[ Home ] [ Up ] [ Anterior Body Wall ] [ Embryonic Body Cavity ] [ Lunglecture ] [ Mediastinum ] [ Heart ] [ Autonomic NS ] [ Rotation of the Gut/Abdomen ] [ Abdominal-Peritoneal Cavities ] [ Glands ,Lymphoid Organs and Blood Supply ] [ Pelvic Cavity ] [ Posterior body wall ] [ Perineum ]
Fall 1999 Moore, pp 332-388
Lecture 19 Dr. C. Dlugos
PELVIC CAVITY AND ORGANS
Overview: An understanding of the pelvis and the organs contained within it is
essential in several medical disciplines such as gynecology, obstetrics, urology and
gastroenterology. The functions of the pelvis include protection of the viscera,
composition of the girdle by which the lower limb is attached to the axial skeleton, and
an attachment site for the external genitalia. This lecture should provide the student
with basic information concerning the pelvis, differences in the pelvis within the sexes,
and a general knowledge of the anatomy of the pelvic organs in males and females.
1. to learn the anatomy of the bony pelvis and what regions comprise the false and
the true pelvis
2. to be aware of sexual differences in the pelvis
3. to understand the anatomy of the pelvic diaphragm in the male and the female
4. to understand the anatomy of the pelvic organs in the male and the female
Pelvis:(Latin for basin), region of transition where the trunk and the lower limbs
meet, inferior portion of the trunk, contains pelvic cavity, the inferior portion
of the abdominopelvic cavity, below the pelvic brim.
1. The pelvis is divided into two parts (Moore Fig. 3.1. pp332-333):
a. the greater pelvis or pelvis major (false pelvis), between iliac
fossae, part of the abdominopelvic cavity proper
b. the lesser pelvis or pelvis minor (true pelvis), "obstetric
pelvis", boundaries : anterior (pubic symphysis), posterior (sacrum and coccyx) and
lateral (bodies of ischia).
2. Separation between the false and the true pelvis is the pelvic brim or inlet readily
discernable because of the presence of the linea terminalis or iliopectineal
line, an oblique ridge on the internal surface of the ilium which is continued on the
pubis. Most of these terms are review from first block.
3. Bony and cartilaginous constituents of the pelvis: (Moore Fig.3.2., p334)
a os coxae or hip bones: three bones which fuse at age 16-17, ilium, pubis, and
b. sacrum: five sacral vertebrae fuse together
(1) anterior and posterior sacral foramina, meet with anterior and posterior rami of
(2) large articulating surface for joining with os coxae
c. Ligaments which prevent sacrum from rotating on the sacroiliac joints and demarcate
the greater and lesser sciatic foramina
(1) sacrotuberous ligament : extends between sacrum and ischial
(2) sacrospinous ligament: extends between sacrum and ischial spine
d. Coccyx: 3-5 fused vertebrae
(1) may fuse to sacrum late in life
(2) partially closes pelvic outlet and functions as an attachment for muscles which
close pelvic diaphragm.
4. Pubic symphysis: fibrocartilage, unites two sides of pubic bones
5 . Acetabulum: head of the femur articulates with os coxae, point at which all
three bones comprising the hip bone meet. (Moore, Fig.3.2., 3.3., pp334-335).
The false pelvis you have already studied, it lies between the iliac fossa at vertebral
levels L5 and S1 and contains the ileum and the sigmoid colon. The true pelvis or pelvis
minor is situated between the pelvic inlet and pelvic outlet and contains the pelvic
organs such as the urinary bladder, rectum, and reproductive organs.
Regions of true pelvis:
Superior pelvic aperture (pelvic inlet): oval (female) or heart
shaped (male) opening, larger in females than in males, periphery is demarcated by linea
terminalis which separates the false from the true pelvis. The linea terminalis has a
pubic portion (pectineal line) and an illial portion, (arcuate line). This boundaries of
the inlet are; 1) anteriorly the pubic symphysis, 2) laterally, the linea terminalis and
3) posteriorly, the sacrum and the sacral promotory or the projection on the
ventral portion of the sacrum where it is connected to the last lumbar vertebrae.
2. Pelvic cavity: contains rectum, bladder, and reproductive organs. The walls
of the pelvic cavity are formed by the pubic symphysis anteriorly, the obturator internus
muscle laterally and the piriformis muscle posteriorly.
3. Inferior pelvic aperture (pelvic outlet): bounded
anteriorly by pubic symphysis, posteriorly by sacrum and coccyx, and laterally by ischial
tuberosities, diamond shaped, partially closed because of coccyx. Pelvic diaphragm
comprises this area.
Differences in the pelvis between sexes (Moore, Table p336).
1. In the female, the bones are more delicate, the female pelvis is less
massive, and the muscular impressions are less marked.
2. In the female, the ilia flare more laterally and the anterior iliac spines
are more widely separated causing a widening of the hips with respect to the male.
3. In the female, the superior aperture of the lesser pelvis is wider.
4. In the female, the subpubic angle (angle between the ischiopubic rami) is
wider (usually greater than 90°)
5. In the female, the sacrum is shorter, wider, and less curved
6. In the female, the acetabulum is smaller.
7. In the female, the pelvic inlet is round or oval with respect to the
heart-shaped pelvic inlet in the male.
Pelvic diaphragm: funnel shaped fibromuscular diaphragm comprised of two levator
ani and two coccygeus muscles. This diaphragm closes the pelvic outlet posteriorly . It is
open anteriorly where the urethra, vagina, and anal canal exit (Moore 3.5, p342-343).
Muscles:(Moore, Fig. 3.6. p344-345)
1. Levator ani: broad muscle which forms the hammock-like floor of the pelvis
and has several parts:
1. Pubococcygeus muscle:attaches on pubis, coccyx , and anococcygeal ligament
(the region where the two halves of pubococcygeus meet behind the rectum), the main
portion of the levator ani
2. Puborectalis muscle: lies deep to pubococcygeus and forms a supportive sling
around the rectum (Fig. 3.6., p344 and Fig. 3.7., p345).
3. Iliococcygeus muscle: thin muscle which attaches to the obturator fascia, the
ischial spine, the coccyx and anococcygeal ligament.
e. Innervation of the levator ani: branches of S3,4 supply the pelvic surface
and the perineal nerve (S2,3,4,) supplies its perineal surface.
2. Coccygeus (ischiococcygeus): smaller and less important, dorsal to
levator ani, attaches to ischial spine, sacrospinous ligament, and coccyx
Innervation:pudendal plexus from 4 and 5 sacral nerves
Functions of pelvic diaphragm (levator ani and coccygeus muscles):
1. supports pelvic viscera and closes pelvic outlet
a. In particular, a part of the diaphragm, the puborectal sling ( puborectalis
muscle ) holds the front portion of the anorectal junction anteriorly. This action takes
pressure from the external anal sphincter and supports the vagina and bladder in the
female and the bladder, seminal vesicles, and prostate in the male.
2. Resists the inferior thrust of increases in abdominal pressure (ie. coughing,
sneezing) for maintaining urinary continence.
3. Raises the pelvic floor and assists in urination and defecation.
4. Supports fetal head during uterine contractions during delivery.
Peritoneum: covers the superior portions of the pelvis (Moore, Fig. 3.15, p360,
Table 3.5., p388).
1. In males the peritoneum passed from the anterior body wall, superior to the
the pubic bone and covers the superior and part of the posterior surface of the urinary
bladder and superior tips of the seminal vesicles. It invaginates between the
bladder and the rectum as the rectovesicular pouch ,the most inferior extent of the
peritoneum in the male. It attaches to the anterior aspect of the rectum.
2. In females, the peritoneum takes the same course except that it forms a
shallow pouch between the bladder and the uterus, the vesicouterine pouch and the
deeper rectouterine pouch between the rectum and the uterus. In the female, the
rectouterine pouch is the most inferior extent of the peritoneum.
Fascia of the pelvis:
1. Visceral fascia:covers organs, binds the pelvic viscera to each other and to
the parietal fascia
2. Parietal fascia: covers the pelvic surfaces of muscles and lines the pelvic
a. superior parietal fascia is thickened at the neck of the urinary bladder to form the
pubovesicular ligament (female) and the puboprostatic ligament (male),
anchors neck of urinary bladder to the pubis. The pubovesicular ligament in the female,
attaches to the vagina as well. (Moore,Fig. 3.16., ,p360-61).
Spaces within the fascia
1. retropubic space: fascial plane between bladder and pubic symphysis which
allows for expansion of the bladder and access to the bladder and the prostate without
entering the peritoneal cavity.
Bladder (vesica urinaria) (Moore, Fig.3.61., p361).
1. Location: In adults the bladder is located within the pelvis minor in back of
the pubic symphysis. In infants, the bladder is located in the abdomen and descends into
the pelvis major at about age 6. The bladder does not reside in the pelvis minor until
2. Surfaces: superior (supports sigmoid colon and urethra), two inferiolateral
(cover levator ani), and posterior surfaces (fundus of the bladder)
3. Angles: four angles (a duct is attached to each), anterior (urachus),
posteriolateral angles (ureter), and inferior (urethra).
a. The smooth muscle of bladder is also called the detrusor muscle and consists of
three layers. It is thickened to form the internal urethral sphincter
b. The urinary trigone is that part of the bladder which is not formed embryologically
from the urogenital sinus. It consists of a triangular region demarcated by the entrance
to the two ureters (united as the interureteric fold) (Moore, Fig.3.17, p363) and the exit
of the internal urethral orifice which initiates the urethra.
5. Arterial Supply: In both sexes, the superior vesicular arteries,
supply the anteriosuperior portion of the bladder. In females, the vaginal artery
supplies the posterioinferior portion of the bladder whereas the inferior vesicular
artery supplies this region in males.
6. Innervation: Parasympathetic by way of the pelvic splanchnics and sympathetic
Rectum: begins superior to level of third sacral vertebrae, extends from sigmoid
colon to puborectalis muscle (Moore, Fig.3.30, pp386)
1. Peritoneal coverings: anterior and lateral surfaces of superior 1/3, anterior
aspect of middle 1/3, none of distal 1/3
2. Flexures: The rectum has three sharp curves or flexures as it follows the
sacrococcygeal curve - forms transverse rectal folds
3. Arterial Supply: The superior rectal artery( termination of inferior
mesenteric artery) and the middle rectal artery (from internal iliac artery) supply most
of the rectum. The inferior rectal artery supplies the anal canal.
4. Venous Drainage: Rectal venous plexus Two parts:
a. internal rectal venous plexus, drains mainly into superior rectal vein and enters
portal system through the connection between the superior rectal vein and the inferior
mesenteric vein. It communicates with the systemic system as well.
external rectal venous plexus drains into the superior rectal vein (portal
system), and the middle and inferior rectal veins (systemic
Anal Canal: from puborectalis to anus
1. Embryology The anal canal is comprised of two embryological regions. At the
pectinate line, (Sadler, Fig. 14.34 and 14.35) the hindgut (an endodermal derivative)
meets the ectoderm of the proctadeum. The pectinate line is demarcated by the distal end
of the anal valves and a transition in epithelial types from the simple columnar
epithelium of the gut to the stratified squamous epithelium of the epidermis.
a. Anal columns: longitudinal columns on walls of rectum contain branches of
superior rectal arteries
b. Anal valves: flaps below the columns
c. Anal sinuses: above valves, secrete mucus, help to expel feces
a. internal, involuntary circular smooth muscle, superior 2/3 of anal canal
b. external, voluntary, inferior 2/3 of anal canal
5 Arterial Supply: The superior rectal artery supplies the area superior to
pectinate line, and the inferior rectal artery supplies the area inferior to the pectinate
line. The middle rectal artery form anastamoses between the two parts.
6. Venous supply: Above the pectinate line, drainage to superior rectal vein,
below pectinate line, drainage into inferior rectal veins.
Two important factors in maintaining fecal continence are:
The support of the the 80° anorectal flexure by the puborectalis muscle
The relaxation of the terminal portion of the rectum or ampulla to accomadate fecal
Embryology: The ovaries and testes are the primary sex organs
ard are derived from the genital or gonadal ridges in close association with the
mesonephric kidneys. The mesonephric ducts detreriorate in the female and the uterine
tubes and uterus in the female are derived from the parmesonephric ducts. In males, the
vas deferens and epididymis is formed from the mesonephric ducts. (Sadler, Fig. 15.20.,
Ovaries: Almond shaped, oval bodies which produce ova (Moore, Fig.3.22, p370 and
Fig. 3.27., p377).
1. Ligaments of ovary
a. suspensory ligament: conveys ovarian vessels
b. ligament of the ovary: part of gubernaculum, thick region of connective
tissue attaching ovary to lateral wall of uterus
c. mesovarium: part of broad ligament attached to surface of ovary
2. Arterial Supply:ovarian artery with a strong anastamosis from the uterine
Uterus: Usually anteverted (tipped anteriorly), pear-shaped muscular organ between
bladder and rectum.(Moore,Fig.3.27., p377 , Fig. 3.22, p370 and Fig. 3.11.p 354).
Regions: The uterus consists of a 1)fundus, above the entry of the uterine
tubes 2) body, 3) isthmus, transitional region between body and isthmus and
4)cervix, the cylindrical inferior 1/3
Openings :uterine tubes, internal os (within uterus) and external os (uterus to
1. Broad ligament connects uterus, oviduct, and ovary to lateral pelvic
wall. Three distinct regions 1)mesosalpinx (covers oviduct), 2)mesovarium (suspends
ovary), 3) broad ligament proper (suspends uterus).
2. Round ligament: connects uterus to labia majora, remnant of the gubernaculum
(Moore, Fig.3.27., p377).
Arterial supply: uterine arteries, branch of internal iliac
Uterine Tubes: oviducts, no direct connection to ovary
Openings: The oviducts open laterally into the peritoneal cavity and medially into
Regions: 1) isthmus (medial constricted 1/3, close to uterus), the ampulla
(dilated portion which curves over ovary), and the infundibulum with fimbiae
Arterial Supply: uterine and ovarian arteries
Vagina: formed from the urogenital sinus, organ of copulation and birth,
musculomembranous tube or sheath, extends from cervix of the uterus to the vestibule of
the vagina, cleft between the labia minora. This organ passes through the urogenital
diaphragm and the pelvic diaphragm.
1.Fornix :spaces between vagina and cervix can be considered to have
anterior, posterior and lateral parts. The pulse of the uterine artery can be felt in the
Arterial supply: Vaginal artery, uterine artery, internal pudendal artery and
middle rectal artery.
Male Reproductive Organs of Pelvis: (Moore, Fig.3.21., p368).
Ductus Deferens: conducts sperm from epididymis, through inguinal ligament, to the
posterior surface of bladder. Here the ductus expands as the ampulla.
Arterial supply: artery to the ductus
Seminal Vesicles: posterior surface of bladder, superior to prostate, does not
store sperm but contributes to the semen. The duct of the seminal vesicle unites
with the ductus deferens at the base of the prostate to form the ejaculatory
Arterial Supply: artery to ductus deferens
Prostate: largest accessory gland of the reproductive system.
1. Prostatic utricle, region within urethra in the prostate which is homologous
to female uterus . Near the utricle on the posterior wall of the urethra or urethral
crest, the ejaculatory ducts open (Moore, Fig.3.17,p363.)
2. prostatic ducts, empty on prostatic sinuses on either end of urethral crest
3. Arterial supply: internal pudendal, inferior vesicular, and middle rectal
4. Venous drainage: prostatic venous plexus into internal iliac arteries
Arteries to pelvis
I. Aorta: ovarian and testicular arteries to gonads median sacral artery -supplies
sacrum (Moore, Fig. 2.75, p303)
II Internal iliac artery (Moore,Fig.3.10.Fig. 3.4. and Table 3.4. p353)
A. Parietal branches
Dorsal parietal branches:
1. iliolumbar: iliacus, psoas, and quadratus lumborum
2. lateral sacral:skin and muscles on dorsum of sacrum
3. superior gluteal:all gluteal muscles
4. inferior gluteal: supplies gluteus maximus and pelvic diaphragm
Ventral parietal branches:
1. Internal pudendal: stuctures of the perineum (sometimes arises form inferior
2. Obturator artery, may arise from external iliacs, supplies obturator muscles and
adductor compartment of the thigh
B. Visceral Branches:
1. Middle rectal artery:rectum, seminal vesicle, vagina, and prostate
2. Uterine artery: only in females, supplies uterus and gives off vaginal branch
(homologue to inferior vesicular artery in the male
a. vaginal artery: usually from uterine, female correlate to inferior vesicular
artery, gives off branch to urinary bladder and to vagina, anastamoses with uterine artery
3. umbilical artery: superior portion of the urinary bladder as superior
vesicular artery, , part is obliterated and forms medial umbilical ligaments.
4. inferior vesicular artery: only in males, posterioinferior portion of the
urinary bladder, seminal vesicles, and prostate. The artery to the ductus deferens is a
branch of the inferior vesicular artery.
Nerves of pelvis:(Table 3.3, p348)
1. Sacral plexus: formed by lumbosacral trunk (descending ventral rami of L4 and
L5 and ventral rami of S1-4).
a. Sciatic nerve (ventral rami of L4,5,S1,2,3)-largest nerve in body
b. Pudendal nerve (ventral rami of S2,3,4)-muscles of perineum, external anal
sphincter and is sensory to genitalia
c. Superior and Inferior gluteal nerves to gluteal region
d. nerves to the piriformis, pelvic diaphragm, and quadratus femoris
2. Coccygeal plexus-supplies parts of levator ani and coccygeus
3. Sympathetics-sympathetic chain ends at ganglion impar of coccyx
Parasympathetics-splanchnic nerves from S2,3,4