WordNet

exhibit the strength of; "The victorious army flexes its invincibility"
the act of flexing; "he gave his biceps a flex to impress the ladies"
bend a joint; "flex your wrists"; "bend your knees" (同)bend
cause (a plastic object) to assume a crooked or angular form; "bend the rod"; "twist the dough into a braid"; "the strong man could turn an iron bar" (同)bend, deform, twist, turn
contract; "flex a muscle"

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(仕事などを始める準備運動として)〈手足など〉‘を'曲げる,〈筋肉〉‘を'縮める
電線,電気のコード

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/02/04 13:08:59」(JST)

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The flexor pollicis brevis is a muscle in the hand that flexes the thumb. It is one of three thenar muscles. It has both a superficial part and a deep part.

Origin and insertion

The muscle's superficial part arises from the distal edge of the flexor retinaculum and the tubercle of the trapezium, a bone in the wrist. It passes along the radial side of the tendon of the flexor pollicis longus, and, becoming tendinous, is inserted into the radial side of the base of the proximal phalanx of the thumb; in its tendon of insertion there is a sesamoid bone.^[1]

The deeper (and medial) portion of the muscle is very small, and arises from the ulnar side of the first metacarpal bone between the oblique part of the adductor pollicis and the lateral head of the first dorsal interosseous muscle, and is inserted into the ulnar side of the base of the first phalanx with the adductor pollicis.^[1]

The deep (medial) part of the flexor brevis pollicis is sometimes described as the first palmar interosseous muscle.^[1] When this muscle is included, the total number of palmar interossei is four. Otherwise, there are only three palmar interossei.

Innervation

The flexor pollicis brevis is mostly innervated by the recurrent branch of the median nerve (C8, T1). The deep part is often innervated by the deep branch of the ulnar nerve.^[2]

Blood supply

The flexor pollicis brevis receives its blood supply from the superficial palmar branches of radial artery.^[2]

Action

The flexor pollicis brevis flexes the thumb at the metacarpophalangeal joint.

Additional images

The muscles of the left hand. Palmar surface. (Flexor pollicis brevis visible at center right, near thumb.)
Flexor pollicis brevis muscle
Bones of the left hand. Volar surface.
Front of the left forearm. Deep muscles.
Transverse section across the wrist and digits.
Superficial palmar nerves.
Deep palmar nerves.
Flexor pollicis brevis muscle
Flexor pollicis brevis muscle
Flexor pollicis brevis muscle
Flexor pollicis brevis muscle
Flexor pollicis brevis muscle
Flexor pollicis brevis muscle
Flexor pollicis brevis muscle
Flexor pollicis brevis muscle
Flexor pollicis brevis muscle
Flexor pollicis brevis muscle
Muscles of hand. Cross section.

References

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)

^ ^a ^b ^c Gray's Anatomy 1918, see infobox
^ ^a ^b "Brachium to Hand Musculature". PTCentral. Retrieved November 2012.

UpToDate Contents

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English Journal

An anatomic and kinematic analysis of a new total wrist arthroplasty design.

Hooke AW1, Pettersson K2, Sagerfors M2, An KN1, Rizzo M3.
Journal of wrist surgery.J Wrist Surg.2015 May;4(2):121-7. doi: 10.1055/s-0035-1549288.
Background Total wrist arthroplasty (TWA) is a viable surgical treatment for disabling wrist arthritis. While current designs are a notable improvement from prior generations, radiographic loosening and failures remain a concern. Purpose The purpose of this investigation is to evaluate a new tot
PMID 25945297

C8 and T1 innervation of forearm muscles.

Chiba T1, Konoeda F2, Higashihara M3, Kamiya H1, Oishi C4, Hatanaka Y1, Sonoo M5.
Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology.Clin Neurophysiol.2015 Apr;126(4):837-42. doi: 10.1016/j.clinph.2014.07.031. Epub 2014 Aug 27.
OBJECTIVE: C8-dominant innervation of ulnar-innervated and T1-dominant innervation of median-innervated intrinsic hand muscles have been suggested, although less is known regarding forearm muscles. We aimed to determine myotomal innervation of the forearm muscles based on the clinical and electromyo
PMID 25227217

Tendon transfer surgery in upper-extremity cerebral palsy is more effective than botulinum toxin injections or regular, ongoing therapy.

Van Heest AE1, Bagley A2, Molitor F2, James MA2.
The Journal of bone and joint surgery. American volume.J Bone Joint Surg Am.2015 Apr 1;97(7):529-36. doi: 10.2106/JBJS.M.01577.
BACKGROUND: For children with upper-extremity cerebral palsy (CP) who meet standard indications for tendon transfer surgery, we hypothesized that surgical treatment would result in greater functional improvement than treatment with botulinum toxin injections or regular, ongoing therapy.METHODS: Thir
PMID 25834076

Japanese Journal

振幅確率密度関数を用いたボールペン使用に伴う筋活動の評価

向大輔,小山秀紀,野呂影勇
日本生理人類学会誌 11(3), 105-111, 2006-08-25
NAID 110004810090

尺骨神経を利用した手根管症候群の電気生理学的検査法 : Preston 法とFPB法との比較

原田義昭
末梢神経 = Peripheral nerve 14(1), 32-38, 2003-06-01
NAID 10017405069

「短母指屈筋」

Flexor pollicis brevis muscle
	Superficial muscles of the left hand, palmar view.
Details
Origin	trapezium, flexor retinaculum
Insertion	thumb, proximal phalanx
Artery	Superficial palmar arch
Nerve	Recurrent branch of the median nerve, deep branch of ulnar nerve (medial head)
Actions	Flexes the thumb at the first metacarpophalangeal joint
Antagonist	Extensor pollicis longus and brevis
Identifiers
Latin	musculus flexor pollicis brevis
Dorlands; /Elsevier	m_22/12549129
TA	A04.6.02.055
FMA	37378
	Anatomical terms of muscle [edit on Wikidata]