What makes up pelvic brim

Pelvic Brim : The bony borders of the pelvic diaphragm, separating the false major pelvis from the true minor pelvis. Secondly, what organs are in the pelvic area? The pelvic cavity primarily contains reproductive organs, the urinary bladder , the pelvic colon, and the rectum. The ilium is the large, superior portion of the hip bone, and the pubis makes up the front portion of the hip bone.

Combined they form the pelvic brim. The hip joint is a ball-and-socket joint between the pelvis and femur, and the pelvis is a large bone structure located in the lower part of the body.

The bony pelvis is the entire structure formed by the two hip bones, the sacrum, and, attached inferiorly to the sacrum, the coccyx Figure 1. The pelvic girdle is formed by a single hip bone. The hip bone attaches the lower limb to the axial skeleton through its articulation with the sacrum.

The pelvis is the lower part of the torso. It's located between the abdomen and the legs. This area provides support for the intestines and also contains the bladder and reproductive organs.

There are some structural differences between the female and the male pelvis. Medical Definition of false pelvis : the upper broader portion of the pelvic cavity. The pelvis is formed by four bones which include a pair of hip bones otherwise known as innominate bones, the sacrum , which comes with the five lower sacral bones that are fused together and the coccyx which has four fused and a single individual terminal vertebra.

The function of the pelvic girdle is to support the trunk and organs in the thoracic cavity with the female being adapted for pregnancy and childbirth. Together with the sacrum and coccyx, the pelvic girdle forms a bowl-shaped region, the pelvis , that protects internal reproductive organs, the urinary bladder, and the lower part of the digestive tract. Flat Bones Protect Internal Organs There are flat bones in the skull occipital, parietal, frontal, nasal, lacrimal, and vomer , the thoracic cage sternum and ribs , and the pelvis ilium , ischium , and pubis.

The function of flat bones is to protect internal organs such as the brain, heart, and pelvic organs. The ischium forms the posterolateral portion of the hip bone see Figure 2.

The large, roughened area of the inferior ischium is the ischial tuberosity. This serves as the attachment for the posterior thigh muscles and also carries the weight of the body when sitting.

You can feel the ischial tuberosity if you wiggle your pelvis against the seat of a chair. Projecting superiorly and anteriorly from the ischial tuberosity is a narrow segment of bone called the ischial ramus.

The slightly curved posterior margin of the ischium above the ischial tuberosity is the lesser sciatic notch. The bony projection separating the lesser sciatic notch and greater sciatic notch is the ischial spine. The pubis forms the anterior portion of the hip bone see Figure 2. The enlarged medial portion of the pubis is the pubic body. Located superiorly on the pubic body is a small bump called the pubic tubercle.

The superior pubic ramus is the segment of bone that passes laterally from the pubic body to join the ilium. The narrow ridge running along the superior margin of the superior pubic ramus is the pectineal line of the pubis. The pubic body is joined to the pubic body of the opposite hip bone by the pubic symphysis.

Extending downward and laterally from the body is the inferior pubic ramus. The pubic arch is the bony structure formed by the pubic symphysis, and the bodies and inferior pubic rami of the adjacent pubic bones.

The inferior pubic ramus extends downward to join the ischial ramus. Together, these form the single ischiopubic ramus , which extends from the pubic body to the ischial tuberosity. The inverted V-shape formed as the ischiopubic rami from both sides come together at the pubic symphysis is called the subpubic angle.

The pelvis consists of four bones: the right and left hip bones, the sacrum, and the coccyx see Figure 1. The pelvis has several important functions. Its primary role is to support the weight of the upper body when sitting and to transfer this weight to the lower limbs when standing.

It serves as an attachment point for trunk and lower limb muscles, and also protects the internal pelvic organs. When standing in the anatomical position, the pelvis is tilted anteriorly.

In this position, the anterior superior iliac spines and the pubic tubercles lie in the same vertical plane, and the anterior internal surface of the sacrum faces forward and downward. The three areas of each hip bone, the ilium, pubis, and ischium, converge centrally to form a deep, cup-shaped cavity called the acetabulum. This is located on the lateral side of the hip bone and is part of the hip joint.

The large opening in the anteroinferior hip bone between the ischium and pubis is the obturator foramen. This space is largely filled in by a layer of connective tissue and serves for the attachment of muscles on both its internal and external surfaces.

Several ligaments unite the bones of the pelvis Figure 3. The largely immobile sacroiliac joint is supported by a pair of strong ligaments that are attached between the sacrum and ilium portions of the hip bone. These are the anterior sacroiliac ligament on the anterior side of the joint and the posterior sacroiliac ligament on the posterior side. Also spanning the sacrum and hip bone are two additional ligaments. The sacrospinous ligament runs from the sacrum to the ischial spine, and the sacrotuberous ligament runs from the sacrum to the ischial tuberosity.

These ligaments help to support and immobilize the sacrum as it carries the weight of the body. Figure 3. Ligaments of the Pelvis. The posterior sacroiliac ligament supports the sacroiliac joint. The sacrospinous ligament spans the sacrum to the ischial spine, and the sacrotuberous ligament spans the sacrum to the ischial tuberosity. The sacrospinous and sacrotuberous ligaments contribute to the formation of the greater and lesser sciatic foramens.

Watch this video for a 3-D view of the pelvis and its associated ligaments. It lies 4 cm anterior to the promontory and 7 cm behind the symphysis. It is the largest diameter in the pelvis. Obstetric transverse diameter: It bisects the true conjugate and is slightly shorter than the anatomical transverse diameter. The Pelvic Cavity It is a segment, the boundaries of which are: the roof is the plane of pelvic brim, the floor is the plane of least pelvic dimension, anteriorly the shorter symphysis pubis, posteriorly the longer sacrum.

The Pelvic Outlet Anatomical outlet It is lozenge-shaped bounded by; the lower border of symphysis pubis, pubic arch, ischial tuberosities, sacrotuberous and sacrospinous ligaments and, tip of the coccyx.

Obstetric outlet It is a segment, the boundaries of which are: the roof is the plane of least pelvic dimension, the floor is the anatomical outlet, anteriorly the lower border of symphysis pubis, posteriorly the coccyx.

Pelvic Planes These are imaginary planes lie as follow: Plane of pelvic inlet: passing with the boundaries of pelvic brim and making an angle of 55o with the horizon angle of pelvic inclination. Plane of mid cavity plane of greatest pelvic dimensions pass between the middle of the posterior surface of the symphysis pubis and the junction between 2nd and 3rd sacral vertebrae.

Laterally, it passes to the centre of the acetabulum and the upper part of the greater sciatic notch. It is a round plane with diameter of Internal rotation of the head occurs when the biparietal diameter occupies this wide pelvic plane while the occiput is on the pelvic floor i. Plane of obstetric outlet plane of least pelvic dimensions : passes from the lower border of the symphysis pubis anteriorly, to the ischial spines laterally, to the tip of the sacrum posteriorly.

Plane of anatomical outlet: passes with the boundaries of anatomical outlet and consists of 2 triangular planes with one base which is the bituberous diameter.

Anterior sagittal plane: its apex at the lower border of the symphysis pubis. Posterior sagittal plane: its apex at the tip of the coccyx.

Anterior sagittal diameter: cm from the lower border of the symphysis pubis to the centre of the bituberous diameter. Posterior sagittal diameter: 7. Pelvic Axes Anatomical axis curve of Carus It is an imaginary line joining the centre points of the planes of the inlet, cavity and outlet.