Deltoid

Last updated on Monday, April 20 2009 by blondarb

Muscle Name: deltoid

AKA: musculus deltoideus

Abbreviation:

Spinal Nerve Roots:
C5
C6

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

Pitfalls:

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.

Related videos:

Middle Deltoid EMG Technique
A demonstration of needle placement and activation technique in an EMG study of the middle head of the Deltoid muscle.

Anterior Deltoid EMG Technique
A demonstration of needle placement and activation technique in an EMG study of the Anterior Head of the Deltoid muscle.

Posterior Deltoid EMG Technique - Method 1
A demonstration of one method needle placement and activation technique in an EMG study of the Posterior Head of the Deltoid muscle.

Posterior Deltoid EMG Technique - Method 2
A demonstration of another method needle placement and activation technique in an EMG study of the Posterior Head of the Deltoid muscle.

Related images:

Deltoid
The superficial muscles of teh chest and anterior arm.

Deltoid
A posterior view of the axillary nerve and its divisions. The axillary nerve has a superior and inferior branch. The inferior branch supplies the posterior head of the deltoid, while the superior branch supplies the anterior and middle heads of the deltoid.