5IO A MANUAL OF ANATOMY 



manner ; the innermost tendon has a special insertion into the 

 dorsal surface of the first phalanx of the great toe near its base. 

 The other three tendons join the outer borders of the long extensor 

 tendons which go to the second, third, and fourth toes, the union 

 taking place at the metatarso-phalangeal joints. 



Nerve- supply. — The external branch of the dorsalis pedis 

 nerve. 



Action. — (i) Innermost tendon. — ^This tendon extends the great 

 toe at the metatarso-phalangeal joint, and it also acts as an adductor 

 of that toe. (2) Second, third, and fourth tendons. — ^These extend 

 the corresponding toes in conjunction with the long extensor 

 tendons. In doing so they tend, by the obliquity of their direction, 

 to draw the toes outwards, and in this way they counteract the 

 opposite tendency of the long extensor tendons, which of themselves 

 would incline the toes inwards. 



The muscle lies obliquely upon the dorsum of the foot, and is 

 directed forwards and inwards. The innermost fleshy bundle is 

 always the largest, and separates from the parent muscle sooner 

 than the others. It has accordingly been regarded as a separate 

 muscle, and as such is called the extensor brevis hallucis. 



Dorsalis Pedis Artery. — This vessel is the continuation of the 

 anterior tibial artery. It commences at the anterior ligament of 

 the ankle-joint, midway between the two malleoli, and terminates 

 at the proximal end of the first interosseous space, where it divides 

 into two branches, plantar or perforating, and arteria dorsalis 

 hallucis or first dorsal interosseous artery. The course of the vessel 

 is along the inner part of the dorsum of the foot, and is indicated 

 by a line drawn from the centre of the front of the ankle-joint, 

 midway between the two malleoli,, to the proximal end of the first 

 interosseous space. 



Relations — Superficial. — ^Theskin, superficial fascia, lower division 

 of anterior annular ligament, deep fascia, and innermost tendon 

 of the extensor brevis digitorum, which crosses it from without 

 inwards near its termination. Deep. — Upper border of the head of 

 the astragalus, navicular, middle cuneiform, base of second meta- 

 tarsal, and the corresponding ligaments. External. — External vena 

 comes, dorsalis pedis nerve, innermost tendon of the extensor longus 

 digitorum, and, near its termination, the innermost tendon of the 

 extensor brevis digitorum as it is about to cross the artery. 

 Internal. — Internal vena comes, tendon of the extensor proprius 

 hallucis, and, near its termination, the innermost tendon of the 

 extensor brevis digitorum after it has crossed the vessel. 



The artery is firmly bound down by connective tissue to the 

 subjacent bones and ligaments. It is .accompanied by two venae 

 comites, one on either side, which communicate with each other by 

 transverse branches lying superficial to the vessel, and ultimately 

 become the vense comites of the anterior tibial artery. 



Branches. — The branches are as follows : internal tarsal, 

 external tarsal, metatarsal, arteria dorsalis hallucis or first dorsal 



