MUSCLES OF THE LEG. 
of the fracture is found in a violent twist of 
the ankle with dislocation, the deformity occa- 
_ sioned by this state of the joint is more or less 
considerable, according to the degree of this 
_ displacement. 
Ve (A. T. S. Dodd.) 
__ MUSCLES OF THE LEG.—The muscles 
lying on the bones of the leg, both before and 
behind, are, with the exception of one, pro- 
perly muscles of the ankle-joint and foot, since 
ir primary action is exclusively upon these 
. (See article Foor, Muscres or.) For 
convenience, however, of description they 
_ will here be demonstrated according to their si- 
 tuation. 
_ The muscles of the leg may be classed into 
mterior, external, and posterior. The anterior 
_ lying in the space between the tibia and fi- 
 bula are four in number, consisting of tibialis 
_ anticus, extensor proprius pollicis, | extensor 
longus digitorum, and peroneus tertius. The 
tibialis anticus and extensor longus alone are 
seen at the upper part of the leg on removing 
the deep fascia; the extensor proprius pol- 
licis emerging from between these muscles 
about one-third down the leg, and the peroneus 
ertius shewing itself as a separate slip of the 
axtensor longus, about the same height, and at 
‘its fibular side. 
1. Tibialis anticus lies upon the fibular and 
‘anterior surface of the tibia; arises, principally 
muscular, from the fibular side of the tibia, 
hrough its two upper thirds, from its tuber- 
osity and spine, and from a small portion of 
the interosseous ligament, from the fascia of 
he leg, and from an aponeurotic septum placed 
between it and the extensor digitorum longus. 
e muscle is larger above than below; its 
fleshy fibres converge to a strong tendon which 
osses from the outside to the fore part of the 
tibia, passes through a distinct ring of the 
annular ligament near the ankle, runs over the 
astragalus and os naviculare, and is inserted 
into the upper part of the os cuneiforme in- 
lernum, and base of the metatarsal bone of the 
great toe. The insertion of the tendon is con- 
“cealed in part by the adductor and flexor brevis 
of the great toe. Between the tendon of this 
‘muscle and the os cuneiforme we find a small 
bursa mucosa. This muscle is covered in front 
hy the fascia of the leg, to which it adheres 
superiorly ; behind it is in contact with the 
“tibia and interosseous ligament, on the fibular 
side with the extensor digitorum communis, 
and extensor proprius pollicis. Its action is to 
flex the foot upon the leg by elevating the an- 
terior part of the foot. 
_ 2. Extensor longus digitorum—This mus- 
cle occupies the fibular side of the tibio-fi- 
bular fossa, as the last filled the inner side. 
This is a tapering muscle also; it arises ten- 
dinous and muscular from the fibular or 
outer part of the head of the tibia, from the 
head of the fibula, and from the anterior angle 
of that bone almost its whole length, and from 
part of the tibial side of it also; it also takes 
origin from the interosseous ligament, from the 
fascia of the leg, and from the aponeurotic 
ne eee 
’ Pere ee 
aie acti 
| 
137 
septum situated between this muscle and the 
last. Below the middle of the leg it splits 
into four tendons. These pass under the ante- 
rior annular ligament in one common sheath 
with the peroneus tertius. They then run along 
the dorsum of the foot, spreading as they go, 
and are inserted into the root of the first pha- 
lanx of each of the four smaller toes. To- 
wards their termination each of the tendons ex- 
pands into an aponeurosis, covering the upper 
surface of the phalanges, and this is strengthened 
by the tendons of the extensor brevis and gives 
attachment to the lumbricales and interossei. 
This muscle is covered in front by the fascia 
of the leg, the annular ligament and the in- 
tegument; posteriorly it rests upon the fibula, 
the interosseous ligament, and the tibia; exter- 
nally it is in relation with the peronei muscles, 
internally with the tibiatts anticus, and extensor 
proprius pollicis; along its lower and fibular 
border lies the peroneus tertius. On the dor- 
sum of the foot its four tendons cross obliquely 
over those of the flexor brevis digitorum. 
Action. To extend all the joints of the four 
smaller toes, and to bend the ankle-joint. 
3. Extensor proprius pollicis lies between 
the two last muscles. Its origin is hidden by 
them. It commences about one-third down 
the leg, from the smooth surface of the fibula, 
between the anterior and tibial angles of that 
bone, of which surface it occupies part, through 
the middle third of its length, also from the 
lower two-thirds of the interosseous ligament. 
The fleshy fibres run obliquely forward into a 
tendon placed at the anterior border of the 
muscle, which after passing beneath the an- 
terior annular ligament, and along the dorsum 
of the foot, is inserted into the bases of the 
first and second phalanges of the great toe. 
Action. To extend the great toe, and to 
bend the ankle. 
By its fibular side this muscle is in relation 
with the extensor digitorum communis ; by its 
inner side with the tibialis anticus and anterior 
tibial vessels. The anterior border is covered 
by these two muscles, as low as about the 
middle of the leg, and inferiorly by the anterior 
annular ligament, under which it passes in a 
separate groove, and by the integuments. The 
posterior border rests upon the fibula and in- 
terosseous ligament, and it crosses in its course 
over the lower end of the tibia the ankle-joint, 
the anterior tibial vessels, and dorsum of the 
foot. 
4. Peroneus tertius——This, which is in fact 
a mere slip of the extensor digitorum com- 
munis, and is situated on its fibular side, is so 
closely connected with it at its origin that it 
can with difficulty be separated. It arises 
from the lower third of the fibula, being at- 
tached to the anterior border and inner surface 
of the bone; also from the interosseous liga- 
ment, and from an aponeurosis which connects 
it on the outer side with the peroneus brevis. 
It is inserted by a flat tendon into the fibular 
side of the base of the metatarsal bone of the 
little toe. Its action is to assist in flexing the 
foot upon the leg. 
It. is in contact with the fascia of the leg 
