Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 3: Ins-Pla
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit29464/148/
140 
MUSCLES OF THE LEG. 
muscles (lumbricales), which may also be con¬ 
sidered as accessories to the flexor longus. 
When passing behind the inner malleolus, 
this tendon is in 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 ; 
passes between the two heads of the flexor 
brevis 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 
peroneus longus is essential to transmit the 
burden of progression from the weaker to the 
stronger side of the foot. (See article Foot, 
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, m 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 
beino-, in fact, by the breadth of base which 
they give to steady the onward progress of the 
body, and to deliver over accurately and se¬ 
curely the weight to the great toe, the main 
organ of propulsion of the body. In order to 
accomplish this to the best effect, it is neces¬ 
sary that the succession of actions should be 
accurate and complete, and that the muscles of 
the smaller toes should exert themselves be¬ 
fore that of the great toe. To this end the 
flexor longus pollicis gives a slip to the flexor 
of the toes, and by the commencement of its 
action, which merely firmly plants the great 
toe against the ground, rouses the muscles of 
the other toes, assisting them to complete 
their part of the process, while its own labour 
continues and is at its height when theirs is 
necessarily accomplished and at an end. Thus, 
by a beautiful combination and series of actions, 
the powerful effort of the great extensors of the 
foot is controlled and guided to its proper end, 
first by the peronei, next by the flexors of the 
smaller toes, assisted by the long flexor of the 
great toe; and the body propelled onwards 
and balanced on this toe, the action is com¬ 
pleted by the further effort of this one power¬ 
ful muscle. The economy of muscular power 
is here not less striking than the combination 
of action, for the flexor longus pollicis being 
inserted into the last phalanx of the great toe, 
its own proper action is not called for till after 
the muscles of the other toes have performed 
their part; this muscle, therefore, considerably 
the most powerful of all this deep layer, were 
it not for the simple expedient of the slip of 
communication to the other flexors, would be 
comparatively useless until the last moment of 
the propulsion onwards of the body. But now 
it lends its powerful assistance to the weaker 
muscles previous to its own peculiar effort, and 
when all its power is called for, the collateral 
demand has ceased. 
4. Tibialis posticus is situated on the back 
of the leg between the last-named muscles. 
It arises fleshy from the posterior surface both 
of the tibia and fibula, immediately below the 
upper articulations of these bones with each 
other. Between the two portions of this at¬ 
tachment is an angular opening through which 
the anterior tibial vessels are transmitted. The 
muscle also arises from the whole interosseous 
ligament ; from the angles of the bones to 
which that ligament is attached, and from two- 
thirds of the flat posterior surface of the fi¬ 
bula. The fibres run obliquely towards a 
round tendon, which passes behind the inner 
ankle, through a groove in the tibia. It is here 
situated close to the bone enclosed in a sepa¬ 
rate synovial sheath. It is inserted into the 
tubercle on the plantar surface of the os navi- 
culare, sending tendinous filaments to most of 
the other bones of the tarsus, and to the meta¬ 
tarsal bones of the second and middle toes. 
This muscle is covered at the lower part of its 
origin by the flexor longus digitorum and flexor 
longus pollicis, and cannot be seen till those 
muscles are separated. But superiorly it is 
covered by the soleus only, and here the poste¬ 
rior tibial vessels rest upon it. Its anterior 
surface is in contact with the interosseous liga-
        

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