Pelvis and Lower Extremity Lecture

Pelvis Overview

• Also known as: Lumbo-pelvic complex
• Primary functions:
  • Provides bony protection for body organs
  • Creates a passageway for GI and GU systems
  • Offers attachment for trunk and lower extremity muscles

Lower Extremity

• Components:
  • Hip joint
  • Knee joint
  • Ankle joint
  • Foot joints
• Main functions:
  • Carries body weight
  • Maintains balance in standing and sitting positions

Pelvic Bones

• Consists of several bones:
  • 2 Ilium bones
  • 2 Ischium bones
  • 2 Pubic bones
  • Sacrum bone
  • Coccyx bone
• Function: Joins the axial skeleton with the appendicular skeleton

Pelvic Joints

• Lumbo-sacral joint: Between L5 and S1 vertebrae
• Sacroiliac (SI) joints: Two joints between the sacrum and ilium bones
• Pubic symphysis: Joint between the two pubic bones, reinforced by ligaments
• Sacrococcygeal joint: Between sacrum and coccyx, reinforced by ligaments

Important Landmarks and Structures

• Ilium landmarks:
  • Anterior superior iliac spine (ASIS)
  • Anterior inferior iliac spine (AIIS)
  • Posterior superior iliac spine (PSIS)
  • Posterior inferior iliac spine (PIIS)
• Ischium landmarks:
  • Ischial tuberosity: Attachment for hamstrings and adductor magnus muscles
  • Obturator foramen: Passage for obturator nerve
• Pubis landmarks:
  • Superior pubic ramus
  • Inferior pubic ramus
  • Pubic symphysis: Secured by inguinal ligament

Functions of Pelvic Joints

• Sacroiliac (SI) joints:
  • Transfer weight between femur and axial skeleton
  • Distribute upper body weight to lower extremities
• Pubic symphysis:
  • Increases pubic outlet during childbirth
• Lumbo-sacral joint:
  • Common site for lumbar spinal disorders
  • Secured by multiple ligaments (anterior, posterior, ilio-lumbar, lumbo-sacral ligaments)
• Sacrococcygeal joint:
  • Increases/decreases pelvic outlet size during labor
  • Attachment site for gluteus maximus muscle

Pelvic Movement

• Pelvic girdle: Considered as a whole unit
• Neutral position: ASIS and pubic symphysis in the same frontal plane
• Anterior tilt: ASIS in front of the pubic symphysis
  • Creates increased lumbar lordosis
  • Combination of trunk extensors pulling upward and hip flexors pulling downward
  • Common in late pregnancy
• Posterior tilt: ASIS behind the pubic symphysis
  • Creates flattened lumbar angle
  • Caused by tight hip extensors pulling downward
  • Often seen in elderly adults with increased kyphosis
• Lateral tilt: One side of the pelvis drops due to gravity (common when standing on one leg)
  • Balanced by same-side trunk flexors and opposite-side hip adductors
  • Can lead to scoliosis if chronic

Clinical Observations

• Anterior tilt: Observed in late-stage pregnancy women
• Posterior tilt: Observed in elderly adults with kyphosis
• Lateral tilt: Can lead to scoliosis due to unbalanced muscle recruitment