Download Unit 37: Joints of the Lower Limb

Unit 37: Joints of the Lower Limb
Dissection Instructions:
Dissection of the joints of the lower limb can be done without regard for the other soft tissues or
it can be done in a manner that reviews all the structures of the limb. The second approach will be
described here. The joints should be dissected in one limb only. Review of muscles includes origin,
insertion, action, nerve and blood supply.
Review the origin and insertion of the psoas major and iliacus muscles. Note the attachments of
the sartorius and its relationships with the femoral triangle, the subsartorial (adductor) canal and pes
anserinus. Remove the sartorius. Study the quadriceps muscle. Now review the femoral nerve with
regard to its origin, course and distribution. Remember that the nerve to the pectineus comes from the
femoral nerve and passes under the femoral vessels. Three inches above the upper border of the patella,
make a transverse incision through the entire quadriceps muscle. Remove the heads of the quadriceps
above the incision. Review the gracilis, pectineus and adductor longus muscles, then remove them. Note
the origin and insertion of the adductor brevis and its relationship to the obturator nerve, then remove it.
Review the obturator externus and adductor magnus muscles from the anterior view.
Remove the visceral organs from the pelvic cavity. Review the sacral plexus, especially its origin
and its branches in the gluteal region.
Review the gluteus maximus, then remove it. The superior gluteal nerve innervates the gluteus
medius, gluteus minimus and tensor fascia lata. Review them and then remove them, including the
iliotibial tract down to the lateral condyle of the tibia. Cut the tendon of the piriformis muscle next to the
greater trochanter of the femur, then retract it through the greater sciatic foramen into the pelvic cavity.
Cut the tendon of the obturator internus in the same manner and retract it through the lesser sciatic
foramen. Remove the quadratus femoris. Pull the anterior primary rami of L4, 5, S1, 2, 3, 4 out of the
intervertebral foramina or anterior sacral foramina and pull the sacral plexus through the greater sciatic
foramen into the gluteal region. Review the hamstring muscles and then remove them, but before cutting
the insertion of the semimembranosus, pull it medially and posteriorly and note its relationship to the
oblique popliteal ligament (Plate 493). Remove the iliopsoas muscle. Review the obturator externus
and adductor magnus from the posterior view. Review the deep femoral, lateral femoral circumflex and
medial femoral circumflex vessels, especially noting the perforating arteries. Remove the obturator
externus and adductor magnus muscles.
Clean the loose areolar connective tissue from the surface of the capsule of the hip joint. Identify
the iliofemoral, ischiofemoral and pubofemoral ligaments (Plates 486, 474; 5.29A & B). Note the
direction of their collagen bundles when the joint is extended and when it is flexed. Note that extension
of the hip joint causes tightening of the capsule so that the head of the femur is pushed harder into the
acetabulum. If the ligaments have been identified, cut through the capsule entirely around its
circumference about mid-way between hip bone and femoral shaft. Identify the ligament of the head of
the femur (round ligament) as the head is retracted from the acetabulum (Plates 486, 5.30). It is
attached to the notch of the acetabulum and the pit in the head of the femur. Identify the acetabular
labrum and note that the capsule of the joint attaches to the bony lip of the acetabulum except where it
attaches to the transverse ligament. The transverse acetabular ligament completes the circle formed by
the labrum (Plates 486; 5.30, 5.32, 5.33, 5.35).
Unit 37 - 1
Review the gastrocnemius, soleus and plantaris muscles, then remove them. Study the patellar
ligament and medial and lateral patellar retinacula (Plates 488, 489; 5.41, 5.42). These structures
account for the strength of the capsule of the knee joint anteriorly. On the lateral surface, the iliotibial
tract strengthens the capsule. The lateral/fibular collateral ligament is an accessory ligament attached
superiorly to the lateral epicondyle and inferiorly to the head of the fibula where it splits the insertion of
the biceps femoris muscle (Plates 488 - 491, 493; 5.42, 5.44 - 5.47). It helps maintain the integrity of the
knee joint, but is not related to the joint capsule. The medial aspect of the knee joint is strengthened by
the medial/tibial collateral ligament (Plates 488 - 491, 493; 5.41, 5.44 - 5.47). It is said to consist of
superficial and deep components, but both are fused to the capsule. The superficial part extends
considerably below the joint. Posteriorly, the oblique popliteal and arcuate ligaments strengthen the
capsule.
Elevate the lower end of the quadriceps muscle and look for muscle fibers attaching to the
upward extension of the synovial membrane lining the cavity of the knee joint. These muscle fibers
belong to the quadriceps muscle and contract when it does, but are named the articularis genu muscle.
Cut through the synovial membrane and retinacular ligaments so that the lower quadriceps, patella and
patellar ligament can be pulled downward to expose the cavity of the knee joint from the front. Note the
fat pads covered with synovial membrane around the patella. Identify the menisci. Insert a blade of your
forceps under the menisci until you reach the capsule. The portion of the capsule between the menisci
and the tibia is called the coronary ligament because it sits like a crown on the tibia. The periphery of
the menisci are fused to the capsule of the joint. The medial/tibial collateral ligament is a part of the
capsule and therefore the medial meniscus is more firmly fixed than the lateral meniscus, since the
lateral/fibular collateral ligament is not fused to the capsule and cannot help hold the meniscus
(Plates 491; 5.44). Note that the menisci are joined anteriorly by the transverse ligament. Identify the
anterior cruciate ligament and the femoral attachment of the posterior cruciate ligament (Plates 490,
491; 5.44 -5.46, 5.47C).. The cruciate ligaments are named for their attachment to the tibia and because
they cross each other. Where they cross, the anterior cruciate is lateral to the posterior cruciate ligament.
The synovial membrane posterior to the femoral condyles does not pass posterior to the cruciate
ligaments, but passes anterior to them, excluding them from the synovial cavity.
Review the superior and inferior extensor, superior and inferior peroneal/fibular, and flexor
retinacula in the ankle region (Plates 498, 499, 501,, 503, 511, 512; 5.53, 5.56B,5.58B, 5.59). Identify
each of the tendons which cross the ankle joint. As each is identified, review the entire muscle. Then cut
the tendon proximal to the insertion and remove the superior portion of the muscle. When all have been
reviewed, study the articulations between the tibia and fibula. They are the proximal, intermediate and
inferior tibiofibular articulations. The proximal tibiofibular joint is a plane synovial joint with a
capsule which is thickened anteriorly and posteriorly (Plates 507, 509; 5.69 - 5.71, 5.72A). The
intermediate tibiofibular joint is a syndesmosis consisting of the interosseous membrane (Plates
483; 5.80, 5.81). Note the openings through which the anterior tibial and perforating branch of the
peroneal arteries pass between tibia and fibula. The inferior tibiofibular joint is also a fibrous joint It
is strengthened by the anterior and posterior tibiofibular ligaments and the transverse tibiofibular
ligament. The latter ligament increases the articular surface of the ankle joint.
The ankle joint is the joint between the tibia, fibula and talus. It is a hinge type joint, therefore
has collateral ligaments with weak capsules anteriorly and posteriorly where most of the movement is.
The medial collateral ligament is called the deltoid ligament (Plates 509; 5.70, 5.72C). This ligament
attaches to the borders of the medial malleolus of the tibia above and below to the navicular, talus and
calcaneus. The deltoid ligament has several components because of its various attachments. Named
portions include the anterior tibiotalar, tibionavicular, tibiocalcaneal and posterior tibiotalar
ligaments. In addition, the deepest fibers of the tibiocalcaneal ligament attach to the talus. The lateral
Unit 37 - 2
ligaments consist of three different bands, the anterior talofibular, calcaneofibular and posterior
talofibular ligaments (Plate 509; 5.70, 5.72A). They are connected by capsule between bands. The
posterior tibiofibular, transverse tibiofibular and posterior talofibular ligaments are continuous at their
fibular attachments. The anterior talofibular ligament may be more deeply placed than the other
ligaments. It is frequently torn in ankle injuries and must be repaired to insure a stable joint.
Review the muscles, nerves and vessels on the plantar surface of the foot as they are removed to
expose the ligaments there. The tarsal bones have several important ligaments.
In order to look at the joint of the foot (Table 5.16-p. 442) be sure to look at an articulated foot
skeleton and locate the tarsal sinus between the talus and calcaneus. This should not be confused by the
term, tarsal tunnel, which is the space under the flexor retinaculum. Within this sinus is a strong
interosseous ligament which separates the subtalar joint from the talocalceonavicular joint. On the
dorsum of the foot at the junction of calcaneus, cuboid and navicular bones, locate the capsular
ligament. Remove this first layer of capsule and locate the stronger bifurcate ligament deep to it (Plates
509; 5.72A, 5.80). It consists of dorsal calcaneocuboid and dorsal calcaneonavicular portions. On
the plantar surface of the foot, clean the ligaments extending forward from the calcaneus. The largest and
most prominent is the long plantar ligament which extends all the way to the metatarsal bones (Plate
510; 5.82). On its way, it crosses superficial to the peroneus longus tendon, forming a tunnel for it.
Clean the tendon to its insertion on the lateral side of the articulation between the medial cuneiform and
first metatarsal bones. The short plantar ligament is more properly called the plantar calcaneocuboid
ligament (Plates 510; 5.82). It is deep to the long plantar ligament but can be seen on its medial side. It
appears to be continuous over to the navicular bone. The plantar calcaneonavicular ligament is also
called the spring ligament (Plate 510; 5.82, 5.83). It is closely related to the insertion of the tibialis
posterior. It lies directly under the head of the talus, supporting it. The portion of the calcaneus to which
it is attached is called the sustentaculum tali.
The metatarsophalangeal joints are similar to those in the hand and are connected by the deep
transverse metatarsal ligament (Plates 510; 5.82, 5.83). This differs from that in the hand because the
great toe is held to the second toe by this ligament while the thumb is not. When the great toe separates
from the second toe, the condition known as flat foot develops. The interphalangeal joints are also
similar to those of the fingers.
Unit 37 - 3
Be sure to identify all of the following:
iliofemoral ligament
ischiofemoral ligament
pubofemoral ligament
acetabulum
ligament of head of femur/round ligament
acetabular labrum
transverse acetabular ligament
patellar ligament
medial patellar retinaculum
lateral patellar retinaculum
iliotibial tract
lateral collateral ligament/fibular
medial collateral ligament/tibial
oblique popliteal ligament
arcuate ligament
medial meniscus
lateral meniscus
coronary ligament
transverse ligament
anterior cruciate ligament
posterior cruciate ligament
anterior tibiofibular ligament
posterior tibiofibular ligament
transverse tibiofibular ligament
deltoid ligament/medial collateral ligament
anterior tibiotalar ligament
tibionavicular ligament
tibiocalcaneal ligament
posterior tibiotalar ligament
anterior talofibular ligament
calcaneofibular ligament
posterior talofibular ligament
tarsal tunnel
flexor reticulum
capsular ligament
bifurcate ligament
dorsal calcaneocuboid ligament
dorsal calcaneonavicular ligament
long plantar ligament
short plantar ligament/
plantar calcaneocuboid ligament
sustentaculum tali
deep transverse metatarsal ligament
Unit 37 - 4