L1 Defining the pelvic region Flashcards
What are the 4 bones that together make the pelvis?
- 2 innominate bones: ilium, ischium and pubis
- sacrum (formed by fusion of the 5 sacral vertebrae)
- coccyx (formed by 4 coccygeal vertebrae)
What are the features of the innominate bones? (5)
iliac fossa
ischial spine
ischial tuberosity
inferior ramus of pubis bone
superior rams of pubis bone
Components of the articulated pelvis (8)
L5
intervertebral disc
posterior sacral foramina
sacroiliac joint (under ligament)
sacrum
sacrococcygeal joint
coccyx
pubic symphysis (=interpubic disc + ligaments)
Name the ligaments of the pelvis (3)
sacroiliac ligament
sacrotuberous ligament
sacrospinous ligament
Ligaments of the pelvis: sacroiliac
between the sacrum and the ilium
has an anterior and posterior component
Ligaments of the pelvis: sacrococcygeal
between the sacrum and the coccyx
Ligaments of the pelvis: sacrocpinous
between the ischial spine and the sacrum/coccyx
Ligaments of the pelvis: sacrotuberous
posterior to the sacrospinous
between the lateral aspect of the sacrum +coccyx onto medial margin of the ischial tuberosity
Perineum
refers to what?
the space located at the pelvic outlet and inferior to the pelvic diaphragm (i.e. muscles of the pelvic floor)
Perineum
what does it describe?
narrow region between the thighs
Perineum
shape and boundaries?
diamond shaped surface extending from the mons pubis (in females) to the medial surface of the thighs and posteriorly to the gluteal folds
Perineum
what splits it into two?
a transverse line joining the 2 ischial tuberosities
Perineum
what are the 2 triangles called?
urogenital and anal triangles
Perineum
what does the midpoint of the transverse line define?
the perineal body
Perineum
what happens at the perineal body?
the convergence of several sphincter and perineal muscles
Perineum
anatomy (9 labels)
pubic symphysis
inferior pubic ligament
ischial tuberosity
perineal membrane
deep perineal pouch
opening for urethra
pubic arch
obturator foramen
inf pubic ramus
Perineum
what does the deep perineal pouch enclose? (4)
urethra
vagina, in females
glands, such as bulbourethral (Cowper) glands in males
perineal muscles that act as sphincters, such as compressor urethrae or urethrovaginal sphincter in females
Perineum
what does the superficial perineal pouch enclose? (4)
urethra
vagina in females; root of penis in males
glands, such as Bartholin in females (the equivalent to Cowper glands in males)
perineal muscles that provide support to the external genitalia, such as the bulbospongiosus or ischiocavernosus muscles
What is the pelvic brim formed by?
promontory and ala (wing) of sacrum
right + left linea terminals:
- arcuate line
- pectineal line
What are the borders of the pelvic cavity?
posterior - sacrum/coccyx
anterior - pubic symphysis
inferior - pelvic floor
superior - pelvic brim
lateral - obturator internus m
What are the contents of the pelvic cavity?
reproductive organs/tracts
bladder
rectum
The pelvic musculature is composed of muscles that do what 2 things?
line the wall
line the floor
Pelvic musculature
which line the wall?
piroformis
obturator internus
Pelvic musculature
which line the floor?
coccygeus
levator ani (iliococcygeus, pubococcygeus and puborectalis)
The pelvic wall
Piriformis
from the anterior surface of the sacrum; through the greater sciatic foramen i.e. over the ischial spine; inserts onto the greater trochanter of femur
The pelvic wall
Obturator internus
from the internal surface of the obturator membrane; through the lesser sciatic foramen i.e. below the ischial spine; also inserts onto the greater trochanter of femur
The pelvic floor - 1 (5 muscles)
puborectalis muscle
pubococcygeus muscle
iliococcygeus muscle
coccygeus muscle
piriformis muscle
The pelvic floor - 2
Coccygeal
from the ischial spine to the inferior end of the sacrum + coccyx
The pelvic floor - 2
Iliococcygeus
from the tendinous arch - a line extending from the ischial spine to the posterior aspect of the pubic bone - to the annococcygeal body
The pelvic floor - 3
Pubococcygeus
from the posterior aspect of the pubic bone and inserting to the coccyx (lateral fibres) or merging with the contralateral fibres of the same named muscle (medial fibres)
The pelvic floor - 3
Puborectalis
a continuous muscle that originates from the posterior aspect of the pubic bone and slings behind the rectum
Blood supply & drainage
Arteries
anterior division of internal iliac, providing several branches, e.g. uterine, vesical or internal pudendal
Gonadal, from abdominal aorta, supplying the gonads
Blood supply & drainage
Veins
internal iliac, to common iliac veins
gonadal, to IVC or L renal vein
Nervous control
Somatic plexuses (L4-Co)
subdivided into:
lumbosacral (L4-S4 <=note: joined by lumbar L4/5)
coccygeal (S4-Co)
function as motor or sensory e.g. sciatic nerve, sup/inf gluteal, pudendal nerve
Nervous control
Visceral plexuses
Paravertebral/Prevertebral
sympathetic/parasympathetic/visceral fibres
erection/ejaculation e.g. inf hypogastric plexus
Lumbosacral trunk (4)
superior gluteal
inferior gluteal
sciatic
pudendal
Visceral plexuses: parasympathetic flow
pelvic splanchnic nerves (S2-4)
Visceral plexuses: sympathetic flow
sacral sympathetic trunk
superior and inferior hypogastric plexuses
Posterior pelvis (gluteal) (3)
sciatic nerve
pudendal nerve
gluteal vessels
- superior
- inferior
Pudendal nerve (diagram with 5 labels)
dorsal nerve of clitoris
deep perineal nerve
pudendal nerve
sacrotuberous ligament
