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mission of vessels and nerves into the interior of the joint.

Dissection. Make a transverse incision through the quadri-
ceps extensor, immediately proximal to the patella, and prolong
each end of the incision downwards, about 37 mm. posterior to
the patella, to the condyles of the tibia, then turn the patella
downwards. The joint is now opened from the front and the
following structures can be seen and examined, viz., the synovial
lining, the cruciate ligaments, which connect the femur with the
tibia, and the menisci, which lie upon and are attached to the
tibia. Immediately above the joint, between the distal part of
the quadriceps extensor and the front of the femur there is a
large suprapatellar bursa which is frequently continuous with the
joint cavity. To display the extent of that bursa, split the lower
part of the quadriceps by a vertical incision in the middle line
of the thigh and turn the two parts aside.

Interior of the Joint. First note the great pad of soft fat
which is placed on the deep surface of the ligamentum patellae.
In vertical section the fatty mass is triangular in form (Fig. 181).
It is termed the infra-patellar pad, and it fills up the interval
between the patella, femur, and tibia, and adapts itself to
the varied forms which that recess assumes in the different
movements of the joint. It is separated from the interior
of the joint by a covering of the synovial layer, and from
its surface a fold of that layer extends backwards and
upwards to the anterior margin of the intercondylar fossa
of the femur, where it is attached. That band is termed
the patellar synovial fold (O.T. ligamentum mucosuni). As
it approaches the femur it becomes narrow and slender;
but where it covers the surface of the infra-patellar pad it is
broad and triangular, and presents two free margins which
extend along the borders of the distal part of the patella,
and receive the name of plicce alares (O.T. ligamenta alaria],
It must be clearly understood that these are not ligaments
in the ordinary sense of the word, but merely folds of the
synovial layer.

Stratum Synoviale (O.T. Synovial Membrane). As the
knee joint is the largest joint in the body its synovial stratum is
more extensive than that of any other joint. It lines the deep
surfaces of the ligamentous structures of the lateral, medial
and anterior parts of the joint. It lines the deep surfaces



KNEE JOINT 411

of the medial and lateral portions of the posterior part of the
capsule also, and from them it is prolonged anteriorly, along
the sides and round the front of the cruciate ligaments. In the
anterior part of the joint it is prolonged upwards, beyond
the articular surface of the distal end of the femur, in the
form of a great cul-de-sac, under cover of the tendon of the
quadriceps (Fig. 181). The proximal extremity of this cul-de-sac
usually communicates by an orifice of greater or less width
with the suprapatellar bursa. The synovial layer also invests
the menisci, and a pouch -like diverticulum is prolonged
posteriorly and distally, along the tendon of the popliteus,
which it partially ensheaths, across the posterior part of the
external border of the lateral meniscus to the posterior aspect
of the proximal end of the tibia. That prolongation lies in
close relation with the capsule of the tibio-fibular joint, and
in some cases a communication is established between the
cavity of the diverticulum and the cavity of the tibio-fibular
joint.

Dissection. Divide the patellar synovial fold and remove
the infrapatellar pad of fat. Then open and examine the bursa
between the ligamentum patellae and the proximal part of the
tibia. Next dissect away the intermediate part of the posterior
portion of the capsule (oblique popliteal ligament) and trace the
middle genicular artery, which pierces it, forwards to the cruciate
ligaments. It will now be seen that the posterior surface of
the posterior cruciate ligament is not covered by the synovial
layer, and that it is connected by areolar tissue to the deep
surface of the posterior part of the fibrous stratum of the
capsule. Define the attachments of the cruciate ligaments by
removing the synovial layer which covers them at the sides and
in front, and the areolar tissue in connection with them. The
menisci also should receive the attention of the dissector, and the
manner in which their fibrous, pointed extremities are fixed to
the tibia must be studied. At this stage the changes produced in
the degree of tension of the cruciate ligaments, and the change
in the position of the menisci brought about by movements
of the joint, should be examined.

Movements at the Knee Joint. The movements of the knee joint are
those of flexion and extension. The leg can be bent posteriorly until the
prominence of the calf comes into contact with the posterior aspect of the
thigh ; but in extension the movement is brought to a close when the leg
comes into a line with the thigh. In that position the joint is firmly locked,
and the anterior cruciate, the tibial and the fibular collateral ligaments, and
the posterior part of the capsule with the oblique popliteal ligament
being fully stretched, the leg and thigh are converted into a rigid column
of support. In flexion, however, the ligaments mentioned are relaxed, and
a certain amount of rotation of the tibia upon the femur is allowed.

Flex the joint acutely, and examine the cartilage-covered surface of
the distal end of the femur. It consists of an anterior trochlear portion



412



THE INFERIOR EXTREMITY



for the patella, and two condylar surfaces which move on the menisci and
tibia. The trochlea is separated from the surface of the lateral condyle by a
faintly marked groove, which takes a slightly curved course, from the lateral
border of the distal end of the femur, medially and posteriorly to the fore
part of the intercondylar fossa. At each extremity this groove widens out
into a distinct depression. In full extension the lateral depression rests
upon the anterior part of the lateral meniscus, whilst the medial depres-
sion rests against the anterior border of the lateral tubercle of the inter-
condyloid eminence of the tibia (Bruce Young). The line of demarcation
between the trochlea and the distal surface of the medial condyle of the
femur is not so distinct. Close to the medial margin of the bone there is a



Popliteal artery

M. semitendinosus
M. semimembranosus
Deep fascia



Middle genicular arte

Popliteal fascia

Anterior cruciate

ligament

Oblique popliteal/
ligament

Popliteal artery

Popliteal vei
Tibial nerve

Plantaris tendon
M. popliteus

M. gastrocnemius




Supra-patellar

U~7*"'ir "ursa, continuous
'



with cavity of joint



4- Quadriceps tendon



jT-T-TT Patella

t'' y/3 Subcutaneous

* //'T prepatellar bursa
Wl Ip^'ity f knee
TIT-IT i 'joint

/ // Infra-patellar pad
- J- /of fat

-j Patellar synovial fold
-/ Apices of menisci

- Deep infra-patellar bursa

-Subcutaneous infra-
patellar bursa

Tuberosity of tibia
Tibia



FIG. 181. Sagittal Section of the Knee Joint.



depression which, in full extension, rests upon part of the anterior horn of
the medial meniscus (Bruce Young) : but lateral to this the trochlear
surface is prolonged posteriorly for a certain distance along the anterior
and medial margin of the intercondylar fossa. A portion of the medial
condyle is thus included in the trochlear surface, viz., the portion skirting
the medial border of the anterior part of the intercondylar fossa, and this
is termed the " crescentic facet " of the medial condyle.

The posterior surface of the patella may next be examined (Fig. 178), and
its movements in connection with flexion and extension of the knee joint
studied. A high vertical ridge divides the posterior surface into a large
lateral and a smaller medial area. Each of these is still further subdivided
by faint ridges on the cartilage which coats the surface. A faint line upon
the medial area of the patella descends in a vertical direction so as to mark
off a narrow strip close to the medial border of the bone. This strip is



KNEE JOINT 413

called the medial perpendicular facet. Two horizontal lines extend laterally
from the lateral border of the medial perpendicular facet to the lateral
border of the bone, and subdivide the remainder of the medial area and
the whole of the lateral area into three facets each. In a well-marked
patella, therefore, the posterior cartilage-covered surface shows seven facets,
viz., a proximal pair, a middle pair, a distal pair, and a medial perpen-
dicular facet (Goodsir).

The facetted appearance of the posterior surface of the patella indicates
that, in the movements of that bone upon the trochlear surface of the femur,
the entire articular surface is never in contact with the femur at the same time.
In flexion and extension of the knee, the patella moves distally and proxi-
mally in a curved path, the concavity of which looks upwards, backwards,
and laterally. The different facets come into contact and break contact
with the femur in regular succession. Let us suppose the knee joint to be
acutely flexed : in that condition of the limb the medial perpendicular facet
of the patella rests upon the crescentic facet of the medial condyle of the
femur, while the lateral of the two proximal patellar facets is in contact with
the lateral lip of the trochlear surface of the femur. No part of the patella
touches the medial lip of the trochlear surface. As the leg is moved from
the fully flexed to the fully extended position, the two proximal facets, then
the two middle facets, and, lastly, the two distal facets, come successively
into contact with the trochlear surface of the femur (Goodsir). In Fig. 182,
183, 187 the position of the patella in the fully extended knee is exhibited.

Now examine the condylar surfaces of the femur (Fig. 178). The posterior
two-thirds of the medial condyle will be seen to be of equal extent with,
and parallel to, the lateral condyle. The anterior third of the medial
condyle, however, turns obliquely laterally to join the trochlear surface.
The lateral condylar surface has no corresponding part. The obliquely
directed part of the medial condyle gives rise to the " screw - home"
movement, which is so characteristic of the knee joint when fully
extended. At the commencement of flexion and at the completion of
extension there is a screw movement, or a movement of rotation of the
tibia and femur on each other. As the leg is moved forwards from the
condition of acute flexion, the condyles of the femur roll and glide over the
surfaces of the menisci and the proximal end of the tibia until the surface
of the lateral condyle, and the corresponding part of the medial condyle,
are exhausted. This movement of the femoral condyles has been compared
to that of " a wheel partially restrained by a drag" (Goodsir). Any
additional movement must necessarily take place in connection with the
anterior oblique third of the medial condyle, and the result is a rotation or
screw-like motion of the femur medially. The medial condyle travels back-
wards round the intercondyloid eminence of the tibia, and the anterior part of
the intercondylar fossa comes into contact with the anterior cruciate ligament
and the medial tubercle of the intercondyloid eminence (Bruce Young).
The joint is now "screwed home" or locked. In the initial stage of
flexion the reverse movement must be accomplished. The unlocking of
the joint can be brought about only by a rotation medially of the tibia,
or a rotation laterally of the femur.

When fully extended, the joint is locked, and the posterior part of the
capsule, the collateral ligaments, and the anterior cruciate ligaments are
tense. The limb is converted into a rigid column, and the upright posture
is thereby maintained with the smallest possible degree of muscular
exertion.

The muscles which operate upon the bones of the leg so as to produce
flexion and extension of the limb at the knee joint are : (i) extensors, the
four parts of the quadriceps extensor ; (2) flexors^ the biceps femoris,



4 i4 THE INFERIOR EXTREMITY

popliteus, sartorius, gracilis, semitendinosus, and semimembranosus. Of
these, only one is inserted on the lateral side of the limb, viz. , the biceps.
The other five are inserted into the tibia on the medial side of the leg.

Medial rotation is produced by the popliteus, gracilis, sartorius, semi-
tendinosus, and semimembranosus. Lateral rotation by the biceps femoris.

Dissection. In order to obtain a proper view of the attach-
ments of the cruciate ligaments the following dissection must
be made : The femur must be sawn across about two inches
proximal to its distal articular surface. When that has been
done divide the distal part of the bone by a vertical, antero-
posterior saw-cut, which should end distally in the intercondylar
fossa between the condyles and between the proximal attach-
ments of the two cruciate ligaments. After this procedure the
cruciate ligaments can be studied singly, or together, and their
relation to the collateral ligaments of the joint can be examined.
It will be seen that the fibular collateral ligament and the anterior
cruciate ligament constitute a pair of ligaments which are fixed
to opposite sides of the lateral condyle. The tibial collateral
and the posterior cruciate ligaments belong to the medial condyle
of the femur, and are attached to its medial and lateral surfaces,
respectively. When that relationship has been noted, the tibial
collateral ligament may be divided to free the medial condyle,
and give greater space for the study of the cruciate ligaments.

Ligamenta Cruciata Genu (O.T. Crucial Ligaments). The
cruciate ligaments are well named, because they cross each
other, like the limbs of the letter X, in the interval between
the two condyles of the femur. This cruciate arrangement
is seen whether they are viewed from the side, by the removal
of the distal part of one condyle, or from the front or the
back of the joint. The anterior cruciate ligament is attached
to the tibia in front of the intercondylar eminence and to
the medial surface of the lateral condyle of the femur, whilst
the posterior is fixed to the tibia behind the intercondylar
eminence and to the lateral surface of the medial condyle of
the femur.

The anterior cruciate ligament springs from the intermediate
rough area on the proximal surface of the tibia, in the
anterior intercondylar fossa of the tibia, immediately anterior
to the medial tubercle which surmounts the intercondylar
eminence. Thence it proceeds upwards, backwards, and
laterally, to gain attachment to the posterior part of the
medial surface of the lateral condyle of the femur (Fig. 186).

The posterior cruciate ligament springs from the posterior
intercondylar fossa of the tibia posterior to the inter-
condyloid eminence, and posterior also to the attachments
of the posterior horns of both menisci. It passes upwards,



PLATE XXXVI



Patella



Tibia




Fibula




FIG. 182. Radiograph of the Knee ot an adult.
(Major T. Rankine. )



PLATE XXXVII



Femur



Patella




Fibula



FIG. 183. Radiograph of the Knee of an adult in extension.

(Prof. Alexis Thomson.)
Note the relations of the femur to the patella and to the tibia.



PLATE XXXVIII



Medial con-
dyle of femur



Lateral con-
dyle of femur



Tibia



Fibula



FIG. 184. Radiograph of a Semiflexed Knee.

(Mr. Hugh M. Martin.)
Note the relations of the femur to the patella and the tibia.



PLATE XXXIX



Femur



Patella




Fibula



Medial con-
dyleof femui



Tibia




FIG. 185. Radiograph of a fully flexed Knee.

(Mr. Hugh M. Martin.)
Note the relations of the femur to the patella and the tibia.



KNEE JOINT



forwards, and somewhat medially, and, crossing the anterior
cruciate ligament obliquely, is attached to the anterior
portion of the lateral surface of the medial condyle. It
receives one, or sometimes two, strong slips from the posterior
horn of the lateral meniscus (Fig. 186).

The anterior cruciate ligament is tight in extension, and



Tendon of insertion

of adductor magnus

muscle (cut)



Popliteal surface of femur



'Anterior cruciate ligament

Tendon of popliteus
muscle (cut)



Lateral meniscus




Groove on tibia for ten-
don of popliteus muscle
Capsule of proximal
tibio-fibular articulation
Fibular collateral
ligament

Posterior tibio-fibular
ligament

Head of fibula



Accessory attach-
ment of lateral
meniscus

Medial meniscus



Posterior cruciate
ligament



Tendon of
semi me rn-
branosus muscle (cut)

Tibial collateral

ligament

Popliteal surface

of tibia



FIG. 186. The Knee Joint opened from behind by the removal of the
Posterior part of the Capsule.

the posterior cruciate ligament is tight inflexion of the knee
joint.

Menisci (O.T. Semilunar Cartilages). The menisci are two
crescentic plates of nbro-cartilage which are placed on the
condylar surfaces of the tibia. They deepen the surfaces upon
which the condyles of the femur roll, and, being movable, they
fill up the gaps which would otherwise arise during the move-



4 i6 THE INFERIOR EXTREMITY

ments of the joint. Each meniscus presents two fibrous
extremities, or horns, which are attached to the rough inter-
mediate surface on the proximal end of the tibia. They are
thick towards the circumference of the joint, but thin away to a
fine free concave edge in the opposite direction. Both surfaces
are smooth and covered with the synovial layer. They do not
cover the entire extent of the condylar surfaces of the tibia.
The central parts of the latter, as well as the sloping surfaces
of the tubercles of the intercondyloid eminence, are free.
When the cartilages are raised from the surface upon which
they rest, distinct impressions, similar in shape and extent,
are seen on the subjacent encrusting cartilage of the tibia.

Dissection. Carefully define the attachments of the fibrous
horns of the menisci.

The lateral meniscus is usually somewhat thicker around
its circumference than the medial meniscus. It forms the
segment of a smaller circle, and its horns being fixed to the
tibia close together, a very nearly complete circle is formed.
The anterior fibrous horn is attached, immediately in front of
the intercondylar eminence, to the lateral side of and partly
under cover of the attachment of the anterior cruciate ligament.
The posterior horn is fixed to the summit of the inter-
condylar eminence in the interval between the two tubercles.
It gives a strong slip also to the posterior cruciate ligament.
The fibular collateral ligament is separated from the lateral
meniscus by the lateral part of the articular capsule and also
by the tendon of the popliteus which lies inside the fibrous
stratum of the lateral part of the capsule. The tendon of
the popliteus grooves the posterior part of the lateral border
of the lateral meniscus, but behind and in front of the groove
the peripheral margin of the lateral meniscus is blended with
the internal surface of the fibrous stratum of the articular
capsule.

The medial meniscus is semicircular in outline, and forms
the segment of a much larger circle than the lateral meniscus.
Its anterior fibrous horn is fixed to the anterior part of the
anterior intercondylar fossa of the tibia, in front of the attach-
ment of the anterior cruciate ligament ; its posterior horn is
attached in the posterior intercondylar fossa of the tibia,
behind the intercondylar eminence and in front of the
attachment of the posterior cruciate ligament. The greater



PLATE XL



Patella




Femur



Distal
epiphyseal
line of fern



femur



Medial con-
dyle of femur



Proximal

epiphysis of

fibula

Proximal



Proximal
epiphysis of
tibia



Proximal
epiphyseal
line of tibia



Fibula



Tibij



FIG. 187. Radiograph of the Knee of a child.



PLATE XL I



Distal

epiphysis of
femur



Patella





Femur



Distal




Tibia,






Fibuls



FIG. 1 88. Radiograph of the partly flexed Knee of a child.
Note the relations of the femur to the patella and the tibia.



PLATE XLII

Femur Epiphyseal line of distal end of femur



Fibula




Proximal
epiphysis of
tibia

Proximal
epiphyseal
line of tibia



Tibia



FIG. 189. Radiograph of the Knee of a child.

Ossification of the patella and the proximal end of the fibula has not
yet commenced.



PLATE XLIII

Femur



Distal
epiphysea'
line of fern




Tibia Proximal epiphyseal line of lib

FIG. 190. Radiograph of the Knee of a child.
Ossification of the patella has commenced.



KNEE JOINT



4'7



part of the peripheral border of the medial meniscus is
closely connected with the deep surface of the fibrous stratum
of the articular capsule. Through their connections with
the fibrous stratum of the articular capsule both menisci gain
attachment to the distal end of the femur and the proximal
end of the tibia.

Ligamentum Transversum Germ. The transverse ligament
is a fibrous band which stretches across from the anterior part




FIG. 191. Parts attached to the proximal end of the Right Tibia.



T. Transverse ligament.

2. Anterior cornu of medial meniscus.

3. Anterior cruciate ligament.

4. Medial tubercle of intercondyloid emin-

ence of tibia.

5. Medial meniscus.

6. Posterior cornu of medial meniscus.

7. Posterior cruciate ligament.



Fasciculus from lateral meniscus to
posterior cruciate ligament.

Posterior cornu of lateral meniscus.

Lateral tubercle of intercondyloid
eminence of tibia.

Lateral meniscus.

Anterior cornu of lateral meniscus.



of one meniscus to the corresponding part of the other, con-
stituting a bond of union between them.

Dissection. The condyles of the femur should now be
detached by dividing the fibular collateral ligament, the cruciate
ligaments, and the remains of the articular capsule close to their
femoral attachments.

Attachment of Parts to trie Proximal Surface of the Tibia.

The ligamentous structures and the menisci are attached to
the intermediate area on the proximal surface of the tibia in
the following order from before backwards : ( i ) The anterior
horn of the medial meniscus, on the medial side of the
extreme anterior part of the area. (2) and (3) The anterior
cruciate ligament and the anterior horn of the lateral
VOL. i 27



418



THE INFERIOR EXTREMITY



meniscus : these are placed side by side, but the attachment
of the ligament, which lies to the medial side, overlaps that
of the lateral meniscus. (4) The posterior horn of the lateral
meniscus, on the summit of the intercondylar eminence
between its two tubercles. (5) The posterior horn of the
medial meniscus, immediately behind the intercondylar
eminence. (6) The posterior cruciate ligament, at the
posterior part of the area.



ARTICULATIO TALOCRURALIS (ANKLE JOINT).

The ankle joint is a diarthrodial articulation of the
ginglymus or hinge variety. The articulation takes place



Anterior talo-fibular
ligament



Fibular facet



Anterior ligament of lateral malleolus

(O.T. Anterior inferior tibio-fibular -ligament)



Deltoid ligament



Lateral malleolus -



Calcaneo-fibular
ligament

Posterior ligament o:
lateral malleolus

Posterior talo-fibular
ligament




Medial malleolus



Distal ligament of



syno
the lateral malleolus of fat



Synovial pad



FIG. 192. Articular Surfaces of Tibia and Fibula which articulate
with the Talus.



between the bones of the leg and the talus, and the weight of
the body is transferred through it to the foot. It is a joint
of great strength ; its stability being ensured not only by the
powerful ligaments which surround it, but also by the close
interlocking of the articulating surfaces.

The bones which enter into the formation of the ankle
joint are the distal ends of the tibia and fibula and the
proximal, medial, and lateral surfaces of the talus. The distal
ends of the leg bones are very firmly united together by inter-
osseous and other ligaments which give the joint a certain
amount of elasticity or spring. They form a deep hollow



ANKLE JOINT



419



resembling a mortice and the upper part of the talus is
received into the cavity.

Dissection. Remove the remains of the laciniate and trans-
verse ligaments and cut through and displace the tendons which
are in relation with the joint, but do not remove them. Then



Distal end of shaft of tibia



Groove on medial

lalleolus for tendon of

tibialis posterior

Trochlcar surface
of talus

Deltoid ligament \



Fibrous sheath for tendon of



Online LibraryD. J. (Daniel John) CunninghamCunningham's manual of practical anatomy (Volume 1) → online text (page 41 of 44)