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Muscles of the Arm

Origin, Insertion & Innervation


we delve into the detailed anatomy of the muscles of the arm, focusing on both the anterior and posterior compartments. We'll explore the origin, insertion, and innervation of these crucial muscles.

Division of Arm

The arm is divided by the deep fascia into 

Anterior and Posterior compartments.

  • Anterior compartment contains the Flexor muscles.
  • Posterior compartment contains the Extensor muscles.

Muscles of Anterior Compartment

The muscles of the Anterior compartment of the arm are:

1.Biceps Brachii

2. Brachialis

3. Coracobrachialis

1. Biceps Brachii

 It lies superficial in the anterior compartment, crossing the shoulder and elbow joints.


  • Origin:

Long Head: Supraglenoid tubercle of the scapula.

Short Head: Coracoid process of the scapula.


  • Insertion: Radial tuberosity and bicipital aponeurosis.


  • Innervation: Musculocutaneous nerve (C5, C6).

2. Brachialis

It is positioned deep to the biceps brachii.


  • Origin: Lower half of the anterior surface of the humerus.


  • Insertion: Coronoid process and tuberosity of the ulna.


  • Innervation: Musculocutaneous nerve (C5, C6) and radial nerve (C7).

3. Brachialis

It is located medially, assisting in shoulder flexion and adduction.


  • Origin: Coracoid process of the scapula.


  • Insertion: Medial surface of the humerus at the level of the deltoid tuberosity.


  • Innervation: Musculocutaneous nerve (C5, C6, C7).

Muscles of Posterior Compartment

The Posterior Compartment has only One muscle:

Triceps Brachii Muscle


 Triceps Brachii Muscle

 It is the only muscle in the posterior compartment, providing powerful extension of the elbow.


Origin:

  • Long Head: Infraglenoid tubercle of the scapula.
  • Lateral Head: Posterior surface of the humerus, above the radial groove.
  • Medial Head: Posterior surface of the humerus, below the radial groove.


Insertion: Olecranon process of the ulna.


Innervation: Radial nerve (C6, C7, C8).