Shoulder muscles
The muscles that act on the shoulder are responsible for elevation, protraction, retraction and upward and downward rotation of the scapula. Scapular depression is mainly caused by the force of gravity, but also supported by muscles.
Adjusting the position of the scapula allows a wider range of movement in the shoulder girdle and upper limb.
These six movements are accomplished by so-called axioappendicular muscles. These shoulder muscles all originate from the axial skeleton and insert at different locations of the scapula bone to fulfill their various functions:
- The anterior axioappendicular muscles contain the pectoralis major and minor, subclavius and serratus anterior.
- The posterior axioappendicular muscles include
- extrinsic muscles: trapezius, latissimus dorsi, levator scapulae, rhomboid major and minor
- intrinsic muscles: deltoid, teres major and the rotator cuff muscles (supraspinatus, infraspinatus, subscapularis and teres minor)
Learn all about them with our interactive diagrams below!
Deltoid 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.
Teres Major Muscle – Attachments, Action & Innervation
Teres major is a thick and ovoid muscle in the upper arm. Despite their similar names, Teres major has different actions and innervation from the Teres minor. It’s mainly responsible for the medial rotation of the arm and it also contributes to static posture and arm-swinging.
Supraspinatus Muscle – Attachments, Actions & Innervation
Supraspinatus is a small muscle of the upper arm. It’s one of the four muscles that make up the rotator cuff. It arises from the supraspinatus fossa to eventually inserts on the greater tubercle of the humerus.
Infraspinatus Muscle – Attachments, Actions & Innervation
The infraspinatus is a thick and triangular muscle. It’s one of the Rotator Cuff muscles providing the mechanical link between the posterosuperior and anterior parts of the rotator cuff.
Subscapularis Muscle – Attachments, Action & Innervation
The subscapularis is a triangular muscle that fills the subscapular fossa. The Subscapularis muscle is one of the rotator cuff muscles, helping to stabilize the head of the humerus in the glenoid fossa during shoulder movements.
Teres Minor Muscle – Attachments, Actions & Innervation
Teres minor is one of four muscles that comprise what’s called the Rotator Cuff. It’s narrow and elongated in shape and sometimes may be fused with infraspinatus. Its main function is to stabilize the humerus in the glenoid fossa when the shoulder moves.
Pectoralis Major Muscle – Attachment, Action & Innervation
Pectoralis major is a thick, fan-shaped muscle contributing to the thoracobrachial motion. It consists of a clavicular part and a sternal part, both converging to a flat tendon that inserts on the humerus. It’s innervated by both medial and lateral pectoral nerves.
Pectoralis Minor Muscle – Attachment, Action & Innervation
Pectoralis Minor Muscle (Insertion, Origin, Actions & Innervations); explained beautifully in an illustrated and interactive way.
Serratus Anterior Muscle
Serratus Anterior Muscle (Insertion, Origin, Actions & Innervations); explained beautifully in an illustrated and interactive way.
Trapezius Muscle
An interactive demonstration of the Trapezius Muscle (Insertion, Origin, Actions & Innervations) featuring the iconic GBS illustrations.
Latissimus Dorsi Muscle – Attachments, Action & Innervation
Latissimus Dorsi is one of four muscles responsible for the thoracobrachial motion. It is large, flat and triangular in shape originating from large parts of the lumbar region and lower thorax to insert on the humerus through a narrow tendon.
Levator Scapulae Muscle
An interactive demonstration of the Levator Scapulae Muscle (Insertion, Origin, Actions & Innervations) featuring the iconic GBS illustrations.
Rhomboid Minor Muscle
An interactive demonstration of the Rhomboid Minor Muscle (Insertion, Origin, Actions & Innervations) featuring the iconic GBS illustrations.
Rhomboid Major Muscle
An interactive demonstration of the Rhomboid Major Muscle (Insertion, Origin, Actions & Innervations) featuring the iconic GBS illustrations.