Clinical Considerations of lower limbs
-Upon examination of a patient, it is found that the patient is unable to extend
his/her knee against resistance. Further examination leads you to tap the patellar
ligament with a percussion hammer to elicit the knee jerk reaction. However,
there is no response.
Q-What nerve could be damaged? What muscles are innervated by this nerve?
A-Damage to the femoral nerve can cause impaired flexion of the hip (iliacus) and
impaired extension of the leg due to paralysis of the quadriceps femoris. The
patellar reflex is blocked by damage to the femoral nerve or a component of the
patellar reflex arc. When normal the reflex arc should cause extension of the leg
via the quadriceps muscle contraction.
Q-An individual is stabbed in the popliteal fossa. Upon examination there is no
damage to the major vessels in the area (popliteal artery and vein). However, the
patient appears to have damage to the tibial nerve also found in the popliteal fossa.
What possible functions are diminished or gone?
A-The tibial nerve innervates the posterior compartment. The flexor compartment
of the leg and intrinsic muscles of the foot would be affected. Thus, inversion and
plantar flexion would be lost due to loss of innervation of the tibilialis anterior.
The toes would be unable to be flexed due to loss of the flexor digitorum longus
and flexor hallucis longus. The individual would have difficulty getting the heel off
the ground without plantarflexing.
- Venous return largely depends on muscular activity of the triceps surae which
pump blood into the deep veins. When valves of the perforating limb become
dilated they are unable to prevent reverse flow through veins and blood flows from
deep to superficial veins. As a result, perforating and superficial veins become
torturous and dilated and become varicose veins.
Q-What are the main superficial veins in the leg and what deep veins do they drain
into? Where are they usually located in the leg?
A-The great saphenous vein ascends anterior to the medial malleolus of the tibia
accompanied by the saphenous nerve and drains into the femoral vein by passing
through the saphenous opening in the deep fascia of the thigh. The small (short)
saphenous vein begins posterior to the lateral malleolus passing between the two
heads of the gastrocnemius to enter the popliteal fascia to end in the popliteal
vein.
Q-What do people refer to when they speak of groin injuries?
A-It refers to strain, stretching, and tearing away of the attachments of the
anterior and medial muscles of the thigh. The attachments of these muscles are
located in the inguinal region (junction of the abdomen and thigh)
Q-You need to perform a left cardiac angiography and want to find the femoral
artery when it is in a superficial location. Where could you palpate for the
pulsations of the femoral artery? Where is the femoral vein in reference to the
femoral artery?
A-The superficial part of the femoral artery before it dives deep is in the femoral
triangle. The femoral vein is found lateral to the artery. (i.e. NAVEL) The
femoral artery and vein are found in the femoral sheath (Fig 5-32 Moore)
Q-An individual walks with a waddling gait known as a gluteal gait. When the
person lifts his/her right foot the pelvis falls on the left side. What could be
happening?
A-The gluteal gait is usually caused by paralysis of the gluteus medius muscle which
is innervated by the superior gluteal nerve. This muscle usually functions to
stabilize the pelvis when the opposite foot is off the ground.
Q-When injecting drugs into the thigh. What nerves can be damaged and thus
what regions should be avoided for intramuscular injections.
A-Injections are performed in the anterolateral portion of the thigh. This avoids
injury to the sciatic nerve which divide into the common fibular nerve and the tibial
nerve. Also avoids injury to gluteal nerves. To avoid injury to the femoral nerve
the injection should be done posterior to the anterior superior iliac spine. Thus
what muscle(s) would you probably inject into to avoid both regions? (tensor
fasciae lata and vastus lateralis)
Q-Because the heads of the biceps femoris have a different nerve supply a wound
in the thigh may sever a nerve paralyzing one head but not the other. What nerve
supplies each head?
A-Short head-Common fibular nerve Long Head-Tibial nerve
Q-An individual comes in with laceration at the side of the knee and presents with
loss of eversion of the foot and dorsiflexion of the foot. This results in foot drop
where the foot is raised so toes do not hit the ground. There is also some loss of
sensation in the anterolateral aspect of the leg and the dorsum of the foot.
A-Laceration of the common fibular nerve results in loss of dorsiflexion of the
foot since the anterior compartment of the leg is innervated by the deep peroneal
nerve a branch of the common peroneal nerve. The lateral compartment containing
the fibularis longus and brevis is innervated by the superficial peroneal nerve, the
other branch of the common fibular nerve. See Case 5-2 Moore
Causes for damage to the common fibular nerve can be deduced by its relations.
Its relations to the biceps femoris tendon, the fibula, and the fibular collateral
ligaments is important. Damage to any of these structures could cause damage to
the adjacent common peroneal nerve.
Q-What are the functions of the tibial and fibular collateral ligaments, how are
they caused, and what are consequences of injuries to these structures?
A-The two ligaments prevent disruption of the sides of the knee joint and prevent
rotation of the tibia laterally and the femor medially. The fibular collateral
ligament is very strong and not commonly torn. Severe blows to the MEDIAL side
of the knee would force the knee towards the lateral side and tear the fibular
collateral ligament.
The tibial collateral ligament is attached to the medial meniscus and damage to this
ligament can lead to damage to the medial meniscus as well. Damage is frequently
caused by blows to the LATERAL side of the knee which would force the knee
medially and tear the tibial collateral ligament.
Q-Where are the ACL and PCL found. What purpose do they serve in the knee
joint? How are they usually damaged? How can you test for damage to either of
these ligaments of the knee joint?
A-The ACL is the weaker of two ligaments and arises from the anterior part of the
intercondylar area of the tibia to attach to the medial side of the lateral condyle
of the femur. The anterior cruciate ligament prevents anterior dislocation of the
tibia. The ACL injury is often associated with injuries to the medial meniscus and
tibial collateral ligament. The ACL is damaged if the knee is severely
hyperextended, tibia is driven anteriorly, or femur is driven posteriorly. To test
the stability of the ACL one should test its function. Try to move the tibia
anteriorly. If it moves a tear of the ACL is indicated.
The PCL is the stronger of the two ligaments and arises from the posterior part
of the intercondylar area and attaches to the lateral side of the medial condyle of
the femur. The posterior cruciate ligament prevents posterior displacement of the
tibia and hyperextension of the knee. The PCL is torn when the tibia is driven
posteriorly on the femur when the knee is flexed (i.e. when knee hits dashboard in
an accident) or if the knee is hyperflexed. To test the function of the posterior
cruciate ligament test for its ability to prevent posterior displacement of the tibia.
(See fig 5-108)
In summary:
Femoral nerve damage-impaired flexion of the hip and impaired extension of the
leg due to paralysis of the quadriceps femoris
Obturator nerve damage-impaired adduction and lateral swinging of the limb during
walking because of unopposed abductors.
Common fibular nerve damage-foot drop and paralysis of dorsiflexor (anterior
compartment) and evertor muscles (lateral compartment) of the foot.
Tibial nerve damage-Loss in plantar flexion, inversion of the foot, and flexion of
the toes. (Posterior compartment of the leg)
Deep peroneal nerve-loss of dorsiflexion
Superficial peroneal nerve-loss of eversion
Also look at the clinical problems in Moore.