Anatomy for MRCEM primary exam

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Upper limb Anatomy

Serratus anterior muscle

Surface markings, actions and nerve supply of Serratus anterior

OriginLateral surfaces of Upper 8 ribs 
InsertionAnterior surface of “Medial border and inferior angle” of the scapula
Nerve supplyLong Thoracic nerve
ActionsAbduction, Protraction, Upward rotation of the scapula

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

The scapula anterior surface has subscapularis muscle and serratus anterior muscles. These two muscles will be sandwiched between scapula and ribcage.

When this muscle contracts, the scapula will glide forward and it pulls the tip of scapula up, leading to some rotation upward.

Winging of scapula

To test the muscle function, we will ask the patient to lean on to the wall and push the wall with both hands. If the muscle is too weak or paralyzed, it fails to stabilize the scapula. This results in the medial border of the scapula protrude like a wing. – Signifies Long thoracic nerve damage.

Check previous lesson for Latissimus dorsi and Next lesson for Sternoclavicular joint.