Lecture Summary: Triceps Brachii

Overview

The triceps brachii is a large muscle forming most of the area on the back of the arm.
The name "triceps" indicates three heads (tri = three, ceps = heads).

Long Head: Originates from the infraglenoid tubercle of the scapula.
- Infraglenoid tubercle is the specific origin point.
Lateral Head: Arises from the oblique ridge above the spiral groove on the upper part of the posterior surface of the humerus shaft.
- Oblique ridge is the specific origin point.
Medial Head: Originates from the posterior surface of the humerus below the radial groove.
- Named due to the radial groove lying medial to the lateral head.

Inserted by a common tendon into the posterior part of the superior surface of the olecranon process of the ulna.
Medial Head (Deep Head): Some fibers insert into the posterior aspect of the elbow joint capsule, known as "articularis cubiti" or "subanconeus muscle."

Below the lateral head lie the profunda brachii artery and the radial nerve.

Supplied by the radial nerve.
Each head receives a separate branch from the radial nerve:
- Long Head: Nerve arises in the axilla.
- Lateral Head: Nerve arises in the radial groove.
- Medial Head: Nerve arises in the radial groove.

The triceps brachii is a powerful extensor of the elbow joint.
The long head supports the head of the humerus during hyperabduction of the arm.

Radial Nerve Injury: In the radial groove, can result in loss of elbow extension and triceps reflex.
- Due to the nerve to the long head arising from the radial nerve in the axilla.

This lecture covered the structure, nerve supply, and functions of the triceps brachii.

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