Biomechanics of the Pelvis, Hip, and Knee
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Questions and Answers

What is the primary function of the pelvic girdle?

  • To facilitate breathing during physical activity
  • To protect the reproductive organs
  • To aid in the process of childbirth
  • To support the abdomen and link the vertebral column to lower limbs (correct)

Which muscle is NOT part of the pelvic floor?

  • Pubococcygeus
  • Iliococcygeus
  • Coccygeus
  • Obturator internus (correct)

How do hormones during pregnancy affect pelvic floor muscles?

  • They decrease the size of muscle fibers
  • They cause muscles to contract involuntarily
  • They increase muscle strength
  • They can increase ligament laxity, affecting muscle performance (correct)

What occurs to the pelvis during the late swing phase of the gait cycle?

<p>It tilts posteriorly. (C)</p> Signup and view all the answers

What notable change occurs to a woman's center of mass during pregnancy?

<p>It shifts forward due to the enlarging uterus (B)</p> Signup and view all the answers

During which phase of the gait cycle does the knee reach near full extension until heel off?

<p>Pre swing phase (C)</p> Signup and view all the answers

Which stage of labor is described as the longest?

<p>Dilation stage (A)</p> Signup and view all the answers

What is the primary role of the meniscus in the knee?

<p>To reduce localized pressure on articular surfaces. (C)</p> Signup and view all the answers

At what degree of hip flexion does the gait cycle begin?

<p>30 degrees (C)</p> Signup and view all the answers

Which of the following factors contribute to the stability of the knee joint?

<p>Ligaments and gravity (C)</p> Signup and view all the answers

How does the loading response phase assist in gait?

<p>By providing propulsion and deceleration. (B)</p> Signup and view all the answers

What is the typical flexion degree of the knee at heel contact?

<p>5 degrees (C)</p> Signup and view all the answers

What occurs to the hip position during the 80% mark of the gait cycle?

<p>It flexes. (B)</p> Signup and view all the answers

What ligament primarily limits hyperextension of the hip joint?

<p>Iliofemoral Ligament (B)</p> Signup and view all the answers

Which artery is NOT a contributor to the blood supply of the hip joint?

<p>Radial Artery (D)</p> Signup and view all the answers

Which of the following myotomes is responsible for hip adduction?

<p>L1, L2, L3, L4 (C)</p> Signup and view all the answers

What joints do the medial and lateral menisci primarily relate to?

<p>Knee Joint (A)</p> Signup and view all the answers

What role does the Pubofemoral Ligament play in the hip joint?

<p>Limits hyperextension and abduction (B)</p> Signup and view all the answers

Which of the following arteries supplies the muscles of the medial compartment of the thigh?

<p>Obturator Artery (A)</p> Signup and view all the answers

Which movement is associated with the myotome L5?

<p>Hip Abduction (B)</p> Signup and view all the answers

What function does the Ischiofemoral Ligament primarily limit?

<p>Hip Adduction and Flexion (D)</p> Signup and view all the answers

What is the primary reason for the Trendelenburg sign?

<p>Damage to the superior gluteal nerve (A)</p> Signup and view all the answers

Which motion describes counternutation at the sacroiliac joint?

<p>Posterior iliac-on-sacral rotation (B)</p> Signup and view all the answers

What is the main role of the gluteus medius during gait?

<p>To stabilize the pelvis (B)</p> Signup and view all the answers

Which ligamentous support is critical for the function of the sacroiliac joint?

<p>Iliolumbar ligament (D)</p> Signup and view all the answers

What muscles are primarily involved in posterior pelvic tilt?

<p>Hip extensors and lumbar flexors (C)</p> Signup and view all the answers

Which structure is primarily responsible for smoothness and coordination of lower leg movements?

<p>Cerebellum (B)</p> Signup and view all the answers

Which nerve innervates the Semitendinosus muscle?

<p>Tibial Division of the Sciatic nerve (D)</p> Signup and view all the answers

What movement is primarily controlled by the hip flexors during gait?

<p>Flexing hip at toe off (C)</p> Signup and view all the answers

Which nerve innervates the gluteus maximus?

<p>Inferior gluteal nerve (A)</p> Signup and view all the answers

Which muscle group is primarily responsible for hip extension during the early stance phase of gait?

<p>Hip extensors (A)</p> Signup and view all the answers

During gait, which muscle is responsible for a hip hike on the contralateral side?

<p>Gluteus medius (B)</p> Signup and view all the answers

Which nerve innervates the Adductor Magnus muscle's hamstring part?

<p>Tibial Division of the Sciatic nerve (A)</p> Signup and view all the answers

What role does hip internal rotation (IR) play during gait?

<p>Facilitates contralateral forward motion (B)</p> Signup and view all the answers

Which muscle's innervation is provided by the Obturator nerve?

<p>Gracilis (B)</p> Signup and view all the answers

Which muscle is NOT innervated by the Tibial nerve?

<p>Fibularis Brevis (A)</p> Signup and view all the answers

Which of the following muscles is responsible for eccentric control of hip extension after midstance?

<p>Hip flexors (A)</p> Signup and view all the answers

What is the primary function of the medial tibial plateau's 'C' shape?

<p>Accommodate the larger medial meniscus (C)</p> Signup and view all the answers

Which movement corresponds to the anterior roll and posterior glide of the femur on the acetabulum?

<p>External rotation (A)</p> Signup and view all the answers

In a closed chain movement, what occurs during hip extension?

<p>Posterior spin of the femur (C)</p> Signup and view all the answers

When the pelvis posteriorly tilts during forward bending and rising, which muscles primarily assist this movement?

<p>Glutes and hamstrings (B)</p> Signup and view all the answers

What is the effect of the shape of the lateral tibial plateau on its corresponding meniscus?

<p>It accommodates a larger lateral meniscus (B)</p> Signup and view all the answers

Which of the following describes closed chain abduction at the hip?

<p>Lateral roll and glide of the acetabulum (B)</p> Signup and view all the answers

What biomechanical movement occurs during hip flexion in an open chain?

<p>Posterior spin (A)</p> Signup and view all the answers

What is the consequence of increased concavity of the tibial condyle?

<p>Improved proprioception (B)</p> Signup and view all the answers

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Flashcards

Pelvic Floor Muscles

A group of muscles that form a sling-like structure supporting organs in the pelvic cavity. These muscles control bowel and bladder function, sexual function, and support the pelvic organs.

Iliococcygeus

A key pelvic floor muscle that connects the ilium (hip bone) to the coccyx (tailbone). It helps support the pelvic organs and control urination.

Pregnancy & Cardiac Output

During pregnancy, the heart pumps more blood per minute to meet the increased metabolic demands of both the mother and the developing fetus.

Pregnancy & Gait Changes

A woman's gait changes during pregnancy due to the shifting center of mass and hormonal changes causing ligament laxity.

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Pelvic Floor during Labor

The pelvic floor muscles play a crucial role in labor by acting as a supportive sling for the baby's head and stretching to allow the baby to pass through the birth canal.

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Tibial Condyle Concavity

The curvature of the tibial condyle, which increases joint stability by providing a better fit with the femoral condyles.

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Proprioception

The ability of the body to sense its position and movement in space.

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Tibial Plateau Shape

The top surface of the tibia has a distinctive shape. The medial plateau is 'C' shaped and larger to accommodate the medial meniscus. The lateral plateau is smaller to accommodate the 'O' shaped lateral meniscus.

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Hip Joint Movement Planes

The hip joint moves in all 3 planes of motion: sagittal, frontal, and transverse.

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Hip Joint Open Chain

When the femur moves on the fixed acetabulum. This occurs during activities like kicking or swinging.

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Hip Joint Closed Chain

When the femur is fixed and the acetabulum moves on it. This occurs during movements like standing or squatting.

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Lumbopelvic Rhythm

A coordinated movement pattern between the pelvis and the spine during bending and extending.

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Pelvic Tilt During Stance

The pelvis tilts forward during the first half of the stance phase (initial contact to mid-stance) and tilts backward during the second half (mid-stance to toe-off).

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Lumbopelvic Rhythm - Posterior Tilt

During bending, the pelvis tilts backward and rotates over the head of the femur before the spine extends.

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Hip Motion During Gait

The hip flexes at the beginning of gait, extends gradually, and then flexes again during the swing phase.

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Knee Motion During Stance

The knee flexes slightly at initial contact and continues to flex during the loading phase. It then extends during mid-stance and remains nearly fully extended until heel-off.

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Knee Stability Drivers

Knee stability is maintained by muscles, ligaments, the force of gravity, and the joint reaction forces.

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Meniscus Function

The meniscus acts as a shock absorber, reducing pressure on the knee joint and improving the fit between the bones.

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Tibial Plateau

The upper surface of the shinbone (tibia) which forms the joint surface for the knee.

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Propulsion & Deceleration in Gait

Loading and unloading phases of gait help propel the body forward and decelerate it during transitions.

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Osteo/Arthrokinematics of the Knee

The combined movement of bones and joints, including how the femur rolls and glides on the tibia during knee motion.

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Hip IR/ER Movement

Internal and external rotation of the hip joint is primarily driven by the forward momentum of the upper body during movement.

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Hip Joint Blood Supply

The hip joint receives blood from the Medial and Lateral Femoral Circumflex Arteries (from the profunda femoral artery) and the Obturator Artery.

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Thigh Blood Supply

The thigh receives blood from various arteries, including the Femoral Artery (anterior compartment), Profunda Femoris Artery (adductors), Obturator Artery (medial compartment muscles), Superior Gluteal Artery (glutes, TFL), and Inferior Gluteal Artery (pelvic diaphragm, glute max, etc.).

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Iliofemoral Ligament

This ligament limits hyperextension of the hip joint.

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Pubofemoral Ligament

This ligament limits both hyperextension and abduction of the hip joint.

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Ischiofemoral Ligament

This ligament helps limit hyperextension, adduction, and flexion of the hip joint.

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Pes Anserinus

This is the area where the tendons of the Sartorius, Gracilis, and Semitendinosus muscles attach to the tibia just below the knee.

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Tibial Tuberosity

This is the prominent bump on the front of the tibia, serving as the attachment point for the patellar ligament.

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Sartorius Nerve

The nerve that supplies the Sartorius muscle, responsible for flexing, abducting, and laterally rotating the thigh.

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Quadriceps Femoris Nerve

The nerve that supplies the four muscles of the quadriceps group: rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. These muscles are crucial for extending the knee and flexing the hip.

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Hamstring Nerve

The nerve that supplies the hamstring muscles: semitendinosus, semimembranosus, and biceps femoris (long head). These muscles are key for extending the hip and flexing the knee.

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Adductor Muscles Nerve

The nerve that supplies the adductor muscles of the thigh: adductor longus, adductor brevis, adductor magnus, and gracilis. These muscles are responsible for adducting the thigh (drawing it towards the midline).

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Tibialis Anterior Nerve

The nerve that supplies the tibialis anterior muscle, responsible for dorsiflexion (pointing toes upwards) and inversion (turning the sole of the foot inwards).

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Gastrocnemius Nerve

The nerve that supplies the gastrocnemius, soleus, and plantaris. These muscles are crucial for plantar flexion (pointing toes downwards) and contribute to ankle stability.

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Hip Extensors Role During Gait

The hip extensors, during the stance phase of walking, concentrically extend the hip for propulsion (pushing off) and then eccentrically control the hip extension at the end of the swing phase for deceleration.

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Hip Flexors Role During Gait

The hip flexors eccentrically control hip extension after midstance, then concentrically flex the hip during toe-off and swing. They're essential for bringing the leg forward.

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Trendelenburg Sign

A positive Trendelenburg sign is observed when the contralateral (opposite) pelvis drops during single-leg stance, indicating weakness of the gluteus medius and minimus muscles due to superior gluteal nerve damage.

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SI Joint Function

The sacroiliac (SI) joint transmits body weight from the spine to the lower extremities. It allows for small amounts of movement, particularly during pregnancy and postpartum.

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SI Joint Nutation

Nutation is an anterior sacral-on-iliac rotation, with a simultaneous posterior iliac-on-sacral rotation.

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Couple Forces: Anterior Tilt

An anterior pelvic tilt is achieved by contraction of the hip flexors and lumbar extensors.

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Couple Forces: Posterior Tilt

A posterior pelvic tilt is achieved by contraction of the hip extensors and lumbar flexors.

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Couple Forces: Hip Hike

A hip hike is achieved by the contralateral gluteus medius and ipsilateral quadratus lumborum (QL) muscles.

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DCML: Sensation

The Dorsal Column Medial Lemniscus (DCML) pathway carries sensation of fine touch, proprioception, and vibration from the ankle and foot to the brain.

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ALS: Sensation

The Anterior Lateral Spinal Tract (ALS) carries sensation of pain, temperature, and crude touch from the ankle and foot to the brain.

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Study Notes

Biomechanics of the Pelvis, Hip, and Knee

  • Pelvis: Begins tilting anteriorly during single-limb support, becoming slightly more anterior post-toe-off (second half of stance), and then tilting anterior again in early mid-swing before tilting posteriorly in late swing.
  • Hip: 30 degrees of hip flexion at the beginning of the gait cycle; hip extends gradually to ~10 degrees of hip extension at 80% of the gait cycle, with hip flexion occurring at the end of this cycle.
  • Knee: Flexed approximately 5 degrees at heel contact, flexing further to 10–15 degrees during loading phase; the knee extends to near full extension during the pre-swing phase before flexing again during the swing phase. In the stance phase the quads are activated eccentrically during loading phase.
  • Loading/Unloading in Gait: Simple explanation, not overly analytical—propulsion and deceleration.
  • Knee Stability: Factors influencing knee stability include muscles, ligaments, gravity, and joint reaction forces.
  • Meniscus Role: Reduces localized pressure/compressive stress on articular surfaces by increasing tibial condyle concavity, improving congruency and joint stability; effects of proprioception, friction, and weight distribution.
  • Tibial Plateau Shape: Medial is "C" shaped and larger to accommodate the larger medial meniscus, whereas the lateral tibial plateau is smaller and accommodating the "O" shaped lateral meniscus.

Biomechanics of the Hip

  • Hip Osteokinematics: Moves in all three planes, with differences in open-chain (convex femur on concave acetabulum) and closed-chain movements (fixed femur, concave acetabulum moves). Abduction/adduction, internal/external rotation, and flexion/extension all involve different aspects of rolling and gliding.
  • Pelvic Rhythm: Pelvis tilts posterior first, rotating over the head of the femur, before the spine extending subsequently. The glutes and hamstrings perform pelvic retrograde movement, pulling the pelvis backward.
  • Trendelenburg Sign: A contralateral pelvis drop, indicating damage to the superior gluteal nerve, weakening the gluteus medius and minimus muscles.

The Sacroiliac (SI) Joint

  • Function: Transmits body weight from the spine to the lower extremities, with limited available movement.
  • Nutation/Counternutation: Anterior sacral-on-iliac, posterior iliac-on-sacral rotation ("simultaneously").
  • Ligamentous Support: Iliofemoral, pubofemoral, and ischiofemoral ligaments; these limit hyperextension, abduction, and flexion respectively.

Pelvic Couple Forces

  • Couple forces at the pelvis during gait (pelvic anterior/posterior tilts) occur.

Innervation of Lower Extremity Musculature

  • Gluteal Region: Gluteus Maximus (inferior gluteal n.), Medius/Minimus (superior gluteal n.). Tensor Fasciae Latae (superior gluteal n.) and piriformis (anterior rami of S1–S2).
  • Anterior Thigh: Pectineus (femoral n.), Psoas Major/Minor (anterior rami of L1–L3), Iliacus (femoral n.). Sartorius, Rectus Femoris, Vastus Lateralis/Medialis/Intermedius (femoral n.).
  • Posterior Thigh: Semitendinosus/Semimembranosus/Biceps Femoris (tibial division of the sciatic n.).

Blood Supply to the Hip Joint and Thigh

  • Hip Joint: Medial/Lateral femoral circumflex arteries (from profunda femoral artery), obturator artery.
  • Thigh: Anterior/Posterior compartments (femoral, profunda femoris, perforating, obturator).

Important Landmarks at the Knee

  • Pes Anserinus: Tendons of sartorius, gracilis, semitendinosus.
  • Tibial Tuberosity: Patellar ligament attachment.
  • Tibial Plateau: Medial/Lateral menisci.
  • Intercondylar Eminence: Attachment sites for ACL and PCL.

Pelvic Floor

  • Pelvic floor muscles include iliococcygeus, pubococcygeus, puborectalis, and coccygeus.

Pelvic Girdle

  • Function: Supports abdomen, connects vertebral column to lower limbs, and transmits forces.

Pregnancy and Its Effects

  • Increased cardiac output, elevated metabolic demands.
  • Increased pulmonary blood flow.
  • Reproductive system alterations: Breast tissue, hormones, intra-abdominal pressure changes, and shifting centers of gravity/altered gait.

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IFS2 Exam 2 Study Guide PDF

Description

Explore the fundamental biomechanics involved in the pelvis, hip, and knee during the gait cycle. This quiz covers the tilting motions of the pelvis, the various stages of hip flexion and extension, and knee function. Test your understanding of how these elements work together for efficient movement.

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