Presentation on theme: "WINDSOR UNIVERSITY SCHOOL OF MEDICINE"— Presentation transcript:
1 WINDSOR UNIVERSITY SCHOOL OF MEDICINE DEPARTMENT OF ANATOMYPelvis and PerineumDr. SREEKANTH THOTA
2 Pelvis Introduction Bones and Features of the Pelvic Girdle Pelvic wallPelvic nervesPelvic arteriesPelvic veinsPelvic lymph nodes
3 PelvisPelvis is the part of the trunk infero posterior to the abdomen and is the area of transition between the trunk and the lower limbs.PerineumThe perineum is inferior to the floor of the pelvic cavity; its boundaries form the pelvic outlet. The perineum contains the external genitalia and external openings of the genitourinary and gastrointestinal systems
5 Subdivision of Pelvis The pelvis is divided into two regions The superior region is the false pelvis (greater pelvis) and is generally considered part of the abdomen .The true pelvis (lesser pelvis) is related to the inferior parts of the pelvic bones, sacrum, and coccyx, and has an inlet and an outlet.
7 Lesser pelvisBelow the pelvic brimAbove is opened into the abdominal cavityBelow is closed by the pelvic diaphragmGreater pelvisAbove the pelvic brimForms the lowest part of the abdominal cavity
8 Bones and Features of the Pelvic Girdle In the mature individual, the pelvic girdle is formed by three bonesRight and left hip bones:develops from the fusion of three bones, the ilium, ischium, and pubis.Sacrum: formed by the fusion of five, originally separate, sacral vertebrae.
10 Pelvic inletThe pelvic inlet is somewhat heart shaped and completely ringed by bone .Posteriorly, the inlet is bordered by the body of vertebra S1, which projects into the inlet as the sacral promontoryLaterally, a prominent rim on the pelvic bone continues the boundary of the inlet forward to the pubic symphysis, where the two pelvic bones are joined in the midline.
12 Pelvic outletThe diamond-shaped pelvic outlet is formed by both bone and ligaments.Two ligaments-the sacrospinous and the sacrotuberous ligaments-are important architectural elements of the walls because they link each pelvic bone to the sacrum and coccyx . These ligaments also convert two notches on the pelvic bones-the greater and lesser sciatic notches-into foramina on the lateral pelvic walls
20 Diagonal conjugate: The distance from the promontory of the sacrum to the lower margin of the pubic symphysis. Also call ed false conjugate.True conjugate: radiographic measurement of the distance from the upper margin of the symphysis pubis to the sacral promontory. It is usually 1.5 to 2 cm less than the diagonal conjugate.
21 Procedure used in measuring the diagonal conjugate
23 The gynecoid type, present in about 41% of women, is the typical female pelvis. The android type, present in about 33% of white females and 16% of black females, is the male or funnel-shaped pelvis with a contracted outlet.The anthropoid type, present in about 24% of white females and 41% of black females, is long, narrow, and oval shaped.The platypelloid type, present in only about 2% of women, is a wide pelvis flattened at the brim, with the promontory of the sacrum pushed forward.
24 Pelvic wall Structure of the Pelvic Walls 1.Anterior Pelvic Wall 2. Posterior Pelvic Wall3. Lateral Pelvic Wall4. Inferior Pelvic Wall, or Pelvic Floor
25 Anterior Pelvic WallThe anterior pelvic wall is the shallowest wall and is formed by the bodies of the pubic bones, the pubic rami, and the symphysis pubis.It participates in bearing the weight of the urinary bladder.
29 Lateral Pelvic WallThe lateral pelvic wall is formed by part of the hip bone below the pelvic inlet, the obturator membrane, the sacrotuberous and sacrospinous ligaments, and the obturator internus muscle and its covering fascia
31 Pelvic DiaphragmThe pelvic floor is formed by the bowl- or funnel-shaped pelvic diaphragm, which consists of the coccygeus and levator ani muscles and the fascias.The floor of the pelvis supports the pelvic viscera and is formed by the pelvic diaphragm.It is incomplete anteriorly to allow passage of the urethra in males and the urethra and the vagina in females.
33 Pelvic Diaphragm 1. Levator Ani Muscle A.Anterior fibers: levator prostatae or sphincter vaginae form a sling around the prostate or vagina and are inserted into a mass of fibrous tissue, called the perineal body, in front of the anal canal.B.Intermediate fibers:Puborectalis forms a sling around the junction of the rectum and anal canalPubococcygeus passes posteriorly to be inserted into a small fibrous mass, called the anococcygeal body
35 Puborectalis muscleThe puborectalis forms a puborectal sling, the tonus of which is responsible for maintaining the anorectal angle (perineal flexure).Puborectalis portion is important in maintaining fecal continence immediately after rectal filling or during peristalsis when the rectum is full and the involuntary sphincter muscle is inhibited (relaxed).
36 Pelvic DiaphragmC. Posterior fibers: The iliococcygeus is inserted into the anococcygeal body and the coccyx.2. Coccygeus Muscle(ischio-coccygeus):This small triangular muscle arises from the spine of the ischium and is inserted into the lower end of the sacrum and into the coccyxNerve supply: Fourth and fifth sacral nerve (pudendal nerve)
37 Main Action of Pelvic Diaphragm The levatores ani muscles of the two sides form an efficient muscular sling that supports and maintains the pelvic viscera in position.They also have an important sphincter action on the anorectal junction, and in the female they serve also as a sphincter of the vagina.The levator ani must relax to allow urination and defecation
38 Injury to the Pelvic Floor Injury to the pelvic floor during a difficult childbirth can result in the loss of support for the pelvic viscera leading to uterine and vaginal prolapse, herniation of the bladder (cystocele).
40 Arteries of the Pelvis Common Iliac Artery External Iliac Artery The following arteries enter the pelvic cavity:Internal iliac arterySuperior rectal arteryOvarian arteryMedian sacral artery
41 Internal iliac arteryThe internal iliac artery originates from the common iliac artery on each side, approximately at the level of the intervertebral disc between LV and SI and lies anteromedial to the sacro-iliac joint.
42 Branches of the anterior trunk 1.Umbilical artery: superior vesical artery2.Inferior vesical artery3.Middle rectal artery4.Uterine artery5.Vaginal artery6.Obturator artery7. Internal pudendal artery8.Inferior gluteal artery
47 VeinsPelvic veins follow the course of all branches of the internal iliac artery except for the umbilical artery and the iliolumbar artery.On each side, the veins drain into internal iliac veins, which leave the pelvic cavity to join common iliac veins situated just superior and lateral to the pelvic inlet
50 Sacral PlexusThe sacral plexus lies on the posterior pelvic wall in front of the piriformis muscle .It is formed from the anterior rami of the fourth and fifth lumbar nerves and the anterior rami of the first, second, third, and fourth sacral nerves . The fourth lumbar nerve joins the fifth lumbar nerve to form the lumbosacral trunk.
53 Pudendal nerve (Imp)Branches to the pelvic muscles, pelvic viscera, and perineum:The pudendal nerve (S2, 3, and 4)It passes between the piriformis and coccygeus muscles and leaves the pelvis through the lower part of the greater sciatic foramen.It crosses the spine of the ischium, and reenters the pelvis through the lesser sciatic foramen.
55 Pudendal canalThe pudendal canal (also called Alcock's canal) is an anatomical structure in the pelvis through which the internal pudendal artery, internal pudendal veins, and the pudendal nerve pass.
56 Pudendal nerve blockThe anesthesia is produced by blocking the pudendal nerves near the ischial spine of the pelvis.A pudendal block is usually given in the second stage of labor just before delivery of the baby.It relieves pain around the vagina and rectum as the baby comes down the birth canal.It is also helpful just before an episiotomy .