Lower Limb Nerve Injuries and Gait Flashcards
If gravity causes flexion at a particular joint, then the extensor muscles that cross that joint function in an
Isometric fashion to prevent gravitational movement
When analyzing muscle action in the lower limb, it is essential to be cognizant of whether the limb is
Weight bearing or not
When weight bearing, the distal end of the limb is
Fixed
When not weight bearing, the distal end of the limb is
Moveable
During quiet standing, without sway, at the HIP, gravity tends to cause
Extension
Gravity tends to cause extension at the hip during quiet standing. This is resisted by the
Illiofemoral ligament and ischiofemoral ligament
During quiet standing, at the KNEE, gravity tends to cause
Extension
The extension of the knee caused by gravity during quiet standing is resisted by the
Posterior joint capsule of the knee
During quiet standing, at the ANKLE, gravity tends to cause
Dorsiflexion
The dorsiflexion of the ankle caused by gravity during quiet standing is resisted by
Plantar flexors
In an average adult male in anatomical position, the center of gravity is located immediately anterior to
S2
Vector connecting the center of gravity to the center of the earth
-i.e. perpendicular to the ground
Line of gravity
In order for an object to maintain stability, the line of gravity must pass within the
Supporting base
Stability is increased by widening the
Supporting base
In order to maintain stability, in a jointed structure, the line of gravity must pass through the
Axis of rotation of each joint
At the hip, posterior displacement of the center of gravity increases
Extension torque
This extension torque is resisted by
Hip flexors
At the hip, anterior displacement of the center of gravity decreases
Extension torque
Further anterior displacement of the center of gravity converts gravity to
Flexion torque
Flexion torque at the hip is resisted by
Hip extensors (i.e. hamstrings)
At the knee, posterior displacement of the center of gravity decreases
Extension torque
Further posterior displacement of the center of gravity converts gravity at the knee to
Flexion torque at the knee
-resisted by knee extensors
At the knee, anterior displacement of the center of gravity increases
Extension torque
-resisted by hamstrings
At the ankle, what is the effect of posterior displacement of the center of gravity?
Dorsiflexion torque is decreased
At the ankle, what is the effect of anterior displacement of the center of gravity?
Increased dorsiflexion torque
What are the 5 stages of the gait cycle?
- ) Heel strike
- ) Foot flat
- ) Midstance
- ) Heel off
- ) Toe off
What are the effects of anterior sway at the
- ) Hip
- ) Knee
- ) Ankle
- ) Flexion
- ) Extension
- ) Dorsiflexion
What are the effects of posterior sway at the
- ) Hip
- ) Knee
- ) Ankle
- ) Extension
- ) Flexion
- ) Platarflexion
At heel strike, what is the tendency at the
- ) Hip
- ) Knee
- ) Ankle
- ) Flexion
- ) Flexion
- ) Plantarflexion
At heel strike, the following are controlled by?
- ) Flexion at hip
- ) Flexion at knee
- ) Plantarflexion at ankle
- ) Gluteus maximus and hamstrings
- ) Quadriceps femoris
- ) Dorsiflexors
At midstance, what is the tendency at the
- ) Hip
- ) Knee
- ) Ankle
- ) Adduction
- ) Flexion
- ) Dorsiflexion
At midstance, the following are controlled by?
- ) adduction at hip
- ) Flexion at knee
- ) Dorsiflexion at ankle
- ) Gluteus medius and minimus
- ) Quadriceps femoris
- ) Gastrocnemius and soleus
At heel off and toe off, there is a tendency for the hip to be
Extended
The extension of the hip at heel off and toe off is resisted by the
Hip flexors
The propulsive force during gait is provided by the
Plantarflexors
This plantarflexion pushes the ground
Downward and backward
The efficiency of gait is improved by positioning the limb so that at heel off and toe off, more of the vector pushes
The ground bckwards, and less pushing downwards
The gluteus maximus is innervated by the
Inferior gluteal nerve (L5, S1, and S2)
What happens if the gluteus maximus is paralyzed and no compensatory mechanism is activated?
Patient will fall over at heel strike
To prevent this, the patient compensated by
Displacing mass of torso posteriorly at heel strike (gluteus maximus gait or lurch gait)
The gluteus medius-minimus complex is innervated by the
Superior gluteal nerve (L4, L5, and L6)
Active at the time of midstance to prevent gravitational adduction of the pelvis at the hip
Gluteus medius-minimus complex
If the gluteus medius-minimus complex is paralyzed, the patient will compensate by
Displacing mass of upper torso laterally to the supported side at the time of midstance
The gait resulting from gluteus medius-minimus paralysis is called
Tredelenburg gait
The quadriceps femoris are innervated by the
Femoral nerve (L2, L3, and L4)
Active throughout the stance phase to control gravitational flexion of the thigh at the knee
Quadriceps
If the quadriceps were paralyzed, the patients knee would buckle in the stance phase. to compensate for this, the patient goes through the stance phase with
The knee completely extended and locked (“quadriceps gait”)
This converts gravity from a knee flexor into a
Knee extensor
The anterior tibial muscles are innervated by the
Deep fibular nerve (L4, L5, and S1)
Active during the swing phase to dorsiflex the foot and thus avoid having the toes hit the ground
Anterior tibial muscles
Become very active at heel strike in order to gradually lower the foot to the foot flat position
Anterior tibial muscles
If the anterior tibialis muscles are weak, we will see
“Foot slap” immediately after heel strike
If the anterior tibialis muscles are paralyzed, the patient will enter the stance phase with a
Toe strike instead of heel strike
To avoid having the toes hit the ground during the swing phase, the patient will
Increase flexion at the hip and knee, bringing foot higher above ground (“steppage gait)
The fibularis (peroneus) longus and brevis are everters of the ankle and are innervated by the
Superficial fibular nerve (L5, S1, and S2)
If these muscles are paralyzed in addition to the anterior tibialis muscles, then during the swing phase the foot will be
Inverted in addition to plantarflexed
To avoid entering the stance phase in the inverted position, the patient will
Swing the lower limb laterally during swing, thus bringing plantar surface of the foot in contact with the ground at end of swing
