Pelvis Flashcards
Anatomy: Pelvis res & Bones
perineum
located between the thighs nd represents most inferior part of pelvic outlet.
Contains structures that support the urogenital and gastrointestinal systems,
anatomical boundaries of perineum
Anterior; pubic symphysis posterior: tip of coccyx laterally: inferior pubic rami and inferior ischial rami and sacrotuberous ligament Roof: pelvic floor Base: skin and fascia
boundaries of anal triangle
Coccyx, sacrotuberous ligament and line between ischial tuberosities
Contents of nail triangle
Anal aperture.
External anal sphincter muscle
Ischioanal fossa (fat & connective tissue. Extend from skin of anal region to pelvic diaphragm)
Nerve supply of perineum
pudendal nerve: supplies whole perineum with somatic fibres
Urogenital triangle boundaries
pubic symphysis
ischiopubic rami
line between ischial tuberosities
Associated with structures of urogenital system: external genitalia and urethra
Layers of urogenital triangle
deep perineal pouch perineal membrane superficial peroneal pouch perineal fascia skin
Deep perineal pouch
potential space between deep fascia of pelvic floor and perineal membrane
Contains urethra, external urethral sphincter and vagina
Perineal membrane
layer of tough fascia, perforated by urethra and vagina
provides attachment for muscles of external genitalia
superficial perineal pouch
potential space between perineal membrane and superficial perineal fascia
Contains erectile tissue that forms clitoris.
Muscles: ischiocavernosis, bulbospongiosus and superficial transverse perineal muscles
Location of Bartholin’s glands
Perineal fascia
continuity of abdominal fascia that has 2 components: superficial and deep fascia
Deep fascia; coverei superficial perineal muscles and protruding structures
Superficial fascia has superficial and deep layer
Skin of urogenital triangle
urethral and vaginal orifices open out onto skin
perineal body
irregular fibromuscular masss
located at junction of urogenital and anal triangles.
contains skeletal muscle, smooth muscle, and collagenous and elastic fibres
Perineal body- attachments
Acts as a point of attachment for muscle fibres from pelvic floor and perineum itself
- levator ani
- bulbospongiosus muscle
- superficial and deep transverse perineal muscles
- external anal sphincter muscles
- external urethral sphincter muscle fibres
perineal body function
Point of attachment
Tear resistant body between vagina and external anal sphincter
Supports posterior part of vaginal wall against prolapse
perineum neuromuscular supply
Pudendal nerve (S2-S4) Internal pudendal nerve
sciatic foramen
greater and lesser sciatic foramen,
2 openings in posterior aspect of pelvis
Separated by Sacrospinous ligament
greater sciatic foramen
provides passageway for structures to pass from pelvis into gluteal region
greater sciatic foramen borders
superior: anterior sacroiliac ligament
posteromedial: sacrotuberous ligament
Anterolateral: greater sciatic notch of ilium
Inferior: Sacrospinous ligament and ischial spine
contents of greater sciatic foramen
divided into 2 by piriformis muscle
Suprapiriform
- superior gluteal artery and nerve
- superior gluteal nerve
Infrapiriform foramen
- sciatic nerve
- pudendal nerve
- inferior gluteal artery and vein
- inferior gluteal nerve
- posterior femoral cutaneous nerve
- nerve to obturator interns
- nerve to quadratus femoris
Lesser sciatic foramen
provide a communication between perineum of pelvis and gluteal region.
Lies inferiorly to pelvic floor.
lesser sciatic foramen borders
superior; Sacrospinous ligament and ischial spine
Anterior: ischial spin, lesser sciatic notch, and ischial tuberosity
Posterior: sacrotuberous ligament
contents of lesser sciatic foramen
internal pudendal artery and vein
pudendal nerve
obturator interns tendon
nerve to obturator internis
articulations of hip bone
sacroiliac joint
pubic symphysis
hip joint
composition of hip bone
ilium, pubic and ischium
Form cup-shaped socket-> acetabulum,
Head of femur articulates with acetabulum-> hip joint
triradiate cartilage
separates ilium, pubis and ischium
Fusion only begins 15-17
what does body of ilium form
superior part of the acetabulum (acetabular roof).
Surfaces of wing of ilium
Inner surface: concave shape, produces iliac fossa
External surface: convex shape, attachments to gluteal muscles
Superior margin is thickened -> forming iliac crest.
Indentation on posterior aspect of ilium
greater sciatic notch
pubis
most anterior portion of hip bone
Consists of a body, superior ramus and inferior ramps
pubic body
located medially
Articulated with opposite pubic body at pubic symphysis
Superior aspect is marked by rounded thickening (pubic crest), extends laterally as tubercle
superior pubic ramus
extends laterally from body to form part of acetabulum
inferior pubic ramus
projects towards ischium
ischium
forms posteroinferior part of the hip bone,
Composed of body, inferior ramus and superior ramus
posteromedial projection of bone near junction of superior ramps and body
ischial spine
Ligaments attached to ischium
Sacrospinous
sacrotuberous
pelvic girdle
2 hip bones, sacrum and coccyx
articulations within pelvis
sacroiliac joints
sacrococcygeal symphysis
pubic symphysis
functions of pelvis
transfer of weight from upper axial skeleton to lower appendicular components of skeleton
provide attachment for several muscles and ligaments used in locomotion
contains and protects abdominopelvic and pelvic viscera
Greater pelvis
false pelvis
located superiorly
provides support of lower abdo viscera
lesser pelvis
true pelvis
located inferiorly
within lesser pelvis reside pelvic cavity nd pelvic visceral
junction between greater and lesser pelvis
pelvic inlet
pelvic inlet (+ borders)
marks boundary between greater and lesser pelvis
Determines size and shape of birth canal
Posterior: sacral promontory and sacral wings
lateral: arcuate lines on inner surface of ilium, and pectineal line on superior pubic ramus
anterior: pubic symphysis
Pelvic outlet (+borders)
located at end of lesser pelvis, and beginning of pelvic wall
Posterior: tip of coccyx
lateral: ischial tuberosities and inferior margin of sacrotuberous ligament
anterior: pubic arch
Adaptation for childbirth
gynaecoid pelvis
- oval-shaped inlet
- Less prominent ischial spines
- greater angled sub-pubic arch
- shorter and more curved sacrum
Sacrum
large bone located at terminal part of vertebral canal
bony landmarks of sacrum
formed by fusion of 5 sacral vertebrae
base: articulates superiorly with fifth lumbar vertebrae and assoc. intervertebral disc
apex: coccyx
auricular surface: located internally
dorsal surface of sacrum
coarse and rugged
central ridge of bone: median sacral crest
Immediate sacral crest
Lateral sacral crest
Median sacral crest attachment
supraspinous ligament
immediate sacral crest attachment
posterior sacroiliac ligaments
Lateral sacral crestattachment
posterior sacroiliac ligaments and sacrotuberous ligament
pelvic surface of sacrum
sacral promontory
- anterior projection of bone
- forms posterior margin of pelvic inlet
Muscular attachments of sacrum (anterior surface)
Piriformis
COccygeus
Illiacus
Muscular attachments of sacrum (posterior surface)
Multifidus lumborum
Erector spinal
vasculature of sacrum
median sacral artery (continuation of abdominal aorta)
lateral sacral arteries (arise from internal iliac artery)
-supply meninges, sacrum and surrounding muscles
coccyx joints
articulates with sacrum at fibrocartilaginous joint: sacrococcygeal symphysis
limited to minor flexion and extension, occurs passively during defecation & labour
Coccyx attachments
Gluteus maximus
levator ani
anococcygeal raphe
