Narrow pelvis Flashcards
Anal Canal - Description Features
• The anal canal measures ~4cm long
• Continuous with the rectum at the anorectal junction (which is the right angle the rectum takes at levator ani)
• Anal canal is a circular muscular tube and has external and internal anal sphincters
• Anal canal ends at the anus
• Dentate (pectinate) line separates the anal canal into an upper and lower parts
o in structure and neurovascular supply (reflecting the differing embryological origin)
o dentate line is a “watershed area”
o above the dentate line the epithelium is a mucous membrane
o below the dentate line the epithelium is considered cutaneous (ie. stratified squamous keratinised)
Anal Canal - neurovaculature
Arterial Supply:
• Above dentate line
o superior rectal artery (from inferior mesenteric artery)
• Below dentate line
o inferior rectal artery (from internal pudendal artery)
o middle rectal artery (from inferior vesical artery)
Venous drainage:
• Above dentate line: superior rectal vein to inferior mesenteric vein (portal venous system)
• Below dentate line: inferior and middle rectal veins to internal iliac veins
Nerve supply:
• Above dentate line: inferior hypogastric plexus
• Below dentate line: inferior rectal branches of the pudendal nerve
Lymphatic drainage:
• Above dentate line: internal iliac nodes
• Below dentate line: superficial inguinal nodes
Anal Canal - variant anatomy
Variant anatomy:
• Imperforate anus
o 1 in 1500-5000 newborns
o failure of the bowel to open to the external world
o may vary from stenosis to blind anal canal/rectum to absent anal canal
Anal Triangle - Description
- Posterior part of the perineum
* Contains the anal canal
Anal Triangle - Boundaries
- Posterior: coccyx bone
- Lateral: ischial tuberosities
- Anterior: perineal membrane
- Posterolateral: sacrotuberous ligaments
Anal Triangle - Contents
- Ischioanal fossa
- Anococcygeal body
- Sacrotuberous ligament
- Sacrospinous ligament
- Pudendal nerve
- Internal pudendal artery and vein
- Anal canal
- Muscles: external anal sphincter, gluteus maximus, obturator internus, levator ani, coccygeus
Epididymis - Description
• Lies upon the lateral edge of the posterior border of the testes
• Parts: head, body and tail (which is continuous with the ductus deferens)
o head located at superior pole and may contain a small projection called the appendix of the epididymis
o tail located at the inferior pole
• The head is connected with the upper end of the testis by efferent ductules
• Between the body and the testis is the sinus of the epididymis
• Primary function is the collection, maturation and transport of sperm via the vas deferens
o seminiferous tubules carry the sperm via tubuli recti into rete testes
o rete testes drains into the epididymis via efferent ductules
o efferent ductules open into the head of the epididymis and unite to form a single duct in the body/tail which continues as the ductus deferens
Epididymis - Neurovasculature
Arterial supply: • Artery of vas Venous drainage: • Pampiniform plexus to testicular vein Lymphatic drainage: • Para-aortic lymph nodes (L2) Nerve supply: • Sympathetic: coeliac ganglion
Epididymis - Embryology
- The epididymis is derived from mesonephric ducts which form the epididymis, vas deferens, seminal vesicle and ejaculatory duct
- The appendix epididymis is vestigial remnant of mesonephric duct
Gonadal veins - Description/course
- Gonadal veins are paired structures that drain the testicles in males and ovaries in females
- Gonadal veins ascend with the gonadal arteries in the abdomen along the psoas muscle anterior to the ureters (retroperitoneal)
Gonadal veins - ovarian veins
o ovarian veins arises from the left and right ovarian plexus (which is continuous with the uterine plexus) and lies lateral to the ureters
o ascends anterior to psoas and parallels the ureter, in the suspensory ligament of the ovary
o crosses the ureter halfway through its course
o right empties into the IVC and left drains into the left renal vein
Gonadal veins - testicular veins
o veins of the testes and epididymis form the pampiniform plexus
which ascends to form four veins at the level of the superficial inguinal ring
then a single testicular vein at the level of the deep inguinal ring
o ascends through the inguinal canal in the spermatic cord
o testicular vein ascends in the retroperitoneum on psoas major
o variable communications with retroperitoneal veins, abdominal wall veins and renal capsular veins
o left drains into the left renal vein, right drains into IVC just below the renal vein
o 90 degree insertion of left testicular vein into left renal vein make left varicocoele more common in left
Gonadal veins - relations
- Posterior: psoas major, crosses ureter
- Anterior: left (sigmoid colon, descending colon), right (caecum, ascending colon)
- Lateral: ureter (upper part), kidney
- Medial: ureter (lower part), aorta, SVC
- Testicular veins are related to structures within spermatic cord
Gonadal veins - variants
- Gonadal vein is often duplicated, more commonly on the left (~13%) than on the right (~2%)
- Right gonadal vein drains into right renal vein
Sciatic Foraminae - Description
- Foramen within the pelvis and is a major conduit of neurovascular structures from the pelvis to the lower limb
- Divided into the greater and lesser sciatic foramen by the sacrotuberous ligament which runs between the sacrum and the ischial tuberosity and the sacrospinous ligament which runs between the sacrum and the ischial spine
Greater sciatic foramen - boundaries
o Anterolateral: Greater sciatic notch of the ilium
o Posteromedial: Sacrotuberous ligament
o Inferior: Sacrospinous ligament
o Superior: Anterior sacroilliac ligament
Lesser sciatic foramen - boundaries
o Anterior: Tuberosity of the ischium
o Superior: Spine of the ischium and sacrospinous ligament
o Posterior: Sacrotuberous ligament
Greater sciatic foramen - Contents
o Piriformis exits the pelvis through the Greater sciatic foramen occupies most of the foramen o Above the Piriformis superior gluteal artery and vein superior gluteal nerve o Below the Piriformis → 7 nerves, 3 vessel sets (artery + vein) (mnemonic = I PIN PINS) inferior gluteal nerve pudendal nerve inferior gluteal artery and vein nerve to obturator internus posterior femoral cutaneous nerve internal pudendal artery and vein nerve to quadratus femoris sciatic nerve
Lesser sciatic foramen - Contents
o pudendal nerve
o internal pudendal vessels
o nerve to the obturator internus
o tendon of the obturator internus
Inguinal Canal - description/features
• Inguinal canal is a passage in the anterior abdominal wall that transmits structures from the pelvis to the perineum
• It has an oblique course which is 4cm in length
• There are two openings:
o deep inguinal ring
round opening in the transversalis fascia
1cm superior to the inguinal ligament, 1cm lateral to the inferior epigastric arteries
o superficial inguinal ring
V-shaped opening in the external oblique aponeurosis
superior and medial to the pubic tubercle
Inguinal Canal - walls
- Roof: internal oblique muscle, transversus abdominis muscle
- Floor: inguinal ligament, lacunar ligament (medial third)
- Anterior wall: external oblique aponeurosis, internal oblique aponeurosis
- Posterior wall: tranversalis fascia, conjoint tendon (internal oblique and transversus abdominis aponeurosis inserts into the pubic crest and pectineal line)
Inguinal Canal - contents Female
o round ligament + ilioinguinal nerve
Inguinal Canal - contents male
o spermatic cord + ilioinguinal nerve
3 arteries: artery to ductus deferens, testicular artery, cremasteric artery
3 fascial layers: external spermatic (continuation of external oblique aponeurosis), cremasteric fascia (continuation of internal oblique aponeurosis), internal spermatic fascia (continuation of transversalis fascia)
tunica vaginalis is continuation of the peritoneum (processus vaginalis)
3 other structures: pampiniform plexus, ductus deferens, testicular lymphatics
3 nerves: genital branch of the genitofemoral nerve (L1/2), sympathetic and visceral afferent fibres, ilioinguinal nerve
ilioinguinal nerve lies outside spermatic cord but travels next to it
Inguinal Ligament - description featuers
- Fibrous band extending from the ASIS to the pubic tubercule
- Denotes the transition of the pelvis to the lower limb
- Formed by the lower border of the external oblique aponeurosis which is thickened and folded in on itself
- Lateral half runs obliquely while the medial half is almost horizontal
- Forms floor of the inguinal canal
- Forms base of Hesselbach triangle
- Continuous with the fascia lata of the thigh
- Also known as Poupart’s ligament
Inguinal Ligament - attachments
• ASIS
• Pubic tubercle
• Some fibres attach elsewhere
o superior pubic ramus forming the lacunar ligament (of Gimbernat)
o fibres that run with the lacunar ligament continue to pass more laterally to attach to the pecten pubis forming pectineal ligament (of Cooper)
o superior fibres run past the pubic tubercle to fuse with those of the contralateral external oblique aponeurosis forming the reflected inguinal ligament
• Upper surface gives origin to the cremaster muscle from its medial part
• Internal oblique muscle from the lateral two-thirds
• Transversus abdominis muscle from its lateral one-third
Inguinal Ligament - relations
• Structures passing through inguinal canal (spermatic cord in males, round ligament of the uterus in females)
• Inferior epigastric vessels
• Deep (retroinguinal passage / subinguinal space)
o iliopsoas muscle
o femoral artery and vein and nerve
o lymphatic channels draining inguinal lymph nodes
• Lateral: deep circumflex iliac artery
Internal Iliac artery - description
• Internal Iliac Artery is the artery that supplies the pelvic walls, pelvic viscera, external genitalia, the perineum, buttock and medial part of the thigh
Internal Iliac artery - origin
• Common iliac artery bifurcates into the internal iliac artery and external iliac artery at the level of the pelvic brim anterior to the sacroiliac joint
Internal Iliac artery - Course/relations
- Courses posteromedially towards the greater sciatic foramen
- Approximately 4 cm in length
- At the superior margin of the greater sciatic foramen it divides into an anterior and posterior division
- Anterior division continues down to the ischial spine anterior to piriformis giving off visceral and parietal branches
- Posterior division only gives rise to parietal branches
Internal Iliac artery - branches
o I: iliolumbar artery - psoas and iliacus
o L: lateral sacral artery - sacral canal and muscle of the back
o G: gluteal (superior and inferior) arteries
o P: (internal) pudendal artery - external genitalia, one of two terminal branches of internal iliac artery
o I: inferior vesical artery - fundus of the bladder, the prostate, and the seminal vesicles; artery to the ductus deferens is a branch
o M: middle rectal artery - rectum, usually arises from the inferior vesical artery
o V: vaginal artery (females) - usually arises from uterine artery
o O: obturator artery - divides into an anterior and posterior branch, supplied pelvic walls
o U: umbilical artery - gives rise to superior vesical artery
o U: uterine artery - runs lateral to the cervix, crosses in front of the ureter, ascends between the two layers of the broad ligament to the junction of the uterine tube and uterus
Internal Iliac artery - relations
- Anteriorly: ureter, ovary, uterine tube
- Posteriorly: internal iliac vein, lumbosacral trunk, sacroiliac joint
- Medially: peritoneum
- Laterally: external iliac vein, obturator nerve
Internal Iliac artery - variants
ommon iliac artery is absent and internal and external iliac arteries arise from the aorta (<1%)
• All arteries branch from one main stem of the internal iliac artery (10%)
• The internal iliac divides into two main stems which give off the other branches (60%)
• The internal iliac divides into three main stems which give off the other branches (20%)
• The internal iliac divides into four or more main stems which give off the other branches (10%)
• High division of internal iliac (higher than pelvic brim)
Branches of the internal pudendal artery
- Inferior rectal artery
- Artery of the bulb of the penis / vestibule
- Perineal artery
- Posterior scrotal / labial branches
- Deep artery of the penis / clitoris
- Dorsal artery of the penis / clitoris
Ischioanal fossa - description
• The ischioanal fossa is a paired triangular-shaped space lateral to the anal canal
• Fat filled space in the perineum
• The apex is directed anteromedially towards the pubic symphysis
• Each ischioanal fossa is separated from the other by the anococcygeal body
o fibrous median raphe in the floor of the pelvis which extends between the coccyx and the anus
• They communicate superior to anococcygeal body and posterior to the anal canal
Ischioanal fossa - boundaries
- Roof - levator ani muscle
- Floor - deep transverse perineal fascia, skin
- Medial wall - external anal sphincter, levator ani muscle
- Lateral wall - ischial tuberosity, obturator internus muscle, obturator fascia
- Apex - intersection of levator ani and obturator internus muscle
- Base - sacrotuberous ligament, gluteus maximus muscle
Ischioanal fossa - contents
• Inside Alcock’s canal (on the lateral wall)
o internal pudendal artery
o internal pudendal vein
o pudendal nerve
• Outside Alcock’s canal (crossing the space transversely)
o inferior rectal artery
o inferior rectal veins
o inferior anal nerves
o fatty tissue across which numerous fibrous bands extend from side to side
Levator ani - description
• Levator ani is a musculotendinous sheet that forms the majority of the pelvic floor (other component is the coccygeus muscles)
• Three main components (each of which is paired)
o iliococcygeus muscle
o pubococcygeus muscle
subparts: puboperineal, pubovaginal, puboanal
o puborectalis muscle
Levator ani - origin
- Iliococcygeus: arises from the posterior part of the tendinous arch / obturator internus fascia and ischial spine
- Pubococcygeus: inner surface of the pubis, anterior part of the tendinous arch / fascia of the obturator internus
- Puborectalis: arises from the inner surface of the pubic bone
- Coccygeus: ischial spine/lig
Levator ani - insertion
- Iliococcygeus: coccyx/anococcygeal lig+raphe
- Pubococcygeus: coccyx/anococcygeal lig+raphe
- Puborectailis: unites behind the anorectal junction to form a sling
Levator ani - action
- Supports the pelvic viscera
- Aids in urinary and fecal evacuation
- Maintains continence
Levator ani - relations
- Rectum, vagina, urethra penetrate through the diaphragm
- Inferior: forms the roof of the ischioanal fossa (contents: inferior rectal vessels, inferior anal nerves)
- Superior: pelvic organs
Levator ani - neurovasculature
Nerve supply: • Inferior rectal nerve from pudendal nerve (S3, S4) • Levator ani nerve (S4) Blood supply: • Inferior gluteal artery
Lumbar plexus - description
Formed by the lower thoracic and lumbar ventral nerve roots (T12 to L5) which supplies motor and sensory innervation to the lower limb and pelvic girdle
Additionally, the ventral rami of L4-5 pass communicating branches, the lumbosacral trunk, to the sacral plexus
Lumbar plexus - branches
I: iliohypogastric nerve I: ilioinguinal nerve G: genitofemoral nerve L: lateral cutaneous nerve of the thigh O: obturator nerve F: femoral nerve
Lumbar plexus - roots
I: L1 I: L1 G: L1, L2 L: L2, L3 O: L2, L3, L4 F: L2, L3, L4
Lumbar plexus - exiting points
- anterior: genitofemoral
- medial: obturator, lumbosacral trunk
- lateral: iliohypogastric, ilioinguinal, lateral femoral cutaneous, femoral
Male urethra - description
- Commences at the internal urethral orifice in the trigone of the bladder
- Opens at the glans penis at the external urethral meatus
Male urethra - pre-prostatic urethra
- Intramural part of the urethra
- 0.5-1.5 cm in length
- Transitional cell epithelium
Male urethra - prostatic urethra
• Crosses through the prostate gland
• Several openings
o ejaculatory duct receives sperm from the vas deferens and ejaculate fluid from the seminal vesicle
o several prostatic ducts where fluid from the prostate enters and contributes to the ejaculate
o prostatic utricle is merely an indentation
o openings are collectively called the seminal colliculis / verumontanum
• Transitional cell epithelium
Male urethra - spongy urethra
• Runs along the length of the penis on its undersurface
• Bulbar urethra is part of the spongy urethra: traverses the root of the penis
• Is about 15-16 cm in length
• Travels through the corpus spongiosum
• Receives the ducts from the bulbourethral glands and the urethral glands (of Littré)
• Epithelium
o proximal: pseudostratified columnar
o distal: stratified squamous
Male urethra - membranous urethra
- 1-2 cm portion passing through the external urethral sphincter
- Narrowest part of the urethra
- Located in the deep perineal pouch
- Bulbourethral glands (Cowper’s gland) are found posterior to this region but open in the spongy urethra
- Pseudostratified columnar epithelium
Ovary - description
• Paired organs of the female reproductive and endocrine systems
• Lie within the ovarian fossa on the posterior wall of the true pelvis
• Suspensory ligament of the ovary is a peritoneal fold and runs from the side wall of the pelvis to the ovary
o the ovarian vessels run in this ligament, crossing over the external iliac vessels.
• Portion of broad ligament that attaches ovary to uterus is mesovarium
• Portion of broad ligament that attaches ovary to uterine tube is mesosalpinx
• Ovarian ligament is a continuation of the round ligament and attaches the ovary to the side of the uterus
Ovary - relations
- Medial: uterus, ovarian ligament
- Lateral: obturator vessels and nerves
- Anterior: broad ligament, mesovarium, ovarian vessels, obliterated umbilical vein
- Posterior: internal iliac vessels, ureter
- Superior: external iliac vessels
- Inferior: levator ani
Ovary - neurovasculature
Arterial supply:
• Ovarian artery
Venous drainage:
• Pampiniform plexus to the ovarian veins
o right ovarian vein drains into the inferior vena cava
o left ovarian ven drains into the left renal vein
Lymphatic drainage:
• Para-aortic nodes
Nerve supply:
• Ovarian plexus (formed by the aortic, renal, and superior and inferior hypogastric plexuses)
Ovary - variants
- Position: It may fail to descend and lie in the suprapelvic region; or follow the round ligament through the inguinal canal to the labia majora.
- Irregular Shape: triangular, crescenteric
- Ovaries may contain displaced adrenal tissue
- Supernumerary ovaries
- Absence is rare
Perineal Body - description
- Pyramidal fibromuscular mass in the middle line of the perineum at the junction between the urogenital triangle and the anal triangle
- In males it is found between the bulb of penis and the anus
- In females it is found between the vagina and anus
- Essential for the integrity of the pelvic floor
Perineal Body - muscle attachements
- Bulbospongiosus muscle
- Levator ani
- External anal sphincter
- External urinary sphincter
- Deep transverse perineal muscle
- Superficial transverse perineal muscle
Prostate - description
• The prostate is an exocrine gland of the male reproductive system
• Inverted pyramid shaped
• Base of the prostate is in continuity with the bladder
• Surrounds the proximal urethra
• Ends at the urogenital diaphragm
• Prostate is connected to the pubic bone by the puboprostatic ligaments
• Anterior surface forms the posterior wall of the retropubic space
• Inferolateral surface rests on the levator ani fascia
• Palpable via a rectal exam
• Seminal vesicles are superior and posterior to the prostate gland, and the ejaculatory ducts pierce the posterior surface of the prostate below the bladder
• Prostate secretes a slightly alkaline fluid through the prostatic utricle which constitutes 30% of the volume of the semen
• It is comprised of three distinct zones with different embryologic origins:
o central zone: surrounds the ejaculatory ducts (25% of glandular tissue)
o transitional zone: surrounds the proximal urethra and is the region of the prostate gland that grows throughout life (5%)
responsible for BPH
o peripheral zone: sub-capsular portion of the posterior aspect of the prostate gland that surrounds the distal urethra (70%)
70-80% of cancers arise from here
o anterior fibromusclar zone: devoid of glandular components, and composed only of muscle and fibrous tissue
• The prostate gland has a true capsule and a fibrous pseudocapsule
Prostate - relations
- Anteriorly: pubic symphysis, retropubic fatty space (of Retzius)
- Inferiorly: urogenital membrane, sphincter urethrae, bulbourethral gland
- Superiorly: bladder
- Posteriorly: rectum, seminal vesicles
- Laterally: prostatic venous plexus, levator ani
- Prostatic urethra traverses through the prostate
Prostate - neurovasculature
Arterial supply:
• Inferior vesical artery (division of the internal iliac artery)
Venous drainage:
• Prostatic and inferior vesical plexus that surrounds the gland drains to the internal iliac veins
Nerve supply:
• Inferior hypogastric plexus
Lymph drainage:
• Drainage mainly to obturator and internal iliac nodes
• Some drainage to external iliac, pre-sacral and para-aortic nodes
Rectum - Description
- Rectum is the last part of the large intestine, and is located in the pelvis
- At S3 the sigmoid colon loses it mesentery and becomes the rectum at the rectosigmoid junction
- Taena coli also flatten and fuse to from an outer longitudinal muscular layer (rectum does not have the distinctive haustra)
- Rectal ampulla: dilated lower part of the rectum
- Three semilunar transverse rectal folds (valves of Houston) which project into the rectum
- Takes on an acute angle (the perineal flexure) as it passes through the puborectalis muscle and becomes the anal canal
- The peritoneum covers the upper two thirds of the rectum
Rectum - Relations
- Anterior: bladder, ureter, prostate (M), seminal vesicle (M), vagina (F), rectovaginal septum (F)
- Posterior: sacrum, median sacral vessels, superior rectal vessels, sacral sympathetic chain
- Inferior: piriformis muscle, levator ani
- Lateral: sigmoid colon, terminal ileum
Rectum - neurovasculature
Arterial supply:
• Superior rectal artery (terminal branch of IMA)
• Middle rectal artery (branch of internal iliac artery)
Venous drainage:
• Internal rectal plexus in the submucosa and external rectal plexus outside the muscular wall
• These drain by the superior rectal vein to IMV and inferior rectal vein to the internal iliac vein
Lymphatic drainage:
• Upper third of the rectum drains to the inferior mesenteric nodes
• Lower two thirds of the rectum drains to the internal iliac nodes
Innervations:
• Inferior mesenteric plexus
• Superior hypogastric plexus
• Inferior hypogastric plexus
Rectum - variations
• Imperforate rectum / anorectal malformations
o low lesion: colon remains close to the skin, stenosis (narrowing) of the anus, or the anus may be missing altogether, with the rectum ending in a blind pouch
o high lesion: colon is higher up in the pelvis and there is a fistula connecting the rectum and the bladder, urethra or the vagina
o persistent cloaca: the rectum, vagina and urinary tract are joined into a single channel
Sacral Plexus - description
Description/Features:
• The sacral plexus is formed by anterior rami of L4 to S4
• Its branches innervate the pelvis, perineum and lower limb
• Forms on the anterior belly of the piriformis muscle
o the lumbosacral trunk (L4-5) of the lumbar plexus enters the pelvis coursing medially to psoas major
o unites with the ventral rami of the S1 to S4 nerve roots, which emerge from the anterior foramen of the sacrum
Sacral Plexus - branches
• Anterior sacral rami give off six branches and then divide into anterior and posterior division, each giving off further branches
o Anterior rami (6 P’s)
nerve to piriformis (S1-S2)
perforating cutaneous nerve (S2-S3)
posterior femoral cutaneous nerve (S1-S3): skin of the perineum and posterior surface of the thigh and leg
parasympathetic pelvic splanchnic nerves (S2-S4)
pudendal nerve (S2-S4): supplies the external genitalia
perineal nerve (S4)
o Anterior division of anterior rami
nerve to quadratus femoris (and inferior gemellus muscles) (L4-S1)
nerve to obturator internus (and superior gemellus muscles) (L5-S2)
tibial part (L4-S2) of the sciatic nerve (L4-S3)
o Posterior division of anterior rami
superior gluteal nerve (L4-S1): supplies gluteus medius, gluteus minimus and tensor fascia latae
inferior gluteal nerve (L5-S2): supplies gluteus maximus
common peroneal part (L4-S2) of the sciatic nerve
Sacral Plexus - relations
- Posterior: piriformis
- Anterior: the internal iliac vessels, the ureter and the sigmoid colon
- The superior gluteal vessels run between the lumbosacral trunk and the first sacral nerve
- The inferior gluteal vessels between the second and third sacral nerves
Sacroiliac joint - description
- Synovial and fibrous joint between ilium and the sacrum
- Main function is to transfer weight between the axial and lower appendicular skeletons
- The joint has an oblique orientation and is located at the S1-3 level
- Articular surfaces are lined by hyaline cartilage
- Part of pelvic brim
Sacroiliac joint - ligaments
• Anterior sacroiliac ligament • Interosseous sacroiliac ligament • Posterior sacroiliac ligament • Accessory ligaments o sacrotuberous ligament o sacrospinous ligament o iliolumbar ligament
Sacroiliac joint - relations
- Anterior or ant/inf: psoas major, common iliac vessels, ureter, anterior sacral rami, sacral plexus
- Posterior: erector spinae, dorsal sacral rami, gluteus maximus
- Medial: vertebral column
Sacroiliac joint - nervous supply
• Branches from the lumbosacral plexus:
o dorsal rami of S1 and S2
o superior gluteal nerve
o obturator nerve
Sacroiliac joint - movements
- Movement at the SIJ is minimal and is limited to gliding and rotation
- During pregnancy there is increased movement due to laxity of ligaments
- Joint typically fuses after the age 50
Sacrospinous ligaments- description
- Sacrospinous ligament is a stabiliser of the sacro-iliac joint
- Forms a boundary of the greater and lesser sciatic foramen
Sacrospinous ligament - attachments
- Anterior sacrum (S2-S4) and coccyx
* Ischial spine
Sacrospinous ligament - relations
- Anterior: coccygeus muscle (to which it is closely connected), PINT
- Posterior: sacrotuberous ligament, IPINPINS (6 nerves, 2 sets of vessels)
- Upper Border: forms the boundary of the greater sciatic foramen
- Lower Border: forms the boundary of the lesser sciatic foramen
Sacrotuberous ligament - Description
- Sacrotuberous ligament is a stabiliser of the sacro-iliac joint
- Forms a boundary of the greater and lesser sciatic foramen
- Provides insertion for the gluteus maximus muscle
- Distal fibres partially blend with the proximal tendon of the long head of biceps femoris
Sacrotuberous ligament - attachments
- Broad fan-like origin from the sacrum, coccyx, ilium and sacro-iliac joint capsule
- Courses caudally to insert into the medial ischial tuberosity
- Fibres (known as the falciform ligament) extend to he ischial ramus
Sacrotuberous ligament - relations
- Posterior: gluteus maximus
- Anterior: IPINPINS, partly united to the sacrospinous ligament
- Superior: PINT
- Lateral Border: forms the medial boundary of the greater sciatic and lesser sciatic foramina respectively
- Pierced by: coccygeal branches of the inferior gluteal artery, perforating cutaneous nerve and branches of the coccygeal plexus
Sacrum - description
• Five vertebrae are fused in the adult to form the sacrum
• Roughly triangular appearance with a pelvic and dorsal surface and a lateral mass on each side
• Pelvic surface has four paired anterior sacral foramina for the ventral primary rami of sacral nerves 1 to 4
• Dorsal surface has four paired posterior sacral foramina for the dorsal primary rami of sacral nerves 1 to 4
• Dorsal aspect has a modified series of spinous processes termed the median sacral crest and transverse processes termed the lateral sacral crest
• Sacral cornua below which have a variable gap termed the sacral hiatus
o the cornua articulate with the corresponding horns of the coccyx
• Superior surface which arises laterally from S1 is termed the ala
• Superior part of first sacral vertebra has a prominent anterior margin termed the promontory
• Sacral canal terminates at the sacral hiatus
o contains sacral and coccygeal nerve roots, spinal meninges (to the level of S2) and filum terminale
Sacrum - articulations
- Superior - inferior endplate of L5 via the L5/S1 intervertebral disc, superior articular processes of S1 articulates with the L5 inferior articular facets to form the L5/S1 facet (zygapophyseal) joints
- Inferiorly - first coccygeal segment at the sacrococcygeal joint
- Laterally - the sacral ala articulate with the ilium to form the sacroiliac joints
Sacrum - muscle attachments
- Piriformis muscle: antero-inferiorly
* Erector spinae muscle, gluteus maximus: posteriorly
Sacrum - ligament attachments
- Lumbosacral ligaments
- Ligamentum flavum (S1 to L5): closes the spinal/sacral canal posteriorly
- Tectorial membrane of the sacrum (continuation of the PLL)
- Sacroiliac ligaments: anterior, posterior, middle
- Sacrotuberous ligament
- Sacrospinous ligament
- Superficial sacrococcygeal ligament
Sacrum - relations
- Anteriorly: fascia of Waldeyer, superior rectal vessels, peritoneum (S1-S2), rectum (S3-S5), median sacral artery, lymph nodes, piriformis muscle
- Lateral: sacral plexus
Sacrum - arterial supply
- Iliolumbar arteries (internal iliac)
- Lateral sacral arteries (internal iliac)
- Median sacral artery (abdominal aorta)
Sacrum - variant anatomy
- Sacralisation
- Lumbarisation
- Sacral agenesis
Testicle - description
• Male genital organs, and are contained within the scrotum
• Responsible for production of sperm and testosterone
• Structure
o from the mediastinum testis, several radiating septae extend into the testis forming 250-400 lobules
o each lobule contains 2-3 seminiferous tubules
o seminiferous tubules carry the sperm via tubuli recti into a dilated space within mediastinum testis (rete testis)
o rete testes drains into the epididymis through 10-15 efferent ductules
o efferent ducts in head of epididymis (globus major) unite to form a single duct (globus minor) in body / tail
o which continues as the ductus deferens
• Tunica albuginea is the fibrous covering of the testis
• Tunica vaginalis invests the surface of the testis and is reflected on to the internal surface of the scrotum
• Appendix of the testis (hydatid of Morgagni) is the remnant of the upper end of the Müllerian duct
Testicle - relations
- Contents of the spermatic cord: 3 arteries, 3 nerves, 3 other, 3 layers
- Between the epididymis and the testis is a pouch, named the sinus of the epididymis
Testicle - neurovasculature
Arterial supply:
• Testicular artery
• Minor collateral supply from cremasteric artery and the artery to the ductus deferens
Venous drainage:
• Pampiniform plexus passes through the spermatic cord to form a single testicular vein at the deep inguinal region
• Left testicular vein drains into the left renal vein, right testicular vein joins the IVC
Lymphatic drainage:
• Para-aortic lymph nodes
Innervation:
• Sympathetic plexus originating from the para-aortic ganglia
Testicle - variants
- Cryptorchidism: undescended testis
- Polyorchidism
- Bilobed testes
- Testicular appendages
- Congenital inguinal hernia: patency of the processus vaginalis
- Hydrocoele
Urogenital triangle - description
- Anterior part of the perineum
* In females, contains the vagina and associated parts of the external genitalia
Urogenital triangle - boundaries
- Anterior: pubic symphysis
- Lateral: ischial tuberosities
- Posterior: perineal membrane
Urogenital triangle - contents
- Posterior scrotal nerves / posterior labial nerves
- Urethra
- Vagina
- Bulbourethral gland / Bartholin’s gland
- Muscles: superficial transverse perineal, ischiocavernosus muscle, bulbospongiosus, crus penis / clitoral crura, bulb of penis / vestibular bulb, urogenital diaphragm, muscular perineal body
- Superficial and deep perineal pouch
- Blood vessels and lymphatics
Fallopian tube - description
• Uterine tube bridges the ovary and the uterus
• Functions to convey the ovum between the two
• Conception occurs within the tube
• Each tube opens proximally into the cornua of the uterus
• The uterine tube is divided into 5 parts:
o Fimbriae: finger-like projections that drape over the ovary
o Infundibulum: is the funnel-shaped distal end of the uterine tube
o Ampulla: begins medially from the infundibulum and is the longest part of the uterine tube
o Isthmus: leads from the ampulla
o Intramural: is the segment that passes through the thick myometrium of the uterus and opens via the uterine ostium into the uterine cavity
Fallopian tube - relations
- Lateral: ovary
- Medial: uterus
- Inferior: ureter, uterine artery
- Posterior: rectum, ureter
- Broad ligament, mesosalpinx
Fallopian tube - neurovasculature
Arterial supply:
• Tubal branch of the Uterine Arteries (Branch of Internal Iliac)
• Tubal branch of the Ovarian Arteries
Venous drainage:
• Venous plexus that drains to Uterine and Ovarian Veins
Lymphatic drainage:
• Lymph drainage is predominantly to the para-aortic lymph nodes (like the ovaries)
Nerve supply:
• Ovarian and uterine plexuses (from T11 - L1)
Fallopian tube - variants
- Accessory openings that may lie close to the fimbriated end or at some distance along the tube
- Uterine tubes may be uncanalized
- Congenital absence of the uterine tubes is rare
Uterus - Description
• Hollow, thick-walled, muscular organ of the female reproductive tract that lies in the lesser pelvis
• Lies between the bladder and the rectum
• The uterus consists of 2 major parts: the body and the the cervix
• Uterine tubes enter at the cornua
• Fundus is the part of the uterus that lies ahove where uterine tubes enter
• The cervix projects into the vagina
o communicates with the vagina via the external ostium of the uterus
• Vaginal recess around the cervix is called the fornix (anterior, posterior and lateral parts)
• The isthmus of the uterus is a slightly constricted transitional zone between the body and cervix
• Wall of the uterus consists of 3 layers
o perimetrium - outer serous layer
o myometrium - middle muscular layer
o endometrium - inner mucous layer
Uterus - ligaments
- Pubocervical ligament
- Transverse cervical ligaments
- Uterosacral ligaments
- Round ligament - extends from uterine horn to the labia majora, between layers of the broad ligament and though inguinal canal
- Broad ligament - extends from sides of uterus to the lateral walls and floor of the pelvis
- Ovarian ligament - attaches ovary to the uterus
Uterus - relations
- Anteriorly - bladder, uterovesical pouch
- Posteriorly - rectum, pouch of Douglas
- Laterally - broad ligament, uterine vessels, ovaries, uterine tubes
- Inferiorly - vagina
- Superiorly - abdominal cavity
Uterus - neurovasculature
Arterial supply:
• Arteries unite and form an anastomotic trunk from which branches are given off to supply the uterus
o Uterine arteries (branch of the internal iliac artery)
o Ovarian arteries
Venous drainage:
• Uterine plexus which drains into the internal iliac vein
Lymphatics:
• Fundus drains to para-aortic lymph nodes
• Body drains with the broad ligament to the external iliac lymph nodes
• Cervix drains to the internal iliac and sacral lymph nodes
Nerve supply:
• Hypogastric and ovarian
Uterus - variants
• Anteverted / Retroverted • Anteflexed / Retroflexed • Müllerian ducts anomalies o Arcuate o Septate o Unicornuate o Bicornuate (bicollis / unicollis) o Didelphys (complete failure of fusion)
