Pronator quadratus

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Pronator quadratus
Front of the left forearm. Deep muscles. (Pronator quadratus visible at bottom-center right.)
Latin	musculus pronator quadratus
Gray's	subject #125 449
Origin	medial, anterior surface of the ulna
Insertion	lateral, anterior surface of the radius
Artery:	anterior interosseous artery
Nerve:	median nerve (anterior interosseous nerve)
Action:	pronates the forearm
Antagonist:	Supinator muscle
Dorlands /Elsevier	m_22/12550251

Pronator quadratus is a square shaped muscle on the distal forearm that acts to pronate (turn so the palm faces downwards) the hand.

As it is on the anterior side of the arm, it is innervated by a branch of the median nerve, the anterior interosseous nerve. Arterial blood comes via the interosseous artery.

Contents 1 Origin and insertion 2 Action 3 Additional images 4 External links

[edit] Origin and insertion

Its fibres run perpendicular to the direction of the arm, running from the most distal quarter of the anterior ulna to the distal quarter of the anterior radius.

[edit] Action

When pronator quadratus contracts, it pulls the lateral side of the radius towards the ulna, thus pronating the hand. It also helps to keep the two bones in the forearm bound together.

[edit] Additional images

Bones of left forearm. Anterior aspect.

Transverse section across distal ends of radius and ulna.

Deep palmar nerves.

[edit] External links

• 114294862 at GPnotebook
• UWASH pronatorquadratus
• Pronator+quadratus+muscle at eMedicine Dictionary

v • d • e List of muscles of upper limbs VERTEBRAL COLUMN trapezius - latissimus dorsi - rhomboid (major, minor) - levator scapulae THORACIC WALLS pectoralis major - pectoralis minor - subclavius - serratus anterior SHOULDER deltoid - rotator cuff (supraspinatus, infraspinatus, teres minor, subscapularis) - teres major ARM anterior compartment: coracobrachialis - biceps brachii - brachialis posterior compartment: triceps brachii - anconeus FOREARM anterior compartment: superf. - pronator teres - palmaris longus - flexor carpi radialis - flexor carpi ulnaris - flexor digitorum superficialis anterior compartment: deep - pronator quadratus - flexor digitorum profundus - flexor pollicis longus posterior compartment: superf. - mobile wad (brachioradialis, extensor carpi radialis longus and brevis) - extensor digitorum, - extensor digiti minimi - extensor carpi ulnaris posterior compartment: deep - supinator - anatomical snuff box (abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus) - extensor indicis HAND lateral volar - thenar (opponens pollicis, flexor pollicis brevis, abductor pollicis brevis) - adductor pollicis medial volar - hypothenar (opponens digiti minimi, flexor digiti minimi brevis, abductor minimi digiti) - palmaris brevis intermediate - lumbrical - interossei (dorsal, palmar)