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Pelvic floor and ischioainal fossa, These 4 bones are connected by 4…
Pelvic floor and ischioainal fossa
Pelvis
The bony pelvis with its joints and muscles form a strong basin-shaped structure (with multiple foramina),
The pelvis contains and protects the lower parts of the alimentary canal & urinary tracts & internal organs of reproduction.
Formed by
Bones
Sacrum and coccyx, which form the posterior wall.
Two hip bones, which form the anterior and lateral walls.
Muscles see the table
Joints
1- Anteriorly:Symphysis pubis (cartilaginous joint).
2- Posterolateral:Two Sacroiliac joints. (Synovial joins)
3- Posteriorly:Sacrococcygeal joint (cartilaginous),
Divided into two parts by the pelvic brim.
Above the brim is the False or greater pelvis, which is part of the abdominal cavity.
boundaries
:
• Posteriorly: •Lumbar vertebrae.
•Laterally: • Iliac fossae and the iliacus muscle.
•Anteriorly: Lower part of the anterior abdominal wall. It supports the abdominal contents.
Below the brim is the True or lesser pelvis. It has
Inlet.
Anteriorly: Symphysis pubis.
Posteriorly: Promontory of sacrum, ala of sacrum.
Laterally: Ileopectineal (arcuate) lines.
An Outlet.
Anteriorly: Symphysis pubis.
Posteriorly : Coccyx,
Anterolaterally: ischiopubic ramus
Posterolaterally: Sacrotuberous ligament.
A Cavity:
It is short, curved canal, with a shallow anterior wall and deeper posterior wall.
lies between the inlet and the outlet.
pelvic walls —> The walls are formed by bones and ligaments that are lined with muscles covered with fascia and parietal peritoneum. it has 4 walls:
Anterior
the
shallowest
wall formed by the posterior surfaces of the bodies of the pubic bones, the pubic rami, and the symphysis pubis.
Posterior
large
and formed by sacrum, coccyx , piriformis muscles and their covering of parietal pelvic fascia.
Lateral
Formed by:
1- Upper part of the hip bone below the pelvic inlet.
2-Obturator membrane
3- Obturator internus and its covering fascia (the obturator fascia).
4- Sacrotuberous ligament.
5- Sacrospinous ligament.
Inferior or floor.
Basin-like structure which supports the pelvic viscera and is formed by the pelvic diaphragm. It stretches across the true pelvis and divides it into: True (main) pelvic cavity above, which contains the pelvic viscera, & Perineum below which carries the external genital organs.
Pelvic Diaphragm
It is incomplete anteriorly (urogenital hiatus)to allow passage of the urethra in males and urethra and vagina in females.
It is formed by the levator ani and the coccygeus muscles and their covering fasciae on both sides.
Perineum is the region of the body below the pelvic diaphragm
• It is a diamond shaped area between the thighs
contents
:
Lower ends of urethra, vagina & anal canal External genitalia Perineal body & Anococcygeal body
•
Boundaries
:
Anteriorly
Mons pubis
Laterally
Medial surfaces of the thighs
Posteriorly
gluteal folds & superior end of the intergluteal (natal) cleft .
bony boundaries
:
Anterior
: Symphysis pubis.
Posterior
: Coccyx.
Lateral
: Ischiopubic rami, ischial tuberosities & sacrotuberous ligament.
By an imaginary line through two ischial tuberosities it is divided into:
1.Urogenital triangle anteriorly.
2.Anal triangle posteriorly.
Boundaries
:
Anteriorly
: Transverse line passing through the 2 ischial tuberosities.
Posteriorly
: coccyx
Laterally
: ischial tuberosity & sacrotuberous lig.
Contents
:
• Lower part of Anal canal • Ano-coccygeal body • Ischiorectal fossa on each side.
Ischiorectal/Ischioanal Fossa
A fascial lined wedge-shaped space on each side of the anal canal.
Boundaries
: Base: Skin of the perineum& sup.fascia. Medial wall: Levator ani & anal canal(external sphincter). Lateral wall: Ischial tuberosity&Obturator internus, covered with fascia. Posteriolateral:Sacrotuberous liga.&G.maximus muscle.
Contents:
Fat . Tough, fibrous bands(C.T) Pudendal nerve & internal pudendal vessels within the pudendal canal Inferior rectal nerve(br.from pudendal n) & vessels(inf.rectal) crossing the fossa to reach anal canal.
Pudendal Canal(Alcock's canal)
A fascial canal formed by obturator fascia, located on the lateral wall of the ischiorectal fossa
contents
:
Pudendal nerve(S2-S4):
It leaves the pelvis through the greater sciatic foramen between the piriformis and coccygeus muscles. It then hooks around the ischial spine and sacrospinous ligament and enters the perineum through the lesser sciatic foramen.
Internal pudendal vessels
CLINICAL NOTE Pudendal block:
To relieve perineal pain during childbirth, pudendal nerve block anesthesia may be performed by injecting a local anesthetic agent into the tissues surrounding the pudendal nerve near ischial spine .
Nerve
Somatic
: • Sacral plexus
•
Autonomic
:
•
Sympathetic
: Pelvic part of sympathetic trunk:
l-The 2 sympathetic trunks unite inferiorly in front of the coccyx and form a single ganglion (Ganglion Impar).
II- Superior & Inferior Hypogastric plexuses
•
Parasympathetic
: Pelvic splanchnic nerves (From S 2 , 3 & 4)
Lymphatics
The lymph nodes and vessels are arranged in a chain along the main blood vessels. Thus, there are
external iliac nodes, internal iliac nodes, and common iliac nodes
.
lymph from Common iliac nodes & the (Ovaries, uterine tubes & fundus of uterus) passes to Lateral aortic (paraortic) nodes.
Venous Drainage
Internal Iliac Vein
It collect tributaries corresponding to the branches of the
internal iliac artery.
joins the
external iliac vein
in front of the sacroiliac joint to form the
common iliac vein
Ovarian vein:
-Right vein drains into IVC Left vein drains into left renal Vein.
Arteries
Common iliac artery
I) Internal iliac artery(IIA): Arises in front of the sacroiliac joint It descends downward & backwards over the pelvic inlet. It divides at the upper border of the
greater sciatic foramen
into:
Anterior division supplies
:
Gluteal region
Perineum.
Pelvic viscera.
Medial (adductor) region of thigh
5.The fetus (through the umbilical arteries).
anterior division of the internal iliac artery are mainly visceral (i.e., they supply the bladder, rectum, and reproductive organs), but they also include parietal branches that pass to the thigh and buttocks
Visceral Branches
(all from anterior division)
1.Umbilical artery : Gives the superior vesical artery: The distal part of this artery fibrosed and forms the Medial Umbilical Ligament. 2. Inferior Vesical artery in male or vaginal in female: Internal pudendal In the male it supplies, the Prostate and the Seminal Vesicles. It also gives the artery of the Vas Deferens. Middle rectal artery. Internal pudendal artery: It is the main arterial supply to the perineum.
parietal Branches
1- Obturator
2- Inferior Gluteal
Posterior division Supplies:
Posterior abdominal wall.
Posterior pelvic wall.
Gluteal region.
Branches:
Iliolumbar.(parietal branches)
Lateral sacral (2 branches.) (parietal branches)
Superior gluteal. (parietal branches)
These 4 bones are connected by 4 joints and lined by 4 muscles.