it inserts on the Ulna, it goes between 2 heads of flexor digitorum profundus.

The position of muscle should help you understand the actions when it contracts. It’ll pull the forearm anteriorly (flexion).

All the anterior arm muscles – Coracobrachialis, Brachialis and Biceps brachii are supplied by the same nerve – The Musculocutaneous nerve, the terminal branch of the lateral cord of the brachial plexus (C5-C7). The nerve becomes lateral cutaneous nerve of forearm to supply lateral part of forearm. Muscles of Upper Arm and Skin of Forearm are supplied.

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