Extensor pollicis longus muscle - wikipedia Extensor pollicis longus muscle Extensor pollicis longus muscle Posterior surface of the forearm. Deep muscles. Extensor pollicis longus muscle is labeled in purple. Details Origin Middle third of posterior surface of ulna, interosseous membrane Insertion thumb, distal phalanx Artery posterior interosseous artery Nerve posterior interosseous nerve ( branching from the radial nerve ) Actions extension of the thumb ( metacarpophalangeal and interphalangeal ) Antagonist Flexor pollicis longus muscle, Flexor pollicis brevis muscle Identifiers Latin musculus extensor pollicis longus Dorlands / Elsevier m_22 / 12548955 TA A04. 6.02. 051 FMA 38521 Anatomical terms of muscle ( edit on Wikidata ) In human anatomy, the extensor pollicis longus muscle ( EPL ) 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. Contents 1 Structure 1.1 Relations 1.2 Blood supply 1.3 Innervation 2 Function 3 Clinical significance 3.1 Injury 4 Additional images 5 Notes 6 References Structure The extensor pollicis longus arises from the dorsal surface of the ulna and from the interosseous membrane, next to the origins of abductor pollicis longus and extensor pollicis brevis. Passing through the third tendon compartment, lying in a narrow, oblique groove on the back of the lower end of the radius, it crosses the wrist close to the dorsal midline before turning towards the thumb using Lister 's tubercle on the distal end of the radius as a pulley. It obliquely crosses 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. At the proximal phalanx, the tendon is joined by expansions from abductor pollicis brevis and adductor pollicis. The tendon is finally inserted on the base of the distal phalanx of the thumb. 6.7 to 9.7 centimetres ( 2.6 to 3.8 in ) in length, the tendon passes through a long and superficial synovial sheath which, passing obliquely from the radial border of the foremarm into the thumb, extends from the proximal border of the extensor retinaculum to the first carpometacarpal joint. In the synovial sheath a proximal and a distal mesotendon connect the tendon to the floor of the sheath. Relations Together with the tendons of the extensor pollicis brevis and the abductor pollicis longus, its tendon crosses the radial artery. Blood supply The tendon of extensor pollicis longus is supplied by branches from various arteries. Before the tendon enters its synovial sheath, arteries from the anterior interosseous artery or its muscular branches enter the tendon. The sheath itself is supplied by the posterior ramus of the same artery. In the metacarpal region, beyond the synovial sheath, the tendon is supplied directly from the radial artery. At the phalanges, the tendon forms a dorsal aponeurosis which is supplied by a digital branch of the first dorsal metacarpal artery. Innervation The extensor pollicis longus muscle receives innervation from the posterior interosseous nerve ( C7 and C8 ) which is the continuation of the deep branch of the radial nerve. Function Extensor pollicis longus extends the terminal phalanx of the thumb. While abductor pollicis brevis and adductor pollicis, both attached to the extensor pollicis longus tendon, can extend the thumb 's interphalangeal joint to the neutral position, only extensor pollicis longus can achieve full hyperextension at the interphalangeal joint. This complete extension at the interphalangeal joint is not possible, or considerably more difficult, with the carpal, carpometacarpal, and metacarpophalangeal joints simultaneously extended. Likewise, flexion at the interphalangeal joint by flexor pollicis longus is considerably reduced in wrist flexion. It also applies an extensor force at the metacarpophalangeal joint together with the extensor pollicis brevis and extends and adducts at the carpometacarpal joint of the thumb. Clinical significance Injury Tenosynovitis, inflammatory irritation of the synovial sheath, is relatively common in the third compartment after repetitive activities such as drum playing. Additional images Anatomical snuff box Bones of left forearm. Posterior aspect. Bones of the left hand. Dorsal surface. Tendons of forefinger and vincula tendina. Cross-section through the middle of the forearm. Posterior surface of the forearm. Superficial muscles. Posterior surface of the forearm. Deep muscles. Transverse section across the wrist and digits. Arteries of the back of the forearm and hand. The mucous sheaths of the tendons on the back of the wrist. ( Extensor pollicis longus visible at center right. ) Muscle of the hand. Posterior view. Notes This article incorporates text in the public domain from the 20th edition of Gray 's Anatomy ( 1918 ) ^ Jump up to : Platzer 2004, p. 168 ^ Jump up to : Austin 2005, p. 339 ^ Jump up to : Gray 's Anatomy 1918, see infobox ^ Jump up to : Zbrodowski, Gajisin & Grodecki 1982, Results, pp. 235 -- 9 Jump up ^ Schmitt, Lanz & Buchberger 2008, p. 336 References Austin, Noelle M ( 2005 ). `` Chapter 9 : The Wrist and Hand Complex ''. In Levangie, Pamela K ; Norkin, Cynthia C. Joint Structure and Function : A Comprehensive Analysis ( 4th ed. ). Philadelphia : F.A. Davis Company. ISBN 0 - 8036 - 1191 - 9. Platzer, Werner ( 2004 ). Color Atlas of Human Anatomy, Vol. 1 : Locomotor System ( 5th ed. ). Thieme. ISBN 3 - 13 - 533305 - 1. Schmitt, Rainer ; Lanz, Ulrich ; Buchberger, Wolfgang ( 2008 ). Diagnostic Imaging of the Hand. Thieme. ISBN 9781588904539. Zbrodowski, A ; Gajisin, S ; Grodecki, J ( September 1982 ). `` Vascularization of the tendons of the extensor pollicis longus, extensor carpi radialis longus and extensor carpi radialis brevis muscles ''. J Anat. 135 ( Pt 2 ) : 235 -- 44. PMC 1168229. PMID 7174499. Muscles of the arm Shoulder deltoid rotator cuff supraspinatus infraspinatus teres minor subscapularis teres major fascia : deltoid fascia supraspinous fascia infraspinous fascia Arm ( compartments ) anterior coracobrachialis biceps brachialis posterior triceps brachii anconeus articularis cubiti fascia axillary sheath axillary fascia brachial fascia intermuscular septa lateral medial other spaces quadrangular space triangular space triangular interval Forearm anterior superficial : pronator teres palmaris longus flexor carpi radialis flexor carpi ulnaris flexor digitorum superficialis deep : pronator quadratus flexor digitorum profundus flexor pollicis longus posterior superficial : mobile wad brachioradialis extensor carpi radialis longus and brevis extensor digitorum extensor digiti minimi extensor carpi ulnaris deep : supinator anatomical snuff box abductor pollicis longus extensor pollicis brevis extensor pollicis longus extensor indicis fascia bicipital aponeurosis common tendons extensor flexor antebrachial fascia other cubital tunnel 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 digiti minimi palmaris brevis intermediate lumbrical interossei dorsal palmar fascia posterior : extensor retinaculum extensor expansion anterior : flexor retinaculum palmar aponeurosis Retrieved from `` https://en.wikipedia.org/w/index.php?title=Extensor_pollicis_longus_muscle&oldid=822137120 '' Categories : Wikipedia articles incorporating text from the 20th edition of Gray 's Anatomy ( 1918 ) Muscles of the upper limb Hidden categories : Medicine infobox template using GraySubject or GrayPage Medicine infobox template using Dorlands parameter Pages using infobox muscle with Antagonist Talk Contents About Wikipedia Català Deutsch فارسی Français Galego Hrvatski עברית Magyar Nederlands 日本 語 Polski Português Română Русский Svenska ไทย Edit links This page was last edited on 24 January 2018, at 16 : 30. 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Question: where is the extensor pollicis longus tendon located
Answer: dorsally on the forearm; located dorsally on the forearm