O04 THE MUSCULAR SYSTEM. © 
lateral patellar ligaments. Passing down the leg, the fascia blends over the 
inner surface of the tibia with the periosteum of the bone. It extends round 
the outer side of the leg from the anterior to the internal border of the tibia, 
binding together and giving origin to the muscles, and gaining an attachment to 
the lower part of the shaft of the fibula. Two septa pass from its deep surface ; 
one septum is attached to the anterior border of the fibula, encloses the musculo- 
cutaneous nerve, and separates the extensor from the peronei muscles. The other 
septum is attached to the posterior border of the fibula, and separates the peronei 
from the flexor muscles. From the last-named septum another extends across the 
back of the leg, forms a partition between the superficial and deep flexor muscles, 
and encloses the posterior tibial vessels and nerves. It gives rise to subordinate 
septa attached to the vertical line of the tibia and the oblique line of the fibula, 
which separate the tibialis posticus muscle from the flexors of the toes on either 
side. 
At the ankle the deep fascia is strengthened by additional transverse fibres ; 
it is attached to 
<anever smaetieanent the malleoli_and 
the os caleis, and 
gives rise to the 
annular ligaments. 
The internal 
eutes oe annular ligament 
stretches between 
TIBIALIS POSTICUS the internal mal- 
jee) —Intemel annular eolus and the 
. ‘i i tuberosity of the 
yates os calcis. While 
a, I Internal plantar artery it is continuous at 
= ch Pee plantar nerve its upper border 
(Ke FLEXOR LONGUS HALLUCIS with the general 
ABDUCTOR HALLUCIS investment of the 
deep fascia of the 
leg, it is chiefly 
formed by the 
septal layer cover- 
ing the deep mus- 
cles on the back 
orxsthe® leg. ait 
sometimes gives 
insertion to the plantaris muscle. It is continuous below with the plantar fascia, 
and gives origin to the abductor hallucis muscle. It is pierced by the calcanean 
vessels and nerve. Along with the posterior tibial vessels and nerve, the tendons 
of the tibialis posticus, flexor longus digitorum, and flexor longus hallucis, pass 
beneath it, each enclosed in a separate synovial sheath. 
The external annular ligament, much smaller, is a thickened band of the 
deep fascia stretching between the external malleolus and the os calcis. It binds 
down the tendons of the peronei, which occupy a space beneath the ligament, lined 
by a single synovial membrane. 
The anterior annular ligament is in two parts. An upper band, broad and 
undefined at its upper and lower borders, stretches across the front of the ankle 
between the two malleoli. This band binds down to the lower end of the tibia 
the tendons of the tibialis anticus and extensor muscles of the toes. One synovial 
sheath is found beneath it, surrounding the tendon of the tibialis anticus. 
On the dorsum of the foot, where the general covering of deep fascia is much 
thinner, a special well-defined band stretches over the extensor tendons. This 
lower band of the anterior annular ligament (fundiform or lambdoid ligament) 
has an attachment externally to the greater process of the os ecalcis. It divides 
into two bands as it passes inwards over the dorsum of the foot—an wpper part, 
which joins the upper ligament and is attached to the internal malleolus, and a 
Tibia 
14 Reg 
Interosseous calcaneo- bes: 
astragaloid ligament 
1 Q, 
: \\ LABRET. 
Caleaneum 3 
\ (\\ faces 
PERONEUS srevis——\Vatie Fes > 
ern es ‘ 
\) Melnetarsane etc 
Fibula 
External annular ligament —\4—/ 
PERONEUS LONGUS 
,, External plantar nerve 
Ninstetill plantar artery 
FLEXOR BREVIS DIGITORUM 
THER 
ABDUCTOR MINIMI DIGITI LEG 
iy 
TI e= eer 
1) nS 
"a, 
AG fa\ ts 
Plantar fascia’ Sic. et ite ey 
ACCESSORIUS 
Fic, 259.—CoroNAL SECTION THROUGH THE LEFT ANKLE JOINT, ASTRAGALUS, 
AND CALCANEUM. 
