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Last updated on Monday, April 20 2009 by blondarb

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Muscle Name: deltoid

AKA: musculus deltoideus


Spinal Nerve Roots:

Brachial Plexus Trunks:
    upper trunk

Brachial Plexus Cords:
    posterior cord

Named Nerves:
    axillary nerve

Proximal Attachment:  clavicle, acromion, spine of the scapula

Distal Attachment:  deltoid tuberosity of humerus

Action:  shoulder abduction, flexion and extension

Needle Insertion:  

  Anterior head

     Approximately 3 cm distal to the anterior aspect of the acromion.

   Middle head

      Approximately 4 cm distal to the midpoint of the acromion.

   Posterior head

      Approximately 3 cm distal to the posterior edge of the acromion.

Activation for EMG:  

  Anterior head

    With the arm adducted, have the patient flex at the shoulder. 

  Middle head

     From a neutral position, have the patient abduct the shoulder.

  Posterior head

    With the arm adducted, have the patient extend the shoulder


Notes:  The axillary nerve had a superior and an inferior branch. The superior branch innervates the anterior and middle heads. The inferor branch innervates the posterior head of the deltoid, the teres minor and the cutaneous innervation of the shoulder. This is important when assessing lesion of the axillary nerve.