THE PELVIS DR. J.K. GERALD, (MD, MSc.) DEC. 2014

THE PELVIS The pelvis is the region of the trunk that lies below the abdomen. The pelvic cavity is continuous with the abdominal cavity.

THE OSTEOLOGY OF PELVIS THE BONY PELVIS The bony pelvis is formed by 4 bones; 1) 2 Hip / Innominate bones Each hip bone is formed by fusion of 3 bones – ilium, ischium and pubis. 2) Sacrum formed by fusion of 5 sacral vertebrae 3) Coccyx formed by fusion of 4-5 coccygeal vertebrae

THE BONY PELVIS RIGHT HIP BONE SACRUM LEFT HIP BONE COCCYX

THE BONY PELVIS: JOINTS SACROILIAC JOINT SACROCOCCYGEAL JOINT PUBIC SYMPHYSIS

FUNCTIONS OF BONY PELVIS 1) To protect pelvic viscera 2) To support the weight of the body - transfer the weight of the upper body from the axial to the lower appendicular skeleton 3) Provides attachment for muscles 4) In females, it provide bony support for the birth canal

HIP BONE 2 hip bones are joined anteriorly at the pubic symphysis Hip bones articulate posteriorly with the sacrum at the sacroiliac joints Ilium, ischium and pubis are fused at the acetabulum

Acetabulum

HIP BONE Ilium Acetabulum Pubis Ischium

ILIUM PUBIS ISCHIUM Ala of ileum Body of ilIum Iliac crest Iliac fossa ASIS AIIS PSIS PIIS PUBIS Body of pubis Superior ramus of pubis Inferior ramus of pubis Pubic crest Pubic tubercle Subpubic angle ISCHIUM Body of ischium Ramus of ischium Ischial spine Ischial tuberosity

Body Ramus

Pubic tubercle Body

THE SACRUM Is made up of 5 fused sacral vertebrae Triangular in shape Is divided into central mass and lateral mass Lateral mass Central mass Tranverse ridge

SACRUM: ANTERIOR SURFACE Sacral promontory Ala Ala/wing Ant. sacral foramina Sacrococcygeal joint coccyx

SACRUM: POSTERIOR SURFACE Sacral canal Median crest Post. sacral foramina Sacral cornu Sacral hiatus

THE BONY PELVIS: LIGAMENTS

CLASSIFICATION OF PELVIS The pelvis is divided by the pelvic brim into 2 parts: 1) False pelvis (greater/major pelvis) Lies above the pelvic brim/inlet Part of abdominal cavity 2) True pelvis (minor/lesser pelvis) Lies inferior to pelvic brim/inlet Is the true pelvic cavity

TRUE & FALSE PELVIS False pelvis Abdominal cavity True pelvis

APERTURES OF TRUE PELVIS Two apertures: Pelvic inlet ( = pelvic brim) also called superior pelvic aperture 2. Pelvic outlet also called inferior pelvic aperture closed by the pelvic diaphragm / floor.

PELVIC INLET Pelvic inlet/brim is bounded by: 1. Superior margin of pubic symphysis 2. Pubic crest 3. Iliopectineal line 4. Anterior border of ala of sacrum 5. Sacral promontory

PELVIC INLET

MEASUREMENTS OF PELVIC INLET Four diameters of pelvic inlets 1) Anteroposterior (true conjugate) 2) Diagonal conjugate – can be measured clinically 3) Obstetric conjugate 4) Transverse diameter

DIAMETER OF PELVIC INLET Anterior-posterior ( True conjugate ) Measurement Extension Diameter Anterior-posterior ( True conjugate ) From the sacral promontory  superior margin of pubic symphysis 11.5 cm Diagonal conjugate Sacral promontory  inferior margin of the pubic symphysis 12.0 cm Obstetric conjugate Sacral promontary  nearest point on posterior surface of pubic symphysis 10.5 cm Transverse diameter The widest distance across pelvic brim 13.5 cm

MEASUREMENTS OF PELVIC INLET Obstetric conjugate is clinically important – It is shortest AP diameter through which the head must pass. But cannot be measured clinically. Diagonal diameter can be measured clinically through vaginal examination (PV Exam.)

Vaginal Examination to Determine Diagonal Conjugate

PELVIC OUTLET Diamond shaped Is bounded by: 1) Inferior margin of the pubic symphysis 2) Inferior rami of the pubis 3) Ischial tuberosities 3) Sacrotuberous ligaments 4) Tip of coccyx

MEASUREMENTS OF PELVIC OUTLET Three diameters of pelvic outlet are usually described: 1) Anteroposterior 2) Transverse (intertuberous) - can be estimated 3) Posterior sagittal

Pelvic outlet viewed from below Ischial tuberosity Pelvic outlet viewed from below

sacrococcygeal joint Pubic symphysis

DIAMETER OF PELVIC OUTLET Measurement Extension Diameter Anteroposterior diameter From lower margin of pubic symphysis  sacrococcygeal joint 12.5 cm Transverse diameter (intertuberous) Between the ischial tuberosities (Diameter > 8 cm – normal) 11 cm The largest diameter of pelvic outlet = AP diameter

ROTATION OF FETAL HEAD Widest diameter of pelvic canal changes from transverse diameter at pelvic inlet to AP diameter at pelvic outlet.

To obtain best fit of fetal head, the longest diameter of the fetal head passes through the widest diameter of the pelvis. Therefore the head must rotate during labour. Failure to rotate or unusual presentation of the fetal head will lead to cephalopelvic disproportion (CPD).

WALL OF PELVIC CAVITY The wall of the true pelvis is formed by: Anteriorly: pubic symphasis, body of pubis, pubic rami , rami of ischium and obturator membrane Laterally by ischial bone & sacrosciatic ligaments Posteriorly by sacrum & coccyx

WALLS OF PELVIC CAVITY 1) Anterior pelvic wall 2) Lateral pelvic wall 3) Posterior wall 4) Pelvic floor

PELVIC FLOOR Pelvic floor is formed by pelvic diaphragm which is composed of : 1) 3 Levator ani m. Puborectalis Pubococcygeus Iliococcygeus 2) Coccygeus m. (Ischiococcygeus)

LEVATOR ANI MUSCLES Contraction of levator ani muscles raises the entire pelvic floor Functions: 1) Control of urination & defecation Relaxation of levator ani muscle allow urination & defecation to occur 2) Support for viscera (eg. uterus, bladder) 3) Helps direct fetal head toward birth canal at parturition

LEVATOR ANI MUSCLES INJURY Levator ani muscles often stretch and can be injured during childbirth. Of these, pubococcygeus muscle is more commonly damaged These injuries may predispose women to greater risk of pelvic organ prolapse and urinary incontinence.

MALE VS FEMALE PELVIS There are a large number of differences between male and female pelvis. These differences are basically related to 2 factors : 1) In male - the heavier build and stronger muscles in the males accounting for the stronger bone structure and better defined muscle markings. 2) In females - comparatively wider and shallower pelvic cavity in female correlated with its role as bony part of the birth canal.

FEMALE MALE Bones are lighter, thinner False pelvis is shallow Subpubic angle Bones are lighter, thinner False pelvis is shallow Pelvic cavity is wide & shallow Pelvic inlet round/oval Pelvic outlet comparatively large Subpubic angle large Coccyx more flexible, straighter Ischial tuberosities more everted Bones heavier, thicker False pelvis is deep Pelvic cavity is narrow & deep Pelvic inlet heart-shaped + smaller Pelvic outlet comparatively small Subpubic angle more acute Coccyx less flexible, more curved Ischial tuberosities longer, face more medially

VARIATIATION OF PELVIC SHAPE Female pelvis shapes may be subdivided as follows 1. Normal and its variants - Gynaecoid – most common type , suited for delivery - Android – the masculine type of pelvis - Platypelloid – flat pelvis; short AP diameter & wide transverse diameter - Anthropoid – resembling that of anthropoid ape, AP diameter is greater than the transverse diameter (pelvic inlet) 2. Symmetrically contracted pelvis - That of a small women but with a symmetrical shape

- This deformity is caused by rickets (due to Vit D deficiency) 3. Rachitic pelvis - This deformity is caused by rickets (due to Vit D deficiency) - Sacrum is rotated so that the sacral promontory projects forward and coccyx tips backward - AP diameter of inlet is therefore narrowed but the outlet is increased 4. Asymmetrical pelvis - Asymmetry pelvis can be due to variety of causes such as scoliosis, poliomyelitis, pelvic fracture, congenital abnormality due to thalidomide etc Rachitic pelvis Asymmetrical pelvis

Caldwel and Moloy Classification - based on the diameters of the pelvic inlet: 1. Gynecoid (41%) 2. Android (33%) 3. Anthropoid (24%) 4. Platypelloid (2%)

APPLIED ANATOMY 1. Fractures of the Pelvis APPLIED ANATOMY 1. Fractures of the Pelvis - Usually brought about by direct trauma. - Secondary hemorrhage is common cause of death. - Associated with damage to pelvic viscera. 2. Uterine and Vaginal Prolapse - Due to injury to pelvic floor via difficult childbirth.

Fractures of Pelvis

FEMALE PELVIC VISCERA

Female Pelvic viscera: Ovaries Fallopian tubes Uterus Ureters Urinary bladder Urethra External genital

UTERUS Thick, muscular organ Divided into 3 parts: -fundus, body and cervix. Composed of 3 layers: endometrium, myometrium, and perimetrium.

Uterine cavity Fundus Body Cervical canal Cervix

FALLOPIAN TUBES 10-14 cm in length, <1 cm in diameter Isthmus - 1 mm in diameter - perfect spot for tubal ligation. Ampulla - 6mm in diameter - fertilization occurs here as well as most ectopics .

LIGAMENTS Round Ligament: Fibrous and muscle tissue Anterior to the fallopian tubes They extend laterally, cross the external iliac vessels, and enter the internal inguinal ring, and insert in the labia majora. Sampson’s artery; a branch of the uterine artery, runs along the length of the round ligament.

LIGAMENTS Broad Ligament: Double reflection of the peritoneum, draped over the round ligaments. Cardinal Ligament: Found at the base of the broad ligament. Provides the main support for the uterus and cervix. It attaches to the cervix and extends laterally, connecting to the endopelvic fascia.

LIGAMENTS Uterosacral Ligaments: Provide minor cervical support. Originate from the upper posterior cervix, travel around the rectum bilaterally, and fan out to attach to the 1st - 5th sacral vertebrae.

Pouch of Douglas / Rectouterine pouch vesicouterine pouch Peritoneum uterus Pubic symphysis coccyx

Pouch of Douglas: a.k.a Rectouterine pouch. An extension of the peritoneal cavity between the rectum and the post. wall of the uterus. In women it is the deepest point of the peritoneal cavity. As it is the furthest point of the abdominopelvic cavity in women, it is a site where infection and fluids typically collect.

OVARIES They rest in the ovarian fossa, immediately adjacent to the iliac vessels and the ureters. Supported along the lateral pelvic sidewalls by the: Ovarian ligaments: attaching to the posterolateral aspect of the uterus, Mesovarium: anastomotic region of the uterine and ovarian vessels, and Infundibulo-pelvic ligament (IP Ligament) a.k.a suspensory ligament of ovary. Reflections of the broad ligament attaching the ovaries to the lateral pelvis.

URETERS Ureters originate in the renal calyxes and insert into the inferior bladder at the trigone. Lie deep to peritoneum, closely applied to the posterior abd. wall in the upper part, and to the lateral pelvic part in the lower part. Dimensions: length – 25cm, diameter – 3mm. Careful attention to ureters path in the pelvis is essential for dissection in gynecologic surgery.

URINARY BLADDER It has 4 parts: Apex Base (post. surface) Superior surface 2 Inferolateral surfaces The apex is directed towards the top of the pubic symphysis

PELVIS: BLOOD SUPPLY Majority originates from the internal iliac artery (aka: hypogastric artery). Additional supply comes from the ovarian arteries, the inferior mesenteric artery, and the external iliac artery.

BRANCHES OF INTERNAL ILIAC ARTERY

Ovarian arteries Ovarian veins: Originate directly from the aorta, inferior to the renal arteries. Most frequently identified at the IP ligament. Ovarian veins: Left ovarian vein drains into the left renal vein Right ovarian vein drains directly into the inferior vena cava.

Venous drainage of the ovary Lt. renal vein Inf. vena cava Lt. ovarian vein Rt. Ovarian vein LCIV RCIV Rt. ovary Lt. ovary uterus

FEMALE EXTERNAL GENITALIA = VULVA

Urethral Catheterization in female Clitoris Catheter Urethral opening Vaginal opening Anus

APPLIED ANATOMY Cervical Cancer Uterine Cancer Uterine fibroids / myomas Ovarian Cancer Urinary bladder cancer Colorectal cancer Rectovaginal fistula & vesicovaginal fistula

Uterine fibroids

Surgical Removal of Uterine fibroids

CANCER OF CERVIX

CANCER OF OVARY

The End