Osteology of the Pelvis and Hip 6 8

Osteology of the Pelvis and Hip 6. 8. 1

Topic Learning Objective • Describe the anatomy of the pelvis and hip • Identify the anatomical features of the pelvis and hip on an illustration. 2

ANATOMY OF THE PELVIS AND HIP 3

Structures of the Pelvis and Hip • 2 Innominate bones (Os coxae) – – One right and one left Make up lateral and anterior portion of pelvis Divided into three parts Innominate in a child consists of three bones, which fuse (ossify) together in adulthood. Union takes place in and around the large cup shape depression called the Acetabulum 4

Structures of the Pelvis and Hip - Divided into three parts 1) Ilium- largest and most superior 2) Ischium- posterior inferior portions of the innominate, strongest portion 3) Pubis- anterior inferior portion of the innominate • Sacrum- five fused segments- incompletely developed vertebrae • Coccyx- four fused segments incompletely developed vertebrae • The sacrum and coccyx form the posterior wall of the pelvic girdle 5

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Structures of the Pelvis and Hip – Structures and landmarks of the ilium • Consists of a body originating at the acetabulum and an ala also called wing. • Anterior Superior Iliac Spine, Frequently used prominent projection on the anterior superior portion of the ilium (radiographic landmark) 7

Structures of the Pelvis and Hip – Anterior Inferior Iliac Spine - AIIS located below the ASIS and is smaller – Posterior Superior Iliac Spine - PSIS located on the posterior superior aspect of the ilium – Posterior Inferior Iliac Spine - PIIS located below the PSIS and is more prominent – Iliac Crest - top of the ilium between the ASIS and the PSIS – Greater Sciatic Notch - inferior to the PIIS serves as a passageway for the sciatic nerve which is the largest nerve in the body 8

Iliac crest Iliac Tubercle Posterior Superior Iliac Spine Posterior Inferior Iliac Spine Anterior Superior Iliac Spine Anterior Inferior Iliac Spine Anterior Greater Sciatic Notch Posterior Lateral view B-4

Structures of the Pelvis and Hip • Structures and landmarks of the Ischium – Consists of a body originating at the acetabulum and a ramus – Ischial Spine - thin, triangular, pointed eminence between the greater and lesser sciatic notches – Lesser sciatic notch- superior to the ischial tuberosity; is the passageway for muscles and nerves 10

Structures of the Pelvis and Hip • Ischial tuberosity - posterior structure on which you sit. Portion of the ischium in the region of the gluteal folds • Ischial ramus - Projects anteriorly and medially from ischial tuberosity. Thin flattened portion that joins the inferior ramus of the pubis. 11

Right Os Coxa Lateral View Posterior Ischial or Sciatic Spine Lesser Sciatic Notch Ischial Tuberosity Body of Ischium Anterior Superior Ramus of Ischium Inferior Ramus of Ischium Lateral view B-5

Structures of the Pelvis and Hip • Structures and landmarks of the pubis – Consists of a body originating at the acetabulum, superior and inferior rami – Body - forms 1/5 of the acetabulum anteriorly. • Inferior ramus - curves inferiorly then posteriorly from the medial end of the superior ramus and then passes laterally to join with the ramus of the ischium – Superior ramus - extends from the body of the pubis medially and articulates with the opposite superior ramus to form the symphysis pubis. 13

Posterior Anterior Superior Ramus of Pubis Symphyseal Surface Inferior Ramus of Pubis Medial view B-6

Structures of the Pelvis and Hip • Additional structures of the pelvic girdle – Obturator foramen - large rounded foramen situated between the ischium and pubis – Acetabulum – Large cup shaped depression on the inferior lateral aspect of the innominate bone 15

Right Os Coxa Lateral View Acetabulum Anterior Obturator Foramen Posterior Lateral view 16

Structures of the Pelvis and Hip • Formed by – – – • Ilium - superiorly Pubis - anteriorly and inferiorly Ischium - posteriorly and inferiorly The acetabulum is made up 2/5 ilium and 2/5 ischium with the remaining 1/5 made up of the pubis 17

Right Os Coxa Lateral View Ilium Anterior Posterior Pubis Ischium 18

Structures of the Pelvis and Hip • The pelvic brim - divides the pelvis into the greater and lesser pelvis – Greater pelvis • Also called false pelvis • Expanded portion located superior to the pelvic brim • Formed laterally by the ilia and posteriorly by the lumbar spine • Anterior border is soft tissue structures 19

Right Os Coxa Medial View Major, Greater or False pelvis Arcuate Line Minor, Lesser or True pelvis 20

Structures of the Pelvis and Hip – Lesser pelvis surrounded entirely by bone • Also called the true pelvis • Portion of the pelvic girdle that begins with, and is inferior to the pelvic brim • Consists of the sacrum and coccyx posteriorly, the ischium laterally and the pubic portion anteriorly 21

Structures of Terminal Line Major, Minor, B-7

Structures of the Pelvis and Hip • Differences between the male and female pelvis – Male • Ilium narrower • Less flared • Pelvic inlet -Heart shaped opening 23

Structures of the Pelvis and Hip – Female • Ilium broader • More flared • Pelvic inlet - Larger and more Oval shaped opening for childbirth 24

Structures of the Pelvis and Hip • Arthrology of the pelvic girdle – Sacro-iliac joints- formed by the articulation of the auricular surfaces of the ilium and the auricular surfaces of the sacrum – Symphysis pubis- formed by the articulation of the two pubic sections of the two innominate bones – Hip joints- formed by the head of the femur articulating with the acetabulum of the innominate bone 25

Iliac crest Iliac Tubercle Posterior Superior Iliac Spine Posterior Inferior Iliac Spine Anterior Superior Iliac Spine Anterior Inferior Iliac Spine Anterior Greater Sciatic Notch Posterior Lateral view B-4