Deltoid

• Deltoid (Anterior, middle and posterior fibres)

  • Coarse, thick, triangular multipennate muscle
  • Anterior, middle and posterior fibres

  
• Deltoid - Function:

  • Middle fibres are the main abductor of glenohumeral joint after initiation by supraspinatus
  • Resists downward displacement of humerus

  
• • All deltoid insert into the deltoid tuberosity on the lateral humeral shaft via a short thick tendon
  • Ant and Pos deltoids have completely opposite actions (Ant = flexor and medial rotator, Pos = extensor and lateral rotator)
  • All deltoid NS = axillary nerve (c5,c6)