Triceps Brachii Anatomy

Triceps Brachii Long Head

Origin: Infraglenoid tubercle of the scapula
Insertion: Posterior surface of the olcranion process of the ulna
Actions: Extension of the arm at the shoulder, adduction of the arm at the shoulder, extension of the forearm at the elbow
Innervation: Radial nerve (C6, C7)
Blood Supply: Muscular branches and superior ulnar collateral and profunda brachii arteries from the brachial artery

Primary Actions of the Triceps Brachii Long Head

1.  Extension of the arm at the shoulder

  Agonists:

  • Deltoid (posterior part)
  • Latissimus Dorsi
  • Pectoralis Major (sternal head)
  • Teres Major

  Antagonists:

  • Deltoid (anterior part)
  • Coracobrachialis
  • Biceps brachii,
  • Pectoralis major (clavicular head)

2. Adduction of the arm at the shoulder

 Agonists: 

  • Latissimus Dorsi
  • Pectoralis Major
  • Teres Major

  Antagonists: 

  • Supraspinatus
  • Deltoid (middle part)

Note: Coracobrachialis and teres minor assist with adduction of the arm at the shoulder.

3. Extension of the forearm at the elbow

  Agonists:

  • Triceps Brachii (lateral and medial heads)
  • Anconeus

Antagonists:

  • Brachialis
  • Biceps brachii
  • Brachioradialis

Advertisement




Triceps Brachii Lateral Head

Origin: Superior half of the posterior surface of the humeral shaft, lateral to the spiral groove
Insertion: Posterior surface of the olecranon process of the ulna
Actions: Extension of the forearm at the elbow
Innervation: Radial nerve (C6, C7)
Blood Supply: Muscular branches and superior ulnar collateral and profunda brachii arteries from the brachial artery

Primary Actions of the Triceps Brachii Lateral Head

1.  Extension of the forearm at the elbow

  Agonists:

  • Triceps Brachii (long and medial head)
  • Anconeus

  Antagonists:

  • Brachialis
  • Biceps brachii
  • Brachioradialis

Triceps Brachii Medial Head

Origin: Posterior shaft of the humerus, medial and distal to the spiral groove
Insertion: Posterior surface of the olecranon process of the ulna
Actions: Extension of the forearm at the elbow
Innervation: Radial nerve (C6, C7)
Blood Supply: Muscular branches and superior ulnar collateral and profunda brachii arteries from the brachial artery

Primary Actions of the Triceps Brachii Medial Head

1.  Extension of the forearm at the elbow

  Agonists:

  • Triceps Brachii (long and lateral head)
  • Anconeus

  Antagonists:

  • Brachialis
  • Biceps brachii
  • Brachioradialis