CHAPTER 9 Pelvis and Hip

Bones Pelvis Made up of the two innominate (ilium, ischium, pubis) and sacrum Innominates come together at acetabulum

The bony pelvis. 1. Sacrum 2. Ilium 3. Ischium 4. Pubic bone 5 The bony pelvis. 1. Sacrum 2. Ilium 3. Ischium 4. Pubic bone 5. Pubic symphysis 6. Acetabulum 7. Obturator foramen 8. Coccyx Red line: Terminal line/pelvic brim

Joints Hip Synovial ball-and-socket (enarthrodial) joint with three degrees of freedom Same movements as GH joint? Acetabulum Deep sphere rimmed by labrum Stability compared to GH joint? Femoral head larger than acetabulum

Joints Hip—osteokinematics Pelvic motion on femur Anterior/posterior tilt—sagittal plane Lateral tilt—frontal plane Protraction/retraction—transverse plane

Joints Hip—osteokinematics Femur on pelvis Flexion/extension—sagittal plane Abduction/adduction—frontal plane Medial/lateral rotation—transverse plane

Muscles Flexors Iliopsoas Rectus femoris Sartorius Pectineus Only quadriceps to cross the hip Sartorius Pectineus Tensor fascia latae

Muscles Adductors Adductor magnus Adductor longus Adductor brevis Gracilis

Muscles Extensors Gluteus maximus Hamstrings Biceps femoris Except for short head Semitendinosus Semimembranosus

Muscles Abductors Gluteus medius Gluteus minimus Tensor fascia latae

Muscles Lateral rotators Medial rotators Piriformis Gemellus superior and inferior Obturator internus and externus Quadratus femoris Medial rotators No primary medial rotators of the hip

Factors Affecting the Role of Hip Muscles Muscular sufficiency—multiple joints vs. single joint Several two-joint muscles at hip Able to create greatest tension when elongated at one and shortened at other—length/tension Shortening at both joints will lead to active insufficiency

Muscle Activity Analysis of Pelvic and Hip Flexors Iliopsoas most powerful hip flexor

Muscle Activity Analysis of Pelvic and Hip Extensors Gluteus maximus most powerful hip extensor

Muscle Activity Analysis of Pelvic and Hip Abductors Gluteus medius strongest hip abductor