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Abductor Pollicis Longus

The abductor pollicis longus muscle emerges via the associated interosseous membrane and the proximal posterior sides of the radius as well as the ulna. It arises in between the extensor digitorum along with extensor carpi radialis brevis muscles within the distal forearm, in order to create a tendon that enters the thumb and attaches on the lateral side of the base of metacarpal I. The tendon adds to the lateral boundary of the anatomical snuffbox at the wrist.

Interactive Anatomical Interface

Highlight
biceps brachii (long head)
Biceps brachii (short head)
Brachioradialis
flexor carpi radialis
palmaris longus
pronator teres
brachialis
Flexor digitorum superficialis
Extensor carpi radialis longus
Supinator
pronator teres
flexor pollicis longus
coracobrachialis
Tricep brachii (long head)
extensor carpi radialis brevis
extensor digitorum
flexor digitorum profundus
flexor carpi ulnaris
Deltoid
Subscapularis
Teres Major
Teres Minor

Highlight
biceps brachii (long head)
Biceps brachii (short head)
Brachioradialis
flexor carpi radialis
palmaris longus
pronator teres
brachialis
Flexor digitorum superficialis
Extensor carpi radialis longus
Supinator
pronator teres

Highlight
flexor pollicis longus
coracobrachialis
Tricep brachii (long head)
extensor carpi radialis brevis
extensor digitorum
flexor digitorum profundus
flexor carpi ulnaris
Deltoid
Subscapularis
Teres Major
Teres Minor
Highlight
supraspinatus
infraspinatus
deltoid
teres minor
teres major
triceps brachii (lateral head)
biceps brachii
brachialis
triceps brachii (medial head)
brachioradialis
extensor carpi radialis longus
extensor carpi radialis brevis
abductor pollicis longus
extensor digitorum
extensor carpi ulnaris
anconeus
flexor carpi ulnaris
Dorsal interosseus
coracobrachialis
supinator
abductor pollicis longus
extensor pollicis longus
extensor indicis
flexor digitorum profondus
flexor digitorum superficialis
extensor digiti minimi

Highlight
supraspinatus
infraspinatus
deltoid
teres minor
teres major
triceps brachii (lateral head)
biceps brachii
brachialis
triceps brachii (medial head)
brachioradialis
extensor carpi radialis longus
extensor carpi radialis brevis
abductor pollicis longus

Highlight
extensor digitorum
extensor carpi ulnaris
anconeus
flexor carpi ulnaris
Dorsal interosseus
coracobrachialis
supinator
abductor pollicis longus
extensor pollicis longus
extensor indicis
flexor digitorum profondus
flexor digitorum superficialis
extensor digiti minimi
Related:   Facial Artery

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Abductor Pollicis Longus

Abductor Pollicis Longus

Structure

Travelling obliquely down and lateralward, it terminates within a tendon, which goes through an indentation on the lateral part of the lower end of the radius, along with the tendon of the extensor pollicis brevis. The abductor pollicis longus is located instantly under the supinator and is often combined with it. The insertion is split within a distal, superficial portion and a proximal, deep portion. The superficial portion is placed with several tendons into the radial part of the base of the first metacarpal bone, and the deep portion is variably placed within the trapezium, the joint capsule and its ligaments, and in the belly of abductor pollicis brevis or opponens pollicis.

Innervation

Artery Supply

  • The Posterior Interosseus Artery which is a branch of the Ulnar Artery.
  • The perforating branches of the Anterior Interosseus artery which is a branch of the Ulnar Artery.

Action

The abductor pollicis longus crosses the first CMC joint anteriorly in order to connect over the metacarpal of the thumb with its fibers going vertically inside the sagittal plane.

Whenever the abductor pollicis longus constricts, it draws the metacarpal of the thumb anteriorly in the sagittal plane, in an instructions that is perpendicular to, and far from the plane of the palm of the hand. This action is called abduction of the thumb.

Related:   Cerebral Veins

For that reason the abductor pollicis longus abducts the thumb by abducting the metacarpal of the thumb at the first CMC joint. Due to the rotational development of the thumb embryologically, the called actions of abduction and adduction of the thumb happen within the sagittal plane.


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By | 2018-08-08T00:00:00+00:00 August 8th, 2018|Anatomy, Muscles, Upper Limb|0 Comments