Anatomy of the Pelvis | GLOWM
The left and right hip bones (innominate bones, pelvic bones) are two Together , the ilium, pubis and ischium form a cup-shaped socket. We will review the functioning of the organs found in the true pelvis, In an adult, the innominate bones consist of the fused ilium, ischium, and pubis (Figure 1). . The iliococcygeus muscle and posterior fibers of the pubococcygeus fuse at Figure propagacni.info Catherine Hayes, Judith Barbaro Brown three smaller bones, which fuse together in the socket of the hip joint (the acetabulum) to form the tri-radiate cartilage. The three bones are the ilium, ischium and pubis, which provide attachment sites.
This can lead to destruction of this joint, which can lead to loss of information on age and sex of the individual. The author excavating a Medieval skeleton in Germany in Note the damaged anterior aspect of the Pubic Symphysis, which is outlined in red.
Pelvic Anatomy and Elements: As the main weight bearing joint, the bone is also much denser with thicker cortical bone. The greater sciatic notch is also generally a good indicator of the biological sex of the individual. Anatomical landmarks on the right hip Image credit: Pelvic fracture Fractures of the hip bone are termed pelvic fracturesand should not be confused with hip fractureswhich are actually femoral fractures  that occur in the proximal end of the femur.
In animals[ edit ] The hip bone first appears in fishes, where it consists of a simple, usually triangular bone, to which the pelvic fin articulates. The hip bones on each side usually connect with each other at the forward end, and are even solidly fused in lungfishes and sharksbut they never attach to the vertebral column.
The acetabulum is already present at the point where the three bones meet. In these early forms, the connection with the vertebral column is not complete, with a small pair of ribs connecting the two structures; nonetheless the pelvis already forms the complete ring found in most subsequent forms.Bones Of The Hip - Structure Of The Hip - Pelvic Girdle Anatomy - Bones Of The Pelvis
The obturator foramen is generally very small in such animals, although most reptiles do possess a large gap between the pubis and ischium, referred to as the thyroid fenestra, which presents a similar appearance to the obturator foramen in mammals.
In birdsthe pubic symphysis is present only in the ostrichand the two hip bones are usually widely separated, making it easier to lay large eggs. The same pattern is seen in all modern mammals, and the thyroid fenestra and obturator foramen have merged to form a single space. The anterior portion of the external anal sphincter lies within the perineal body. The deep external sphincter is circularly disposed and encompasses the anal canal, while the superficial portion of this muscle is fusiform and runs from the coccyx to the perineal body.
The external anal sphincter is surrounded by a connective tissue capsule that aids in its reapproximation after it has been severed or torn.
The internal anal sphincter is a thickening in the circular muscle of the anal wall. It can be identified just beneath the anal submucosa in a fourth-degree laceration of the perineum and is usually reapproximated along with the wall of the bowel. Cross section of vagina and adjacent organs. Underneath the epithelium of the vagina is a dense layer of connective tissue that forms the submucosa.
Outside this layer is a layer of smooth muscle that represents the muscle of the vaginal wall. This muscle does not have well-defined circular and longitudinal layers such as are found in the bowel wall but has a somewhat more complex spiral arrangement.
This nerve supply modulates the tone of the smooth muscle of the vaginal wall and the vaginal vascular tone. There are only occasional free nerve endings in the vaginal wall. The blood supply to the vagina comes from several different sources, with the largest branches lying on the lateral wall. A downward extension of the uterine artery, the vaginal branch of the internal iliac artery, and the pudendal artery all contribute.
The major branches of these vessels lie outside the muscular coat of the vagina within the loose adventitial layer that surrounds it. Superficial lacerations that extend only as far as the submucosa rarely cause significant hemorrhage, but lacerations that traverse the muscularis may injure some of these large vessels.
When such deep lacerations occur and significant hemorrhage is encountered, surgical repair should be undertaken so as to include the deep vessels that may have retracted within the loose adventitial layer just outside the vaginal wall muscularis.
Lacerations that involve the vaginal wall above the outlet may occasionally involve deeper structures, and an appreciation of the adjacent anatomy will help suggest the nature of these lesions, thereby facilitating their recognition and repair see Fig. The anterior wall lies adjacent to the urethra, bladder, and ureters. The posterior wall is next to the perineal body, rectum, and peritoneal cavity at the pouch of Douglaswhile the two lateral walls lie against the pelvic diaphragm and major vaginal vessels.
Anatomical landmarks within the vagina can be used to locate the position of such structures as the ureter and urethra and warn of their possible involvement in a vaginal laceration. Anteriorly, a narrow ridge the urethral carina can be seen in the lower third of the vagina where the urethra bulges into the vaginal canal.
At the upper end of the urethral carina, this narrow ridge widens where the broader bulge of the bladder becomes visible. The combination of these two anterior ridges is called the anterior column of the vagina. In the upper third of the vagina, the ureters lie between the vaginal wall and the bladder in the anterior and lateral fornices. This bulge is lost in the lower third of the vagina, where the rectum is separated from the vagina by the perineal body.
There was a problem providing the content you requested
In its upper third, the vagina is adjacent to the pouch of Douglas. Awareness of these anatomical relationships will indicate possible occult damage to other visceral or muscular structures and avoid missing a chance to repair this damage primarily. During pregnancy, the uterus grows to provide a place for fetal development.
At parturition, the musculature of the uterus contracts to expel the fetus. Uterus and adnexal structures. The uterus is divided into two portions. The upper part is the uterine corpus and consists primarily of uterine smooth muscle.
The lower part, the uterine cervix, is composed largely of fibrous tissue. Uterine Corpus Within the corpus there is a small, triangularly shaped endometrial cavity surrounded by a thick muscular wall.
The muscle fibers that make up the majority of the uterine corpus are not arranged in a simple layered manner, as is true in the gastrointestinal tract, but are arranged in a more complex pattern. On the anterior uterine wall, the fibers from each side crisscross diagonally with those of the opposite side but run in a predominantly transverse direction. This can be appreciated from the gaping that occurs in a classic uterine incision as well as the predilection of a uterus which contains a scar from a previous classical cesarean section to rupture during and before labor.
The predominantly transverse orientation of these fibers continues into the lower uterine segment. Blunt separation of fibers during a low segment cesarean section results in a transverse laceration.
Inspection of the lateral edges of this wound reveal an overlapping of fibers in this area that belies the fact that they are not completely parallel. Most obstetricians have also noted that there is a grossly recognizable band of muscle fibers that runs in an anterior and posterior direction over the fundus of the uterus.
The Hip Bone
Its significance is not entirely clear. Uterine Cervix The cervix is divided into two portions: The portio vaginalis is covered by nonkeratinizing squamous epithelium. Its canal is lined by a columnar mucus-secreting epithelium which is thrown into a series of folds, the palmate folds or plicae palmatae, which form crypts that are often called the cervical glands. The upper border of the cervical canal is marked by the internal os where the narrow cervical canal widens out into the endometrial cavity.
Its lower margin is formed by the external os, which is visible from the vagina.
Hip bone - Wikipedia
What smooth muscle there is lies on the periphery of the cervix, connecting the myometrium with the muscle of the vaginal wall.
Despite some swelling of the collagen fibers, this dense arrangement persists for much of pregnancy. Near term the cervix becomes softer and thinner and begins to dilate in a process known as ripening. This is associated with a decline in the collagen cross-linking, making it more loosely dispersed and, therefore, less able to resist stretching. Its weight increases from approximately 60 g to 1 kg. Uterine growth in pregnancy. Principles of uterine growth in pregnancy.
Am J Obstet Gynecol The growth that occurs in the substance of the uterus itself occurs during the first half of gestation. During the first 5 months of pregnancy the uterus grows faster than the conceptus so that it is only during the middle of pregnancy that the conceptus actually catches up with the growth of the uterus to fill the uterine cavity, as will be seen when the development of the isthmus of the cervix is considered. There are three phases of uterine growth During the first and early second trimesters of pregnancy, the mass of the uterus increases in a fairly linear fashion to the full weight that it will be at term.
This means that although the external dimensions of the uterus will continue to enlarge during the second half of pregnancy, the uterus will not gain additional tissue. The wall of the uterus, therefore, thickens or remains a constant thickness in the first half of pregnancy but becomes thinner as it must stretch to surround a growing fetus later on. In contrast to the uterus, which has achieved its full weight by the middle of the second trimester, at this same time the fetus has only undergone one sixth of the total growth that it will achieve by term.
Lower Uterine Segment The lower uterine segment is that portion of the myometrium that must dilate during the process of delivery in order to allow the presenting part to deliver Fig.
The tissue that will make up the lower uterine segment begins as a part of the cervix, and as pregnancy progresses, it comes to lie in the lower portion of the corpus. It goes through several stages of development. Development of the lower uterine segment. The cross-hatched area represents the myometrium. Fundamentals of Obstetrics and Gynecology, 2nd ed. Based on observations of C. The division between the muscular uterine wall and the fibrous cervix is not always at the internal os of the cervix.
In the nonpregnant and early pregnant uterus the line of demarcation between the fibrous and muscular parts of the uterus actually occurs below the anatomical internal os of the uterus see Fig. Early in pregnancy the relatively small conceptus occupies a portion of a large uterus.
At about the 16th week, fetal growth catches up with uterine growth so that the products of conception fill the entire uterine cavity. The continued fetal growth past the time when uterine hypertrophy has ceased stretches the uterine wall, 24 as evidenced by the thinning of the muscular wall of the corpus see Fig.
As this stretching increases, the muscular portion of the cervix is placed under tension and, having little collagenous tissue to resist this force, opens as far as the musculofibrous junction. As pregnancy progresses the lower uterine segment begins to develop as a clinically distinctive entity at about 34 weeks' gestation, roughly the same time that Braxton-Hicks contractions become clinically evident.
This widening of the lower uterine segment is responsible for two clinical phenomena. First, it explains the apparent upward migration of a low lying placenta during the latter phases of pregnancy as the lower uterine segment between the placenta and cervix widens. Second, with a placenta that is implanted in the lower uterine segment, stretching of this area may cause shearing between the unyielding placenta and the placental bed, which changes as the lower uterine segment develops.
This phenomenon explains the fact that patients with placenta previa begin to bleed at about 34 weeks' gestation when the lower uterine segment begins to develop. The lower uterine segment is also that portion of the corpus that must dilate during parturition, thinning as the muscle of the corpus shortens and thickens. Because it is thin and avascular, this part of the uterus makes it a good location for cesarean section incisions. The dilation of the cervix enhances the primarily transverse orientation of the fibers in this area, thereby creating little tension on the closure line.
Innervation of the Uterus and Adnexa The uterus receives its nerve supply from the uterovaginal plexus Frankenhauser's ganglionwhich lies in the connective tissue of the cardinal ligament Fig.
The adnexal structures receive their innervation from nerve fibers coursing along the ovarian blood vessels. These latter fibers are derived primarily from the tenth thoracic segment. Nerves of the female genital tract.
The uterovaginal plexus contains fibers that are derived from two sources. It receives sympathetic and sensory fibers from the tenth thoracic through the first lumbar spinal cord segments. These nerves travel through the superior hypogastric plexus along the inferior hypogastric nerve to reach the pelvic inferior hypogastric plexus.
- Hip Bone Anatomy or Pelvic Bone[Ilium-Pubis-Ischium]
The second input comes from the second, third, and fourth sacral segments and consists primarily of parasympathetic nerves, which reach the pelvic plexus through the nervi erigentes. Clinically there appear to be no significant afferent fibers from the uterus and cervix in these sacral nerves. Injection of anesthetic agents into the paracervical tissues, transection of the superior hypogastric plexus presacral neurectomyand segmental blockade of the tenth thoracic through first lumbar spinal nerves all are effective in alleviating the pain of uterine contraction and cervical dilation, while low caudal or saddle anesthesia that blocks the sacral segments is not.
The autonomic nervous system modulates the smooth muscle contractions of most viscera, and its action on the uterus has been clinically useful in the inhibition of uterine activity. There are unmyelinated nerve fibers visible within the wall of the uterus, and although most end in the smooth muscle of the uterine blood vessels, some seem to terminate on smooth muscle cells of the myometrium. There has been one report of a band of specialized muscle cells that run from the cervix to the cornu of the uterus, which, on morphologic grounds, was thought to be a conduction system, but the function of the tissue has not been studied.
Histochemical techniques show presumptive adrenergic nerves within the myometrium, separate from the blood vessels of the uterine wall, which are numerous near the cervix and sparse in the corpus? There is general agreement that the parasympathetic nervous system has little effect on the activity of the myometrium. The parasympathetic fibers that do go to the uterus primarily supply the smooth muscle of vascular walls.
Each of these tubes is connected to the lateral pelvic wall by a mesentery destined to become the broad and cardinal ligaments. Vessels that run within this mesentery become the ovarian, uterine, and vaginal vessels and are interconnected by an anastomotic arcade that runs through the adnexus and along the lateral margin of the uterus and vagina see Fig.
The uterine artery originates from the internal iliac artery. It usually arises independently from this source but may have a common origin with either the internal pudendal or vaginal artery.