A spade-shaped bone that is formed by the fusion of 5 originally separate sacral vertebrae. Coccyx also called the tail bone. Formed by the fusion of 4 originally separated coccygeal bones. Pelvic fractures. A pelvic fracture requires considerable force. Use the links at the bottom of any email to manage the type of emails you receive or to unsubscribe. See our privacy policy for additional details. Learn Site. So, what are the different types of bones?
How are they categorized? There are five types of bones in the skeleton: flat, long, short, irregular, and sesamoid. 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.
Long Bones Support Weight and Facilitate Movement The long bones , longer than they are wide, include the femur the longest bone in the body as well as relatively small bones in the fingers. Short Bones Are Cube-shaped Short bones are about as long as they are wide. Irregular Bones Have Complex Shapes Irregular bones vary in shape and structure and therefore do not fit into any other category flat, short, long, or sesamoid. Sesamoid Bones Reinforce Tendons Sesamoid bones are bones embedded in tendons.
Get our awesome anatomy emails! About News Contact. All Rights Reserved. User Agreement Privacy Permissions. More inferiorly is the posterior inferior iliac spine. This is located at the inferior end of a large, roughened area called the auricular surface of the ilium. The auricular surface articulates with the auricular surface of the sacrum to form the sacroiliac joint. Both the posterior superior and posterior inferior iliac spines serve as attachment points for the muscles and very strong ligaments that support the sacroiliac joint.
The shallow depression located on the anteromedial internal surface of the upper ilium is called the iliac fossa. The inferior margin of this space is formed by the arcuate line of the ilium , the ridge formed by the pronounced change in curvature between the upper and lower portions of the ilium.
The large, inverted U-shaped indentation located on the posterior margin of the lower ilium is called the greater sciatic notch. The ischium forms the posterolateral portion of the hip bone see Figure 8.
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 8. 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 8. 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 8. 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. Watch this video for a 3-D view of the pelvis and its associated ligaments.
0コメント