Extensor pollicis longus muscle
Encyclopedia
In human anatomy
, the extensor pollicis longus is a skeletal muscle
located dorsally on the forearm
. It is much larger than the extensor pollicis brevis
, the origin of which it partly covers, and acts to stretch the thumb
together with this muscle.
and from the interosseous membrane
.
Passing through the third tendon compartment, lying in a narrow, oblique groove on the back of the lower end of the radius
, its tendon is inserted on the base of the distal phalanx
of the thumb. It uses the dorsal tubercle on the radius as fulcrum.
It crosses obliquely the tendons of the extensores carpi radialis longus
and brevis
, and is separated from the extensor pollicis brevis
by a triangular interval, the anatomical snuff box
in which the radial artery
is found.
, its tendon crosses the radial artery
.
the wrist
.
Human anatomy
Human anatomy is primarily the scientific study of the morphology of the human body. Anatomy is subdivided into gross anatomy and microscopic anatomy. Gross anatomy is the study of anatomical structures that can be seen by the naked eye...
, the extensor pollicis longus is a skeletal muscle
Skeletal muscle
Skeletal muscle is a form of striated muscle tissue existing under control of the somatic nervous system- i.e. it is voluntarily controlled. It is one of three major muscle types, the others being cardiac and smooth muscle...
located dorsally on the forearm
Forearm
-See also:*Forearm flexors*Forearm muscles...
. It is much larger than the extensor pollicis brevis
Extensor pollicis brevis muscle
In human anatomy, the extensor pollicis brevis is a skeletal muscle on the dorsal side of the forearm. It lies on the medial side of, and is closely connected with, the abductor pollicis longus.-Origin and insertion:...
, the origin of which it partly covers, and acts to stretch the thumb
Thumb
The thumb is the first digit of the hand. When a person is standing in the medical anatomical position , the thumb is the lateral-most digit...
together with this muscle.
Origin and insertion
It arises from the dorsal surface of the ulnaUlna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
and from the interosseous membrane
Interosseous membrane of the forearm
The interosseous membrane of the forearm is a fibrous sheet that connects the radius and the ulna...
.
Passing through the third tendon compartment, lying in a narrow, oblique groove on the back of the lower end of the radius
Radius (bone)
The radius is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna, which exceeds it in length and size. It is a long bone, prism-shaped and slightly curved longitudinally...
, its tendon is inserted on the base of the distal phalanx
Distal phalanges
The distal or terminal phalanges are the terminal limb bones located at the tip of the digits...
of the thumb. It uses the dorsal tubercle on the radius as fulcrum.
It crosses obliquely the tendons of the extensores carpi radialis longus
Extensor carpi radialis longus muscle
Extensor carpi radialis longus is one of the five main muscles that control movements at the wrist. This muscle is quite long, starting on the lateral side of the humerus, and attaching to the base of the second metacarpal bone .-Function:As the name suggests, this muscle is an extensor at the...
and brevis
Extensor carpi radialis brevis muscle
The Extensor carpi radialis brevis is shorter and thicker than the extensor carpi radialis longus. The longus muscle can be found above the distal end of the Extensor carpi radialis brevis.-Origin and insertion:...
, and is separated from the extensor pollicis brevis
Extensor pollicis brevis muscle
In human anatomy, the extensor pollicis brevis is a skeletal muscle on the dorsal side of the forearm. It lies on the medial side of, and is closely connected with, the abductor pollicis longus.-Origin and insertion:...
by a triangular interval, the anatomical snuff box
Anatomical snuff box
The anatomical snuffbox is a triangular deepening on the radial, dorsal aspect of the hand—at the level of the carpal bones, specifically, the scaphoid and trapezium bones forming the floor...
in which the radial artery
Radial artery
In human anatomy, the radial artery is the main blood vessel, with oxygenated blood, of the lateral aspect of the forearm.-Course:The radial artery arises from the bifurcation of the brachial artery in the cubital fossa. It runs distally on the anterior part of the forearm...
is found.
Relations
Together with the tendons of the extensor pollicis brevis and the abductor pollicis longusAbductor pollicis longus muscle
The abductor pollicis longus muscle is one of the extrinsic muscles of the hand. It lies immediately below the supinator muscle and is sometimes united with it.-Origin and insertion:...
, its tendon crosses the radial artery
Radial artery
In human anatomy, the radial artery is the main blood vessel, with oxygenated blood, of the lateral aspect of the forearm.-Course:The radial artery arises from the bifurcation of the brachial artery in the cubital fossa. It runs distally on the anterior part of the forearm...
.
Action
Extensor pollicis longus extends the terminal phalanx of the thumb; in combination with the extensor pollicis brevis, it helps to extend and abductAbduction (kinesiology)
Abduction, in functional anatomy, is a movement which draws a limb away from the median plane of the body. It is thus opposed to adduction.-Upper limb:* of arm at shoulder ** Supraspinatus** Deltoid* of hand at wrist...
the wrist
Wrist
In human anatomy, the wrist is variously defined as 1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand;...
.