112 ANATOMY IN A NUTSHELL. 



Blood Supply. From superficialis volae artery. 



Opponent pollicis. ■■-( Flexor ossis metacarpi pollieis.) — Description. — 

 (Plate XXXI.) This is a small triangular muscle placed beneath the preceding. 



Origin.— (Plate XXVI.)— Palmar surface of trapezium and annular 

 ligament. 



I nsertii in. Whole length of metacarpal of thumb on radial side. (Plate 

 XXVI. 



Action. Flexes metacarpal of thumb. 



Nerve Supply. Sixth cervical through the median. 



Blood Supply. From radial and superficialis volse arteries. 



Flexor brevis pollicis. Description. — (Plate XXXI.) — This muscle con- 

 sists of two portions outer and inner, having separate origins and insertions. 

 The outer portion is the more superficial and has a sesamoid hone developed in 

 its tendon. The inner and deeper portion is very small. 



Origin.- (Outer portion) Trapezium and outer two-thirds of annular lig- 

 ament. ( Inner portion) Ulnar side of first metacarpal bone. (Plate XXVIII.) 



Insertion. — Both sides of base of first phalanx of thumb by two tendons. 

 (Plate XXVII.) 



Action.- Flexes thumb. 



Nerve Supply. — Outer portion, sixth cervical through median; inner 

 portion, eighth cervical through ulnar. 



Blood Supply. — From radial artery. 



Adductor obliquus pollicis. — Description. — (Plate XXXI.) — This muscle 

 arises by several slips. The greater number of fillers pass obliquely downward 

 and converge to a tendon which mutes with the tendons of the deeper portion 

 of the flexor brevis and Adductor transversus pollicis, a sesamoid bone being 

 developed in the tendon of insertion. A considerable fasciculus passes ob- 

 liquely outward beneath the tendon of the long flexors to join the superficial 

 portion of the short flexor and the Abductor pollicis. This muscle was formerly 

 described as the deep portion of the Flexor brevis pollicis. 



Origin.— (1) Os magnum; (2) bases of second and third metacarpal 

 bones; (3) anterior carpal ligaments; (4) sheath of tendon of Flexor carpi 

 radialis. (Plate XXVII.) 



Insertion.- Inner side of base of first phalanx of thumb. (Plate XXVII.) 



Action. Moves thumb inward toward index finger. 



Nerve Supply. Eighth cervical through ulnar. 



Blood Supply.- From the palmar arches. 



Adductor transversus pollicis. Description. — (Plate XXXI.) — This is 

 the mosl deeply seated of tins group of muscles; it is triangular in form, arising 

 by its broad base. The libers converge toward their insertion which is in com- 

 mon with the inner part of the Flexor brevis pollicis and the Adductor obliquus 

 pollicis. From this common tendon a slip is prolonged to the Extensor longus 

 pollicis. 



Origin. bower tw< -thirds of metacarpal of middle finger on palmar sur- 

 face. (Plate XXVII.) 



Insertion. Ulnar side of base of firsl phalanx of thumb by common ten- 

 don. (Plate XXVU i 



