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
Blood: interosseous artery
Nerve: median nerve
Action:
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.

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.

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.

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

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Muscles of the HeadNeckTrunkUpper limbLower limbLIST OF ALL MUSCLES

VERTEBRAL COLUMN: trapezius | latissimus dorsi | rhomboid major | rhomboid minor | levator scapulae | (Gray's s121)

ANTERIOR AND LATERAL THORACIC WALLS: pectoralis major | pectoralis minor | subclavius | serratus anterior | (Gray's s122)

SHOULDER: deltoid | rotator cuff (subscapularis, supraspinatus, infraspinatus, teres minor) | teres major | (Gray's s123)

ARM: coracobrachialis | biceps brachii | brachialis | triceps brachii | (Gray's s124)

FOREARM: Volar super. | pronator teres | palmaris longus | flexor carpi radialis | flexor carpi ulnaris | flexor digitorum superficialis
Volar deep | flexor digitorum profundus | flexor pollicis longus | pronator quadratus
Dorsal super. | brachioradialis | extensor digitorum | extensor carpi radialis longus | extensor digiti minimi | extensor carpi radialis brevis | extensor carpi ulnaris | anconeus
Dorsal deep | supinator | abductor pollicis longus | extensor pollicis brevis | extensor pollicis longus | extensor indicis | (Gray's s125)

HAND: Lateral volar | abductor pollicis brevis | thenar (opponens pollicis, flexor pollicis brevis, adductor pollicis)
Medial volar | palmaris brevis | hypothenar (abductor minimi digiti, flexor digiti minimi brevis, opponens digiti minimi)
Intermediate | lumbrical | dorsal interossei | palmar interossei | (Gray's s126)

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