Anatomy - Pelvis Flashcards
The sella turcica is located in and directly behind? What are its boundaries?
The sella turcica is located in the sphenoid bone behind the chiasmatic groove and the tuberculum sellae (anterior border). It belongs to the middle cranial fossa.
Posterior boundary is formed by the dorsum sellae, the supero-lateral angles of which are raised to form the posterior clinoid process. Anteriorly bound by tuberculum sellae
Anatomic boundaries of pelvis cavity
● Inferoposterior part of the abdominopelvic cavity
● Continuous superiorly with the abdominal cavity at the pelvic inlet
● Limited inferiorly by the musculofascial pelvic diaphragm that forms a bowl-like pelvic floor.
● Bounded posteriorly by coccyx and inferior sacrum
● Roof formed by superior part of the sacrum
Peritoneal coverings of the pelvic cavity
● Reflects onto pelvic viscera
● Only fallopian tubes and ovaries covered by peritoneum.
● Pockets
○ pararectal fossa
○ Rectovesicle pouch in males
○ rectouterine and vesicouterine pouch in females.
● Rectum is subperitoneal inferiorly and retroperitoneal superiorly
● Sigmoid colon becomes intraperitoneal.
Antero-inferior wall of pelvic cavity
○ bodies and rami of pubic bones and pubic symphysis.
○ Bears the weight of the urinary bladder
Lateral walls of pelvic cavity
○ Formed by right and left hip bones
○ Obturator foramen closed by obturator membrane
○ Padded by obturator internus.
Posterior wall (posterolateral wall and roof) of pelvis
○ Bony wall and roof in the midline, formed by sacrum and coccyx.
○ Musculoligamentous posterolateral wall:
■ formed by piriformis muscle
■ and sacro-iliac, sacrospinous and sacrotuberous ligaments.
Floor of pelvic cavity
○ Formed by pelvic diaphragm
○ coccygeus and levator ani muscles. Separates pelvic floor from perineum
○ Levator ani consists of puborectalis, pubococcygeus, iliococcygeus.
Transcoelomic spread describes the spread of a malignancy into ……
that occurs via ……
Transcoelomic spread describes the spread of a malignancy into
Body cavities
That occurs via penetrating the surface of the peritoneal, pleural, pericardial, or subarachnoid spaces.
Histology of the rectum:
What are the implications for direct tumour spread?
mucosa, submucosa, muscular propria.
There is no serosal layer - therefore spread past muscularis is into peri-rectal space/fat.
There are four articulations within the pelvis:
Sacroiliac joints (x2)
Sacrococcygeal symphysis
Pubic symphysi
The osteology of the pelvic girdle allows the pelvic region to be divided into two:
Greater pelvis (false pelvis) – located superiorly, it provides support of the lower abdominal viscera Lesser pelvis (true pelvis) – located inferiorly. Within the resides the pelvic cavity and pelvic viscera.
The junction between the greater and lesser pelvis is known as the ……. …….. The outer bony edges of the ….. …. are called the….. …….
The junction between the greater and lesser pelvis is known as the pelvic inlet. The outer bony edges of the pelvic inlet are called the pelvic brim.
The borders of the pelvic inlet:
Posterior – sacral promontory (the superior portion of the sacrum) and sacral wings (ala).
Lateral – arcuate line on the inner surface of the ilium, and the pectineal line on the superior pubic ramus.
Anterior – pubic symphysis
Pelvic outlet borders are:
Posterior: The tip of the coccyx
Lateral: The ischial tuberosities and the inferior margin of the sacrotuberous ligament
Anterior: The pubic arch (the inferior border of the ischiopubic rami).
The angle beneath the pubic arch is known as the sub-pubic angle and is of a greater size in women.
The hip bone is comprised of the three parts:
Prior to puberty, the ……. cartilage separates these parts – and fusion only begins at the age of 15-17.
The hip bone is comprised of the three parts; the ilium, pubis and ischium. Prior to puberty, the triradiate cartilage separates these parts – and fusion only begins at the age of 15-17.
The inferior ischial ramus combines with the ……. ……. ……. forming the ischiopubic ramus, which encloses part of the …… foramen. The posterorinferior aspect of the ischium forms the ischial tuberosities and when sitting, it is these tuberosities on which our body weight falls.
The inferior ischial ramus combines with the inferior pubic ramus forming the ischiopubic ramus, which encloses part of the obturator foramen. The posterorinferior aspect of the ischium forms the ischial tuberosities and when sitting, it is these tuberosities on which our body weight falls.
Two important ligaments attach to the ischium:
Sacrospinous ligament – runs from the ischial spine to the sacrum, thus creating the greater sciatic foramen through which lower limb neurovasculature (including the sciatic nerve) transcends.
Sacrotuberous ligament – runs from the sacrum to the ischial tuberosity, forming the lesser sciatic foramen
From where in the hip bone does the gluteus medius originate?
The external surface of the ileal wing is also known as the ‘gluteal surface’ - as it is the site of origin for the gluteal muscles
Course of the ureter Abdo part.
Origin ureteropelvic junction, the ureters descend “retroperitonealy” along the anterior surface of the psoas major.
Course of the ureter pelvic part.
At S1 and SI joints cross pelvic brim, and over the external iliac aa. directly below the bifurcation of common iliac at L5/S1.
Travel down the lateral pelvic walls. At the level of the ischial spines, they turn anteromedially, moving in a transverse plane towards the bladder.
Point A brachytherapy
ureters pierce lateral aspect of bladder in an oblique manner. This creates a one way valve, where high intramural pressure collapses the ureters – preventing the back-flow of urine.
In Females as the ureter cross the pelvic brim they are in close proximity to
Approximately 2cm superior to the ischial spine, the ureters run underneath the uterine artery.
As they cross the pelvic brim, the ureters are in close proximity to the ovaries.
Approximately 2cm superior to the ischial spine, the ureters run underneath the uterine artery. During a hysterectomy, the uterus and uterine artery are removed, the ureter is in danger of being accidentally damaged. ‘water under the bridge’.
In men, instead of the uterine arteries, the ……. cross the ureters anteriorly.
In men, instead of the uterine arteries, the vas deferens cross the ureters anteriorly.
Rectum anatomical relations
● Anteriorly: ○ peritoneum in upper and middle third ○ males: rectovesical pouch, bladder, prostate, seminal vesicles, vas deferens ○ females: rectouterine pouch, uterus and vagina ● Posteriorly: ○ sacrum, coccyx and pelvic diaphragm ● Laterally: ○ peritoneum in upper third ○ ileum ○ Ischiorectal fossa ○ Rectal vessels ● Superiorly ○ Rectosigmoid junction and sigmoid colon ● Inferiorly ○ Anal canal
Arterial and venous supply to the rectum
● Arterial supply
○ superior rectal artery (continuation of inferior mesenteric artery) supplies proximal part of the rectum
○ Middle rectal arteries (from internal iliac) supply middle and inferior parts of the rectum
○ Inferior rectal arteries (from internal pudendal arteries, also from internal iliac) supply anorectal junction and anal canal.
Venous drainage
○ Superior rectal veins drain into the portal system
○ Middle and inferior rectal veins drain into systemic system
○ anastomoses between portal and systemic system exists in the anal canal.
○ Rectal venous plexus exists at the anorectal junction
Innervation of the rectum
● Sympathetic supply from the lumbar spinal cord, via lumbar splanchnic nerves and hypogastric plexus.
● Parasympathetic supply from S2-4 via pelvic splanchnic nerves, inferior hypogastric and rectal plexuses.
Lymphatic drainage of the rectum
● Superior part of the rectum drain into pararectal and sacral lymph nodes, then to inferior mesenteric lymph nodes to paraaortic nodes.
● Inferior rectum drains into internal iliac nodes → common iliac
● very distal part of rectum drains to superficial inguinal, then to external iliac nodes.
Macroscopic appearance of the prostate
● Conical shaped organ, base at the neck of the bladder.
● Apex directed inferiorly
● Approx 3cm long, 4cm wide, 2 cm depth.
● Covered by a fibrous capsule which is dense and neurovascular
○ incorporates the prostatic plexus of veins and nerves
○ surrounded by visceral layer of pelvic fascia to form the prostatic sheath.
To where do the prostatic ducts open?
Prostatic ducts open either side of seminal colliculus
Anatomical relations of the prostate
○ Anteriorly: pubic symphysis ○ Posteriorly: rectum ○ Superiorly: bladder and seminal vesicles ○ Inferio-laterally: levator ani ○ Internally: prostatic urethra.
Lobes of the prostate
Two main histologic components
Two main histologic components: of 70% glandular tissue and 30% fibromuscular stroma
● Anterior lobe is fibromuscular, contains little glandular tissue
● Right and left lateral lobes
● Median lobe surrounding the ejaculatory ducts and lateral to urethra
● posterior lobe
Parasympathetic innervation of male genital organs is via:
Sympathetic innervation of male genital organs is via:
In both sexes originates in the sacral segments S2–S4 (Sacral splanchnic nerves) and reaches the target organs via the pelvic nerves. Parasympathetic ganglia causes dilation of penile or clitoral arteries, and a corresponding relaxation of the smooth muscles of the venous (cavernous) sinusoids, which leads to expansion of the sinusoidal spaces.
Sympathetic activity -> vasoconstriction -> loss of erection. The lumbar (lumbar Splanchnic nerves) sympathetic pathway to the sexual organs originates in the thoraco-lumbar segments (T11-L2) and reaches the target organs via the corresponding sympathetic chain ganglia and the inferior mesenteric and pelvic ganglia, as in the case of the autonomic bladder control.
Arterial and venous supply to prostate
● Arterial supply
○ prostatic arteries, branches of internal iliac artery
● Venous drainage
○ Form the prostatic venous plexus surrounding the prostate, between the fibrous capsule and prostatic sheath.
■ drains into internal iliac veins
■ communicates superiorly with vesical venous plexus.
Lymphatic drainage of the prostate
● Superiorly to internal iliac nodes
● Inferiorly to presacral nodes.
Zones of the prostate
● Central zone surrounding ejaculatory ducts and lateral to urethra
● Anterior zone of fibromuscular tissue
● Peripheral zone, posterolateral aspect of prostate gland (majority of prostate ca)
● Transitional zone surrounding the proximal urethra (most common site of BPH)
○ Contains transitional cell epithelium similar to the bladder
Most common zone to find prostate Ca
Most common zone to find BPH
● Peripheral zone, posterolateral aspect of prostate gland (majority of prostate ca)
● Transitional zone surrounding the proximal urethra (most common site of BPH)
Macroscopic appearance of uterus
Thick walled, inverted pear shaped
Divided into the body/fundus and inferiorly the cervix ~2.5cm in length which is narrower and more cylindrical - connected by a narrowing called the ithmus of cervix
Usually the uterus is antiverted and antiflexed
Usually the uterus is …….verted and ……flexed
Usually the uterus is antiverted and antiflexed
Body of the uterus ● Gradually narrows from the fundus to the ...... ● Anterior surface lies on ...... ● Posterior surface is ........ ● Laterally con..... ● Surfaces covered sup and inf in
● Gradually narrows from the fundus to the isthmus
● Anterior surface lies on bladder
● Posterior surface is horizontal
● Laterally convex
● Covered in peritoneum
○ Reflects anteriorly onto the bladder to form the vesicouterine pouch
○ Reflects posteriorly onto the anterior rectum to form the rectouterine pouch (of Douglas)
The Tubes and ligaments attaching to the uterus and their sites of attachment:
Two uterine tubes enter the superolateral aspect
Anteroinferior to it the round ligament attaches
Posteroinferiorly the ovarian ligament attaches
The contents of the broad ligament include the following:
1) Reproductive:
Uterine tubes (or Fallopian tube)
ovary (some sources consider the ovary to be on the broad ligament, but not in it.)
2) Vessels:
ovarian artery (in the suspensory ligament)
uterine artery (in reality, travels in the cardinal ligament)
3) ligaments:
ovarian ligament
round ligament of uterus
suspensory ligament of the ovary
The cervix is divided into two parts:
Give the anatomical relations of each:
1) Supravaginal part
■ Anteriorly
● bladder, parametrium
■ Laterally
● parametrium, uterine arteries
■ Posteriorly
● peritoneum, rectouterine pouch, rectum
2) Vaginal part
■ forms the vaginal fornices
■ has an external os
Primary cell types of the testes:
Within the seminiferous tubules
1) germ cells develop into spermatogonia, spermatocytes, spermatids and spermatozoon through the process of spermatogenesis.
2) Sertoli cells – the true epithelium of the seminiferous epithelium, critical for the support of germ cell development into spermatozoa. Sertoli cells secrete inhibin.
3) Peritubular myoid cells surround the seminiferous tubules.
Layers of the tests
SDECITTa - Some Dumb English Elite Called Italy Totally Trashy
1) Skin
2) Dartos
- Spermatic Cord - 3) External spermatic fascia 4) Cremaster 5) Internal Spermatic fascia 6) Tunica vaginalis 7) Tunica Albicans
Coverings of the testes within the internal sprematic fascia:
● Tunica vaginalis- closed peritoneal sac.
○ parietal and visceral layers separated by a small amount of fluid.
● Tunica albuginea- tough fibrous layer.
○ On its inner surface forms septa that divide the testes internally into lobules.
Blood supply of the scrotum
And lymphatic drainage
Arterial:
Internal iliac -> Internal pudendal
Venous:
Anterior scrotal vv ->External pudendal
Posterior scrotal vv -> Internal pudendal
Lymphatics:
Superficial inguinal -> Deep inguinal ->external iliac.
What is the parametria? Why is it useful?
● Tissue encompassed by broad ligament
● Borders (for CTV delineation):
Borders of the parametrium:
○ Superiorly
■ Top of broad ligament
○ Inferiorly
■ Pelvic floor
○ Anteriorly
■ Post wall of bladder, or
■ Post border of external iliac vessels (in patients with very small bladders)
○ Posteriorly
■ Uterosacral ligaments and mesorectal fascia
○ Laterally
■ Pelvic side wall excluding bone and muscle
To where do the testicular arteries drain?
Venous drainage of the scrotum?
Left T.a -> Renal vein ->IVC
Right T.a -> IVC
Venous drainage of scrotum = Internal pudendal -> internal iliac ->IVC
Lymphatic drainage of the balls?
follows left and right testicular artery and vein to the para-aortic nodes.
Internal structure of the balls?
Wrapped in tunica albuginea, which forms internal septae:
● Divided into lobules formed by seminiferous tubules where sperm are produced.
● Seminiferous tubules are joined by straight tubules to the rete testis.
● Efferent ductules transport sperm from rete testis to the epididymis.
Nerve supply to the balls?
Testicular plexus on the testicular artery, carries autonomic nerves from T10-T11
Structure of the epididymis:
● Formed by tightly compacted minute convolutions of the duct of the epididymis.
● The duct becomes progressively smaller from head to tail
● At the tail, duct continues as the ductus deferens.
Describe the seminal vesicles:
Give Relations
● Elongated structure between fundus of the bladder and rectum
● Obliquely placed superior to the prostate.
● Superiorly covered by peritoneum and rectovesical pouch.
● Inferoposteriorly related to rectum
● Ducts join vas deferens to form the ejaculatory duct
What are splanchnic nerves?
(Give the key exception)
Why are they important?
Paired visceral nerves, carrying fibers of the autonomic nervous system (visceral efferent fibers) as well as sensory - visceral afferent fibres. All carry sympathetic fibers except for the pelvic splanchnic nerves, which carry parasympathetic fibres.
Important to end an exam question on innervation.
When does the vagus nerve give up supplying parasympathetic innervation?
What takes over?
At the distal 1/3 of Tv colon.
Pelvic splanchnic nerves then take over parasympathetic supply.
