300 



THE MUSCLES. 



Fig. 136. 



tibia, passing to the external side of the tarsus, where it is enclosed in a very 

 firm sheath, and is inflected forwards to become united to the tendon of the 

 anterior extensor, near the middle of the metatarsal region. 



Attachments. The lateral extensor is attached, by the superior extremity 

 of its muscular fibres, to the external femoro-tibial ligament, to the whole 

 extent of the fibula, and to the fibrous partition which separates this muscle 

 from the perforans origin. It terminates in the tendon of the anterior 

 extensor. 



Relations. Its muscular body is enveloped in a special containing 

 aponeurosis, which separates it, in fr.ont, from the anterior extensor, and 

 behind from the perforans. The tendon covers the tibia, and margins the 

 external and superficial ligament of the tibio-tarsal articulation ; which liga- 

 ment supplies a fibrous ring destined for the formation of its reflected sheath. 

 A vaginal synovial membrane facilitates its motion in the interior of this 

 sheath. 



Action. It acts like the preceding. 



3. Flexor of tlie Metatarsus. (Fig. 136.) 



Synonyms. Tibio-premetntarsus Girard. Its muscular portion represents the 

 tibialis anticus of anthropotoiuists. {Flexor Metatarsi Percivall.) 



This muscle is situated beneath the anterior extensor of the phalanges, on 

 the external surface of the tibia, and is composed of two distinct portions : one 

 muscular, the other aponeurotic, not united from end to 

 end, but placed parallel one before the other. 



A. TENDINOUS PORTION (Fig. 136, 1). Course Attach- 

 ments. This is a strong, pearly-white cord, comprised 

 between the muscular portion and the anterior extensor of 

 the phalanges. It commences at the inferior extremity of 

 the femur, in the fossa excavated between the trochlea 

 and the external condyle ; it afterwards passes through the 

 superior groove of the tibia, where it is enveloped by 

 a prolongation from one of the synovial membranes of 

 the femoro-tibial articulation, giving origin, below this 

 groove, to the muscular fibres of the anterior extensor 

 of the phalanges. Lower, it receives some of the fasciculi 

 from the muscular portion, to which it sends in exchange 

 several aponeurotic layers ; it passes under the superior 

 annular band in front of the hock, in company with the 

 anterior extensor, and reaches the level of the trochlea of 

 the astragalus, where it is perforated to form a ring for 

 the passage of the inferior extremity of the muscular 

 portion. It finally terminates in two branches : a large 

 one, inserted in front of the superior extremity of the 

 principal metatarsus (Fig. 136, 4); the other, narrower, 

 deviates outwards to reach the anterior surface of the 

 cuboid bone (Fig. 136, 3). 



1, Tendinous portion ; 2, Its attachment to the femur ; 3, Its 

 cuboid branch; 4, Its metatarsal branch; 5, Muscular portion; 

 6, Its succeeding tendon passing through the ring of the tendi- 

 FLEXOH MUSCLE OF nous p 0r tion ; 7, Cuneiform portion of this tendon ; 8, Its meta- 

 THE METATARSUS. tarsal branch; 9, Anterior extensor of the phalanges drawn 

 outwards by a hook. A, Lateral extensor ; B, Tibial insertion of the middle patellar 

 ligament ; c, Femoral trochlea. 



