Author: Dr Peter de Souza
Last modified: 14 November 2022

The deltoid muscle is thick, triangular shaped muscle which arises from the lateral third of the clavicle, the superior acromion process and the spine of the scapular. It attaches to the deltoid tubercle of the lateral proximal humeral shaft.


  • Clavicle
  • Acromion process
  • Spine of scapula


  • Deltoid tuberosity


  • Anterior fibres: flexion of arm
  • Middle fibres: abduction of arm
  • Posterior fibres: extension of arm


  • Axillary nerve: C5, 6

Blood Supply

  • Deltoid branch of thoracoacromial artery