Deltoid - Podcast Version 0:00 / 0:00 1x 0.25x 0.5x 0.75x 1x 1.25x 1.5x 1.75x 2x The deltoid is an intrinsic muscle of the shoulder region. It is shaped like an inverted triangle and can be divided into three parts (anterior, middle and posterior). Attachments: Originates from the lateral third of the clavicle, the acromion and the spine of the scapula. It attaches to the deltoid tuberosity on the lateral aspect of the humerus. Innervation: Axillary nerve. Actions: Anterior fibres – flexion and medial rotation at the shoulder Posterior fibres – extension and lateral rotation at the shoulder Middle fibres – abduction at the shoulder (takes over from the supraspinatus, which abducts the first 15 degrees). Blood supply: Anterior and posterior circumflex humeral artery. By TeachMeSeries Ltd (2026) Fig 1The deltoid and teres major Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Pro Feature - Dissection Atlas Prosection of the posterior shoulder region. The axillary nerve and posterior circumflex humeral artery can be seen passing through the quadrangular space Prosection of the posterior shoulder region. The axillary nerve and posterior circumflex humeral artery can be seen passing through the quadrangular space You've Discovered a Pro Feature Access our Dissection Image Library Enhance your understanding with high-resolution dissection images showcasing real-life anatomy. Learn More Frequent questions What is the deltoid muscle and where is it located? The deltoid muscle is an intrinsic muscle of the shoulder region, characterised by its inverted triangle shape. It is situated over the shoulder joint and plays a crucial role in arm movement. What are the main attachments of the deltoid muscle? The deltoid muscle originates from the lateral third of the clavicle, the acromion, and the spine of the scapula, and it attaches to the deltoid tuberosity on the lateral side of the humerus. What actions does the deltoid muscle perform at the shoulder? The deltoid muscle facilitates several movements at the shoulder: the anterior fibres enable flexion and medial rotation, the posterior fibres allow for extension and lateral rotation, and the middle fibres are responsible for abduction. Which nerve innervates the deltoid muscle? The deltoid muscle is innervated by the axillary nerve, which is essential for its motor function and overall shoulder stability. What is the blood supply for the deltoid muscle? The deltoid muscle receives its blood supply primarily from the anterior and posterior circumflex humeral arteries, ensuring adequate oxygenation and nutrient delivery for its activity. Rate This Article