Lecture 14 - 16 Pelvis and Perineum Flashcards
What are the functions of the pelvis (2)?
Weight bearing
Attachment of lower limbs
Where does the head of the femur attach?
Acetabulum
What does the pelvis consist of?
2 x hip bones
1 x sacrum
1 x coccyx
Where do the pair of hip bones join anteriorly and posteriorly?
A - Pubic symphysis
P - Sacrum
What are the three parts of the pelvis?
Ilium, ischium and pubis
Where is the junction of the parts of the pelvis?
Acetabulum
What is the greater cavity surrounded by?
Ilium and upper sacrum
What is the lesser cavity surrounded by?
Soft tissue of pelvic floor
What is the pelvic brim/inlet
The junction between the greater and lesser pelvis
What is the function of the greater and lesser trochanter
They are where muscles that move the thigh outwards attach at the hip joint (abductors)
What does the head of the femur do
Create the “ball and socket joint” or hip joint with the pelvis
What are the anterior and posterior ends of the iliac crest?
Anterosuperior Iliac Spine
Posterosuperior Iliac Spine
What is the anteroinferior iliac spine adjacent to?
The acetabulum
What is the difference between the iliac tuberosity and the tubercle of the iliac crest?
- site of attachment of interosseous ligament
2. thickening of the central part of the iliac crest
What is the gluteal surface? What is attached to the gluteal surface?
Outer posterior surface of the ilum. The gluteal muscles
What is the iliac fossa? What is attached to the iliac fossa?
Inner concave surface. Iliacus
What type of joint is the pubic symphysis?
Cartilaginous
What is attached to the pubic tubercle?
Inguinal ligament
What is the pecten pubis and what is attached to it?
Sharp side running posteriorly from the pubic tubercle. Lacunar ligament
What is the obturator foramen bound by?
The pubis and ilium
What does the inferior pubic ramus join the ischial ramus to form?
Ischiopubic ramus
What is at the junction of the ilium and pubis?
Ileopubic eminence
What are the features of the ilium? (9)
- Anteroinferior iliac spine
- Anterosuperior iliac spine
- Iliac fossa
- Tubercle of iliac crest
- Iliac tuberosity
- Posterosuperior iliac spine
- Posteroinferior iliac spine
- Gluteal surface
- Auricular surface
What are the features of the pubis? (8)
- Pecten pubis
- Pubic tubercle
- Body of pubis
- Pubic symphysis
- Superior pubic ramus
- Inferior pubic ramus
- Ileopubic eminence
- Obturator foramen
What are the features of the ischium?
- Body
- Ischial tuberosity
- Ischial spine
What is attached to the ischial tuberosity?
Sacrotuberous ligament
What is above the ischial tuberosity?
Ischial spine
Where is the greater sciatic notch?
Between the PIIS and ischial spine
What does the greater sciatic notch transmit?
Piriformis
Where is the lesser sciatic notch?
Below the ischial spine
What does the lesser sciatic notch transmit? (4)
- Tendon of obturator internus
- Obturator nerve
- Internal pudendal vessels
- Pudendal nerve
What is the joint formed by the acetabulum and the head of the femur?
Acetabulofemoral joint
What is the acetabulofemoral joint supported by?
Capsule
Ligaments
Some pelvic muscles
What is the sacrum made of?
Five fused vertebrae
What is the median sacral crest?
Fused spines of sacral vertebrae
What does the anterosuperior margin of the sacrum form?
Sacral promontary
Does the sacral canal contain spinal cord?
No, it ends at L2, but it has spinal nerves + meninges
What is joined to the auricular surface of the sacrum?
Sacroiliac joint, the roughened area posterior is for the interosseous ligament
What is the coccyx
4 fused rudimentary vertebrae
What is the tip of the coccyx level with?
Pubic symphysis
What type of joint is the sacroiliac joint?
Synovial
What are the 3 joints of the pelvis
- Sacroiliac
- Lumbosacral
- Acetabulofemoral
What are the 7 ligaments of the pelvis
- Interosseous ligament
- Iliolumbar ligament
- Sacroiliac ligament
- Sacrotuberous ligament
- Sacrospinous ligament
- Inguinal ligament
- Lacunar ligament
What stabilises the lumbosacral joint?
Iliolumbar ligament which prevents L5 from slipping anteriorly and transmits some of the weight directly to the ilium, by passing the sacroiliac joint
What is the interosseous ligament posterior to?
Sacroiliac joint
What does the iliolumbar ligament join?
5th lumbar vertebra to iliac crest
Where does the anterior part of the sacroiliac ligaments run?
Sacrum to iliac fossa
What does the sacrotuberous ligament join?
Ischial tuberosity to the sacrum. Also a band which extend upwards to PSIS and PIIS
What does the sacrospinous ligament join?
Ischial spine to lateral sacrum and coccyx.
What is anterior to the sacrospinous ligament?
Coccygeus muscle
What does the sacrospinous and sacrotuberous ligament do?
Prevent rotation of the sacrum in the vertical plane.
What makes up the superior aperture of the lesser pelvis (pelvic brim or inlet)
- Pubic symphysis
- Pubic crest
- Arcuate line
- Pecten pubis
- Sacral promontary
- Sacral ala
What makes up the inferior pelvic aperture (pelvic outlet)
- Pubic symphysis
- Ischiopubic ramus
- Ischial tuberosity
- Sacrotuberous ligament
- Coccyx
What are the muscles of the pelvic wall
Obturator internus and piriformis
What are the muscles of the pelvic floor
Levator ani and coccygeus
What forms the tendinous arch below obturator foramen
Obturator fascia
What is levator ani comprised of? (4)
Iliococcygeus
Pubococcygeus
Puborectalis
Pubovaginalis
What are the attachments of iliococcygeus (4)
- Posterior half of tendinous arch
- Ischial spine
- Anococcygeal ligament
- Coccyx
What is pubococcygeus attached to (2)
- Back of body of pubic bone
2. Anterior half of tendinous arch
What is the role of puborectalis
Fecal continence
What does the puborectalis form
A sling around the anorectal junction
What does pubovaginalis or LEVATOR PROSTATE form
A sling that attaches to the walls of the prostate or vagina which then passes into the perineal body
What role does pubovaginalis play
Role in urinary contience as it also relates to sphincter urethrae
What does the anococcygeal ligament join
Coccyx to anal margin
What fibres insert into the anococcygeal ligament?
- Left and right iliococcygeus
- Pubococcygeus
- Puborectalis
- External anal sphincter
What does the pelvic diaphragm consist of (3)
- Levator ani
- Coccygeus
- Superior and inferior fasciae
What are the two divisions of the perineum?
Anal triangle and urogenital triangle
What are the anal triangle layers from superficial to deep (4.5)
Fatty superifical fossa Ischiorectal fossa (more lateral) Pudendal nerve and internal pudendal vessels Deep fascia (shared) (also external anal sphincter)
What runs in the ischiorectal fossa
Pudendal vessels and nerves which enter it through the lesser sciatic foramen and run in pudendal canal in lateral wall of the fossa
What is the origin of the pudendal nerve?
Ventral rami S2-4
What is the origin of the internal pudendal artery
Anterior trunk of the internal iliac
What does the internal pudendal vein drain?
Penis and inferior rectal vessels
Where does the internal pudendal vein drain into?
The internal iliac vein
What do branches of the pudendal nerve supply (above and below perineum)
Above: levator ani, external anal sphincter, lower anal canal
Below: Perineum and dorsal nerve of penis or clitoris
What are the layers of the urogenital triangle from superficial to deep?
Perineal body
Superficial fascia
Superficial perineal space
Perineal membrane
Deep perineal space or urogenital diaphram
Deep fascia (shared with pelvic diaphragm and urogenital diaphragm)
What does the urogenital diaphragm contain?
Urethral sphincter and deep transverse perineal muscle
What does the superficial perineal space contain?
- Bulbospongiosis
- Ischiocavernous
- Superficial transverse perineal muscles
What is the perineal body
Where fibres from transverse perineal muscles interlace at the midline
