• Ball and socket joint • Head of the femur articulates with the Chapter 8 concave acetabulum • More stable than the shoulder because Biomechanics of the Human – Bone structure Lower Extremity – # muscles and ligaments – Strength of muscles and ligaments
Hip Structure Pelvic Girdle
• Includes 2 ilia and the sacrum • Can be rotated to optimize positioning of the hip • Integrity of the hip is enhanced by the strong – Forward ligaments crossing the joint – Backward – Laterally
Hip Movements are Facilitated by Hip Flexors Pelvic Tilt Pelvic Tilt Femoral Movement • Iliacus • Psoas Major • Posterior • Flexion
• Anterior • Extension • Assisted by: – Pectineus • Lateral • Abduction – Rectus Femoris – Sartorius – Tensor Fascia Latae
1 Muscle Contributing to Hip Hip Abductors Extension
• Gluteus Maximus • Hamstrings – Biceps femoris – Semimembranosus – Semitendinosus
• Gluteus Medius • Assisted by: – Gluteus Minimus
Hip Adductors Tibiofemoral Joint
• Dual condyloid articulation between – Medial and lateral condyles of tibia and femur • Adductors – Magnus – Longus • Main hinge joint considered the knee – Brevis
Knee Structure Patellofemoral Joint
• Articulation between the patella and the femur • Bony structure of the tibiofemoral joint • Purpose – Improves mechanical advantage of the knee extensors by up to 50%
2 Menisci Major Knee Ligaments
• Cartilaginous discs located between the tibial • Collateral Ligaments and femoral condyles – Cross the medial and lateral aspects of the knee • Structures that distribute the load • Cruciate Ligaments • Help absorb shock – Cross each other in connecting the anterior and posterior aspects of the knee
Popliteus Knee Flexors
• Contributes to flexion • Hamstrings
• Laterally rotates the femur relative to the tibia • Assisted by: • “unlocks” fully extended – Gracilis knee – Sartorius – Popliteus – Gastrocnemius
Knee Extensors Tibiotalar Joint
• Hinge joint • Quadriceps – Convex surface of the – Rectus Femoris superior talus articulates – Vastus Lateralis with the concave surface of the distal tibia – Vastus Medialis – Vastus Intermedius • Considered Ankle Joint
3 Distal Tibiofibular Joint Ankle Dorsiflexors
• Syndesmosis • Tibialis Anterior – Dense fibrous tissue binds the distal tibia and • Extensor Digitorum fibula together Longus • Peroneus Tertius
• Assisted by: – Extensor Hallucis longus
Ankle Plantarflexors Subtalar Joint • Gastrocnemius • Soleus
• Assisted by: – Tibialis posterior – Plantaris – Peroneus longus – Flexor hallucis longus – Peroneus brevis • Anterior and posterior facets of the talus – Flexor digitorum articulate with sustencalculum on the the longus superior calcaneus
Tarsometatarsal and Plantar Arches Intermetatarsal Joints • Nonaxial joints that permit only gliding movements
• Enable the foot to function as a semirigid unit and to adapt flexibly to uneven surfaces during weight bearing activity • Medial and lateral longitudinal arches stretch from the calcaneus to the metatarsals and tarsals • Transverse arch is formed by the bases of the metatarsal bones
4 Plantar Fascia Foot Inversion Muscles
• Tibialis posterior • Tibialis anterior
• Thick bands of fascia covering the plantar aspect of the foot • Stores mechanical energy during weight bearing actiity • Releases energy to assist push-off of foot
Foot Eversion Muscles Foot Pronation
• Peroneus longus • Peroneus brevis
• Assisted by: – Peroneus tertius
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