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336 THE INFERIOR EXTREMITY

medial terminal branch of the superficial peroneal nerve was
found, or the communicating branch from the sural nerve to
the lateral terminal branch of the superficial peroneal nerve
was found, follow one or the other of those branches upwards
to the trunk. Otherwise cut down through the fat, at the
junction of the middle and distal thirds of the leg, about 25 mm.
to the medial side of the fibula, and secure the trunk of the
superficial peroneal nerve as it pierces the deep fascia. Follow
it distally to its division into medial and lateral branches,
and then trace each of the branches and their subdivisions to
their terminations on the toes. One of the subdivisions passes
to the medial side of the great toe. A second passes to the cleft
between the first and second toe ; follow it with care, and find,
springing from its medial side, a twig of communication to the
medial division of the deep peroneal nerve. Follow the twig
of communication, secure the medial division of the deep
peroneal nerve, and follow its two terminal branches to the
adjacent sides of the first and second toes.

Vense Superficiales (the Cutaneous Veins of the Dorsum
of the Foot and the Front of the Leg). The cutaneous veins
of the dorsum of the foot and the anterior region of the leg
are the digital veins, the dorsal venous arch, and the parts
of the great and small saphenous veins.

There are two dorsal digital veins in each toe, one on each
side of the dorsum of the toe. The medial dorsal digital vein
of the great toe joins with the medial end of the dorsal venous
arch to form the commencement of the great saphenous
vein, and the lateral dorsal digital vein of the little toe unites
with the lateral end of the dorsal venous arch to form the
small saphenous vein. The two dorsal digital veins which
run along the adjacent sides of each of the four interdigital
clefts unite at the apices of the clefts to form a common
stem, and the four stems thus formed, which are sometimes
called the common digital veins, end in the dorsal venous
arch.

The dorsal venous arch lies in the superficial fascia on
the anterior parts of the bodies of the metatarsal bones,
superficial to the terminal branches of the superficial peroneal
nerve. Its medial end, joining with the medial dorsal digital
vein of the great toe, forms the commencement of the great
saphenous vein, and its lateral end unites with the lateral
dorsal digital vein of the little toe in the formation of the
small saphenous vein.

The majority of the superficial veins of the front of the
leg pass medially and upwards, and they terminate in the
great saphenous vein, and as the great saphenous vein lies



THE LEG 337

in front of the medial malleolus it receives tributaries from
the medial side of the foot.

The Superficial Lymph Vessels of the Dorsum of the Foot
and the Front of the Leg. The main superficial lymph
vessels accompany the veins. The greater part of the lymph
from the dorsum of the foot passes along vessels which
accompany the great saphenous vein to the distal set of
superficial subinguinal lymph glands (p. 228), but some of
the lymph vessels from the lateral border of the foot, and the
lateral part of the dorsum, accompany the small saphenous
vein and terminate in the lymph glands in the popliteal
fossa. The lymph vessels from the front of the leg pass to
the larger lymph vessels which accompany the great saphenous
vein (Fig. 159).

Nervi Cutanei (the cutaneous nerves of the dorsum of
the foot and the front of the leg). The dissector should
note that branches of three nerves supply the skin of the
front of the leg, branches of three nerves supply the dorsum
of the foot, arid that the dorsal aspects of the toes are, for
the main part, supplied by branches of three nerves, but
that only one nerve, the superficial peroneal, is common to all
three regions.

The proximal part of the front of the leg, below the
patella, is supplied by the infrapatellar branch of the saphenous
nerve (Figs. 107, 163).

The lateral cutaneous nerve of the /eg, a branch of the
common peroneal nerve, is distributed to the skin of the
anterior surface from the infrapatellar region to the junction
of the middle and distal thirds of the leg, and the re-
mainder of the front of the leg is supplied by the superficial
peroneal nerve.

The medial side of the dorsum of the foot is supplied by
the saphenous nerve, the lateral side by the sural nerve, and
the intermediate area by the superficial peroneal nerve.

The adjacent sides of the first and second toes are supplied
by the medial division of the deep peroneal nerve, the lateral
sides of the little toe by the sural nerve, and all the remaining
parts by branches of the superficial peroneal nerve.

The skin over the terminal phalanges of the first, second, third and
the medial part of the fourth toes is supplied by branches of the ?nedial
plantar nerve.

Nervus Peronaeus Superficialis. The superficial peroneal
VOL. i 22



338 THE INFERIOR EXTREMITY

nerve pierces the deep fascia at the junction of the middle
and distal thirds of the leg, and either at once or
shortly afterwards it divides into a medial and a lateral
division, which are quite unnecessarily called the medial and
intermediate dorsal cutaneous nerves of the foot, the sural
nerve, when it reaches the dorsum of the foot, being called
the lateral dorsal cutaneous nerve of the foot to make the
series complete. The medial division supplies the medial
part of the dorsum of the foot and divides into two branches,
one of which is distributed to the medial side of the great
toe, and the other to the adjacent sides of the second and
third toes; it also gives a communicating twig to the deep
peroneal nerve (Fig. 107). The lateral division supplies the
intermediate part of the dorsum of the foot, and also divides
into two branches, one of which supplies the adjacent sides
of the third and fourth toes, and the other, after receiving a
twig from the sural nerve, supplies the adjacent sides of the
fourth and fifth toes (Fig. 107). The branches of both
divisions lie deep to the dorsal venous arch.

Nervus Suralis. The sural nerve is formed at the back of
the leg by the union of the anastomotic branch of the common
peroneal nerve with the medial cutaneous nerve of the calf
from the tibial nerve (Fig. 163). It accompanies the small
saphenous vein, passes behind and below the lateral malleolus,
and then runs along the lateral border of the foot, where it
gives off a twig to the most lateral branch of the superficial
peroneal nerve (Fig. 164), and then runs on to supply the
lateral part of the dorsum of the little toe.

The account given above of the cutaneous nerves of the dorsum of the
foot and toes indicates the general arrangement frequently met with, but
the dissector must be prepared to meet with many variations, especially on
the lateral side, where the sural nerve and the lateral division of the
superficial peroneal nerve not uncommonly replace one another to a
greater or a less extent.

Dissection. After the cutaneous veins and nerves of the
dorsum of the foot and the front of the leg have been examined,
the remains of the fatty superficial fascia must be removed to
display the deep fascia.

Deep Fascia. The deep fascia does not form a complete
investment for the leg. It is absent over the medial area of
the tibia, and is attached to the anterior and medial borders
of that bone. It is also absent over the triangular subcutaneous
surface on the distal part of the fibula, being attached to the



THE LEG 339

ridges which limit that area anteriorly and posteriorly. It is
not equally dense throughout, but becomes thinner towards
the distal part of the leg until the region of the ankle is
reached, where thickened bands are formed in it ; beyond the
ankle in the region of the dorsum of the foot it becomes
exceedingly thin and fine. Its great strength in the proximal
part of the anterior crural region is due to the fact that there
it gives origin to fibres of the subjacent muscles. The bands
in the region of the ankle are formed to retain the tendons in
position when the muscles which move the joint are in action.
Four of the bands must be examined at this stage of the
dissection, viz., the ligamentum transversum cruris, the
ligamentum cruciatum cruris, and the superior and inferior
retinacula of the peroneal muscles. 1

The ligamentum transversum cruris (O.T. upper part of
anterior annular ligament] is a strong, broad band which
stretches across the front of the leg, immediately proximal to
the ankle joint. By one extremity it is attached to the fibula,
and by the other to the tibia. The tig. cruciatum cruris (O.T.
lower part of anterior annular ligament} is placed over the ankle
joint. Laterally it presents the appearance of a narrow, well-
defined band, which is fixed firmly to the anterior part of the
calcaneus. As it passes medially it divides into two diverging
limbs. Of these the proximal is attached to the medial
malleolus, whilst the distal passes to the medial margin of the
foot, and becomes connected with the plantar aponeurosis.
The transverse and the cruciate ligaments of the leg are
merely portions of the deep fascia which are distinguishable
on account of their thickness (Figs. 153, 154).

The superior peroneal retinaculum is a thickened por-
tion of the deep fascia which passes from the posterior and
distal part of the lateral malleolus to the upper and posterior
part of the lateral surface of the calcaneus (Fig. 158).

The inferior peroneal retinaculum springs from the anterior
part of the upper surface of the calcaneus, where it is con-
tinuous with the lateral extremity of the cruciate ligament ;
its opposite extremity is attached, on the lateral border of the
foot, to the trochlear process of the calcaneus and to the
lateral surface of the calcaneus below that process. The

1 In the old terminology the first two bands were respectively the upper
and lower parts of the anterior annular ligament of the ankle, and the last two
were included under the term external annular ligament.
I 22 a



34



THE INFERIOR EXTREMITY



peroneal retinacula bind the tendons of the peronaeus longus
and brevis to the lateral surface of the calcaneus (Fig. 158).

Intermuscular Septa. As the deep fascia of the leg passes
backwards over the fibular region, two strong intermuscular
septa are given off from its deep surface. These are dis-
tinguished as the anterior and posterior fibular septa. The
anterior fibular septum intervenes between the peroneal muscles
and the extensor muscles of the toes, and is attached to the
anterior crest of the fibula. The posterior fibular septum is

interposed between the
peroneal muscles and the
muscles on the back of
the leg, and is attached
to the lateral crest of the
fibula.

The leg is thus sub-
divided into three osteo-
fascial compartments, cor-
responding to the anterior,
lateral, and posterior
crural regions. The an-
terior compartment is
bounded by the investing
deep fascia, the anterior

FIG. 152. Diagrammatic representation of fibular septum, the anterior




the Fascia of the Leg. The fascia of the c , , . , r

tibialis posterior is more a muscular P art of the medial surface
aponeurosis than a true fascial septum ; of the fibula (that part
but it is convenient for descriptive pur-
poses to regard it as one of the parti-
tions.



which lies anterior to the
interosseous crest), the
interosseous membrane,
and the lateral surface of the tibia. The lateral compartment
is bounded by the lateral surface of the fibula, the investing
fascia, and the two fibular septa. The posterior compartment,
which will be studied later, is much the largest ; its walls are
formed by the posterior surface of the tibia, the posterior
part of the medial surface and the whole of the posterior
surface of the fibula, the interosseous membrane, the posterior
fibular septum, and the investing deep fascia.

Dissection. The anterior compartment of the leg should
now be opened by the removal of the deep fascia. The transverse
and cruciate ligaments, however, must be retained, and their
borders should be separated artificially, by the knife, from the



THE LEG 341

deep fascia with which they are continuous. Great care must
be taken not to injure the mucous sheaths of the tibialis anterior
and the extensor tendons of the toes, when the margins of the
transverse and cruciate ligaments are being defined, and whilst
the deep fascia is being reflected. They lie close to the deep surface
of the deep fascia. In the proximal part of the leg it will be
found impossible to raise the deep fascia from the subjacent
muscles without lacerating their surfaces. It should, therefore,
be left in position. At a more distal level it can readily be
separated. Divide it in a longitudinal direction midway between
the tibia and fibula. Turn the medial piece to the medial side,
until its attachment to the anterior border of the tibia is demon-
strated ; then turn the lateral piece to the lateral side, until its
continuity with the anterior fibular septum is displayed.

After the medial and lateral attachments of the deep fascia
have been studied attempt to distend the synovial sheaths of
the tendons, either by inflation with a blow-pipe, or by the
injection of some fluid by means of a small syringe. Three
sheaths are to be examined; from the medial to the lateral side
they are, the sheath of the tibiaiis anterior, the sheath of the
extensor hallucis longus, and the sheath common to the extensor
digitorum longus and the peronaeus tertius (see Fig. 153, p. 342).
If the blow-pipe is used make a small incision through the
deep fascia of the foot into each sheath in turn, either between
the two bands of the cruciate ligament or beyond the lower
border of the cruciate ligament, and if a syringe is used insert
the needle into the sheaths in the same regions. If inflation
or injection fails, the positions and extents of the sheaths can be
fairly satisfactorily demonstrated by the use of a blunt probe,
introduced into the cavities of the sheaths through the openings
made through their boundaries.

The Mucous Sheaths on the Dorsum of the Foot. Three
mucous sheaths are found in the region of the front of the
ankle and on the dorsum of the foot one round the tendon
of the tibialis anterior, the second round the tendon of the
extensor hallucis longus, and the third encloses the tendons
of the extensor digitorirm longus and the peronaeus tertius.
The first extends from the proximal border of the transverse
ligament to within a short distance of the insertion of the
tibialis anterior into the medial side of the first cuneiform
bone. The second extends from behind the lower part of
the transverse ligament to the first phalanx of the great toe ;
and the limits of the third are the lower border of the
transverse ligament, proximally, and the middle of the
dorsum of the foot distally. The sheaths facilitate the
movements of the tendons behind the ligaments when the
muscles are in action, and they are of surgical importance
because they are liable to become inflamed.

1226



342



THE INFERIOR EXTREMITY



After the mucous sheaths have been examined, the contents
of the anterior crural compartment may be investigated.

Contents of the Anterior Crural Compartment. Four

muscles are brought into view when the deep fascia of the



M. extensor digitorum longus
M. peronaeus tertiu

M. peronaeus brevi
M. peronaeus longus
Ligamentum transversum



Sheath of peronei tendons

Lig. malleoli lateralis

anterius

Lig. talo-fibularis anterior

Retinaculum mm. pero-

naeorum superius-

Retinaculum mm. pero-
naeorum inferius



M. extensor digitorum brevi
aTendon of peroneus tertiu




Tibia

M. extensor longus hallucis

M. tibialis anterior



Lig. cruciatum

Sheath of tibialis anterior

Sheath of tibialis posterior

> Ligamentum cruciatum

.Sheath of extensor digitorum
longus

Sheath of extensor hallucis
longus

M. extensor hallucis brevis



D



FIG. 153. Mucous sheath of the Dorsum of the Foot.

front of the leg has been removed, viz., the tibialis anterior,
the extensor digitorum longus, the extensor hallucis longus,
and the peronaeus tertius. The tibialis anterior lies in relation
to the tibia ; the extensor digitorum longus is placed along the
fibula; and when those muscles are separated from one another
the extensor hallucis longus will be seen in the interval between



THE LEG 343

them. The peronaus tertius lies upon the distal portion of



- Patella
Ligamentum patellae



-Tendon of biceps femoris
Fibular collateral ligament



[Common peroneal nerve (O.T. ext. popliteal)
Recurrent articular nerve
-Deep peroneal nerve (O.T. anterior tibial)

[ - Anterior tibial artery
M. tibialis anterior
-M. peronaeus longus

Superficial peroneal nerve (O.T. musculo-cutaneous)
M. extensor digitorum longus



M. peronseus brevis



^M. extensor hallucis longus



Transverse ligament (O.T. upper baud of anterior
"annular lig.)

-Perforating branch of peroneal artery



..Cruciate ligament (O.T. lower band of ant. ann. lig.)
jt-Dorsalis pedis artery

l_Deepperoneal nerve (O.T. ant. tibial)
' .M. extensor digitorum brevis
Tendon of peronaeus tertius



FIG. 154. Dissection of the Anterior and Lateral Crural Regions.
I 22 c



344 THE INFERIOR EXTREMITY

the fibula, and in most cases is continuous with the extensor
digitorum longus. The anterior tibial vessels and the deep
peroneal nerve (O.T. anterior tibial] proceed distally in this
compartment. At first they are deeply placed, but as they
approach the ankle they come nearer to the surface.

Dissection. To expose the anterior tibial vessels and the
deep peroneal nerve in their entire course on the front of the
leg, the tibialis anterior and the extensor digitorum longus must
be separated from each other, along the line of a strong inter-
muscular septum which dips backwards between them, and
affords a surface of origin to each. The knife should be carried
proximally along the plane of this septum. If the peronaeus
tertius muscle is drawn aside, the perforating branch of the
peroneal artery will be seen piercing the interosseous membrane.
It is a small artery which descends upon the distal end of the
fibula. As the structures in the anterior crural compartment
are being exposed and cleaned, the dissector should, at the same
time, carry on the dissection of the dorsum of the foot. There
the tendons of the mus 3les on the front of the leg must be followed
to their insertions, then the tendons of the extensor digitorum
longus must bfi pulled aside in order that the extensor hallucis
brevis and the extensor digitorum brevis, which lie deep to the
tendons of the long extensor of the toes, may be cleaned and
their tendons followed to their terminations. The dorsalis
pedis artery, which is the continuation of the anterior tibial
artery, and the deep peroneal nerve, and their branches, must
also be cleaned and followed to their terminations.

M. Tibialis Anterior (O.T. Tibialis Anticus). The tibialis
anterior is a powerful muscle, which takes origin from the
distal part of the lateral condyle of the tibia, and from the
proximal half of the lateral surface of its body (Fig. 154, p. 343).
It derives many fibres also from the deep fascia which covers
it, from the fascial septum between it and the extensor digi-
torum longus, and from the portion of the interosseous
membrane on which it rests. In other words, it springs from
the structures which form the walls of the medial portion of
the osteo-fascial compartment in which it lies. 1 A strong
tendon issues from its fleshy belly in the distal third of the
leg, and this reaches the dorsum of the foot by passing

1 To understand the attachments of the muscles of the leg, it is necessary
to bear in mind that the interosseous membrane, which stretches across the
interval between the two bones of the leg, and thus extends the surface of
origin for these muscles, is attached to the interosseous crest of the tibia (i.e.
between its lateral and posterior surfaces) and to the interosseous crest of the
fibula. The interosseous crest of the fibula traverses the medial surface of
that bone, and divides it into an anterior and a posterior part. The anterior
part gives origin to the extensor muscles and the posterior part to the tibialis
posterior.



THE LEG



345



through both the transverse and cruciate ligaments. On
the foot it inclines medially, and, turning round the medial
margin, gains insertion, by two slips, into the medial and
distal part of the first cuneiform bone, and into the adjoin-
ing part of the base of the first metatarsal bone. The tibialis
anterior is supplied by the deep peroneal nerve. It is a dorsi-
flexor and an inverter of the foot.

M. Extensor Digitomm Longus. The extensor longus
digitorum muscle arises, for the most part, from the
structures which form the lateral portion of the wall of the

M. ext. hallucis longus
M. ext. dig. longus ^\ -;
Peronaeus brevis v ,, \ < .
Superficial peroneal
nerve>



Peroneal -|

artery

M. flexor hal-
lucis longus




.** M. flex, dig. 'long.

Posterior tibial
"" artery
...Tibial nerve (O.T.

posterior tibial)



-/' - M. plantaris



Sural nerve and small sapbenous vein

FIG. 155. Transverse section through the Middle of the Leg.

anterior crural region. Thus, it springs from the distal part
of the lateral condyle of the tibia, from the head of the
fibula, and from the proximal three-fourths of the anterior
part of the medial surface of the body of the fibula
(Fig. 154, p. 343). It takes origin also from a small portion
of the proximal part of the interosseous membrane, the
deep investing fascia of the leg, the anterior fibular septum,
and the inter-muscular septum which lies between it and
the tibialis anterior. The tendon of the extensor digitorum
longus descends anterior to the ankle joint, and, passing
through the transverse and cruciate ligaments (p. 339),
divides into four slips, which diverge from each other on



346 THE INFERIOR EXTREMITY

the dorsum of the foot to reach the lateral four toes.
On the dorsum of the first phalanx of each of the medial
three of the lateral four toes each slip is joined, on its lateral
side, by a tendon from the extensor digitorum brevis.

The manner in which the four tendons of the long
extensor are inserted is similar, in all essential respects, to
that in which the corresponding tendons of the fingers are
attached, but there are slight differences, and as the dissector
of the foot may not have dissected the hand a description
of the conditions met with is necessary. The tendons of
the extensor digitorum longus go to the second, third, fourth,
and fifth toes, and those of the extensor digitorum brevis to
the first, second, third, and fourth toes. In the cases of the
second, third, and fourth toes the tendons of the long and
short extensors unite, and the conjoined tendons form an
expansion on the dorsal aspect of the first phalanx. The
expansion is joined by the slender tendons of one lumbrical
and two interossei, and then it divides into a central and
two collateral parts. The slender central part is inserted
into the base of the second phalanx; the stronger
collateral parts are prolonged forwards, and, after they have
united together, they are inserted into the base of the terminal
phalanx; thus five tendons gain insertion into the dorsal
aspects of the bases of each of the second and terminal
phalanges of the second, third, and fourth toes, and move-
ments become possible which could not be readily obtained
in any other way, for whilst the flexor tendons flex the
metacarpo-phalangeal joints the lumbricals and interossei can
extend the interphalangeal joints by virtue of their connection
with the extensor expansion. In the case of the foot this is
not a very important matter, but in the case of the hand it
is of extreme importance, for it is only by the means indicated
that it is possible to place the fingers in the " writing position,"
and use them in the usual manner adopted for writing
(see p. 178). The extensor digitorum longus is supplied by
the deep per oneal nerve. It is an extensor of the interphalangeal
and metatarso-phalangeal joints of the lateral four toes and
it dorsi-flexes the foot.

M. Extensor Hallucis Longus. The long extensor of the
great toe is placed in the interval between the tibialis anterior
and the extensor digitorum longus. In its proximal part it
is hidden from view by those muscles, but near the ankle it



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