Lower extremity anatomy

Hip region

The hip region comprises two (2) bony structures- the acetabulum and femur.

The normal angle of inclination is 115-125 degrees (angel of inclination between femur and acetabulum)- if angle is >125 degree then referred to as coxa valga; if angle is <115 degrees then referred to as coxa varus. Femoral neck angle is positioned anteriorly at a 10-15 degree angle; excessive anterior rotation >25 degrees is anteversion and excessive posterior rotation <10 degrees in retroversion.

The primary movements of the hip are that are:

• Hip flexion/ extension
• Hip external rotation/ internal rotation
• Hip abduction/adduction

The hip joint is a stable synovial joint due to the bony anatomy and strength of ligaments, capsule, and labrum.

• Capsule encloses the entire joint
• Labrum
  • Attached to the acetabulum and serves to deepen structure to allow for greater articulation
• Ligaments
  • Iliofemoral
    • Two (2) bands that originate at anterior iliac spine (ASIS), run medially to distal intertrochanteric line and lateral running to proximal aspect of intertrochanteric line
    • Both bands tighten with extension and external rotation; superior band tight with adduction; inferior band tightens with abduction
  • Pubofemoral
    • Band tightens with extension, external rotation, and abduction
  • Ischiofemoral
    • Band tightens with medial rotation, abduction, and extension

Other pertinent structures of the hip joint are:

• Zona orbicularis- aids in holding head of femur in acetabulum
• Inguinal ligament- forms tunnel for vital arteries, veins, and nerves in lower extremity
• Bursae- act as fluid-filled sac that provides cushioning and friction reduction between tendons, joints, muscles and bone

Knee region

The knee region is composed of four (4) bony structures- femur, tibia, fibula, and patella. These bony structures then form three (3) joints- tibiofemoral, patellafemoral, and proximal tibiofibular joint.

The primary movements of the knee that are aided by the three joints of the knee are:

• Knee flexion/extension

Other pertinent structures of the knee joint are:

• Capsule
  • Tibiofemoral capsule covers distal femur and proximal tibia- posteriorly divided into medial and lateral sections, anterior cut-out for patella
  • Proximal tibofibular capsule is continuous with knee 10% of time
• Ligaments
  • Tibiofemoral and patellofemoral joints
    • Medial collateral ligament
      • Tightened in extension; slackened in flexion
      • Prevents internal rotation and provides stability against valgus forces
    • Lateral collateral ligament
      • Tightened in extension; slackened in flexion
      • Prevents external rotation and provides stability against varus forces
    • Anterior cruciate ligament
      • Prevents anterior displacement of tibia on femur and provides rotation stability
    • Posterior cruciate ligament
      • Prevents posterior displacement of tibia on femur
    • Meniscofemoral ligament
      • Aids posterior cruciate ligament in preventing posterior displacement of tibia on femur
    • Transverse ligament
      • Connects medial and lateral meniscus anteriorly
    • Alar fold
      • Keeps patella in contact with tibia
  • Proximal tibiofibular joint ligaments
    • Anterior tibiofibular ligament
      • Reinforces anterior capsule
    • Posterior tibiofibular
      • Reinforces posterior capsule
• Menisci
  • Function
    • Deepen fossa of tibia
    • Increased congruency of tibia and femur
    • Reduces friction between joints during movement
    • Improves weight distribution
    • Provides shock absorption and lubrication to knee
    • Provide stability to tibiofemoral joint
  • Lateral meniscus
    • Outer side of joint
    • Attached to popitieus and joint capsule
    • Stabilizes knee against lateral rotation and tibial rotation
  • Medial meniscus
    • Inner side of joint
    • Attached to medial collateral ligament and joint capsule
    • Stabilizes knee against medial rotation and tibial translation
• Bursae- act as fluid-filled sac that provides cushioning and friction reduction between tendons, joints, muscles and bone

Foot and ankle region

The ankle/foot joint is composed of eight (8) articulations which include the talocrural, subtalar, talocalaneonavicular, calcaneocuboid, transverse tarsal, tarsometatarsal, metatarsophalangeal, and interphalangeal joint.

The primary movements of the foot/ankle joint are:

• Ankle plantarflexion/dorsiflexion
• Ankle inversion/eversion

Other pertinent structures of the ankle/foot joint are:

• Capsule
  • Provides stability to the joints of the ankle/foot
• Ligaments
  • Talocrural joint
    • Medial collateral ligament- deep and superficial fibers
    • Lateral collateral ligament
  • Subtalar joint
    • Interosseous talocalcaneal ligament
    • Lateral talocalcaneal ligament
    • Posterior talocalcaneal ligament
    • Medial talocalcaneal ligament
  • Talonavicular joint
    • Plantar calcaneonavicular ligament
    • Dorsal talonavicular ligament
  • Calcaneocuboid joint
    • Medial band of bifurcate ligament
    • Medial calcaneocuboid
    • Long plantar ligament
    • Plantar calcaneocuboid
  • Tarsometatarsal joint
    • Medial dorsal ligament
    • Lateral dorsal ligament
  • Cuneonavicular joint
    • Plantar ligaments
    • Three (3) dorsal cuneonavicular ligaments
  • Metatarsophalangeal joint
    • Plantar ligaments
    • collateral ligaments
  • Interphalangeal joint
    • Plantar ligament
    • Collateral ligament
• Plantar fascia
  • Collagen fibers connecting from medial calcaneus to phalanges
  • Fascia tightens during dorsiflexion- leads to supination and inversion
• Bursa - act as fluid-filled sac that provides cushioning and friction reduction between tendons, joints, muscles and bone

Lower extremity range of motion normals