Area of Pelvic Brim and Their Significant

Subject: Midwifery I (Theory)

Overview

The pelvis is a bony girdle that is created anteriorly, laterally, by the innominate bone and posteriorly, by the sacrum and coccyx. The bony pelvis, which from an obstetrical aspect resembles a basin, is valuable in whole and separately. Two innominate bones, one innominate bone, and one coccyx bone make up its four bones. The two innominate bones are also referred to as the hip bone or the unnamed bone. The three sides of the pelvis are formed by the two innominate bones. The innominate bone is made up of three components.Ilium, ischium, and pubis are their names. Five fused vertebrae make up one innominate bone, a wedge-shaped triangular bone with its base above and apex below. The last segment of the spine, or the vestigial tail, is one coccyx bone. It is made up of four fused vertebrae that together make a tiny triangular bone. It has backward and forward movement.

Female pelvis

The pelvis is a skeletal girdle formed posteriorly by the sacrum and coccyx, anteriorly and laterally by the innominate bone.

Bones

  • Two innominate bones
    It goes by the names hip bone and unnamed bone as well. The three sides of the pelvis are formed by the two innominate bones. The innominate bone is made up of three components. Ilium, ischium, and pubis are their names.
  • One innominate bone
    It is a triangular bone with five fused vertebrae that is wedge-shaped and has its base above and apex below.
  • One coccyx bone
    It is a remnant tail that is located at the end of the spine. It is made up of four fused vertebrae that together make a little triangular bone. It has backward and forward movement.

Joints

  • One symphysis pubis
    It develops where the two pubic bones, which are connected by a pad cartilage, meet

  • Two sacroiliac joints
    The strongest joint in the body is this one. They connect the pelvis to the spine by connecting the sacrum to the ilium.

  • One sacrococcygeal joint
    This joint connects the sacrum to the coccyx. It is significant for midwives because it might widen the pelvic exit.

Ligaments, part, measurement

  • Sacrotuberous ligaments
    It is fastened to the medial border of the ischial tuberosity and the posterior aspect of the lower three sacral vertebrae.
  • Sacrospinous ligamentsIt is thin and triangular. It reaches the ischial spines from the lateral edge of the sacrum and coccyx.

Specific pelvic brim areas and their importance

 

Diameter

Measurement

Significance
Antero-posterior diameters
Anterior-posterior anatomical diameter (true conjugate)

11 cm

Reduced plyatepellinoid pelvis
maternity conjugate (from the tip of the sacral promontory to the most bulging point on the back of symphysis pubis which is about 1cm below its upper borfer.it is the shortest antero-posterior diameter.)

10.5 cm

 The A.P. is this. the fetus must navigate the brim's diameter

Diagonal conjugate

12.5cm

 during a clinical evaluation, be measured

External conjugate

20cm

  
Transverse diameters

Anatomical transverse diameter

 13cm  

Obstetrictranverac diameter

    
Oblique diameter
  • Right oblique diameter
  • Left oblique diameter

 

12cm

 

12cm

 

 The diameter that the head typically engages in

 

 REFERENCE

Chaudhari B.D., 1996, Handbook of General anatomy, 3rd edition CBS Publisher and distributors

Chaudhari B.D., 1998, Human Anatomy (Vol. 1, 2, 3), 3rd edition CBS Publisher and distributors

Pathak T., 2057, A handbook of Anatomy and Physiology, 3rd edition, Vidhyarthi Pustak Bhandar, Bhotahiti, Kathmandu

Tuitui R., suwal, S.N. 2001, Human anatomy and physiology, first edition, Makalu Books and stationers, Putalisadak, Kathmandu

Tuitui R. 2002, A textbook of Midwifery A (Antenatal), 3rd edition, Vidyarthi Pustak Bhandari (Publisher and Distributor), Bhotahity, Kathmandu

Tuladhar K., Shrestha U., Henk C., 1992, Integrated science, First Edition, HLMC
Things to remember
  • The pelvis is a skeletal girdle formed posteriorly by the sacrum and coccyx, anteriorly and laterally by the innominate bone.
  • The bony pelvis is a component of the pelvis that, from an obstetrical perspective, functions better as a whole than separately.
  • It is made up of four bones: a coccyx bone, two innominate bones, and one innominate bone.
  • The hip bone and unnamed bone are two innominate bones. The three sides of the pelvis are formed by the two innominate bones.
  • The innominate bone is made up of three components. Ilium, ischium, and pubis are their names.
  • Five united vertebrae make up one innominate bone, a wedge-shaped triangular bone with its base above and tip below.
  • The last segment of the spine, or the vestigial tail, is one coccyx bone. It is made up of four fused vertebrae that together make a little triangular bone. It has backward and forward movement.
Questions and Answers

Specific pelvic brim areas and their importance:

Diameter

Measurement

Significance

1. Antero-posterior diameters

    

a. Anatomical antero-posterior diameter(true conjugate)

11 cm

Reduced plyatepellinoid pelvis

b. Obstetric conjugate

(from the tip of the sacral promontory to the most bulging point on the back of symphysis pubis which is about 1cm below its upper borfer.it is the shortest antero-posterior diameter.)

10.5 cm

This is the A.P. diameter of the brim which the fetus must negotiate

c. Diagonal conjugate

12.5cm

Can be measured at clinical examination

d. External conjugate

20cm

  

2. Transverse diameters

    

a. Anatomical transverse diameter

13cm

  

b. Obstetrictranverac diameter

    

c. Oblique diameter

i. Right oblique diameter

ii. Left oblique diameter

 

12cm

 

12cm

The diameter in which the head commonly engaged

 

The pelvis is a bony girdle that is formed posteriorly by the sacrum and coccyx and anteriorly and laterally by the innominate bone.

  • Bones:

    • Two innominate bones: It goes by the names hip bone and unnamed bone as well. The three sides of the pelvis are formed by the two innominate bones. The innominate bone is made up of three components. Ilium, ischium, and pubis are their names.

    • One innominate bones: It is a triangular bone with five fused vertebrae that is wedge-shaped and has its base above and apex below.

    • One coccyx bone: It is a remnant tail that is located at the end of the spine. It is made up of four fused vertebrae, which together make a tiny triangular bone. It has both forward and backward movement.

  • Joints:

    • One symphysis pubis: It develops where the two pubic bones, which are connected by a pad cartilage, meet.

    • Two sacro-iliac joints: The strongest joint in the body is this one. They connect the pelvis to the spine by connecting the sacrum to the ilium.

    • One sacrococcygeal joint: This joint connects the sacrum to the coccyx. It is significant for midwives because it can widen the pelvic outlet.

  • Ligaments, part, measurement:

    • Sacro-tuberous ligaments: It is fastened to the medial border of the ischial tuberosity and the posterior aspect of the lower three sacral vertebrae.

    • Sacro spinous ligaments: It is thin and triangular. It reaches the ischial spines from the lateral edge of the sacrum and coccyx.

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