The pelvis is consists of four bones.

1-two innominate bone.

2-sacrum

3-coccyx

INNOMINATE BONE

.    The innominate bone is also called hip bone or os coxae.

.  it is a large irregular flat bone.it forms part of the pelvis.

·  The two innominate bone forms front and side of the pelvis

.   left and right pelvic bone connect at pubic symphysis in the anterior part of the pelvis and with      sacrum in the posterior part of the pelvis.

·each innominate bone composed of three parts,ilium,ischium,and pubis,

SACRUM

· The sacrum is fixed in the middle the right and left hip bones or innominate bones.

·The sacrum is composed  by the union of five sacral vertebral,

· sacrum bear all part of body weight.

COCCYX

. The coccyx is also known as tail bone.

· It is a small triangular bone situated at the lowest point of the spine.

· It is formed by three to five coccygeal vertebrae or spinal bones.

ILIUM

Ilium divided into three parts.

1-two end

2-three border

3-three surface

      1- The upper end of the ilium is called the iliac crest.

2-The lower end of ilium fused with pubis and ischium at the acetabulum.

ILIAC CREST

·  Iliac crest extend from anterior superior iliac spine to posterior superior iliac spine.

IT IS DIVIDED INTO TWO SEGMENT

Ventral segment

· Anterior  two-third  of the iliac crest is called the ventral segment.

Dorsal segment

1-   Posterior one-third of the iliac crest is called the dorsal segment.

  2 -The inner margin of the iliac crest is called inner the lip of iliac crest.

  3-  The outer margin of the iliac crest is called the outer lip of iliac crest.

  4-   Between the inner lip and outer lip of iliac crest.there is a line that is called the intermediate zone.

5-  The outer lip of iliac crest has a tubercle called as tubercle of the iliac crest.

GREATER SCIATIC NOTCH

.   Below the posterior inferior iliac spine.there is a big notch which is called the greater sciatic notch.

·    It is present in between the posterior inferior iliac spine. (above) and ischial spine ( below).

LESSER SCIATIC NOTCH

·  Below the ischial spine, there is a small notch which is called the lesser sciatic notch.

·   It is situated in between ischial spine(above)and ischial tuberosity below.

ISCHIAL SPINE

· 1-The ischium is situated below the ilium.

· 2-  There is a projection of thin three-sided bony prominence from the posterior border of ischium            which is called the ischial spine.

 3-   It is situated in between greater  sciatic notch and lesser sciatic notch

ANTERIOR GLUTEAL LINE

1-  It is the longest line of the gluteal surface.

2- There is a point 4 cm ahead from the anterior superior iliac spine in the iliac crest. From that point, a line runs downward and ends at the upper part of the greater sciatic notch. this line is called the anterior gluteal line.

POSTERIOR GLUTEAL LINE

1-  It is the shortest line of gluteal surface than the three gluteal lines.

2-   There is a point  5cm ahead in iliac crest from the posterior superior iliac spine and from that point the line runs downward and ends in the upper part of the greater sciatic notch. this line is called the posterior gluteal line.

INFERIOR GLUTEAL LINE

• ·      This is the slightest noticeable line of three gluteal line.
•  it  starts in front of the notch( the notch which is present below anterior superior iliac spine)on the anterior border of the ilium and runs downward and backward and ends at the middle of  greater  sciatic notch..this line is called the inferior gluteal line.

ISCHIUM

· the ischium is situated below the ileum, upper part of ischium connected with the lower part of ilium at  acetabulum.anteriorly it is connected with pubis.

IT IS COMPOSED OF THREE PARTS

1-The body

2-the superior ischial ramus

3-the inferior  ischial ramus

BODY OF ISCHIUM

Body of ischium  situated between  superior ischial ramous and inferior ischial ramous.

SUPERIOR  ISCHIAL  RAMUS

Superior ischial ramus situated above the body of the ischium.

INFERIOR ISCHIAL RAMUS

Inferior ischial ramus situated below the body of the ischium.

PUBIS

It is the bone that forms the pelvis. the situated anterior part of the pelvis.

IT IS COMPOSED OF THREE PARTS

1-The body

2-the superior ramus

3-the inferior ramus

BODY OF PUBIS

The body of pubis joins at the acetabulum. It takes part to form the hip socket.

SUPERIOR RAMUS OF PUBIS

It extends laterally from the body and forms the part of acetabulum.

INFERIOR RAMUS OF PUBIS

From the body of pubis its projects toward ischium .the superior pubic ramus and inferior pubic ramus  enclose  the obturator foramen through which  vein, nerve a

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