deltoid

Introduction

Intrinsic muscle of the shoulder (scapulohumeral).

Origin

• lateral 1/3 of the anterior border of the scapula
• lateral & posterior border of the acromion
• lower border of the spine of the scapula

Insertion

• lateral side or the shaft of the humerus (deltoid tuberosity) a little above the middle of the humerus

Action

• abduction of the arm at the shoulder
• flexion of the arm at the shoulder
• extension of the arm at the shoulder
• rotation of the arm at the shoulder
• anterior, middle & posterior portions of the muscle act independently

Innervation

• axillary nerve (C5, C6) via brachial plexus

More general terms

• skeletal muscle (voluntary muscle)

More specific terms

• deltoid tubercle of spine of scapula