D. J. (Daniel John) Cunningham.

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medially under cover of the flexor digitorum brevis. The
posterior part of the latter muscle which "has already been
divided must, therefore, be turned well backwards to expose
the medial part of the origin of the abductor of the little toe.
The abductor digiti quinti is then seen to have a broad origin
from both the medial and lateral processes of the calcaneus.
It also arises from the lateral intermuscular septum, and the
lateral part of the plantar aponeurosis, which covers it. Its
tendon is inserted into the lateral aspect of the base of the
first phalanx of the little toe. The abductor digiti quinti
is supplied by the lateral plantar nerve. It abducts the little
toe from the middle line of the second toe.

Dissection. The abductor hallucis has already been sepa-
rated from the medial side of the medial process of the calcaneus.
Separate it now from the distal border of the laciniate ligament,
and turn it medially ; then divide the laciniate ligament until the
origins of the plantar arteries and nerves are exposed. They are
the terminal branches of the posterior tibial artery and the tibial
nerve, and they arise in the distal part of the leg under cover of
the proximal part of the laciniate ligament.



388 THE INFERIOR EXTREMITY

Art. Plantaris Medialis (O.T. Internal Plantar Artery).
The medial plantar artery is the smaller of the two terminal
branches of the posterior tibial artery. It arises in the hollow
between the medial malleolus and the prominence of the
calcaneus, under cover of the ligamentum laciniatum. At
the distal border of the ligamentum laciniatum it passes
under cover of the abductor hallucis ; but, as it proceeds
forwards, it appears in the interval between that muscle and
the flexor digitorum brevis. Finally, at the root of the great
toe, it ends by joining the plantar metatarsal artery to the
medial side of the hallux.

The branches which proceed from the medial plantar artery
are small but very numerous. They are (i) three twigs
which accompany the digital branches of the medial plantar
nerve to the clefts between the medial four toes they
end by joining the metatarsal branches of the plantar
arch ; (a) a series of cutaneous branches to the skin of the
sole, which pierce the aponeurosis in the furrow between its
medial and intermediate parts ; (3) a number of branches to
the muscles in the vicinity; (4) some offsets which pass
medially under cover of the abductor hallucis to reach the
medial border of the foot.

Art. Plantaris Lateralis (O.T. External Plantar Artery).
The lateral plantar artery is much larger than the medial
plantar. It is accompanied by the lateral plantar nerve and
two vena comites. From its origin in the hollow of the calcaneus,
under cover of the laciniate ligament, it passes laterally,
across the sole, to reach the interval between the flexor
digitorum brevis and the abductor digiti quinti. In that
interval it is continued forwards for a short distance, and
then, at the level of the base of the fifth metatarsal bone, it
turns suddenly to the medial side, and crosses the sole a
second time, under cover of the flexor tendons and the
adductor hallucis, forming the plantar arch. In the present
stage of the dissection it is displayed only as far as the base
of the fifth metatarsal bone. Between its origin and that
point its relations are as follows: (i) it is under cover of
the laciniate ligament; (2) it is placed between the abductor
hallucis and the hollow of the calcaneus ; (3) it lies between
the flexor digitorum brevis and the quadratus plantse ; (4) it
occupies the interval between the flexor digitorum brevis and
the abductor digiti quinti. In the latter situation it is near



SOLE OF THE FOOT 389

the surface, and is covered merely by the integument and
fasciae.

The branches which proceed from this part of the vessel are
(i) twigs to the neighbouring muscles; (2) medial calcanean
branches^ which arise near its origin, and gain the heel by
passing through the cleft between the flexor digitorum brevis
and the abductor hallucis or by piercing the origin of the
abductor hallucis; (3) cutaneous branches, which appear
through the plantar aponeurosis along the line of the lateral
intermuscular septum ; (4) twigs to the lateral margin of the
foot, which anastomose with the lateral tarsal and arcuate
branches of the dorsalis pedis.

Nervus Plantaris Medialis (O.T. Internal Plantar Nerve).
The medial plantar nerve arises as the larger of the two
terminal branches of the tibial nerve in the hollow of the
calcaneus, under cover of the ligamentum laciniatum. It
accompanies the medial plantar artery, and has similar
relations. After it emerges from under cover of the abductor
hallucis it gives off a digital branch to the medial side of the
hallux, and then ends, in the interval between the abductor
hallucis and the flexor digitorum brevis, by dividing into three
terminal digital branches.

The branches of the medial plantar nerve nre :

1. Cutaneous twigs to the skin of the sole.

2. Muscular branches.

3. Four digital branches.

The cutaneous twigs to the integument of the sole spring
from the trunk of the nerve, and pierce the aponeurosis in
the line of the medial intermuscular septum.

The digital branches of the medial plantar nerve supply
the skin of the plantar surfaces of three and a half toes, the
first, second, third, and half the fourth. They also supply
the skin over the dorsal aspects of the terminal phalanges
of those toes and the joints and ligaments of the toes to
which they are distributed.

The digital nerve to the great toe supplies the medial side
of that toe.

The three terminal digital branches pass to the proximal
ends of the medial three interdigital clefts, where each
divides to supply the adjacent sides of the toes which bound
the .clefts. From the third terminal digital branch of the

1256



39



THE INFERIOR EXTREMITY



medial plantar nerve a communication is given to the super-
ficial part of the lateral plantai nerve. The digital distribution



M. quadratus plantae
Peronaeus long




M. abductor digiti quinti

M. flexor digitorum brevis

Twig from lateral
plantar nerve to
abductor dig. quint.

\ Lateral plantar
/ artery and nerve



1 Medial plantar
J nerve and artery

M. abductor hallucis

Tendon of flexor
digitorum longus

Tendon of flexor
hallucis longus

M. flexor digiti quinti
brevis



Mm. lumbricales



M. flexor hallucis brevi



FIG. 171. Dissection of the Sole of the Foot ; the Flexor Digitorum Brevis
has been reflected.



of the medial plantar nerve in the foot closely resembles that
of the median nerve in the hand.



SOLE OF THE FOOT 391

The muscular branches go to four muscles of the sole, viz.,
the abductor hallucis, the flexor digitorum brevis, the flexor
hallucis brevis, and the most medial or first lumbrical muscle.
The branches which supply the abductor hallucis and the
flexor digitorum brevis arise from the trunk of the medial
plantar nerve a short distance from its origin. The nerve
to the flexor hallucis brevis arises from the digital nerve to
the medial side of the great toe, and the nerve to the first
lumbrical muscle springs from the digital nerve which
supplies the adjacent sides of the first and second toes.

Nenrus Plantaris Lateralis (O.T. External Plantar Nerve).
The lateral plantar nerve corresponds to -the ulnar nerve in
the palm of the hand. It accompanies the lateral plantar artery
and possesses the same relations. In the interval between the
abductor digiti quinti and the flexor digitorum brevis, opposite
the base of the fifth metatarsal bone, it divides into a deep
and a superficial part. The deep division follows the plantar
arch, under cover of the flexor tendons. The superficial
division divides into two digital branches.

From the trunk of the lateral plantar nerve proceed two
muscular branches, viz., to the abductor digiti quinti and to the
quadratus plantse.

The first or lateral digital branch of the superficial part of
the lateral plantar nerve goes to the lateral side of the little
toe. It also gives muscular twigs to the flexor brevis digiti
quinti and the interosseous muscles in the fourth intermeta-
tarsal space.

The second digital branch divides to supply the adjacent
sides of the fourth toe and little toe. It sends also a twig of
communication to the third terminal digital branch of the
medial plantar nerve.

Dissection. Detach the abductor digiti quinti from its origin,
and turn it forwards, in order that a good display may be obtained
of the structures composing the second stratum of the sole.

Second Layer of Muscles and Tendons. As the tendon
of the flexor hallucis longus enters the sole it grooves the
plantar surface of the sustentaculum tali and inclines medially,
deep to the tendon of the flexor digitorum longus, towards
the great toe. The tendon of the flexor digitorum longus, on
the other hand, inclines laterally superficial to the tendon
of the flexor hallucis longus to reach the middle of the foot,
i 25 c



392 THE INFERIOR EXTREMITY

where it divides into four tendons for the lateral four toes.
Where the tendons cross, the tendon of the flexor hallucis
longus gives a slip to the deep surface of the tendon of the
flexor digitorum longus.

Sir William Turner called attention to the fact that the slip, which
passes from the tendon of the flexor hallucis longus to the tendon of the
flexor longus digitorum, varies greatly in magnitude and in the manner in
which it is connected with the flexor tendons of the toes. In the majority
of cases it goes to the tendons of the second and third toes or to the tendons
of the second, third, and fourth toes ; in some cases, however, only to
the tendon of the second toe. Very rarely does it divide so as to bring
all the tendons of the flexor digitorum longus into connection with the
tendon of the flexor hallucis longus.

The musculus quadratus plantce, which is inserted into the
tendon of the long flexor of the toes, and also the four
lumbrical muscles, which arise from the flexor tendons, can
now be distinguished. Note the position of the long
plantar ligament between the two heads of origin of the
quadratus plantse.

Dissection. Before the flexor tendons are traced forwards
to the toes, the fibrous flexor sheaths of the toes must be dis-
played and examined. The skin on the plantar aspects of the
toes has already been reflected and the digital vessels and nerves
have been cleaned. Now remove the remains of the superficial
fascia and expose the flexor sheaths.

Each sheath consists of two strong portions, called the digital
vaginal ligaments, which lie opposite the bodies of the first and
second phalanges and are attached to their margins, and weaker
portions, opposite the interphalangeal joints, which are attached
to the ends of the adjacent phalanges and the margins of the
plantar accessory ligaments of the joints. The stronger parts
are to prevent the tendons springing away from the bones when
the joints are flexed, whilst the weaker parts allow the move-
ments of the joints to take place.

Clean the surfaces of at least two sheaths, then open one of
them by a longitudinal incision, to display the mucous lining
and the two tendons which are enclosed by the sheath.

The Flexor Sheaths of the Digits and the Insertions of
the Flexor Tendons. In each digit an osteo-fibrous canal is
formed. It is bounded, dorsally, by the plantar surfaces of
the phalanges and the plantar ligaments of the interphalangeal
joints, and, plantarwards and at the sides, by the fibrous
flexor sheaths. Two tendons enter each canal a tendon
of the short flexor of the toe and a tendon of the long flexor.
Opposite the posterior part of the first phalanx the short
flexor is superficial and the tendon of the long flexor lies



SOLE OF THE FOOT



393



Calcaneus



Quaclratus plantae
(O.T. accessorius)



between it and the bone, but at the middle of the phalanx
the tendon of the short flexor is perforated by the tendon of
the long flexor, which passes forwards to be inserted into the
base of the terminal phalanx, whilst the tendon of the short
flexor, beyond the perforation, splits into two parts which are
attached to the margins of the second phalanx.

The osteo-fibrous canal is lined with a mucous sheath,
which not only facilitates
the play of the tendons,
when the muscles are in
action, but also forms folds
called vincula which aid
in attaching the tendons to
the bones.

There are two sets of
vincula, short and long.
Two short vincula are
present in each sheath.
They are short triangular
folds containing some
yellow elastic tissue. One
of them connects the ten-
don of the long flexor to
the plantar ligament of the
terminal interphalangeal
joint and the adjacent part
of the second phalanx, and
the other connects the
tendon of the short flexor
in a similar manner to the
plantar ligament of the first
interphalangeal joint and

to the adjacent part of the first phalanx. The condition is
exactly similar to that found in the fingers (Fig. 72). The
vincula longa are more slender, they are irregular in number
and position.

Tendon of the Flexor Hallucis Longus. After giving its
slip to the tendon of the flexor digitorum longus, the tendon
of the flexor hallucis longus is prolonged forwards to the
great toe. On the plantar aspect of the hallux it is retained
in place by a fibrous flexor sheath, and, finally, it is inserted
into the base of the terminal phalanx.




Lumbricals



FIG. 172. Second layer of Muscles and
Tendons in the Sole of the Foot.



394 THE INFERIOR EXTREMITY

M. Quadratus Plants (O.T. Flexor Accessorius). This
muscle takes a course straight forwards from the heel, and
acts as a direct flexor of the toes. It also tends to bring the
tendons of the long flexor muscle into a line with the toes upon
which they operate. It arises by two heads which embrace
the calcaneus and the long plantar ligament. The medial
head, wide and fleshy, springs from the medial concave
surface of the calcaneus ; the lateral head, narrow, pointed,
and tendinous, takes origin from the lateral surface of the
calcaneus, and also from the long plantar ligament. The
quadratus plantse is inserted into the tendon of the flexor
digitorum longus in the middle of the sole. It is supplied
by a branch from the lateral plantar nerve.

Mm. Lumbricales. The lumbrical muscles of the foot are
not so strong as the corresponding muscles in the palm of the
hand. They are four in number, and arise from the tendons
of the flexor digitorum longus. The lateral three lumbricals
spring from the adjacent sides of the tendons between which
they lie ; the first or most medial muscle takes origin from the
medial side of the tendon of the long flexor which goes to the
second toe. The slender tendons of the lumbrical muscles
proceed to the medial sides of the lateral four toes, and are
inserted into the expansions of the extensor tendons on the
dorsal aspects of the proximal phalanges (see p. 346). The
first or most medial lumbrical is supplied by the medial plantar
nerve : the others are supplied by the lateral plantar nerve.

Dissection. To bring the third layer of muscles into view
the following dissection must be made : Divide the two heads
of the quadratus plantae and draw the muscle forwards from
under the lateral plantar vessels and nerve. Sever also the
tendons of the flexor digitorum longus and the flexor hallucis
longus at the point where they emerge from under cover of the
ligamentum laciniatum, and turn them towards the toes, after
cutting the branch from the lateral plantar nerve to the quadratus
plantae. As the tendons of the long flexor of the toes are turned
forwards the lumbrical muscles will be raised, and the twigs which
are furnished to the second, third, and fourth by the deep division
of the lateral plantar nerve must be looked for. That for the
second lumbrical muscle will be seen to take a recurrent course
round the transverse head of the adductor hallucis muscle.
Lastly, cut the medial plantar nerve close to its origin and turn
it aside.

Third Layer of Muscles. The flexor hallucis brevis lies
along the lateral side of the abductor hallucis.

The oblique head of the adductor hallucis has a very oblique



SOLE OF THE FOOT 395

position in the sole, and hides the interosseous muscles to a
great extent. It lies to the lateral side of the flexor hallucis
brevis.

The transverse head of the adductor hallucis is placed
transversely across the heads of the metatarsal bones and the
plantar ligaments of the metatarso-phalangeal joints.

The flexor digiti quinti brevis (O.T. minimi digiti) lies upon
the fifth metatarsal bone.

The deep division of the lateral plantar nerve and the
plantar arterial arch are partially exposed, but they will be
more fully displayed at a later stage.

Dissection. Clean all the above-named muscles from their
origins to their insertions. Clean also the exposed part of the
plantar arch.

M. Flexor Hallucis Brevis. The short flexor of the great
toe arises from the slip from the tendon of the tibialis posterior
muscle which goes to the second and third cuneiform bones
and from the adjoining part of the cuboid bone. It is narrow
and tendinous at its origin, but it soon divides into two separate
fleshy bellies, which are ultimately inserted one upon each
side of the base of the proximal phalanx of the great toe.
In the tendons of insertion two large sesamoid bones are
developed (Fig. 1 74). The medial head of the flexor hallucis
brevis is closely connected with the tendon of the abductor
hallucis, and is inserted in common with it. The flexor
hallucis brevis is supplied by the medial plantar nerve. It
is a flexor of the metatarso-phalangeal joint of the great toe.

M. Adductor Hallucis (O.T. Adductor Obliquus Hallucis
and Adductor Trans versus Hallucis). The adductor hallucis
consists of two separate portions called the oblique and the
transverse heads of the muscle. The oblique head arises
from the sheath of the peronaeus longus tendon and from
the bases of the second, third, and fourth metatarsal bones.
It tapers as it approaches the root of the hallux, and is
inserted, with the lateral head of the flexor hallucis brevis,
into the lateral aspect of the base of the proximal phalanx
of the great toe. It is supplied by the deep division of
the lateral plantar nerve. The transverse head springs by
a series of slips from the plantar metatarso-phalangeal
ligaments of the third, fourth, and fifth toes, and proceeds
transversely medially, under cover of the flexor tendons,
to find insertion into the lateral side of the base of the



396



THE INFERIOR EXTREMITY



proximal phalanx of the great toe, in common with the
oblique head. Its nerve of supply comes from the deep

Origin of M. abductor digiti quinti
Origin of M. flexor digitorum brevis

Long plantar ligament

Lateral plantar artery and nerve
t Medial plantar artery and nerve
M. abductor hallucis

M. quadratus plantae
Flexor digitorum longus
Flexor hallucis longus
Peronaeus longus .

Lateral plantar artery
and nerve

M. flexor digiti quinti brevis

M. adductor hallucis. oblique
head

M. flexor hallucis brevis

M. adductor hallucis, trans-
Averse head

Mm. lumbricales




FIG. 173. Deep Dissection of the Foot ; the Superficial Muscles and also
the Flexor Tendons, etc., have been removed.

division of the lateral plantar nerve. It is an adductor of the
great toe.



PLATE XXXV



Second plantar
metatarsal ''artery



First plantar
metatarsal artery
. Deep plantar con-
tinuation of the
dorsalis pedis artery



Second cuneiform
bone

First cuneiform
bone



Navicular bone



Medial plantar
artery



Talus



Lateral plantar
artery



Calcanean branch

of lateral plantar

artery




Second dorsal
metatarsal artery

Third plantar
metatarsal artery



Third dorsal
metatarsal artery

Fourth dorsal
metatarsal artery
Fourth plantar
metatarsal artery

Plantar arch



Fifth metatarsal bo
Third cuneiform bo



Cuboid



Lateral plantar
artery



Calcaneus



FIG. 174. Radiograph of an Injected Foot showing the relations of some
of the arteries to the bones.



SOLE OF THE FOOT 397

Flexor Digit! Quinti Brevis (O.T. Flexor Brevis Minimi
Digiti). The short flexor of the little toe is a single fleshy slip,
which springs from the base of the fifth metatarsal bone and
the sheath of the peronaeus longus tendon. It is inserted into
the lateral side of the base of the proximal phalanx of the
little toe. Its nerve of supply arises from the superficial
division of the lateral plantar nerve. It is a flexor of the
metatarso-phalangeal joint of the little toe.

Dissection. The oblique head of the adductor hallucis, and
the flexor hallucis brevis, must now be detached from their origins
and thrown towards their insertions, in order that the entire
length of the plantar arterial arch, the deep division of the lateral
plantar nerve, and the termination of the dorsalis pedis artery
may be displayed. As the oblique head of the adductor hallucis
is raised the branch which is given to it by the deep division of
the lateral plantar nerve must be secured and retained.

Arcus Plantaris. - The plantar arterial arch is the
continuation of the lateral plantar artery across the sole
of the foot. It runs from the level of the base of the fifth
metatarsal bone to the base of the first interosseous space,
where it is joined by the terminal plantar portion of the
dorsalis pedis artery. The arch is deeply placed ; it rests
against the interosseous muscles, close to the proximal ends
of the metatarsal bones (Figs. 174, 175), and it is concealed
by the flexor tendons, the lumbrical muscles, and the oblique
head of the adductor hallucis. It is accompanied by the
deep division of the lateral plantar nerve and by two venae
comites.

The branches which proceed from the arch are :

1. Articular.

2. Posterior perforating.

3. Second, third, and fourth plantar metatarsal arteries.

4. Plantar digital artery to the lateral side of the little toe.

The articular branches arise from the concavity of the arch,
and run posteriorly to supply the tarsal joints.

The posterior perforating branches are three in number.
They pass dorsally through the posterior ends of the lateral
three intermetatarsal spaces and between the heads of the
corresponding dorsal interosseous muscles. Each ends, on
the dorsum of the foot, by joining the corresponding dorsal
metatarsal artery.

The second, third^ and fourth plantar metatarsal branches



398 THE INFERIOR EXTREMITY

run forwards opposite the second, third, and fourth inter-
metatarsal spaces, pass dorsal to the transverse head of the
adductor hallucis, and, at the proximal end of the corre-
sponding interdigital cleft, each plantar metatarsal artery ends
by dividing into two branches which supply the adjacent
sides of the digits bounding the cleft. The branches of
the second plantar metatarsal artery supply the adjacent
sides of the second and third toes ; those of the third
supply the adjacent sides of the third and fourth toes ;
and those of the fourth the adjacent sides of the fourth and
fifth toes.

Immediately before it divides, each plantar metatarsal
artery sends dorsally an anterior perforating artery which
joins the corresponding dorsal metatarsal artery.

Upon the sides of the toes the plantar digital branches of
the metatarsal arteries are distributed in exactly the same
manner as the digital arteries of the fingers (see p. 155).

The plantar metatarsal branch to the lateral border of the
little toe springs from the lateral extremity of the plantar arch,
crosses the plantar surface of the flexor digiti quinti brevis,
and runs forwards to the distal end of the toe.

The First Plantar Metatarsal Artery (O.T. Arteria
Magna Hallucis) corresponds with the arteria volaris indicis
radialis and the arteria princeps pollicis of the hand. It arises
from the plantar extremity of the dorsalis pedis, at the point
where the latter joins the plantar arch, and runs forwards to
the cleft between the great toe and the second toe, where
it divides into two branches for the supply of the adjacent
sides of the first and second toes. Before it divides, it gives
off a branch to the medial side of the great toe which is
joined by the terminal part of the medial plantar artery.

Deep Division of the Lateral Plantar Nerve. The deep
division of the lateral plantar nerve accompanies the plantar
arch in its course medialwards across the sole. It lies
posterior to the arch, and ends in the deep surface of the



Online LibraryD. J. (Daniel John) CunninghamCunningham's manual of practical anatomy (Volume 1) → online text (page 39 of 44)