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Deltoid Muscle – Anterior and Middle Heads

image descriptionDeltoid Muscle - Anterior and Middle Heads

The Deltoid muscle (derived its name from the Greek letter delta) is a large, triangular muscle occupying the upper arm and the shoulder giving it this rounded shape. The deltoid consists three sets of fibers: anterior, middle, and posterior.

An image showing the Deltoid Muscle (highlighted) attached to the upper limb along with other muscles (Pectoralis major, Lattisimus dorsi, Biceps brachii, Brachioradialis)
An image showing the Deltoid Muscle (highlighted) attached to the upper limb along with other muscles (Coracobrachialis, Latissimus dorsi, Biceps brachii, Brachioradialis)
An image showing the Deltoid Muscle (highlighted) attached to the upper limb along with other muscles (Subscapularis, Latissimus dorsi)
An image showing the Deltoid muscle attached to the upper limb
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image descriptionAttachments of Deltoid Muscle: Origin & Insertion

Origin: (proximal attachments)
a. Anterior (clavicular) head: anterior surface of the lateral clavicle.
b. Middle (acromial) head: acromion process and spine of the scapula.

Insertion: (distal attachments)
a. Deltoid tuberosity of the humerus.

An image showing the Deltoid Muscle (highlighted) attached to the upper limb along with other muscles (Pectoralis major, Lattisimus dorsi, Biceps brachii, Brachioradialis)
An image showing the Deltoid muscle attached to the upper limb
An image showing the Origin and insertion of the deltoid muscle on the upper limb
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Actions of Deltoid Muscle:

Anterior Head:

image descriptiona. Flex the arm at the (glenohumeral) shoulder joint.

image descriptionb. Medially rotates the arm at the (glenohumeral) shoulder joint.

Arm rotation (medially)
Arm rotation (medially)
Arm rotation (medially)
Arm rotation (medially)
Arm rotation (medially)

Middle Head:
image descriptiona. Abducts the arm at the (glenohumeral) shoulder joint.

Arm abduction at shoulder joint
Arm abduction at shoulder joint
Arm abduction at shoulder joint
Arm abduction at shoulder joint
Arm abduction at shoulder joint

Innervation of Deltoid Muscle:

image descriptionNerves to the muscle:
Axillary nerve
image descriptionNerve roots:
C5 and C6.
An image showing the Axillary nerve coming out of the brachial plexus
An image showing the Axillary nerve coming out of the brachial plexus
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