Triceps brachii (Muscles of the Posterior Arm)
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Posterior Arm
Overview
- Three heads of triceps brachii and anconeus comprise the posterior arm muscles.
- They extend the arm.
- They are innervated by the radial nerve of the brachial plexus.
- Triceps brachii tendonitis is inflammation of the elbow; caused by repetitive use.
Muscles
Anconeus:
- Originates on the lateral epicondyle of the humerus
- Inserts on the proximal ulna
- It extends the forearm and abducts the ulna during pronation (turning the palms down; "pouring" the soup).
- Each inserts on the olecranon process.
Long head of triceps brachii:
- Originates on the infraglenoid tubercle of the scapula.
- Long head of triceps brachii aids in extension and adduction of the arm at the shoulder.
Medial head of triceps brachii:
- Originates on the posterior surface of the humerus inferior to the radial groove.
Lateral head of triceps brachii:
- Originates superior to the radial groove on the humerus.
- The medial and lateral heads extend the forearm.
Related Anatomy
Nerve
Radial nerve
Plexus
Brachial plexus
Muscle Action
Elbow extension
Nerve Root
C6
C7
C8
Brachial Plexus Trunk
Upper trunk
Middle trunk
Lower trunk
Brachial Plexus Cord
Posterior cord
Brachial Plexus Division
Posterior division