Pelvis and Perineum Flashcards
What bony landmarks make up the pelvic brim/ inlet?
Sacral promontory
Arcuate line of the ilium
Pubic crest
Pubic symphysis
Pubic tubercle
Ala of the sacrum
What are the bony features and ligaments which make up the pelvic outlet?
Inferior rami of pubis
Tip of coccyx
Inferior margin of pubic symphysis
Sacro-tuberous ligaments
What part of the pelvis are termed the true and false pelvis?
True - inferior
False - superior
Pelvic inlet is the junction between true and false
What type of joint is the sacroiliac joint?
Synovial plane joint
What type of joint is the pubic symphysis?
Secondary cartilaginous joint
What are the features of the female pelvis when compared to male?
Shallow greater pelvis, wide and shallow lesser pelvis, inlet is oval shaped, outlet is larger, subpubic angle is obtuse (Over 90), oval obturator foramen and small acetabulum
What are the features of the male pelvis when compared to female?
Deep greater pelvis, narrow and deep lesser pelvis, heart shaped inlet, smaller outlet, acute subpubic angle (less than 90), round obturator foramen and large acetabulum
What is the narrowest diameter of the pelvic inlet?
10.5cm - obstetrical conjugate diameter
Smallest area baby’s head has to pass through in childbirth
What is the narrowest diameter of the pelvic outlet?
13.5cm
What is A?
Piriformis muscle
What is B?
Obturator internus muscle
What muscle is present in the posterior wall of the pelvis?
Piriformis
What nerve network lies on the piriformis muscle?
Sacral plexus
What is A?
Urethral hiatus
What is B?
Vaginal canal
What is C?
Rectal hiatus
What is E?
Puborectalis
What is F?
Iliococcygeus
What is the perineal body?
Fibromuscular node lying in the midline of the perineum - provides an anchor point for several muscles
What is the anococcygeal body?
layered musculotendinous intersection of 2 halves of levator ani muscles
What are the 2 muscles which make up the majority of the pelvic floor?
Coccygeus
Levator ani - 3 paired separate muscles
What are the functions of the pelvic floor?
Resistance to increase in intra-pelvic/ abdominal pressure
Urinary and faecal continence
What is a cystocele?
Anterior vaginal prolapse - bladder bulges into vagina
What is a rectocele?
Posterior vaginal prolapse - rectum bulges into vagina
What is the distribution/ organs of the superior and inferior vesical artery?
Bladder, seminal gland and prostate in males
What is the origin of the superior and inferior vesical artery?
Anterior division of internal iliac
What is the origin of the uterine artery?
Anterior division of internal iliac
What organ does the uterine artery supply?
Uterus
What does the gonadal artery supply?
Testes and ovaries
What is the origin of the gonadal artery?
Abdominal aorta
What is the origin of the superior rectal artery?
Inferior mesenteric artery
What is the origin of the middle and inferior rectal artery?
Internal iliac artery
What is the origin of the vaginal artery?
Uterine artery
What is the main artery of the perineum and what is its origin?
Internal pudendal artery
Posterior division of the internal iliac
What is the origin of the obturator artery?
Internal iliac artery
What part of the rectum drains into portal circulation?
Superior rectal
What parts of the rectum drain into the systemic circulation?
Inferior and middle
Which venous plexus does the prostatic venous plexus communicate with on it’s posterior side?
Internal vertebral venous plexus
What spinal segment does ilioinguinal nerve originate from?
L1
Describe the course of the ilioinguinal nerve
Enters the inguinal canal at superficial inguinal ring to supply skin at root of penis in males and labia in females
Describe the course of the genitofemoral nerve
Originates from L1-2 and enters the deep inguinal ring
What structures n males are supplied by the genital branch of the genitofemoral nerve?
Cremaster muscle and anterior scrotal skin - involved in the cremasteric reflex
What segmental levels does the pudendal nerve arise from?
S2-4
What bony landmark is used when performing a pudendal nerve block in labour?
Ischial spine
Where do the sympathetic fibres of the pelvis arise from?
L1 and L2 via hypogastric nerve and terminal aspect of sympathetic trunk
Supply all internal pelvic organs
What do the sympathetic fibres supply in the pelvis?
Male - vas deferens, seminal vesicles, prostate and epididymis
Female - ovaries, uterus, fallopian tubes and vagina
Where do the parasympathetic fibres of the pelvis originate from?
Pelvic splanchnic nerves S2-4
All internal pelvic organs and innervate erectile tissues in males and females
What part of the autonomic nervous system is involved in ejaculation in males?
Sympathetic
What do the external iliac lymph nodes drain?
Bladder, uterus and prostate
What do the internal iliac lymph nodes drain?
Gluteal region, deep perineum and inferior pelvic viscera
What do the sacral lymph nodes drain?
Lower part of rectum and upper part of the anal canal
What do the common iliac lymph nodes drain?
3 main groups - external, internal and sacral lymph nodes
