LOWER EXTREMITY KINES Flashcards
Function of collateral ligaments
prevent frontal plane movement of the knee (abduction and adduction)
Medial Collateral Ligament
restraint against VALGUS stress and thus prevents abduction of the knee
Lateral Collateral Ligament
restraint against VARUS stress and thus prevents adduction of the knee
Anterior Cruciate Ligament (ACL)
APEX: runs anterior to posterior and externally
- fibers are taut in extension; primary restraint against hyperextension of the knee
Function of ACL
Limits ANTERIOR translation of tibia on the femur or POSTERIOR translation of femur on the tibia
- also limits axial rotation of the knee, especially external rotation
Posterior Cruciate Ligament (PCL)
PAIN- runs Posterior to Anterior and Internally
- All fibers taut in flexion
Function of PCL
Limits posterior translation of the tibia on the femur or anterior translation of the femur on the tibia
- prevents the femoral condyles from sliding off the anterior edge of the tibia
Primary extensors of the knee
QUADS
- isometric activation helps to stabilize and protect the knee
- eccentric activation helps to dampen loading and acts as a brake or decelerator of knee flexion during walking, squatting, sitting..ect
- concentric activation accelerates the tibia or femur into extension during walking or standing
Eccentric vs Concentric
Stand to sit=eccentric
STAND TO SIT IS EASIER
sit to stand=concentric
SIT TO STAND REQUIRES MORE CONCENTRATION?
The Patella on the quadriceps
- Patella displaces the quads tendon away from the joint axis, thus increasing the moment arm of the quads
- provides substantial augmentation of extensor torque
Knee flexor-rotator muscles
- with exception of the gastrocnemius, all muscles that cross posterior to the knee joint have the ability to flex and axially rotate the knee
includes HAMSTRINGS, SARTORIUS, GRACIALIS, AND POPLITEUS
Primary flexors of the knee
THE HAMSTRINGS
- medial hamstrings (semitendinosus) internally rotate the knee
- lateral hamstring (biceps femoris) externally rotates the knee
The hamstrings and gait
- active eccentrically to decelerate the advancing tibia at the late swing phase
- active concentrically to accelerate knee flexion in order to shorten the lower limb during early swing phase
Other knee flexor-rotator muscles
sartorius, gracilis (flexors and internal rotators of the knee)
- added effect of providing significant dynamic stability to medial knee
Popliteus
- flexes and internally rotates the knee
- “key to the knee” provides the necessary internal rotation torque to mechanically unlock the knee
To maximally stretch the quads you would
extend hip and flex knee
the quads will
flex the hip joint and extend the knee joint!
All of the following are capable of flexing the hip EXCEPT
Semitendinosus (a hamstring muscle) WE KNOW HAMSTRING EXTEND THE HIP JOINT
SARTORIUS, RECTUS FEMORIS, AND ILLIACUS CAN FLEX THE HIP
Dropping of the pelvis on the right side during single limb support over the left leg most likely indicates weakness of
THE LEFT GLUTEUS MEDIUS
The sartorius muscle can perform all of the following except
KNEE EXTENSION
- sartorius can flex hip, flex knee and internally rotate knee
Which of the following muscles can produce movement at both the hip and knee
RECTUS FEMORIS
To maximally stretch HAMSTRING you would
flex hip, extend knee, anterior pelvic tilt
to maximally stretch hip FLEXORS the pelvis should be
Posteriorly tilted
Psoas major
hip flexion
semitendinous
knee internal rotation
biceps femoris
knee external rotation
obturator externus
hip external rotation
pectineus
hip adduction
the knee joints
tibial-femoral joint (medial and lateral articulations)
patello-femoral joint
knee moves in what plane
sagittal and horizontal
Function of menisci
reduce compressive stress SHOCK ABSORPTION and reduce stress on cartilage
- supports 1/2 load across the knee
How is knee joint stabilized?
articular surfaces, quads, retinacular fibers
locking of the knee
Locking of the knee in terminal extension requires 10 degrees of external rotation
Before flexion can occur
the knee must be unlocked by internally rotating the knee
- driven by the popliteus muscle
internal/external rotation of the knee can only occur
AFTER the knee has been unlocked (out of terminal extension)
Ligaments of the hip
- illiofemoral
-ischiofemoral - pubofemoral
limits extremes of all movements of the hip, all three are partially taut in full extension of the hip
The hip joint
Articulation between the large spherical head of the femur and deep socket of acetabulum
TRUE BALL AND SOCKET - made for stability (weight-bearing, propelling the body forward)
Natural bowing to the femur
HELPS WITH LOADING
Lumbo-pelvic rhythm
ipsi-directional
contra-directional
- related to anterior and posterior pelvic tilt
Movements of the hip
3 degrees of freedom
- sagittal plane- flexion and extension
- frontal plane- abduction and adduction
- horizional plane- internal and external rotation
PRIMARY HIP FLEXORS
Iliacus and psoas major (illiopasos)
other hip flexors- sartorius, tensor fascia lata, rectus femoris, pectineus and adductor longus
Anterior pelvic tilt force couple
- between hip flexors and back extensors
(a lot of back pain comes from tight hip flexors)
Primary hip adductors
Pectineus, adductor longus/brevus, gracilis, and adductor magnus
Primary internal rotators of the hip
THERE ARE NONE
Secondary internal rotators of the hip
gluteus medius/minimus, TFL, adductor longus/brevis, pectineus and medial hamstring
Primary hip extensors
GLUTEUS MAXIMUS
- hamstrings and posterior part of adductor magus also capable hip extensors
Posterior pelvic tilt force couple
hip extensors and abdominal muscles
- important in controlling forward trunk lean
STRETCHING HIP FLEXORS
Extend hip and POSTERIORLY TILT PELVIS
STRETCHING HIP EXTENSORS
Flex the hip and ANTERIORLY TILT PELVIS
Primary hip abductors
gluteus medius and minimus
main function- control of frontal plane pelvic on femoral stability during gait
Weakness in hip abductors results in
DROPPING OF THE PELVIS ON THE CONTRALATERAL SIDE DURING SINGLE-LIMB SUPPORT OVER THE WEAK HIP
- referred to as “trendelenburg gait” or “gluteus medius limp”
Primary hip external rotators
Piriformis, obturator internus/externus, superior/inferior gamellus, quadratus femoris, gluteus maximus and sartorius
- serve additional role of providing substantial stability to the posterior hip joint
Movements of the knee joint
- flexion and extension
- internal/external rotation
Ankle joints
- talocrural joint (includes tibia, fibula and talus)
- subtalar joint (articulation between talus and cancaneus)
- transverse tarsal joint
talocrural joint
- total contact area is significantly less than the hip and knee joint
- main source of stability is provided by lateral and collateral ligaments
Movement of talocrural joint
plantar/dorsiflexion
- becomes increasingly more stable as dorsiflexion increases to prepare for push-off during gait
Movement of the subtalar joint
pronation: eversion and abduction
supination: inversion and adduction
transverse tarsal joint
articulation between talus-navicular and calcaneus-cuboid
- allows the foot to adapt to a variety of surfaces
combined actions of the joints
- allows the leg and talus to rotate in all 3 planes relative to a fixed calcaneus
- allow the foot to repeatedly transform form a flexible and shock absorbent structure to a more rigid level
Medial longitudinal arch
- provides the concave in-step at the medial side of the foot
- primary load bearing and shock absorbing structure in the foot
- height and general structure are maintained by joint structure, plantar fascia, ligaments and muscles
anterior compartment of the leg- “pretibial” dorsiflexors
tibialis anterior, extensor digitorum longus, extensor hallicus longus, peroneus tertius
dorsiflexors most active as the heel contacts the ground and the foot becomes flat on the foot where they are active
CONCENTRICALLY to control the rate of plantar flexion
As the lower limb is advancing during swing phase, dorsiflexors are active
ECCENTRICALLY to ensure that the foot clears the ground
lateral compartment
PERONEUS LONGUS/BREVIS
- primary action is eversion and pronation
- also assits in plantar flexion
posterior compartment
gastrocnemius, soleus and plantaris (superficial group)
tibialis posterior, flexor digitorum longus and flexor hallicus longus (deep group)
Plantar flex and deep group can invert and supinate
posterior compartment during gait
- active eccentrically to decelerate dorsiflexion during swing phase of gait
- active concentrically to accelerate plantar flexion during push off
Intrinsic muscles of the foot
overall funtion is to provide rigidity to the foot and stabilizing the medial longitudinal arch
- maximally active during late stance phase
3 basic approaches for describing gait
- using the time and distance qualities of the stride
- breaking up the gait cycle up into subdivisions according to the variation in reciprocal foot contact by the 2 feet
- identifying the functional significance of the phases within the gait cycle
Gait cycle is divided into 2 periods
stance phase
- the period during which the foot is on the ground
- begins when the heel contacts the ground and ends when the toes are lifted off the ground
- 60% of gait
swing phase
- time when the foot is in the air for limb advancement
- begins when the foot leaves the ground and ends when the heel contacts the ground
- 40% of gait
normal values for gait
- speed: 3mph
- step rate: 110 steps/min
- step length: 28 in
8 steps of gait
- initial contact
- loading response
- midstance
- terminal stance
- pre-swing
- initial swing
- mid-swing
- terminal swing
Phase 1: initial contact (heel strike)
trunk: erector spinae are active eccentrically/ isometrically to control forward momentum of trunk after heel contact
hip: hamstrings and gluteus max are active eccentrically to control/restrain amount of hip flexion
knee: stabilized by co-contraction of quad and hams
ankle: pre-tibial muscles are active concentrically to position the foot for initial contact
Phase 2: loading response (heel strike to foot flat)
trunk: erector spinae are active eccentrically/ isometrically to control forward momentum of trunk after heel contact
pelvis: hip abductors active to decelerate contralateral pelvic drop (in prep for single limb support)
hip: hamstrings and gluteus max continue to be active eccentrically to control/restrain amount of hip flexion
knee: sharp eccentric activation of quads to control knee flexion and provide shock absorption
ankle: pre-tibial muscles highly active eccentrically to decelerate planar flexion
Phase 3: mid-stance (foot flat to mid stance)
pelvis: hip abductors active to decelerate contralateral pelvic drop
hip: hip extensors begin to relax as passive hip extension is acheived through momentum of body weight
knee: quads active early until passive knee extension occurs and quads become silent
ankle: soleus and gastocnemius becomes active eccentrically to control the rate of forward tibial progression
Phase 4: Terminal stance (mid-stance to heel off)
pelvis: hip abductors continue to be strongly active to stabilize the pelvis
hip: hip flexors are active eccentrically to control/resist hyperextension of hip
knee: little to no activity in quads or hamstrings
ankle: soleus and gastroscnemius active concentrically contributing to heel rise (plantar flexion)
Phase 5: Pre-swing (heel off to toe off)
- corresponds with initial contact of oppositre limb
trunk: erector spinar are active eccentrically/ isometrically to control trunk flexion after contralateral heel contact
hip: hip flexors lightly active as hip flexion is assisted by momentum of the body moving forward
knee: knee passively flexes; quads are quiet unless active eccentrically to restrain rapid knee flexion
ankle: plantar flexors active concentrically but gradually reducing
Phase 6: Initial swing (toe off to early acceleration)
hip: hip flexors are active concentrically but continue to be assisted by passive momentum; increased activity of adductor longus to keep limb in mid-line
knee: passive knee flexion secondary to hip flexion assisted by concentric activity in hams
ankle: pre-tibial dorsiflexors are strongly active concentrically to clear the toes from the floor
Phase 7: Mid-swing
hip: hip flexors are active concentrically but continues to proceed passively primarily by momentum
knee: passive knee extension created by tibial forward momentum; hamstrings begin to activate eccentrically to decelerate knee extension
ankle: pre-tibial dorsiflexors continue to be strongly active concentrically to clear the toes from the floor
Phase 8: Terminal swing (mid swing deceleration)
hip: hip extensors become active eccentrically to control further hip flexion and prepare for initial contact
knee: knee extension is decelerated by eccentric activity of hamstrings and quads become active in prep for initial contact
ankle: pre-tibial dorsiflexors continue to be active concentrically
Dragging the foot during gait (not being able to clear the foot during swing phase) indicates dysfunction in
DORSIFLEXORS
During terminal swing when the knee is extending, the hams would be active
ECCENTRICALLY
During most of the swing phase, the hip flexors are
ASSISTED BY FORWARD MOMENTUM
In a patient with chronic inversion ankle sprains, it would make sense to strengthen which of the following muscles:
Peroneus longus (fibularis longus)
Anterior compartment does
DORSI FLEXION
Posterior compartment does
PLANTAR FLEXION
Lateral compartment does
EVERSION
Dysfunction of the tibilais posterior muscle would result in weakness of
PLANTAR FLEXION AND INVERSION
Soleus
Plantarflexion
Peroneus longus
eversion
tibialis anterior
dorsiflexion
tibialis posterior
inversion
