152 ANATOMY IN A NUTSHELL. 



LESSON XL. 



Tibialis anticus. — Description. — (Plate LXXV.) — The anterior tibial 

 vessels and nerve run along the outer border of this muscle, which is just be- 

 neath the fascia on the outer side of the tibia. It is thick and fleshy above, but 

 tendinous below where it passes through the innermost compartment of the 

 anterior annular ligament. 



Origin. (Plate LI.) — (1) Outer tuberosity of tibia; (2) upper two-thirds 

 of shafl of tibia; (•">) interosseous membrane adjoining; (4) deep surface of 

 fascia; (5) intermuscular septum. 



Insertion. — (Plate LIII). — Inner and under surface of internal cuneiform 

 bone and base of metatarsal of great toe. 



Action. Flexes tarsus upon leg and assists in inverting the foot. 



Nerve Supply. — Fourth and fifth lumbar and first sacral through anterior 

 tibial. 



Blood Supply. — Anterior tibial artery. 



Extensor propius hallucls. — Description. — (Plate LXXV.) — This muscle 

 lies between the Tibialis amicus and Extensor longus digitorum. It is a thin, 

 Hat muscle and hs tendon occupies its anterior border below. This tendon 

 passes through a distinct compartment in the lower portion of the annular lig- 

 ament, it also crosses the anterior tibial vessels near the ankle-joint and then 

 lies on the inner side of these vessels. It gives a thin prolongation on each side 

 of the metatarso-phalangeal articulation, which covers the surface of the joint. 



Origin.- -(Plate LI.) — (1) Anterior surface of fibula, middle two-fourths 

 of same; (2) part of interosseous membrane. 



Insertion. — (Plate I.I I.) — Base of last phalanx of great toe. It usually 

 sends an expansion from the inner side of the tendon to be inserted into base of 

 6rs1 phalanx. 



Action.— Extends great toe and flexes tarsus. 



\'i.i;\ i: Supply.— Fourth and fifth lumbar and first sacral through anterior 

 tibial. 



Blood Supply.— Anterior tibial. 



Extensor Longus digitorum.— Description.— (Plate LXXV.) — This muscle 

 lies external to the other muscles in this region. It is enlongated and flat- 

 tened. It and the Peroneus tertius enter the same canal in annular ligament. 

 It divides into four slip-, one for each of the four inner toes. A tendon from 

 the Extensor brevis digitorum join- the three inner of these tendons on their 

 outer side opposite the metatarso-phalangeal articulation. All four slips re- 

 ceive fibrous expansions from the Interossei and Lumbricales, after which they 

 spread out into a broad aponeurosis which covers the dorsal surface of the first 

 phalanx. This aponeursosis divides Into three slips at the articulation of the 

 first with the second phalanx. 



Origin.— (Plate LI.) (1) Outer tuberosity of tibia; (2) upper three- 

 fourths of anterior surface of shafl of fibula; (3) interosseous membrane; (4) 

 deep surface of Fascia; (5) intermuscular septa. 



