T2 L10, Anatomy of the pelvic region Flashcards
What bones make up the pelvis?
2 innominate (hip) bones formed of the ilium, ischium, and pubis
A sacrum formed by the fusion of the 5 sacral vertebrae
A Coccyx formed by the fusion of the 4 coccygeal vertebrae
Name the pelvic joints
Sacro-iliac joints, a secondary cartilaginous disc (posterior)
Pubic symphysis, a fibrocartilaginous disc (anterior)
Where in the pelvis is weight transferred to when standing?
From the axial skeleton to the ilia via ligaments to the femur
Where in the pelvis is the weight transferred to when sitting?
To the ischial tuberosities
What is the pelvic brim?
The bony edges defining the pelvis
What forms the pelvic brim?
Promontory and ala (wing) of sacrum
The arcuate line (Inner surface of the ilium)
Pectineal line (Superior ramus and body of the pubis
What is the true pelvis vs the false pelvis?
The false pelvis is superior (superior pelvis) and is surrounded by iliac fossa portions of the coccygeal bones and the upper portion of the sacrum
The true pelvis is inferior (inferior pelvis) and is surrounded by the pubis and ischium portions of the coccygeal bones
Where is the sacroiliac ligament?
Between the sacrum and the ilium. It has an anterior and posterior component
Where is the sacrococcygeal ligament?
Between the sacrum and the coccyx
Where is the sacrospinous ligament?
Between the ischial spine and sacrum/coccyx
Where is the sacrotuberous ligament?
It’s posterior to the sacrospinous, between the lateral aspect of the coccyx onto medial margin of ischial tuberosity. It creates the sciatic foramen
What are some sex differences of the pelvis?
- Male is thicker and heavier
- The greater pelvis is shallower in females
- The lesser pelvis is narrow and deep in males and wide and shallow in females
- The pelvic inlet is heart shaped in males and oral in women
- The pubic arch is wider in females
- In males, the obturator foramen is round, in females it’s oval
- The acetabulum is smaller in females
What does the greater pelvis contain?
The abdominal viscera
What does the lesser pelvis contain?
The reproductive, urinary, and GI organs
What does the obturator internus muscle do?
It rotates the thigh internally
What is the obturator foramen for?
To allow passage of the obturator nerve, artery, and vein
What does the piriformis muscle do?
Rotates the thigh internally and abducts the thigh
What is the pelvic floor formed of?
The pelvic diaphragm consisting of the coccygeus (ischiococcygeaus) and levator ani muscles
What is the function of the pelvic floor?
To support the pelvic viscera
They resist rises in pressure when we cough
What is the Levator Ani formed of?
Puborectalis, Pubococcygeus, Iliococcygeus
Which spinal vertebrae innervates the Levator Ani?
S4
What happens when the Puborectalis muscle relaxes?
Allow for defecation
What is the perineum?
The space between the genital outlet ands the anus. It’s the convergence of several sphincter and perineal pouch muscles
The transverse lines there splits the 2 ischial tuberosities into the urinary and anal triangles
Why do males have a longer gonadal artery?
Because the testes are outside of the body
Which artery provides the main blood supply to the pelvis?
The internal iliac artery that splits from the aorta
Which vein mainly drains the pelvis?
The internal iliac to the common iliac veins
What is contained within the anterior division of the internal iliac artery?
Umbilical artery Obturator artery Superior visceral artery Inferior vesical/vaginal artery Uterine artery Middle rectal Internal pudendal Inferior gluteal
What is contained within the posterior division of the internal iliac artery?
Iliolumbar artery
Lateral sacral artery
Superior gluteal artery
Ovarian artery from Aorta
Medial sacral artery from the abdominal Aorta
Superior rectal artery from the inferior mesenteric
Which nerves innervate the pelvis?
The sacral and coccygeal nerves and part of the autonomic NS
They all function as motor or sensory
What is the somatic plexus divided into?
The lumbarsacral L4-S4 and coccygeal (S4-Co)
Where is the sacral plexus located?
On the posterolateral wall of the lesser pelvis
What are the main nerves of the sacral plexus?
Sciatic nerve
Pudendal nerve
Superior gluteal nerve
Inferior gluteal nerve
What does the sciatic nerve supply?
The leg and foot
What does the Pudendal nerve supply?
Sensory info to the genitalia, muscular branches to the perineal muscles, external urethral sphincter, and the external anal sphincter
It gives rise to the inferior rectal, perineal branches, posterior scrotal/labial branches, and dorsal nerve to the penis/clitoris
What does the Superior gluteal nerve supply?
The gluteal region
What does the Inferior gluteal nerve supply?
The gluteal region
Why is the Pudendal nerve known as the perineal nerve now?
Because pudendal nerve means shamed and they want to change that
What is the significance of the pelvic pain line?
Pain above it will be referred to the abdomen
Which nerves provide parasympathetic flow to the pelvis?
Pelvic splanchnic nerves S2-4
Which nerves provide sympathetic flow to the pelvis?
The sacral sympathetic trunk and superior and inferior hypogastric plexuses
