Anatomy Flashcards
Outline the anatomy and blood supply to the female breasts.
Extends from lateral border of sternum to mid-axillary line, overlying ribs 2-6 and the muscles of the anterior thoracic wall
Retromammary space/bursa between breast and fascia overlying muscle (site for breast implants)
Nipple located over 5th intercostal space (in young women)
15-20 lobules radiate from nipple, delineated by septa of fibrous connective tissue extending from the skin to the underlying fascia (suspensory ligaments of Cooper)
—> tumours can shorten the ligaments, distorting the breast
Tumours causing oedema —> peau d’orange
Internal thoracic artery, intercostal artery, axillary artery (lateral thoracic artery & thoracoacromial arteries)
Axillary vein, internal thoracic vein, posterior intercostal veins (1: drains into braciocephalic/vertebral vein, 2-4: drain into superior intercostal vein, remaining: right breast -> azygos vein, left breast -> hemiazygos vein)
—> route for metastasis to lungs
Outline the embryological development of the ovaries.
8-9wks:
- mesonephric duct is degenerating
- paramesonephric duct —> uterine tube
- fused paramesonephric ducts —> uterus
- urogenital sinus —> bladder, lower parts of vagina, urethra
Outline the anatomy and blood supply to the ovaries and uterus.
Arteries:
- ovarian artery (branch of abdominal aorta) & ovarian vein (right drains into IVC, left drains into left renal vein)
- uterine artery (ant. division of internal iliac artery) & uterine vein
- vaginal artery
- internal pudendal vessels (ant. division of internal iliac artery)
Venous drainage of ovaries: pampiniform plexus —> ovarian vein
- right ovarian vein —> IVC
- left ovarian vein —> left renal vein
Ligaments:
- suspensory ligaments of ovary (superior)
- ovarian ligaments (medial —> lateral wall of uterus)
- broad ligament = peritoneal fold (mesentery of uterus - mesometrium, uterine tube - mesosalpinx, suspensory ligament of ovary - mesovarium) enclosing the uterus, uterine tubes, ovaries, and their neurovascular supplies
- uterosacral ligament (opposes anterior pull of round ligament, assists in maintaining anteversion of the uterus)
- round ligament (remnant of gubernaculum which reflects off the uterus and travels through the inguinal canal; drains the superficial inguinal lymph nodes)
Fundus of uterus enlarges during pregnancy to rise above the superior pubic ramus
What are the pouches present in the female abdomen?
Uterovesical pouch
Rectouterine pouch (pouch of Douglas)
note: pouch of Douglas accessible via posterior fornix of the vagina (culdo-centesis)
What are the axes of the female reproductive organs? How is the uterus orientated with respect to the other organs?
Axis of vagina
Axis of cervix
Axis of uterine body
Uterus is anteVerted with respect to the Vagina (tipped forwards)
Uterus is antefleXed with respect to the cerviX (tipped away from)
What are the different components of the uterine tubes?
Ovary —> Fimbriae —> Infundibulum —> Ampulla —> Isthmus —> Fundus of uterus
note: ostium of uterine tube means that the peritoneal cavity is open to the vagina and cervix (infection spread)
Describe the lymphatic drainage of the uterus.
Fundus of uterus —> aortic nodes & inguinal nodes
Ovary —> para-aortic nodes
Body of cervix —> external iliac nodes
Cervix —> internal iliac nodes & sacral nodes
What are the different ligaments which support the pelvic organs in the female?
Pubovesical ligament (around bladder)
Transverse cervical ligament = thickening at base of broad ligament; provides lateral stability to the cervix by attaching to the lateral walls of the pelvis
Uterosacral/rectouterine ligament = opposes anterior pull of round ligament; maintains anteversion of uterus (connects cervix and rectum)
How is the cervix examined? What structure is seen with a speculum?
Insert speculum into vagina and open blades once at external os
Presenting structure = anterior lip of external os of cervix
note: unless uterus is retroverted (tilted posteriorly); then the presenting structure would be the posterior lip of the external os
What is the bimanual examination? What is it assessing?
- Insert thumb and index finger of left hand to separate labia majora and insert index finger of right hand
- Palpate vaginal walls for obvious abnormalities
- Palpate uterus using right hand with left hand on abdomen (for pregnancy/irregularity)
- Place internal fingers in right fornix and press ovary using left hand in iliac fossa
Assesses uterus for: mobility, consistency, pain, regularity, position, size (usually size of plum; 10wks pregnant = orange)
Cervical fornices:
- anterior = bladder, recto-pubic space
- posterior (deepest) = pouch of Douglas, posterior fundus, uterosacral ligaments, posterior broad ligaments/ovaries
- lateral: broad ligaments
note: the fornices form a continuous recess of the cervix
note: posterior fornix is usually deepest; more of posterior part of cervix enters the vagina compared to the anterior part of the cervix
Describe the features of the female external genitalia. What glands are present, and what clinical problems involve these glands?
Labia majora = encloses pudendal cleft
Labia minora:
- clitoris
- bulbus of vestibule (orifices of urethra, vagina, greater & lesser vestibular glands)
Greater vestibular/Bartholin’s glands = secrete mucus to lubricate vagina; homologous to bulbourethral glands in male
- Bartholinitis = inflammation of Bartholin’s gland
- Bartholin’s cyst = blockage of Bartholin’s gland —> infection —> abscess
Lesser vestibular/Skene’s glands = ?female ejaculation
Outline the innervation of the uterus, vagina, and perineum.
Inferior 1/5 of vagina somatic innervation —> pudendal nerve
Superior 4/5 of vagina & uterus —> uterovaginal plexus
Perineum —> pudendal & ilioinguinal nerves (anaesthetised using pudendal nerve block)
note: pudendal nerve exits pelvis via greater sciatic foramen and enters the perineum via the lesser sciatic foramen (travels through pudendal canal)
note: pain afferents vary depending on whether structure is above or below the pelvic pain line (line through peritoneum at point of descent of uterus and other structures into peritoneum)
ABOVE = inferior thoracic lumbar spinal ganglia (~T1-T11) - sympathetic
BELOW = S2-S4 spinal ganglia - parasympathetic
Contrast the osteology of the male and female pelves.
FEMALE (gynecoid) MALE (android)
- round inlet - heart-shaped inlet
- straight side walls - curved side walls (funnelling)
- ischial spines not - prominent ischial spines
too prominent
- well-rounded greater - narrow greater sciatic notch
sciatic notch
- well-curved sacrum - sacrum not well-curved
- sub-pubic arch > 90 degrees - sub-pubic arch 50-80 degrees
What are the pelvic outlet and pelvic inlet?
PELVIC OUTLET = distance between ischial tuberosities
PELVIC INLET = anteroposterior diameter (capacity of birth canal)
- bispinous diameter = distance between ischial spines
What is the difference between the true pelvis and the false pelvis?
False/greater pelvic = superior to the linea terminalis (no obstetric relevance)
Linea terminalis = arcuate line pecten pubis pubic crest
True/lesser pelvis = inferior to linea terminalis (complete bony canal, solid & immobile)
How can the anteroposterior diameter of the pelvis be assessed?
Anatomic conjugate cannot be measured
Obstetric conjugate (minimum diameter) = measured from sacral promontory to midpoint of pubic symphysis (posterior; not palpable)
- ~10cm
- only assessed by imaging
Diagonal conjugate (approximation of min. diameter but measurable) = measured from sacral promontory to inferior border of pubic symphysis (palpable)
- ~11.5cm
- assess by introducing 2 fingers into vagina to palpate sacral promontory and note where one’s hand under the edge of the pubis is
note: anterior = bony demarcation (pubic arch)
posterior = ligamentous demarcation (sacrotuberous ligament)
How does the appearance of the ovaries vary with age?
Pre-pubertal = indistinguishable from PCOS ovaries i.e. lots of cystic areas
Post-pubertal = enlarged and multifollicular
Post-menopausal = ~1.2-5.8cm cubed, lack of follicles, difficult to visualise
What are the anatomical relations of the vagina?
Anterior:
- base of bladder
- urethra (fused to ant. vaginal wall)
Posterior:
- rectum
- anal canal
- pouch of Douglas (most superiorly)
Lateral:
- ureters (just superior to lateral fornices, therefore can sometimes palpate ureteric stones from the vagina)
- broad ligaments (superiorly)
- levator ani muscles (inferiorly)
- greater vestibular glands (inferiorly)
What are the anatomical and surface borders of the perineum? How can the perineum be subdivided?
ANATOMICAL:
- anterior = pubic symphysis
- posterior = tip of coccyx
- anterolateral = ischiopubic ramus (inferior pubic rami, inferior ischial rami)
- lateral = ischial tuberosities
- posterolateral = sacrotuberous ligament
- posterior = tip of coccyx
- roof = pelvic floor
- base = skin & fascia
SURFACE:
- anterior = mons pubis/base of penis
- posterior = superior end of intergluteal cleft
- lateral = medial surface of thighs
Subdivided into anterior urogenital triangle & posterior anal triangle
What is the structure and contents of the anterior urogenital triangle?
Fills gap of pubic arch, stretching between converging ischiopubic rami
Superior fascia —> sphincter urethrae (striated muscle) —> Inferior fascia (perineal membrane)
CONTENTS: roots of external genitalia
- bulbourethral glands (above perineal membrane)
- superficial perineal pouch (urine collects here if urethra is ruptured below perineal membrane)
- Male = superficial transverse perineal membrane + bulbospongiosus + ischiocavernosus
- Female = openings of urethra & vagina
What is the structure and contents of the posterior anal perineum?
Triangle between ischial tuberosities on each side and the coccyx
CONTENTS:
- anus
- levator ani (attached to obturator fascia)
- ischiorectal fossae (continuous with perineal space; may become infected; pudendal nerve passes on lateral wall - S2, 3, 4 keeps your guts off of the floor)
What structures can be palpated in a vaginal examination?
Anterior:
- base of bladder
- urethra
- pubic symphysis
Posterior:
- rectum (prolapsed uterine tubes/ovary)
Lateral:
- ovaries
- uterine tubes
- side wall of pelvis (ischial spines)
Apex: ?anteverted or retroverted
What is the function of the muscles of the perineum in the male?
Bulbospongiosus = helps expel last drops of urine and maintains erections
Ischiocavernosus = compresses veins (helps maintains erections)
Superficial transverse perineal muscle
What is the white line of the pelvic floor?
Arcus tendineous fascia pelvis
Marks line of attachment of special fascia associated with pelvic viscera
What is the pelvic floor, and what is its function? How does it differ from the pelvic diaphragm? What is the blood supply of the pelvic floor?
Muscular & fibrous tissue diaphragm filling the lower part of the pelvic canal
- closes the abdominal cavity
- defines upper border of perineum
- supports the pelvic organs
- pierced by urethra, vagina, & rectum
- pelvic diaphragm + perineum
- contributes to continence (position of neck of bladder)
- contributes to childbirth (rotation of foetal head)
- contributes to truncal stability (diaphragm & muscle contraction)
- sphincter action on rectum & vagina
- resists increased intra-abdominal pressure (coughing, defecation, heavy lifting, etc.)
Pelvic diaphragm = levator ani + coccygeus (over sacrospinous ligament)
Arteries = branches of pos. trunk of internal iliac artery
- pudendal artery
- vaginal artery
- inferior rectal artery (anastomoses with middle rectal artery)
What is the levator ani, and what is its function?
Paired muscles forming three slings of muscle, extending from pos. aspect of pubic bone (fascia over obturator internus & ischial spines), attached to pelvic side wall (ischial spine & white line)
Innervation = pudendal nerve, perineal nerve, inferior rectal nerve (S2-S4)
Origin:
- pubococcygeus = posterior aspect of superior pubic ramus
- iliococcygeus = arcus tendineus (white line) & ischial spine
Insertion:
- pubococcygeus = coccyx
- iliococcygeus = anococcygeal raphe & coccyx
Ant. fibres = around prostate/vagina
Intermediate fibres = around rectum (puborectalis) and into anococcygeal body (pubococcygeus)
Pos. fibres = to anococcygeal body & coccyx (iliococcygeus)
Function = elevation of pelvic floor
note: deep muscles of pelvic floor
note: ischiococcygeus also elevates the pelvic floor
originates from ischial spine and inserts into the side of the coccyx & lower sacrum
Where is the perineal body located? What function does it have?
Fibromuscular node at junction of ant. & pos. perineum
Midpoint of line joining the ischial tuberosities
Point of attachment of:
- anal sphincters
- bulbospongiosus
- superficial transverse perineal fibres
- fibres of levator ani
In women:
- supports the lower posterior part of the vaginal wall against prolapse
- forms dense attachment for the two halves of the levator ani muscles in the midline
- tear-resistant body between vagina and external anal sphincter (but stressed by evolution of large foetal head size)
When performing a digital rectal examination, what muscles are responsible for the contraction around the examiner’s finger?
External anal sphincter contracts around finger
Puborectalis pulls finger anteriorly
Outline the composition of the scrotum and testis. What is the blood supply and lymphatic drainage of the testes?
Scrotum = cutaneous sac developed from labioscrotal folds which contains:
- testis (kept at reduced temp. to support gametogenesis
- epididymis
- spermatic cord (1st part)
Testis = surrounded by tunica vaginalis and enclosed by the tunica albuginea; organised into lobules by fibrous septae
ARTERIES = direct branches of abdominal aorta
VEINS = right testicular vein —> IVC
left testicular vein —> left renal vein
LYMPHATIC DRAINAGE = para-aortic nodes
Where does the spermatic cord run?
inguinal canal & superficial inguinal ring
Deep inguinal ring ———————————————–> posterior border of testis
What are the contents of the spermatic cord?
3 arteries (and corresponding veins), 3 nerves, 3 coverings, 3 other things
ARTERIES =
- testicular artery
- cremasteric artery
- artery to vas deferens
NERVES =
- genital branch of genitofemoral nerve
- cremasteric nerve
- autonomics
COVERINGS =
- external spermatic fascia (remnant of aponeurosis of external oblique)
- cremasteric muscle & fascia (remnant of internal oblique & transversalis taken during descent)
- internal spermatic fascia (remnant of transversalis fascia)
OTHER =
- ductus deferens
- pampiniform plexus
- lymphatics
What is the purpose of the pampiniform plexus?
Reduce the temperature of the blood in the testicular artery via concurrent heat exchange
Keeps the testes below body temp. for gametogenesis
Contrast the innervation and lymphatic drainage of the testes and scrotum.
Innervation:
- testes = testicular plexus (originates from para-aortic ganglia)
- ant. surface of scrotum = lumbar plexus
- pos. surface of scrotum = sacral plexus
Lymphatic drainage:
- testes = para-aortic nodes (therefore malignancy often not detected until tumour burden is great —> intra-thoracic nodes —> cervical lymph nodes)
- scrotum = superficial inguinal nodes
Describe some disorders of the scrotum. How can they be diagnosed?
Swelling of the scrotum:
- HYDROCOELE = serous fluid in tunica vaginalis (painless)
- VARICOCOELE = varicosities of pampiniform plexus
- SPERMATOCOELE = epididymal cyst (unconnected segment of efferent tubules, therefore clear fluid) or retention cyst (segment marginally connected to rete testis, therefore contains degenerate products of spermatogenesis)
- HAEMATOCOELE = blood in tunica vaginalis
- indirect inguinal hernia
Differentiate by transillumination (shine light through scrotum): red light —> blood, white light —> serous fluid
note: epididymal cyst = light shines through, retention cyst = light blocked by turbid contents
TESTICULAR TORSION = abnormal twisting of testis within scrotum (normally occurs just above upper pole) —> risk of necrosis (extremely painful)
note: 12hrs before infertility occurs during testicular torsion (breakdown of blood-testes barrier)
What are the levels of endopelvic fascia present in the female?
Uterosacral/cardinal ligament complex = top of uterus, divided during hysterectomy
Fusion of fascial planes (flattens vagina)
Perineal body = keeps vagina closed when intra-abdominal pressure increases
Why is a varicocoele almost always in the left testicle? What should you consider with a right-sided varicocoele?
- left testicular vein empties into renal vein at a higher point than the right testicular vein
- right testicular vein enters IVC at an oblique angle
Both above points mean that the valves in the right testicular vein are less likely to fail
Unilateral right-sided varicoele = ?retroperitoneal process e.g. mass obstructing the right internal spermatic vein —> thrombosis/occlusion of IVC
Why do hydrocoeles in young boys get bigger when they cough or cry?
Increased abdominal pressure —> more peritoneal fluid forced into processus vaginalis (if a communicating hydrocoele i.e. patent processus vaginalis)
What is the cremasteric reflex?
Lightly stroke medial aspect of thigh (L1 & L2 spinal nerves - genital branch of genitofemoral nerve) —> contraction of cremaster muscle —-> pulls up the ipsilateral testis
This reflex tests L1 & L2 spinal nerves (spinal reflex arc)
May be absent in:
- testicular torsion
- motor neurone disorders
- L1/L2 spinal injury
- damage to ilioinguinal nerve (during hernia repair)
note: L1 = ilioinguinal nerve
L1, L2 = genital branch of genitofemoral nerve
What causes the scrotal skin to wrinkle when exposed to cold temperatures?
Dartos muscle
What is the difference in the surface appearance of the ovaries in women in different stages of puberty?
Pre-pubertal = indistinguishable from PCOS ovaries i.e. lots of cystic areas
Post-pubertal = enlarged & multifollicular
Post-menopausal = shrunken & lack of follicles (difficult to visualise)
Describe the course of the vas deferens.
Ascends in spermatic cord —> inguinal canal —> tracks down pelvic side wall (close to ischial spines) —> passes between bladder & ureter —> forms dilated ampulla —> opens into the ejaculatory duct —> joins prostatic urethra inferior to bladder
What is the seminal vesicle?
Diverticulum (out-pouching) of ductus deferens
Duct of seminal vesicle combines with ductus deferens to form ejaculatory duct (paired)
Lies between bladder & rectum
NOT a storage site
Secretions make up ~70%-80% volume of ejaculate
Describe the anatomy of the prostate gland. How does this relate to disorders of the prostate gland?
~3cm (size of walnut)
Fibromuscular gland, divided into central zone, transition zone, and peripheral zone
Base is at the neck of bladder, apex is at urethral sphincter & deep perineal muscles
Ant. surface (muscular) at urethral sphincter
Pos. surface is at ampulla of rectum (felt during DRE)
Inferolateral surface is at levator ani
Benign prostatic hypertrophy = occurs in middle lobule, rapidly obstructs internal urethral sphincter —> rapid presentation of dysuria, nocturia, urgency, etc.
Prostatic malignancy = presents late, metastasises via lymphatics (internal iliac & sacral nodes) and venous routes (deep dorsal vein ——-> internal iliac vein —> internal vertebral plexus —> vertebrae & brain)
note: valve-less vertebral veins of Baston allow spread of malignancy
What is the least distensible part of the urethra? What is the relevance of this?
Membranous urethra (passes through perineum - fascia & fibrous tissue)
Therefore most prone to rupture during catheterisation
Outline the anatomy, innervation, and blood supply of the penis.
- head = glans penis
- body = corpora cavernosa (dorsal) + corpus spongiosum (ventral; contains urethra)
- root = two crura + bulb of penis + ischiocavernosus + bulbospongiosus
Attachments:
- crus of penis attaches to corpus cavernosa
- bulb of penis attaches to corpus spongiosum
Bulbourethral glands within deep pouch
Arteries = branches of internal pudendal arteries (itself branch of ant. division of internal iliac artery)
- bulbar artery (corpus spongiosum)
- dorsal penile artery (skin, fascia, glands)
- deep arteries & dorsal arteries (crura + corpus cavernosa)
Innervation = pudendal nerve + dorsal penile branch of pudendal nerve
What is a Nabothian cyst?
Infection of endocervical glands (as in chronic cervicitis) blocks ducts, forming cyst (~2mm-1cm)
Makes the cervix inhospitable to sperm (reduces chance of fertilisation)
What are the deep perineal muscles?
External urethral sphincter:
- origin = encircles the urethra
- insertion = lateral surface of prostate and inferior bladder (male), inferior surface of bladder (female)
- function = compresses urethra (and vagina)
Deep transverse perineal muscle:
- origin = medial surface of ischial ramus
- insertion = perineal body/central tendineous point
- function = stabilises perineal body
What are the superficial perineal muscles?
Ischiocavernosus:
- origin = medial surface of ischial tuberosity & ischiopubic ramus
- insertion = corpus cavernosum & crus of penis/clitoris
- function = compresses corpus cavernosum
Bulbospongiosus:
- origin = central tendineous point (male), perineal body (female)
- insertion = perineal membrane, dorsal surface of corpus spongiosum & deep penile fascia (male), corpus cavernosum of clitoris (female)
- function = compresses bulb of penis & spongy urethra (male), compresses vestibular bulb & constricts vaginal orifice (female)
Superficial transverse perineal muscle:
- origin = medial surface of ischial ramus
- insertion = perineal body/central tendinous point
- function = stabilises perineal body/central tendinous point
note: external anal sphincter is superficial
- origin = perineal body/central tendinous point
- insertion = encircles anal canal, superficial fibres attach to coccyx
- function = constricts anal canal
What are some risk factors for pelvic organ prolapse?
- vaginal delivery
- obesity
- increasing age
- increasing parity
- spina bifida
- Ehlers-Danlos syndrome
- Marfan’s syndrome
- heavy lifting
What are the different layers of the pelvic floor?
- Superficial perineal layer:
- bulbospongiosus
- ischiocavernosus
- superficial transverse perineal muscle
- external anal sphincter - Deep urogenital diaphragm layer:
- compressor urethrae
- sphincter urethrovaginalis
- deep transverse perineal muscle - Pelvic diaphragm:
- levator ani (iliococcygeus, pubococcygeus, puborectalis)
- coccygeus
- ischiococcygeus
- piriformus
- obturator internus
What are the anatomical and surface borders of the perineum?
Anatomical:
- ANTERIOR = pubic symphysis
- POSTERIOR = tip of coccyx
- LATERAL = inferior pubic & ischial rami + sacrotuberous ligament
- ROOF = pelvic floor
- BASE = skin & fascia
Surface:
- ANTERIOR = mons pubis/base of penis
- LATERAL = medial surfaces of thighs
- POSTERIOR = superior end of intergluteal cleft
Is the posterior wall of the vagina covered by the peritoneum?
Only the upper 1/4 is covered (pouch of Douglas)
