Chapter 8: The Biomechanics of The Human Lower Extremity

What is the most typical cause of ankle sprain?

forced inversion of the ankle during landing while the foot is plantar flexed

Anterior pelvic tilt positions the acetabulum in a more favorable position for hip ______.

hyperextension

Runner's knee may be associated with symptoms of the anterior knee or the lateral knee (rarely, both). Which structure is associated with possible cause of the symptoms presenting at the lateral knee?

iliotibial band

What can excessive tightness of the iliotibial band cause?

maltracking of the patella

Which muscle does NOT affect both the hip and the knee?

vastus intermedius

Patellofemoral pain syndrome is classically likely associated with what? Additional evidence suggests an imbalance between the hamstring and quadriceps groups to be adding to the problem.

weakness of vastus medialis relative to vastus lateralis

When do two-joint muscles function more effectively at one joint?

when the position of the other joint stretches the muscle slightly

In what gender do ACL injuries occur more frequently?

women

When do ACL injuries occur more frequently situation wise?

non-contact

High body mass is not associated with what?

osteoarthritis

What must the femur do during extension?

slide backwards on the tibia

What is the most common of all knee injuries?

tear of the medial meniscus

The iliopsoas complex is a major flexor of what?

the hip

Where do fractures in the ankle region occur most often?

the lateral malleolus

Where is the weakest point of the femur?

the neck

What are symptoms of plantar fasciatis?

-pain in the arch -pain in the heel

During walking, what actions is combined to cause supination?

-plantar flexion; inversion; and adduction

What is true about pelvic girdle movements?

-position the acetabulum favorably for femoral movement -occurs in all 3 planes -occurs around the lumbosacral joint

Give examples of two-joint muscles (bi-articulate).

-rectus femoris -sartorius The pectineus is NOT.

What are the hamstring muscles? What is not?

-semitendinosus -semimembranosus -biceps femoris The gluteus maximus is NOT a hamstring muscle.

What attaches to the calcaneus? What does not?

-soleus -plantaris -gastrocnemius The sartorius does NOT.

What are examples of nonaxial joints?

-tarsometatarsal joint -intermetatarsal joint

What are the parts of the pelvic girdle?

-the ilium -the ischium -the pubis

What conditions must be met for rotation of the tibia relative to the femur?

-the knee is not bearing weight -the knee is in flexion

What is true about the hip joint?

-triaxial -more stable than shoulder -several bursae present

biceps femoris

1. Biceps femoris: A two-joint muscle that is proximally attached to the lateral ischial tuberosity and distally attached to the posterior lateral condyle of the tibia and the head of the fibula. Its function is extension.

medial collateral ligament

1. Medial Collateral Ligament: The medial collateral ligament merges with the joint capsule and medial meniscus to connect the medial epicondyle to the femur to the medial tibia. This attachment is below the pes anserinus in which the ligament is positioned to resist medially directed shear and rotation forces on the knee.

What is necessary when the knee undergoes a significant amount of flexion?

The femur must slide forward on the tibia in order to prevent its rolling off of the tibial plateau

What bone does NOT bear weight? What bones do?

The fibula does NOT bear weight. -tibia -talus -femur

The anterior and posterior cruciate ligaments limit which type of knee motion?

-knee hyperextension -forward and backward sliding of the femur on the tibia during knee flexion and extension

The medial and lateral collateral ligaments primariliy limit which type of knee motion?

-lateral and medial knee motion

What is true about the menisci of the knee joint?

-made of cartilage -larger surface area to distribute load -absorb shock

Which knee ligament is most likely to be damaged from a lateral blow?

-medial collateral

What are causes of hip adduction?

-adductor brevis -adductor longus -gracilis -adductor magnus

What are causes of hip abduction?

-gluteus medius -gluteus minimus -TFL

What is the anatomical name for the big toe?

-hallux

What is the purpose of the patella?

-increase the angle between the tendon and tibia -increase the mechanical advantage of the quadriceps -to protect the anterior aspect of the knee

List the four major ligaments of the knee, describe the location of each and explain the role each one plays in providing stability to the joint.

1. Medial Collateral Ligament: The medial collateral ligament merges with the joint capsule and medial meniscus to connect the medial epicondyle to the femur to the medial tibia. This attachment is below the pes anserinus in which the ligament is positioned to resist medially directed shear and rotation forces on the knee. 2. Lateral Collateral Ligament: The lateral collateral ligament runs posteriorly to the ridge of the lateral epicondyle of the femur to the head of the fibula. This ligament contributes to lateral stability of the knee. 3. Anterior Cruciate Ligament: The anterior cruciate ligament stretches from the anterior aspect of the intercondyloid fossa of the tibia that is medial and posterior to the anterior tibial spine in a superior, posterior direction to the posterior medial surface of the lateral condyle of the femur. This ligament restricts the anterior sliding of the femur on the tibial plateaus during knee flexion and extension, and also limits knee hyperextension. 4. Posterior Cruciate Ligament: The posterior cruciate ligament runs from the posterior aspect of the tibial intercondyloid fossa in a superior, anterior direction to the lateral anterior medial condyle of the femur. This ligament restricts the posterior sliding of the femur on the tibial plateaus during knee flexion and extension, and also limits knee hyperextension.

patellofemoral pain syndrome

1. Patellofemoral Pain syndrome is painful joint motion that involves anterior knee pain during and after physical activity, specfically when the activities contain repeated flexion at the knee. Maltracking of the patella in this condition injury can be due to anatomical malalignments, imbalance between the VMO and VL in strength or activation timing, decreased quadriceps and hamstring strength, increased hip external rotator strength, and overactivity. Large Q angle could also contribute to malalignment.Treatment is strengthening of the VMO which leads to reduced patellofemoral joint loads.

List and describe at three common overuse injuries of the lower extremity, including symptoms, probably causes and treatment options.

1. Patellofemoral Pain syndrome is painful joint motion that involves anterior knee pain during and after physical activity, specfically when the activities contain repeated flexion at the knee. Maltracking of the patella in this condition injury can be due to anatomical malalignments, imbalance between the VMO and VL in strength or activation timing, decreased quadriceps and hamstring strength, increased hip external rotator strength, and overactivity. Large Q angle could also contribute to malalignment.Treatment is strengthening of the VMO which leads to reduced patellofemoral joint loads. 2. Shin splints are an overuse injury that may involve microdamage to the muscle attachments on the tibia and/ or inflammation of the periosteum. Symptoms are pain along the anterolateral or posteromedial aspect of the lower leg. Causes are running or dancing on a hard surface or running uphill. Treatment is a change in workout condition and rest which alleviate this injuries. 3. Achilles tendinitis is the inflammation and occasional microrupturing of tissues in the Achilles tendon with accompanied swelling. A hypothesized cause is repeated tension develop that results in fatigue and decreased flexibility in the muscle, increasing tensile load on the tendon even during relaxation of the muscle. Another potential cause is repeated loading leads to failure or rupturing of the threads. Treatment ranges from rest to surgery depending on the severity of the injury.

rectus femoris

1. Rectus femoris: A muscle that is proximally attached to the anterior inferior iliac spine and distally attached to the patella. Its function is extension.

List and describe the role(s) of the tensor fascia latae.

1. The tensor fascia latae assists the major hip flexors, psoas major and iliacus muscles, with flexion. 2. The tensor fascia latae assists the gluteus medius and gluteus minimus with abduction. 3. The tensor fascia latae assists the gluteal minimus with medial rotation.

lateral collateral ligament

2. Lateral Collateral Ligament: The lateral collateral ligament runs posteriorly to the ridge of the lateral epicondyle of the femur to the head of the fibula. This ligament contributes to lateral stability of the knee.

shin splints

2. Shin splints are an overuse injury that may involve microdamage to the muscle attachments on the tibia and/ or inflammation of the periosteum. Symptoms are pain along the anterolateral or posteromedial aspect of the lower leg. Causes are running or dancing on a hard surface or running uphill. Treatment is a change in workout condition and rest which alleviate this injuries.

vastus lateralis

2. Vastus lateralis: A muscle that is proximally attached to the greater trochanter and lateral linea aspera and distally attached to the patella. Its function is extension.

semimembranosus

2. semimembranosus: A two-joint muscle that is proximally attached to the lateral ischial tuberosity and distally attached to the proximal, medial tibia. Its function is extension.

achilles tendinitis

3. Achilles tendinitis is the inflammation and occasional microrupturing of tissues in the Achilles tendon with accompanied swelling. A hypothesized cause is repeated tension develop that results in fatigue and decreased flexibility in the muscle, increasing tensile load on the tendon even during relaxation of the muscle. Another potential cause is repeated loading leads to failure or rupturing of the threads. Treatment ranges from rest to surgery depending on the severity of the injury.

anterior cruciate ligament

3. Anterior Cruciate Ligament: The anterior cruciate ligament stretches from the anterior aspect of the intercondyloid fossa of the tibia that is medial and posterior to the anterior tibial spine in a superior, posterior direction to the posterior medial surface of the lateral condyle of the femur. This ligament restricts the anterior sliding of the femur on the tibial plateaus during knee flexion and extension, and also limits knee hyperextension.

vastus medialis

3. Vastus medialis: A muscle that is proximally attached to the medial linea aspera and distally attached to the patella. Its function is extension.

semitendinosus

3. semitendinosus: A two-joint muscle that is proximally attached to the medial ischial tuberosity and distally attached to the proximal, medial tibia. Its function is extension.

posterior cruciate ligament

4. Posterior Cruciate Ligament: The posterior cruciate ligament runs from the posterior aspect of the tibial intercondyloid fossa in a superior, anterior direction to the lateral anterior medial condyle of the femur. This ligament restricts the posterior sliding of the femur on the tibial plateaus during knee flexion and extension, and also limits knee hyperextension.

vastus intermedius

4. Vastus intermedius: A muscle that is proximally attached to the anterior femur and distally attached to the patella. Its function is extension.

What is varus?

A condition of inward or medial deviation in alignment at the distal end of a segment; (compared to neutral).

Describe iliotibial band friction syndrome, including affected area, symptoms and probable causes.

Iliotibial band friction syndrome is when there is friction of the posterior edge of the iliotibial band (ITB) against the lateral condyle of the femur around the time of foot strike. The friction is produced by tension that is developed by the tensor fascia lata when it assists with the stabilization of the pelvis when the knee is in flexion during weight bearing. Signs of the syndrome is inflammation of the distal portion of the ITB and inflammation of the knee joint capsule under the ITB. Symptoms include pain and tenderness over the lateral aspect of the knee. Iliotibial band friction syndrome is an overuse condition that affects runners and cyclists. Training errors such as excessive running in the same direction on the track and and improper seat height predisposes these athletes to ITB syndrome. Anatomical malalignments such as excessive femoral anteversion and excessive pronation also predispose an individual to this condition.

What is the plantar fascia?

The strong layer of fibrous tissue which covers the plantar muscles of the foot

List and describe the three hamstring muscles & four quadriceps muscles, including origin, insertion and function.

The three hamstring muscles are the biceps femoris, semimembranosus, and semitendinosus. 1. Biceps femoris: A two-joint muscle that is proximally attached to the lateral ischial tuberosity and distally attached to the posterior lateral condyle of the tibia and the head of the fibula. Its function is extension. 2. semimembranosus: A two-joint muscle that is proximally attached to the lateral ischial tuberosity and distally attached to the proximal, medial tibia. Its function is extension. 3. semitendinosus: A two-joint muscle that is proximally attached to the medial ischial tuberosity and distally attached to the proximal, medial tibia. Its function is extension. The four quadriceps muscles are the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. 1. Rectus femoris: A muscle that is proximally attached to the anterior inferior iliac spine and distally attached to the patella. Its function is extension. 2. Vastus lateralis: A muscle that is proximally attached to the greater trochanter and lateral linea aspera and distally attached to the patella. Its function is extension. 3. Vastus medialis: A muscle that is proximally attached to the medial linea aspera and distally attached to the patella. Its function is extension. 4. Vastus intermedius: A muscle that is proximally attached to the anterior femur and distally attached to the patella. Its function is extension.

What can osteoarthritis cause?

a spontaneous meniscal tear

Lateral pelvic tilt positions the acetabulum in a more favorable position for hip ______.

abduction

When the legs are not free to move (i.e. they are supporting your body weight), what action will result from contraction of the hip flexors?

anterior pelvic tilt

Knee extensors cross the joint ___ to the ___ axis.

anterior; mediolateral

The hamstring group is what?

bi-articulate

What characterizes a "bow-legged" condition?

femoral valgus and tibial varus

The hip joint is the articulation between the ________ and the _______.

femur;acetabulum

The pelvic girdle is comprised of three bones: ilium, ___________, and pubis.

ischium

The lower extremity is well structured for its functions of weight bearing and __________________.

locomotion

What muscle serves to "unlock" the knee from full extension?

popliteus

What muscle inserts on the patella?

quadriceps