Pelvis and Lower Extremity Lecture

Pelvis Overview

• Sometimes referred to as the lumbo-pelvic complex
• Functions:
  • Provides bony protection for internal organs
  • Passageway for GI (gastrointestinal) and GU (genitourinary) systems
  • Attachment site for trunk and lower extremity muscles

Lower Extremity

• Consists of:
  • Hip joint
  • Knee joint
  • Ankle joint
  • Foot joints
• Functions:
  • Carries body weight
  • Maintains balance in standing and sitting positions

Pelvic Anatomy

• Bones:
  • Two ilium bones
  • Two ischium bones (posterior)
  • Two pubic bones (anterior)
  • Sacrum
  • Coccyx
• Junctions:
  • Join axial skeleton with appendicular skeleton at the sacrum
  • Contains several joints:
    • Lumbosacral joint (L5-S1)
    • Two iliosacral joints
    • Sacrococcygeal joint
    • Pubic symphysis

Landmarks

• Ilium:
  • Anterior Superior Iliac Spine (ASIS)
  • Anterior Inferior Iliac Spine (AIIS)
  • Posterior Superior Iliac Spine (PSIS)
  • Posterior Inferior Iliac Spine (PIIS)
• Ischium:
  • Ischial Tuberosity (hamstring and adductor magnus attachment)
  • Ischial Foramen (obturator nerve passage)
• Pubis:
  • Superior Pubic Ramus
  • Inferior Pubic Ramus
  • Pubic Symphysis secured by the inguinal ligament

Joints and Ligaments

• Sacroiliac (SI) Joint:
  • Transfers weight between femur and axial skeleton
  • Critical for movement and weight distribution
• Pubic Symphysis:
  • Secured by superior and inferior pubic ligaments
  • Expands during childbirth
• Lumbosacral Joint:
  • Commonly affected by lumbar spinal disorders
  • Secured by multiple ligaments (ilio-lumbar, lumbosacral, anterior and posterior longitudinal ligaments)
• Sacrococcygeal Joint:
  • Reinforced by anterior and posterior sacrococcygeal ligaments
  • Adjusts the size of pelvic outlet during labor

Pelvic Movement

• Neutral Position:
  • ASIS and pubic symphysis are in the same frontal plane
• Anterior Tilt:
  • ASIS in front of pubic symphysis
  • Increased lumbar lordosis
  • Caused by trunk extensors and hip flexors
  • Common in late-stage pregnancy
• Posterior Tilt:
  • ASIS behind pubic symphysis
  • Flattened lumbar curve
  • Caused by trunk flexors and hip extensors
  • Seen in elderly with increased kyphosis
• Lateral Tilt:
  • Pelvis tilts to one side, often seen when standing on one leg
  • Compensated by trunk flexors and hip adductors
  • Can result in scoliosis

Clinical Observations

• Tight hip extensors can cause posterior tilt and reduced lumbar lordosis
• Pelvic lateral tilt impacts balance and may lead to scoliosis or unbalanced spine posture