Lower Limb Joints

Overview – Lower Limb Joints

The lower limb joints include strong, weight-bearing articulations that provide stability for upright posture while allowing mobility for walking, running, and balance. These include both axial connections like the sacroiliac joint, and highly mobile synovial joints like the hip, knee, and ankle. Understanding their structure, biomechanics, and ligamentous support is essential for clinical application in orthopaedics, sports medicine, and trauma care.

Sacroiliac Joint

  • Type: Synovial planar joint
  • Features:
    • Transfers weight from axial skeleton to lower limbs
    • Loosens during labour
  • Bones: Sacrum and ilium
  • Ligaments:
    • Anterior sacroiliac ligament
    • Posterior sacroiliac ligament
    • Interosseous sacroiliac ligament
Sacro-Iliac Joint
OpenStax College, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Pubic Symphysis

  • Type: Secondary cartilaginous joint
  • Features:
    • Loosens during labour
    • Contains fibrocartilaginous interpubic disc
  • Bones: Left and right pubic bones
  • Ligaments:
    • Ligamentous capsule surrounding disc
Pubic Symphysis
OpenStax College, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Hip Joint

  • Type: Synovial, multiaxial ball-and-socket joint
  • Features:
    • Acetabular labrum deepens socket → high congruency
    • Fat-filled acetabular fossa
  • Bones:
    • Head of femur
    • Acetabulum of innominate bone
  • Ligaments:
    • Iliofemoral: Limits extension, lateral rotation, adduction, abduction
    • Pubofemoral: Limits extension, lateral rotation, abduction
    • Ischiofemoral: Limits extension, medial rotation, adduction
    • Ligamentum teres: Allows blood vessel passage – not for stability
Lower Limb Joints - hip joints
OpenStax College, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Knee Joint

  • Type: Synovial modified bicondylar hinge joint
  • Features:
    • Allows flexion/extension with some rotation
    • Poor bony congruity – relies on ligaments for stability
    • Includes tibiofemoral and patellofemoral joints
Femur sits on an angle
OpenStax College, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Menisci

  • Fibrocartilaginous pads on tibial plateaus
  • Improve congruity and absorb shock
  • Lateral Meniscus: More mobile
    • Weak capsule attachment
    • Posterior meniscofemoral ligament
  • Medial Meniscus: Less mobile → more prone to injury
    • Firm attachment to capsule and medial collateral ligament
menisci
OpenStax College, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Ligaments

  • Extracapsular:
    • Patellar ligament
    • Medial and lateral collateral ligaments
  • Intracapsular:
    • Anterior cruciate ligament (ACL): Prevents anterior tibial translation
    • Posterior cruciate ligament (PCL): Prevents posterior tibial translation
    • Transverse meniscal ligament
    • Meniscofemoral ligament
menisci
knee ligaments
knee ligament injury
OpenStax College, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Knee Bursae

  • Suprapatellar: Deep to quadriceps tendon; communicates with joint cavity
  • Prepatellar: Subcutaneous; cushioning during kneeling
  • Infrapatellar: Between patellar tendon and fat pads
Lower Limb Joints - Knee Bursae
OpenStax College, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Superior Tibiofibular Joint

  • Type: Synovial planar joint
  • Bones: Tibia and fibula
  • Ligaments: Anterior and posterior tibiofibular ligaments
Lower Limb Joints - sup TibioFibular Joint
https://www.earthslab.com/anatomy/tibiofibular-joints/

Inferior Tibiofibular Joint

  • Type: Syndesmosis
  • Features: Interosseous membrane resists separation
  • Ligaments:
    • Interosseous ligament
    • Strong anterior and posterior tibiofibular ligaments
Lower Limb Joints - inf TibioFibular Joint
OpenStax College, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Ankle Joint (Talo-crural Joint)

  • Type: Synovial hinge joint
  • Features:
    • Excellent congruity during dorsiflexion
    • Supported by strong collateral ligaments
    • Movements: dorsiflexion and plantarflexion
  • Bones:
    • Trochlea of talus
    • Distal tibia and fibula
  • Ligaments:
    • Lateral ligaments: Anterior talofibular, posterior talofibular, calcaneofibular
    • Medial (deltoid) ligament: Four-part complex
Lower Limb Joints - ankle
OpenStax College, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Subtalar Joint

  • Type: Synovial planar joint
  • Movements: Inversion and eversion
  • Bones: Talus and calcaneus
Lower Limb Joints - Subtalar Joint

Transverse Tarsal Joint

  • Type: Composite synovial planar joint
  • Components:
    • Talonavicular joint
    • Calcaneocuboid joint
  • Bones:
    • Talus + navicular
    • Calcaneus + cuboid
Lower Limb Joints - Transverse Tarsal Joint

Arches of the Foot

  • Function: Shock absorption and adaptability on varied surfaces
  • Ligament Support:
    • Spring (calcaneonavicular) ligament
    • Short and long plantar ligaments
    • Plantar aponeurosis
Arches in Foot

Medial Longitudinal Arch

  • Bones:
    • Calcaneus
    • Talus
    • Navicular
    • Medial & intermediate cuneiforms
    • 1st metatarsal
Medial Longitudinal Arch
OpenStax College, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Lateral Longitudinal Arch

  • Bones:
    • Calcaneus
    • Cuboid
    • 4th and 5th metatarsals
Lateral Longitudinal Arch
OpenStax College, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Transverse Arch

  • Bones:
    • Cuneiforms
    • Cuboid
    • Metatarsal bases
Transverse Arch
OpenStax College, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Metatarsophalangeal Joints (MTP)

  • Type: Synovial condyloid joints
  • Movements:
    • Flexion/extension
    • Abduction/adduction
    • Circumduction
Lower Limb Joints - MTPJ

Interphalangeal Joints

  • Type: Synovial hinge joints
  • Movements: Flexion and extension only
Lower Limb Joints - IPJ

Summary – Lower Limb Joints

The lower limb joints encompass a range of articulations from rigid axial connections to highly mobile synovial joints. These include the sacroiliac joint, hip joint, knee, and ankle, along with subtalar and metatarsophalangeal joints. Their biomechanics and ligamentous supports are crucial for posture, locomotion, and load transfer. For a broader context, see our Musculoskeletal Overview page.

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