140 
muscles (lumbricales), which may also be con- 
sidered as accessories to the flexor longus. 
When passing behind the inner malleolus, 
this tendon isin contact with that of the tibialis 
posticus, which lies close to the bone. They are 
inclosed in separate sheaths of synovial mem- 
brane. In the leg this muscle is bound down 
by the deep fascia, and covered partly by the 
posterior tibial vessels which separate it from 
the soleus; its anterior surface rests against 
the tibia, and overlaps the tibialis posticus 
muscle; in the foot, its tendon lies between 
those of the flexor longus pollicis which,are 
above it, and the flexor brevis digitorum which 
lies beneath it. 
3. Flexor longus pollicis is shorter but 
stronger than the former muscle. It is si- 
tuated the outermost of the three deep muscles 
of the leg, in contact with the fibula. It arises 
tendinous and fleshy from the lower half of 
the posterior surface and outer edge of the 
fibula, with the exception of the undermost 
portion. The fleshy fibres terminate in a 
tendon which passes behind the inner ankle, 
through a groove in the tibia; next through a 
groove in the astragalus ; crosses in the sole of 
the foot the tendon of the flexor longus digi- 
torum, to which it gives a slip of tendon; 
ses between the two heads of the flexor 
revis pollicis, and then runs in a sheath of 
tendinous structure which binds it to the under 
surface of the phalanx, and is inserted into the 
base of the last phalanx of ‘the great toe. The 
relations of this muscle in the leg are, pos- 
teriorly it is covered by the deep fascia, 
which separates it from the soleus; anteriorly it 
is in contact with the fibula, and overlaps the 
tibialis posticus muscle and the peroneal ar- 
tery. Its connections in the foot have been 
explained above. The action of the flexor 
longus pollicis is not confined to the great toe ; 
by means of the slip of tendon, which it gives 
to the flexor longus digitorum, it acts also 
upon all the toes, and secondarily upon the 
foot itself, assisting powerfully in the elevation 
of the heel in progression. But the mode of 
action of this muscle, and its complicated rela- 
tions with the other muscles of the foot, are 
too curious to be passed over with a slight ex- 
amination; in fact, we think it may clearly be 
shewn that there is here one of the most curious 
and beautiful arrangements and successions 
of muscular action to be met with in the whole 
system. We have elsewhere shewn that, from 
the peculiar form of the foot, the action of the 
roneus longus is essential to transmit the 
urden of progression from the weaker to the 
stronger side of the foot. (See article Feor, 
MUSCLES OF.) Let us now follow on the pro- 
gress of the foot in the act of walking, and we 
shall readily perceive the succession of action 
of its different parts, and the functions which 
each muscle performs. It is evident that the 
smaller toes being shorter than the large one, 
and nearer to the heel, they will, in the act of 
elevating the heel and propelling forward the 
body, come to their bearing on the ground 
somewhat before the great toe, their action 
being, in fact, by the breadth of base which 
MUSCLES OF THE LEG. 
they give to steady the onward progress of the 
y, and to deliver over accurately and ; 
curely the weight to the great toe, the ma 
organ of ulsion of the body. In 
accomplish this to the best effect, it is nee 
sary that the succession of actions shot 
accurate and complete, and that the musel 
the smaller toes should exert themselves 
fore that of the great toe. To this em 
flexor longus pollicis gives a slip to the fk 
of the toes, and by the commencement o} 
action, which merely firmly plants the 
toe against the ground, rouses the musel 
the other toes, assisting them to com 
their part of the process, while its own lal 
continues and is at its height when t 
necessarily accomplished and at an end. 1] 
by a beautiful combination and series of ac 
the powerful effort of the great extensors 
foot is controlled and guided to its proper 
first by the peronei, next by the flexors of 
smaller toes, assisted by the long flexor o 
great toe; and the body propelled onwa 
and balanced on this toe, the action is 
leted by the further effort of this one po’ 
ul muscle. The economy of muscular pé 
is here not less striking than the combina 
of action, for the flexor longus pollicis b 
inserted into the last phalanx of the grea 
its own proper action is not called for till af 
the muscles of the other toes have perfor 
their part; this muscle, therefore, consid 
the most powerful of all this deep layer, ¥ 
it not for the simple a of the slip 
communication to the other flexors, woul 
comparatively useless until the last moment 
the propulsion onwards of the body. But 
it lends its powerful assistance to the weal 
muscles previous to its own peculiar effort, 
when all its power is called for, the collate 
demand has ceased. 
4. Tibialis posticus is situated on the b 
of the leg between the last-named musel 
It arises fleshy from the posterior surface b 
of the tibia and fibula, immediately bele 
upper articulations of these bones with 
other. Between the two portions of this 
tachment is an angular opening through wi 
the anterior tibial vessels are transmitted. — 
muscle also arises from the whole inter¢ 
ligament; from the angles of the bor 
which that ligament is attached, and ' 
thirds of the flat posterior surface of the 
bula. The fibres run obliquely toward 
round tendon, which passes behind the i 
ankle, through a groove in the tibia. It is 
situated close to the bone enclosed in 
rate synovial sheath. It is inserted into” 
tubercle on the plantar surface of the os na 
culare, sending tendinous filaments to 1 
the other bones of the tarsus, and to the m 
tarsal bones of the second and middle t 
This muscle is covered at the lower part 
origin by the flexor longus digitorum and 
longus pollicis, and cannot be seen till th 
muscles are separated. But superiorly — 
covered by the soleus only, and here the post 
rior tibial, vessels rest upon it. Its 1 
surface is in contact with the interosseous liga 
ne, 
