Anatomy of the Pelvic Girdle and Hip Joint

Overview of the Pelvic Bones

• The pelvic girdle consists of bones that are involved in various functions, including muscle attachments and support for the body.

Key Pelvic Bones and Landmarks

• Pubis Bone: Represents one-fifth of the pelvis.

  • Features notable landmarks important for muscle attachments.

• Ilium: The uppermost part of the pelvis.

  • Iliac Crest: The ridge felt on the top of the hips; runs along the upper border of the ilium.

Anterior Landmarks of the Ilium

• Anterior Superior Iliac Spine (ASIS):

  • The superior spine on the anterior side of the ilium.
  • Easily palpated; commonly noted in clinical and anatomical discussions.

• Anterior Inferior Iliac Spine (AIIS):

  • Located just below the ASIS on the anterior side.
  • Important for muscle attachments.

Posterior Landmarks of the Ilium

• Posterior Superior Iliac Spine (PSIS):

  • Located on the posterior side of the ilium; can be palpated.

• Posterior Inferior Iliac Spine (PIIS):

  • Situated below the PSIS on the posterior side.

Ischium Bone

• The ischium constitutes two-fifths of the pelvis.
• Obturator Foramen: A large hole in the ischium, not primarily associated with human movement.
• Ramus of the Ischium: An arch-like structure connecting the ischium to the pubis.
• Ischial Tuberosity:
  • A bony prominence serving as the origin point for hamstrings.
  • Often described in terms of sensation when sitting on hard surfaces.

Pubis Bone Landmarks

• Pubic Tubercle: A bump on the pubis bone.
• Superior Pubic Ramus: An archway connecting to the ilium.

Sacrum and Coccyx

• The Sacrum is formed from five fused vertebrae, connecting the left and right pelvic bones.
  • Base of the Sacrum: The superior part.
  • Apex of the Sacrum: The inferior part.
• The Coccyx or tailbone, located at the base of the sacrum, is an important landmark for the conclusion of the vertebral column.

Joint Structures

• Acetabulum: The socket for the hip joint created by contributions from the ilium, ischium, and pubis.
• Sacroiliac Joint (SI Joint): The joint formed between the sacrum and ilium, allowing for limited motion and importance in stability.

Hip Joint

• Hip Joint: A ball-and-socket joint formed between the head of the femur and the acetabulum.
  • Acetabular-femoral Joint: Another term for the hip joint, indicating its structure.

Important Ligaments of the Hip

• Pubofemoral Ligament:

  • Connects the pubis to the femur; limits external rotation and hip extension.

• Iliofemoral Ligament:

  • Large ligament connecting the ilium to the femur; assists in postural stability and limits excessive hip extension.

• Ischiofemoral Ligament:

  • Connects the ischium to the femur; limits internal rotation and some adduction.

• Superior and Inferior Pubic Ligaments:

  • Stabilize the pubic symphysis joint.

• Transverse Acetabular Ligament:

  • Bridges the gap in the acetabulum, providing structural support.

• Ligament of the Head of the Femur:

  • Attaches at the fovea capitis, anchoring the femur to the acetabulum.

Muscle Groups in the Pelvic Region

• Iliacus Muscle: Originates at the iliac crest, merging with psoas muscles to form iliopsoas.

• Psoas Major Muscle: Arises from T12 to L5 vertebrae, contributing to flexion at the hip joint.

• Psoas Minor Muscle: Smaller muscle originating around T12 and L1.

• Iliopsoas Muscle: ( ext{Common tendon formed by iliacus and psoas muscles to insert at the lesser trochanter of the femur.} )

• Rectus Femoris Muscle: Originates from ASIS, acting as a hip flexor, and a part of the quadriceps group.

• Sartorius Muscle:

  • Longest muscle in the body; spans from ASIS to tibia, aiding in hip and knee movements.