L11 The hip and thigh

Anatomy of the Hip Region

  • Key Structures

    • Iliac crest, abdominal muscles, anterior and superior iliac spine.

    • Sartorius, hip anatomy involving anterior inferior iliac spine, rectus femoris, greater trochanter, gluteus medius-minimus, lesser trochanter, iliopsoas, ischial tuberosity, symphysis, hamstrings, and adductors.

Objectives of the Study

  • Understanding the Hip Joint

    • Describe the hip joint and its functional anatomy that provides stability.

    • Identify movements at the hip joint and the muscles responsible.

    • Understand the arrangement of the pelvic girdle in relation to the hip joint.

    • Grasp the clinical relevance of the hip joint.

Hip Bone Structure

  • Composition of Hip Bone

    • Each hip (coxal) bone consists of three fused bones:

      • Ilium: Superior part that articulates with the sacrum.

      • Ischium: Postero-inferior part.

      • Pubis: Anterior-medial part.

    • All three bones converge at the acetabulum, forming a concave socket for the femur's head.

The Hip Joint

  • Type of Joint

    • A ball and socket synovial joint, formed by:

      • Head of Femur: More than half a sphere covered by hyaline cartilage except at fovea capitis.

      • Acetabulum Labrum: Enhances joint stability by deepening the acetabulum, maintaining femur position.

Joint Capsule and Ligaments

  • Structure

    • Joint capsule is attached:

      • Medially: Margin of the acetabulum, labrum, and transverse acetabular ligament.

      • Laterally: Intertrochanteric line and neck of femur.

    • Synovial Membrane: Lines the capsule and attaches to articular surfaces.

  • Ligaments

    • Iliofemoral Ligament: Inverted Y-shape; prevents overextension.

    • Pubofemoral Ligament: Limits extension and abduction.

    • Ischiofemoral Ligament: Limits extension.

Muscles Involved in Hip Movements

  • Muscle Groups

    • Anterior Compartment: Quadriceps (extensors) and hip flexors (sartorius, iliopsoas).

    • Medial Compartment: Adductors (pectineus, adductor longus, brevis, magnus, gracilis).

    • Posterior Compartment: Hamstrings (biceps femoris, semitendinosus, semimembranosus).

Detailed Muscle Actions

  • Sartorius: Flexes hip and knee, adducts and laterally rotates thigh.

  • Iliopsoas: Primary hip flexor.

  • Quadriceps Femoris:

    • Rectus femoris: Flexes hip, extends knee.

    • Vastus muscles: Knee extension.

  • Adductors: Adduct and weaken extend the hip.

  • Hamstrings: Extend hip and flex knee joints.

Gluteal Muscles Introduction

  • Gluteus Muscles

    • Maximus, medius, minimus, tensor fascia lata, piriformis, gemelli, obturator internus, and quadratus femoris.

  • Mnemonics: "Please Save Our I Q" (for deep muscle identification).

Gluteal Muscle Actions

  • Gluteus Maximus: Chief thigh extensor and lateral rotator.

  • Gluteus Medius: Abducts and medially rotates thigh; stabilizes pelvis while walking.

  • Gluteus Minimus: Similar functions to gluteus medius.

  • Piriformis: Lateral rotator and stabilizer of hip joint.

Movements of the Hip Joint

  • Flexion: iliopsoas, rectus femoris, sartorius.

  • Extension: gluteus maximus, hamstrings.

  • Adduction: adductor longus, brevis, magnus, pectineus, gracilis.

  • Abduction: gluteus medius, minimus, sartorius, tensor fasciae latae.

  • Medial Rotation: anterior fibers of gluteus medius, minimus, tensor fasciae latae.

  • Lateral Rotation: piriformis, obturator internus/externus, gemelli, quadratus femoris.

  • Circumduction: combination of movements.

Bony Pelvis Structure

  • Composition: Contains two hip bones, sacrum, coccyx.

  • Functions: Supports pelvic viscera, transmits body weight to femurs.

Orientation and Joints of the Pelvis

  • Standard Position: Anterior superior iliac spines and symphysis pubis lie in the same vertical plane.

  • Sacroiliac Joints: Limited movement; transmit weight to hip bones.

  • Symphysis Pubis: Cartilaginous, minimal movement.

  • Sacrococcygeal Joint: Minimal flexion and extension possible.

Clinical Relevance of the Hip Joint

  • Osteoarthritis: Cartilage degradation, bone changes, inflammatory responses lead to pain and stiffness.

  • Hip Fractures: Common in older adults; types include intracapsular (high risk for avascular necrosis) and extracapsular.

  • Dislocation: Often due to high-impact trauma, with posterior dislocation being most common.

  • Developmental Dysplasia: Poor development leading to instability/dislocation, primarily in young children.