Arm muscles
The arm muscles originate from different locations of the scapula to insert on the humerus and carry out their functions via the glenohumeral joint.
The arm muscles are organized into two compartments:
- Anterior (flexor) compartment: biceps brachii, brachialis and coracobrachialis muscles. The muscles of the anterior compartment primarily adduct the arm in the shoulder joint and perform flexion of the forearm in the elbow joint. They also aid with flexion of the shoulder joint and supinate the forearm.
- Posterior (extensor) compartment: triceps brachii and anconeus muscles. These muscles primarily extend the forearm in the elbow joint but also perform weak arm extension and adduction.
Learn the arm muscle anatomy faster with interactive quizzes and video tutorials.
Biceps Brachii – Attachments, Action & Innervation
Biceps brachii is one of the main muscles of the upper arm which acts on both the shoulder joint and the elbow joint. It derives its name from the fact that it consists of two parts (heads), both innervated by the musculocutaneous nerve.
Coracobrachialis Muscle – Attachments, Action & Innervation
Coracobrachialis is one of the three muscles that comprise the anterior compartment of the arm. Its action is mainly antagonist to the action of the Deltoid.
Triceps brachii muscle
The long head of the Triceps brachii is one of three heads that make up the muscle. It descends between teres minor and major, dividing the wedge-shaped interval between them and the humerus into triangular and quadrangular spaces.
Anconeus Muscle – Attachments, Action & Innervation
Anconeus muscle is a small muscle that is triangular in shape. It’s sometimes blended with triceps brachii or extensor carpi ulnaris. It arises from the humerus to later insert on the olecranon of the ulna.
Brachialis Muscle
Brachialis Muscle (Insertion, Origin, Actions & Innervations); explained beautifully in an illustrated and interactive way.