Triceps brachii

• O (origin):

  Long head (most medial):

  • infra-glenoid tubercle on glenoid fossa of scapular
  • glenoid labrum (fibres blending with joint capsule)

  A) Triceps brachii

  B) long

  
• O (origin):

  Medial head:

  • inferior & medial aspect of spiral groove on posterior humerus
  • Posterior aspect of the medial & lateral intermuscular septa

  A) Triceps brachii

  B) medial

  
• O (origin):

  Lateral head:

  • superior & lateral aspect of spiral groove on posterior humerus

  A) Triceps brachii

  B) lateral

  
• R (direction):

  • Inferiorly (three heads merge to create a broad laminated (layered) tendon

  A) Triceps brachii

  
• I (insertions):

  • Insert via tendon (deep and superficial laminae) to posterior aspect of proximal olecranon of ulna
  • deep fascia of forearm on either side

  A) Triceps brachii

  
• A (actions):

  • Extends elbow
  • Long head adducts glenohumeral joint & extends it from flexed position

  A) Triceps brachii

  
• NS (nerve supply):

  • Radial nerve (C5 - T1)

  A) Triceps brachii

  
• • lateral head origin: lateral and superior aspect of spiral groove on posterior humerus
  • medial head origin: medial and inferior aspect of spiral groove on posterior humerus (and posterior aspect of lateral and medial intermuscular septum)