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Muscles of Forearm

Anterior Compartment of Forearm


Compartments of the forearm

The deep fascia of the forearm divides it into 2 compartments:

  • Anterior compartment
  • Posterior compartment.

Anterior compartment of the forearm


The anterior compartment of forearm contains the flexors of hand.


There are 8 flexor muscles in the anterior compartment.

  • 5 flexors are in superficial layer of anterior compartment,
  • 3 flexors are in deep layer.



The anterior compartment of the forearm is divided into two layers:


  • Superficial Layer
  • Deep Layer


Muscles of Superficial Layer

of Anterior Compartment of Forearm

It is located just beneath the skin and fascia.

All muscles of Superficial layer originate from Medial epicondyle of humerus. Thats why, they have a common flexor origin.


Following are the 5 Muscles of Superficial Layer.


1. Pronator Teres

2. Flexor Carpi Radialis

3. Palmaris Longus

4. Flexor Carpi Ulnaris

5. Flexor Digitorum Superficialis


 1. Pronator Teres

 Origin:

  • Humeral Head: Medial epicondyle of the humerus.
  • Ulnar Head: Coronoid process of the ulna.


Insertion: Lateral surface of the radius.


Innervation: Median nerve (C6, C7).

 2. Flexor Carpi Radialis

Origin: Medial epicondyle of the humerus.


Insertion: Base of the second and third metacarpal bones.


Innervation: Median nerve (C6, C7).

 3. Palmaris Longus 

Origin: Medial epicondyle of the humerus.


Insertion: Palmar aponeurosis.


Innervation: Median nerve (C7, C8).

 4. Flexor Carpi Ulnaris

Origin:

  • Humeral Head: Medial epicondyle of the humerus.
  • Ulnar Head: Olecranon and posterior border of the ulna.


Insertion: Pisiform, hook of hamate, and base of the fifth metacarpal bone.


Innervation: Ulnar nerve (C7, C8).​

 5. Flexor Digitorum Superficialis

Origin:

  • Humeroulnar Head: Medial epicondyle of the humerus and coronoid process of the ulna.
  • Radial Head: Anterior surface of the radius.


Insertion: Middle phalanges of the second to fifth fingers.


Innervation: Median nerve (C7, C8, T1).


Muscles of Deep Layer

of Anterior Compartment of Forearm


It is situated close to the bones and interosseous membrane of forearm.

It has 3 muscles.


Following are the 3 muscles of the deep layer of forearm.

1. Flexor Digitorum Profundus

2. Flexor Pollicis Longus

3. Pronator Quadratus


  1. Flexor Digitorum Profundus

 Origin: Anterior and medial surfaces of the ulna and interosseous membrane.


Insertion: Bases of the distal phalanges of the second to fifth fingers.


Innervation:

  • Medial Part: Ulnar nerve (C8, T1).
  • Lateral Part: Anterior interosseous branch of the median nerve (C8, T1).

  2. Flexor Pollicis Longus

 Origin: Anterior surface of the radius and interosseous membrane.


Insertion: Base of the distal phalanx of the thumb.


Innervation: Anterior interosseous branch of the median nerve (C8, T1).​

.

  3. Pronator Quadratus

Origin: Anterior surface of the distal ulna.


Insertion: Anterior surface of the distal radius.


Innervation: Anterior interosseous branch of the median nerve (C8, T1).​