Triceps Brachii - Muscle Physiology & Functional Anatomy

Anatomy

Origin:

• Long head

  • Infraglenoid tubercle of scapula
    

• Lateral head

  • Posterior humerus (upper half)
    

• Medial head

  • Posterior humerus (deep on lower half posterior humerus inferomedial to spiral groove & both intermuscular septa)
    

Insertion

• Posterior part of upper surface of olecranon process of ulna & posterior capsule

Major Arteries:

• Deep brachial artery (profunda brachii)

Neural Innervation:

• Radial nerve

• Axillary nerve (long head)

Trigger Points:

Physiology

Concentric Functions:

• Long head

  • Elbow extension

  • Assists in shoulder extension & abduction
    

• Lateral head

  • Elbow extension
    

• Medial head

  • Elbow extension

Eccentric Functions:

• Long head

  • Assists in deceleration of shoulder flexion

  • Assists in shoulder extension & abduction
    

• Lateral head

  • Decelerates elbow flexion
    

• Medial head

  • Decelerates elbow flexion

Isometric Function:

• Long head

  • Helps dynamically stabilize the glenohumeral joint
    

• Lateral head

  • 
    

• Medial head

Related Muscles

• Anconeus

Antagonist:

• Biceps Brachii

• Brachialis

• Brachioradialis

  
  

Exercises:

• Triceps Exercise Videos

More Images of the Triceps Brachii Muscle

More Information about the Triceps Brachii Muscle

The triceps brachii muscle is biarticulate which means it has actions across 2 joints. 

The long head of the triceps assists in extension & adduction of the shoulder when it is externally rotated.  When the shoulder is internally rotated the ability of the long head of the triceps brachii to extend & adduct the shoulder is lessened.

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