Bones and Joints of the Pelvis and Perineum - Self Study

Gross Anatomy


Bones and Joints of the Pelvis and Perineum - Self Study



ANNOUNCEMENTS
  1. For Xrays of the pelvis, check out the Radiology Atlas Images. You can access these images from your home computer.


ASSIGNMENTS
Moore's Clinically Oriented Anatomy: 332-341


Study Note: Bones and Joints of the Pelvis and Perineum

The study of the bones of the pelvis must be completed prior to beginning the dissection of the anal region. The outline that is provided lists the minimum features that are required for understanding of the muscles and soft tissues that will be studied in the future. You should use your disarticulated half skeleton to study the material outlined. An osseous review will be provided at the beginning of each dissection unit to help you focus on the features that are important for that day of dissection and to help you refresh your memory of these bony features.


BONES OF THE PELVIS AND PERINEUM

For each bone you must be able to identify the features listed below.

BOUNDARIES AND LANDMARKS OF THE PELVIS


ARTICULATIONS OF THE PELVIS (Netter Atlas plates 340, 341)


ANATOMY TABLES FOR TODAY'S TOPIC

Bones of the Pelvis and Perineum

Bone Structure Description Notes
os coxae one of three bones that form the pelvis paired; the os coxae forms the lateral part of the pelvis; it is formed by three fused bones: ischium, ilium & pubis; also known as the innominate bone
acetabulum a cup-shaped depression in the lateral surface of the os coxae bone acetabulum means vinegar cup; it is the socket for the head of the femur; it is formed by the: ilium (1/5), ischium (2/5) and pubis (2/5); the acetabular fossa lies in the floor of the acetabulum
acetabular notch a notch in the inferior margin of the acetabulum it is spanned by the transverse acetabular ligament; the acetabular br. of the obturator a. enters the hip joint by passing through the acetabular notch
acetabular fossa a roughened depression in the center of the acetabulum the ligament of the head of the femur occupies the acetabular fossa
lunate surface of the acetabulum the smooth articular surface of the acetabulum the lunate surface surrounds the acetabular fossa and the acetabular notch
obturator foramen a large foramen formed by the pubic and ischial rami obturator means to occlude or stop up, a reference to the fact that the obturator membrane closes the obturator foramen almost completely; a site of attachment for the obturator externus m. and the obturator internus m.
pubis an angulated bone the forms the anterior part of the pelvis one of three bones that form the os coxae: ilium, ischium, pubis; its body forms 1/5 of the acetabulum; its symphyseal surface unites with the pubis of the opposite side to form the pubic symphysis; the superior and inferior pubic rami participate in the formation of the obturator foramen
body superolateral portion of the pubis the body of the pubis forms about 1/5 of the acetabulum
pubic crest ridge on the superior border of the superior ramus attachment of rectus abdominis & pyramidalis mm.
pubic tubercle process at the lateral end of pubic crest attachment point of the medial end of the inguinal ligament
superior ramus superior "limb" that passes medially from the body of the pubis articulates with the superior ramus of the opposite side at the pubic symphysis
pecten ridge on superior surface of the superior pubic ramus attachment point of the pectineal ligament
inferior ramus inferior "limb" that passes inferolaterally from the pubic symphysis articulates with the ischial ramus to form the ischiopubic ramus; attachment site for the root of the penis (clitoris)
obturator groove groove on the inferior surface of the superior pubic ramus marks the area of passage of the obturator vessels and n. in the obturator canal
ischium   the "V"- shaped bone that forms the posteroinferior part of the pelvis one of the three bones that form the os coxae: ilium, ischium, pubis
  ischial ramus the limb of the ischium that passes anteriorly and superomedially toward the pubis it articulates with the inferior ramus of the pubis
body the part of the ischium that participates in the formation of the acetabulum it articulates with the ilium and the pubis at the acetabulum; the body of the ischium forms 2/5 of the acetabulum
ischial tuberosity the roughened projection that protrudes posteroinferiorly from the body of the ischium it is the site of attachment of the sacrotuberous ligament; it is the site of origin of the inferior gemellus m., quadratus femoris m. and the hamstring mm. (semitendinosus, semimembranosus, long head of biceps femoris, ischiocondylar portion of the adductor magnus)
lesser sciatic notch the notch located between the ischial tuberosity and the ischial spine the lesser sciatic notch is converted to the lesser sciatic foramen by the sacrospinous ligament and the sacrotuberous ligament
ischial spine the spine that arises just superior to the lesser sciatic notch it is the site of attachment of the sacrospinous ligament and the site of origin of the superior gemellus m.
ilium fan-shaped bone that forms the lateral prominence of the pelvis one of three bones that form the os coxae: ilium, ischium, pubis
body the portion of the ilium that participates in the formation of the acetabulum the body of the ilium forms 2/5 of the acetabulum
iliac crest arching superior edge the ilium that forms the rim of the "fan" attachment for abdominal wall muscles
iliac fossa broad depression on the medial surface of the ilium iliac fossa is part of the false (greater) pelvis
iliac tubercle roughened area along the outer edge of the iliac crest
anterior superior iliac spine spine at the anterior end of the iliac crest lateral attachment of the inguinal ligament
posterior superior iliac spine spine at the posterior end of the iliac crest position marked by a dimpling of the skin
arcuate line ridge running from anteroinferior to posterosuperior on the inner surface of the ilium inferior boundary of the iliac fossa; marks the plane of transition from abdominal cavity to pelvic cavity
sacrum   a triangular bone that is the posterior skeletal element forming the pelvis it is formed by 5 fused vertebrae; the sacrum and two os coxae bones form the pelvis
base the superior part of the sacrum the base of the sacrum includes the articular surface for the fifth lumbar vertebra and the superior portion of the two ala
promontory a projection of the superior part of the sacrum in an anterior direction the body of the fifth lumbar vertebra sits on the sacral promontory and articulates with it through a symphysis
ala the lateral portion of the sacrum paired; it projects laterally from the body of the sacrum; it represents the fused costal and transverse processes of the first sacral vertebra
anterior sacral foramina an opening in the anterior surface of the sacrum there are four pairs; each transmits the ventral primary ramus of the respective sacral spinal nerve; branches of the lateral sacral aa. Enter the sacral canal through these openings
posterior sacral foramina an opening in the posterior surface of the sacrum there are four pairs; each transmits the dorsal primary ramus of the respective sacral spinal nerve
sacral canal the opening in the center of the sacrum it is the continuation of the vertebral canal at sacral vertebral levels
sacral hiatus an opening in the posterior surface of the sacrum in the midline it is a normal feature that results from the failure of fusion of the laminae of the fifth sacral segment (and sometimes the fourth) during development
articular surface the roughened area located on the lateral surface of the sacrum this surface articulates with the ilium in the sacroiliac articulation
body the central portion of the sacrum the body is equivalent to the bodies of the other vertebra
base the superior surface of the sacrum the base of the sacrum articulates with the fifth lumbar vertebra through an intervertebral disk
coccyx   the most inferior portion of the vertebral column the coccyx results from the fusion of the four coccygeal vertebrae; it may be a single bone or the first coccygeal vertebra may be separated from the other three; it articulates with the fifth sacral segment; coccygeal vertebrae are reduced in complexity, having no pedicles, laminae or spines


Joints and Ligaments of the Pelvis and Perineum - Listed Alphabetically

Joint or ligament Description Notes
iliolumbar ligament a ligament that connects the transverse process of the L5 vertebra to the iliac crest the iliolumbar ligament stabilizes the lumbosacral joint
lumbosacral joint the articulation between the L5 vertebral body and the body of the first sacral segment a symphysis; this articulation is characterized by all of the features of a typical intervertebral articulation which include: an intervertebral disk, anterior and posterior longitudinal ligaments, synovial joints between articular processes, ligamenta flava, interspinal and supraspinal ligaments; a strong iliolumbar ligament strengthens this joint
pubic symphysis the midline joint uniting the superior rami of the two pubic bones a symphysis; a fibrocartilage interpubic disk unites the bones; the subpubic angle in the female is greater than the subpubic angle in the male
sacroiliac joint the articulation between the ala of the sacrum and the auricular surface of the ilium a synovial joint; the fibrous articular capsule is thickened dorsally and ventrally to form the sacroiliac ligaments; because of the interlocking nature of the joint surfaces and the strong sacroiliac ligaments, only limited movement is permitted at the sacroiliac joint
sacrospinous ligament the ligament that connects the ischial spine to the lateral surface of the sacrum and coccyx together with the sacrotuberous ligament, it converts the greater and lesser sciatic notches into greater and lesser sciatic foramina
sacrotuberous ligament the ligament that connects the ischial tuberosity to the lateral surface of the sacrum and coccyx together with sacrospinous ligament, it converts the greater and lesser sciatic notches into greater and lesser sciatic foramina




Some of the material presented in these tables is contained in the book:
MedCharts Anatomy by Thomas R. Gest and Jaye Schlesinger
Published by ILOC, Inc., New York. Copyright 1995.

Content of tables edited for use in this course by Patrick W. Tank, Ph.D.
Copyright 2001, Department of Anatomy and Neurobiology, University of Arkansas for Medical Sciences.
Unauthorized use is prohibited.



Links to Related World Wide Web Sites
Radiology Atlas Images
Marvin Computer Lab Models
Anatomy Tables
Netter Interactive Atlas
A.D.A.M.



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