Defining The Pelvic Region Flashcards
•The four bones that together* make the pelvis (os coxa/ hip bone):
1. Two innominate bones: ilium, ischium and pubis
The innominate bones, also known as the hip bones or os coxae, are the fused bones of the pelvis either side of the sacrum. The bone comprises the ischium, pubis and ilium which are fused to each other in the acetabulum and are part of the appendicular skeleton
2. Sacrum, formed by the fusion of the 5 sacral vertebrae
3. Coccyx, formed by the fusion of the 4 coccygeal vertebrae
The innominate bones
The primary joints of the pelvis are the
1. sacro-iliac joints ; The sacroiliac joint is a secondary cartilaginous joint
2. pubic symphysis; The pubic symphysis is a fibrocartilaginous disc
During standing, Weight is transferred from the axial skeleton to the
ilia via ligaments.
During the sitting, Weight is transferred from the axial skeleton to the
the ischial tuberosities (aka), the sitting bone
The pelvic brim
The pelvic brim is the edge of the pelvic inlet and its formed by the;
1. Promontory and ala (wing) of the sacrum (White/black line)
2. Right + Left linea terminalis:
a) Arcuate line (blue line) - Marks the transition between the wing and the body of the ilium and also form part of the border of the pelvic inlet.
b) Pectineal line (green line)
These are bonny landmarks associated with the ilium.
Ligaments of the pelvis
1. Sacroiliac
2. Sacrococcygeal
3. Sacrospinous
4. Sacrotuberous
Sacroiliac ligament
between the sacrum and the ilium, has an anterior and posterior components
Sacrococcygeal ligament
between the sacrum to the coccyx
Sacrospinous Ligament
between the ischial spine and the sacrum/coccyx
Sacrotuberous
posterior to the sacrospinous; between the lateral aspect of sacrum + coccyx onto medial margin of ischial tuberosity
The perineum
•Refers to the space located at the pelvic outlet and inferior to the pelvic diaphragm (ie muscles of the pelvic floor)
- It can be said to describe the narrow region between the thighs
- Diamond-shaped surface extending from the mons pubis (in females) to the medial surface of the thighs and posteriorly to the gluteal folds
• A transverse line joining the two ischial tuberosities splits the perineum into two triangles:
1. Urogenital
2. anal triangles
- The midpoint of this line defines the perineal body
- The perineal body sees the convergence of several sphincter and perineal pouch muscles
Male perineum
Perineal Spaces
The space bounded above by the perineal membrane and below by the superficial perineal fascia and containing the root structure of the penis or clitoris.
The arrangement of the fascial layers in the pelvis * create two potential spaces- the superficial and deep perineal spaces.
But- they are not empty spaces, they each contain certain structures. *details of which you do not need to know for 203.
Superficial perineal pouch
• Superficial perineal pouch is a space between the perineal fascia and the perineal membrane.
It contains:
•Males: Root (bulb and crura) of the penis and ischocavernosus and bulbospongiosus
•Females: Clitoris and ischocavernosus and bulb of vestibule (bulbospongiosus), greater vestibular gland
•Urethra
•Superficial Transverse perineal muscle
•Pudendal Vessels
Deep perineal pouch
• Deep perineal pouch is deep to the perineal membrane.
It contains:
- Males: Bulbourethral glands, dorsal neurovasculature of the penis
- Females: Dorsal neurovasculature of the clitoris
•Urethra and external urethra sphincter
•Ischioanal fat pads
•Deep Transverse perineal muscle- maybe more of a smooth mass in females- associated with the perineal body.
Borders of The pelvic cavity (true)
1. Posterior – sacrum/coccyx
2. Anterior – pubic symphysis
3. Inferior – pelvic floor
4. Superior – pelvic brim
5. Lateral – obturator internus muscle
Contents of the pelvic cavity (true)
1. Reproductive organs/tracts
2. Bladder
3. Rectum
Muscles that line the wall of the pelvis
1. Piriformis
2. Obturator internus
-muscles that line the floor of the pelvis
- Coccygeus
- Levator ani (iliococcygeus, pubococcygeus and puborectalis)
Arteries of the Anterior division of internal iliac supply
1. Superior artery
2. vesical artery
3. inferior vesical artery
4. uterine artery
4. vaginal artery
5. obturator artery
6. internal pudendal artery
7. middle rectal, inferior gluteal) artery
Arteries of the posterior division of internal iliac supply
1. Iliolumbar artery
2. lateral sacral artery
3. superior gluteal artery
Gonadal artery
The gonadal arteries are paired vessels that usually originate from the abdominal aorta at the level of second lumbar vertebra. In 5-20% of cases, the gonadal artery has a high origin (superior to L2) and in 5-6% of cases it originates from the main or accessory renal artery.
Internal iliac vein supplies
to common iliac veins to take deoxygenated blood to the inferior vena cava.
Gonadal vein carries deoxygenated blood to the
IVC or L renal vein
Somatic nerve plexuses in the pelvis
- Runs from L4-Coccygeal.
- responsible for motor and sensory functions, and subdivided into;
1. Lumbosacral (L4-S4 <=Note: joined by lumbar L4/5)
2. Coccygeal (S4-Co)
e.g. sciatic nerve, sup/inf gluteal, pudendal nerve
Visceral nerve supply to the pelvis
- Visceral means organs
- These nerves give autonomic innervation to the surrounding orgarns
1•Parasympathetic flow:
Pelvic splanchnic nerves (S2-4)
2•Sympathetic flow:
- Sacral sympathetic trunk
- Superior and Inferior hypogastric plexuses
Pudendal nerve
The pudendal nerve traverses through the greater and lesser foramen to enter the pudendal canal. It gives rise to the inferior rectal, perineal branches, posterior scrotal/labia branches and dorsal nerve to the penis/clitoris.
gretaer and lesser sciatic formina
pubic tubercle
Pubic symphysis
Obturator membrane
Obturator membrane is a tough, thin fibrous sheet which covers the obturator foramen of hip bone. It is superiorly perforated and creates a channel known as the obturator canal through which the obturator vessels and nerves travel across towards the medial section of the thigh.
anterior superior iliac spine
Greater trochanter of the femur
Ischial tuberosity and ischial spine
What goes through the internal and external schiatioc
The following structures pass through the lesser sciatic foramen: Internal pudendal artery and vein.
