<< Chapter < Page Chapter >> Page >
By the end of this section, you will be able to:
  • Define the pelvic girdle and describe the bones and ligaments of the pelvis
  • Explain the three regions of the hip bone and identify their bony landmarks
  • Describe the openings of the pelvis and the boundaries of the greater and lesser pelvis

The pelvic girdle    (hip girdle) is formed by a single bone, the hip bone    or coxal bone    (coxal = “hip”), which serves as the attachment point for each lower limb. Each hip bone, in turn, is firmly joined to the axial skeleton via its attachment to the sacrum of the vertebral column. The right and left hip bones also converge anteriorly to attach to each other. The bony pelvis    is the entire structure formed by the two hip bones, the sacrum, and, attached inferiorly to the sacrum, the coccyx ( [link] ).

Unlike the bones of the pectoral girdle, which are highly mobile to enhance the range of upper limb movements, the bones of the pelvis are strongly united to each other to form a largely immobile, weight-bearing structure. This is important for stability because it enables the weight of the body to be easily transferred laterally from the vertebral column, through the pelvic girdle and hip joints, and into either lower limb whenever the other limb is not bearing weight. Thus, the immobility of the pelvis provides a strong foundation for the upper body as it rests on top of the mobile lower limbs.

Pelvis

This figure shows the bone of the pelvis.
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 right and left hip bones, plus the sacrum and the coccyx, together form the pelvis.

Hip bone

The hip bone, or coxal bone    , forms the pelvic girdle portion of the pelvis. The paired hip bones are the large, curved bones that form the lateral and anterior aspects of the pelvis. Each adult hip bone is formed by three separate bones that fuse together during the late teenage years. These bony components are the ilium, ischium, and pubis ( [link] ). These names are retained and used to define the three regions of the adult hip bone. The pubis curves medially, where it joins to the pubis of the opposite hip bone at a specialized joint called the pubic symphysis    .

The hip bone

This figure shows the right hip bone. The left panel shows the lateral view, and the right panel shows the medial view.
The adult hip bone consists of three regions. The ilium forms the large, fan-shaped superior portion, the ischium forms the posteroinferior portion, and the pubis forms the anteromedial portion.

Pelvis

The pelvis consists of four bones: the right and left hip bones, the sacrum, and the coccyx (see [link] ). 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.

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.

Ligaments of the pelvis

This figure shows the pelvic bone. The ligaments in the pelvis are labeled.
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.

Male and female pelvis

This figure shows the structure of the female pelvic girdle on the left and the male pelvic girdle on the right.
The female pelvis is adapted for childbirth and is broader, with a larger subpubic angle, a rounder pelvic brim, and a wider and more shallow lesser pelvic cavity than the male pelvis.

Comparison of the female and male pelvis

Overview of Differences between the Female and Male Pelvis
Female pelvis Male pelvis
Pelvic weight Bones of the pelvis are lighter and thinner Bones of the pelvis are thicker and heavier
Pelvic inlet shape Pelvic inlet has a round or oval shape Pelvic inlet is heart-shaped
Lesser pelvic cavity shape Lesser pelvic cavity is shorter and wider Lesser pelvic cavity is longer and narrower
Subpubic angle Subpubic angle is greater than 80 degrees Subpubic angle is less than 70 degrees
Pelvic outlet shape Pelvic outlet is rounded and larger Pelvic outlet is smaller

Chapter review

The pelvic girdle, consisting of a hip bone, serves to attach a lower limb to the axial skeleton. The hip bone articulates posteriorly at the sacroiliac joint with the sacrum, which is part of the axial skeleton. The right and left hip bones converge anteriorly and articulate with each other at the pubic symphysis. The combination of the hip bone, the sacrum, and the coccyx forms the pelvis. The pelvis has a pronounced anterior tilt. The primary function of the pelvis is to support the upper body and transfer body weight to the lower limbs. It also serves as the site of attachment for multiple muscles.

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Skeletal system. OpenStax CNX. Apr 17, 2015 Download for free at https://legacy.cnx.org/content/col11779/1.1
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Skeletal system' conversation and receive update notifications?

Ask