week 8 anatomy pelvis

pelvis functions

bear/transfer weight
attachement point
protects urinary/reproductive structures
supports bladder, uterus, peritoneum

ilium

hip bone

ilium parts

iliac crest, iliac fossa, ASIS, AIIS, PSIS, PIIS
(see separate quizlet for picture labeling)

pubis

the medial anterior portion of the pelvis

pubis parts

pubic crest/tubercle
superior and inferior ramus

ischium

the lower, posterior portion of the pelvis

ischium parts

ischial ramus, ischial tuberosity, ischial spine

greater and lesser sciatic notches

separated by the ischial spine

acetabulum

socket for the head of the femur created by all 3 coxae

obturator foramen

opening in hip bone formed by the pubic and ischial rami
-membrane covers this (looks closed in the human body)

pelvic inlet

superior pelvic aperture
-pelvic brim

anterior border of pelvic inlet

pubic symphis

lateral border of pelvic inlet

iliopectineal line

posterior border of pelvic inlet

sacral promontory

pelvic outlet

inferior pelvic aperture

pelvic outlet anterior border

the pubic arch

pelvic outlet lateral border

ischial tuberosity and the sacrotuberous ligament

pelvic outlet posterior border

the tip of the coccyx

pubic arch (subpubic angle)

created by inferior rami

false pelvis (greater pelvis)

Superior to the true pelvis
-larger

true pelvis (lesser pelvis)

smaller and inferior
-where the true pelvis viscera sit

male pelvis

sacrum and coccyx point anteriorly
-deeper pelvic cavity
-higher iliac crest
pubic arch 60-70 degrees

female pelvis

sacrum pointing inferiorly to open up the cavity
-shallow pelvic cavity
-wider and shorter pelvis
pubic arch 80-90 degres
-overall larger structures due to childbirth

lumbosacral joint

between L5 and S1
-cartilaginous --> symphysis
-fibrocartilage disc separates the two bones
-z joint = synovial
-last vertebral joint

sacroccygeal joint

cartilaginous-->symphysis
-two bones separated by a fibrocartilage disc
-stabilized by anterior and posterior sacroccygeal ligaments

sacroiliac joints

anterior and posterior joints
stabilized by anterior, posterior, and interosseous sacroiliac ligaments

anterior sacroiliac joint

synovial
-between auricular surfaces of sacrum and ilium
-more movement in this area

posterior sacroiliac joint

fibrous syndesmosis
-between tuberosities of the bones
-rough surface joined by connective tissue

interosseous sacroiliac ligaments

bounds of tissue connecting bones that are not very distinct, general versions of a ligament

pubic symphysis

cartilaginous --> symphysis
-superior and inferior pubic ligaments

superior pubic ligament

attaches to the pubic tubercles on each side of the body
-stabilizes pubic symphysis

inferior pubic ligament

attaches between the two inferior pubic rami
-stabilizes pubic symphysis

inguinal ligament

ASIS to pubic tubercle

sacrotuberous ligament

ilium/sacrum to ischial tuberosity

sacrospinous ligament

lateral sacrum to the ischial spine

greater sciatic foramen

pelvic opening formed by the greater sciatic notch of the hip bone, the sacrum, and the sacrospinous ligament
-pudendal nerve goes through here

lesser sciatic foramen

pelvic opening formed by the lesser sciatic notch of the hip bone, the sacrospinous ligament, and the sacrotuberous ligament
-pudendal nerve also goes through here

pelvic cavity

continuous with the abdominal cavity
-superior boundary: pelvic inlet

pelvic cavity contents

ureters, bladder, rectum, pelvic genital organs, blood vessels, lymphatics and nerves
some inferior abdominal viscera

pelvic cavity superior boundary

pelvic inlet

pelvic cavity anterior boundary

pubic bones

pelvic cavity lateral boundary

os coxae
-priformis muscle
-obturator membrane
-obturator interns muscle

pelvic cavity posterior boundary

sacrum/coccyx

pelvic cavity floor

pelvic floor
-separates pelvis from perineum

piriformis muscle

deep to gluteus, lateral hip rotator
- goes to ilium and spans backwards
-goes to greater sciatic foramen

obturator membrane

covered by obturator internus

obturator internus muscle

spans across obturator foramen and goes to the femur, it is a lateral rotator

peritoneum

drapes down from abdomen and lays over pelvic viscera
-doesnt wrap the inferior viscera

pelvic fascia

between peritoneum and muscular pelvic walls/floor
-provides routes for vessels

parietal pelvic fascia

lines internal/deep surface of muscles

visceral pelvic fascia

ensheath pelvic organs

pelvic floor musculature functions

-close inferior outlet of pelvis
-support viscera
-roles in micturition, defecation, sexual intercourse
-help maintain continence
-resists increased intra-abdominal pressure
-pierced by rectum, urethra, and vagina in females

pelvic floor musculature

levator ani
-puborectalis
-pubococcygeaus
-iliococcygeus

puborectalis

looks like a slingshot
-two muscles connected by a junction
-next to the rectum

pubococcygeus

slightly more lateral to the rectum

iliococcygeus

looks more like a fan
farthest from the rectum

pelvic diaphragm

levator ani and coccygeus

coccygeus

more posterior to iliococcygeus, attaches to coccyx and sacral bone

anorectal angle

puborectalis will pull the rectum forward and constrict it when you are in a sitting position
-sitting with your knees up and butt to the floor relaxes this muscle and the rectum

blood supply of the pelvis

common iliac artery --> internal iliac artery --> obturator artery, internal pudendal artery, middle rectal artery, and vesicle artery

obturator artery

supplies the pelvic floor and bones in this area
-goes through obturator membrane

internal pudendal artery

main supply to perineum

middle rectal artery

supplies to rectum and glands in male reproductive system

vesical arteries

supplies bladder, uterus in females

pelvic venous plexuses

drain into internal iliac vein
-main drainage site for pelvis

other pelvic venous drainage

superior rectal vein --> inferior mesenteric vein --> hepatic portal vein
-the hepatic portal vein is associated with drainage of small/large intestines, but also drains part of the rectum

lymphatic system of pelvis

sit around corresponding arteries
-many interconnecting nodes means that you can remove them without impairment
-also means that there can be metastases in any directions, tricky for cancer removal

lymphatic pelvis lymph nodes

external iliac lymph nodes
internal iliac lymph nodes
sacral lymph nodes
common iliac lymph nodes
-all darin to cistern chyli

somatic innervation of the pelvis

sacral plexus (L4-S4)
-sciatic nerve
-pudendal nerve
-posterior femoral cutaneous nerve
-superior and inferior gluteal nerves

sciatic nerve

L4-S3
-innervate the lower extremities
-split into fibular and tibial nerves, which are two nerves in one sheath

pudendal nerve

S2-S4
-weave through the greater and lesser sciatic foramen

pudendal nerve somatic motor innervation

distal vagina, levator ani, coccygeus, external (voluntary) urethral & anal sphincter

pudendal nerve somatic sensory innervation

distal vagina, external genitalia/skin around anus/anal canal/perineum

posterior femoral cutaneous nerve

sensory innervation to the posterior thigh and gluteal region

superior and inferior gluteal nerves

innervates the muscles of the buttock/gluteal region

coccygeal plexus

coccygeal nerves +S4-S5 roots

ilioinguinal nerve

L1
-somatic motor: abdominals
-somatic sensory: upper/medial thigh

genitofemoral nerve

L1-L2
-somatic motor: cremaster muscle
-somatic sensory: external genitalia (scrotum, mons pubis), proximal anterior thigh

sympathetic function of the pelvis

-inhibits peristalsis

-inhibits contraction of bladder

-stimulation contraction of genital organs during orgasm

-stimalates ejaculation in males (Point and Shoot)

parasympathetic function of the pelvis

-stimulates peristalsis
-encourages contraction of bladder/micturition
-stimulates erectile bodies for erection

autonomic plexuses of the pelvis

superior hypogastric plexus and inferior hypogastric plexus

superior hypogastric plexus

lumbar splanchnic nerves _pelvic splanchnic nerves + visceral afferent fibers
-R & L hypogastric nerves are formed by this plexus

inferior hypogastric plexus

hypogastric nerves (sympathetic) + pelvic splanchnic nerves + visceral afferent fibers

ureters

muscular ducts that exit the hilum and travel to the bladder to bring urine
-peristalsis in the ureter muscles bring the urine to the bladder
-cross over common iliac artery and vein when descending
-enters bladder on posterior wall
-flap valves

flap valves

located where ureters enter the bladder, encourage one directional flow so we don't have reflux/backflow of urine into the ureters

urinary bladder location

lesser pelvis when it is empty, greater pelvis when it is full

female bladder

bladder is anterior to the uterus, and sits just deep to the pubic bone
-order: pubic bone, bladder, vaginal canal

parts of urinary bladder

apex, fundus, body, neck, trigone, bladder bed, detrusor muscle, internal urethral sphincter

trigone

triangular shaped region of the bladder where the ureters empty into, urethra also exits here

bladder bed

most inferior surface
-not covered by the peritoneum, sits on the pelvic diaphragm

detrusor muscle

muscle in the bladder wall, does the contracting

internal urethral sphincter

involuntary smooth muscle
-controlled by ANS, not concious

external urethral sphincter

skeletal muscle, voluntary, conscious control

urinary bladder blood supply

vesical artery off internal iliac artery
drainage from internal iliac vein

urinary bladder sympathetic innervation

lumbar splanchnic nerves to hypogastric plexuses
-inhibitory to bladder wall, constricts urethral sphincter

urinary bladder parasympathetic innervation

pelvic splanchnic nerves and inferior hypogastric plexus
-stimulates contraction of bladder wall, relaxation of internal urethral sphincter

urethra in males

internal urethral orifice of bladder to external urethral orifice (glans penis)

internal urethral orifice males

deeper, around the neck of the bladder and composed of smooth muscle
-ANS control
-prevents entrance of semen into the bladder/reflux of urine

external urethral orifice males

more superficially located, skeletal striated muscle for conscious control

parts of male urethra

intramural, prostatic, membranous, spongy