Anatomy - Pelvis Flashcards
What type of joint is the sacro-iliac joint?
Synovial joint with no rotation
What type of joint is the symphysis pubis?
Secondary cartilagenous joint with no rotation
List the three bones that make up the hip bone
- Ilium
- Ischium
- Pubis
What makes up the pelvic wall?
- Sacrum, coccyx and pelvic bones
- Sacrospinous and sacrotuberous ligaments
What lines the pelvic outlet?
- Pubic arch
- Iscial tuberosity
- Sacrotuberous ligament
- Coccyx
What is contained by the iliac fossa?
Lower abdominal viscera
Describe the axis of the pelvic cavity
- Antero-inferiorly inclined
- Conical or cylindrical
What muscle covers the pelvic bone facing the pelvic cavity?
The obturator internus muscle and its fascia
Which two muscles are attached to the medial surface of the greater trochanter of the femur?
- Piriformis muscle
- Obturator internus muscle
List the muscles of the pelvic diaphragm
Levator ani muscle (iliococcygeus, pubococcygeus, puborectalis)
List the two ligaments in the medial aspect of the pelvic wall
- Anococcygeal ligament (where the two levator ani muscles join)
- Tendinus arch (or obturator internus)
What is the function of the levator ani?
Supports the pelvic organs (bladder, cervix, uretus and rectum)
What nerve supplies the levator ani?
Pudenal (S2-4) and directly by S4
List the openings in the levator ani
- Urethra
- Anal canal
- Vagina (in females)
What is the perineal membrane?
The inferior layer of fascia of the urogenital part of the pelvic diaphragm
What is below the pelvic diaphragm?
The perineum, containing voluntary sphincters and external genitalia
Describe the shape of the urinary bladder.
- Tetrahedral
- Ureters make 2 borders
- Median umbilical ligament at the apex
- Urethra at the neck
Describe how the ureters enter and the urethras exit the urinary bladder
- Ureters supero-posterior angles
- Urethra inferior angle
Where are the two sphincters of the urinary bladder located?
- Smooth muscle at the neck (sphincter visicae)
- Skeletal muscle in the perineum (sphincter urethrae)
Name the three rectal folds and their location
- Superior and inferior rectal folds are on the left
- Middle rectal fold is inbetween these on the right
List the rectal arteries
- Superior rectal artery
- Middle rectal artery
- Inferior rectal artery
Where are the anorectal flexure and anorectal junciton?
Between the rectum and the anal canal
List the three components of the external anal sphincter
- Deep
- Superficial
- Subcutaneous
Name the skeletal muscle surrounding the anal canal
- Sphincter ani
- Less important than the puborectalis levator ani, which puts a sharp angle in the recto-anal junction
What does the internal iliac artery supply?
- Pelvic walls
- Pelvic viscera
- External genitalia
- Peineum
- Buttock
- Medial part of the thigh
What does the external iliac artery supply?
- The legs
- Has two branches (inferior epigastric artery and deep circumflex artery) which supply the skin in the lower abdominal wall
State the differences between the male and female pelves
- Males have a narrow/heart shaped pelvic inlet
- Females have a oval/round pelvic inlet
- Females have a much larger pubic angle of over 80 degrees, males only 50-60 degrees
Describe the characteristics of an orientated pelvic girdle
- ASIS and pubic tubercles in the same plane
- Greater and lesser pelves are continuous
Distinguish between the true pelvis and false pelvis (or greater and lesser pelvis)
- True pelvis contains the pelvic inlet
- False pelvis is above the pelvic inlet, in the abdomen
What is contained within the space between the pelvic wall and peritoneum?
- Pelvic fascia
- Pelvic fascia form ligaments supporting the cervix, vagina and prostate
List the contents of the male pelvic cavity
- Ureter, bladder and urethra
- Prostate, ductus deferens, sminal vesicles, bulbourethral glands
- Caecum, appendix, ileum and parts of the sigmoid colon
- Vessel, nerves and lymphatics
Which structures in the male pelvis can be felt on a digital rectal examination of a healthy man?
The prostate gland is about 2.5 cm in length, with a medial sulcus, is firm and non-tender.
Where is the prostate gland?
Surrounding the 1st (prostatic part) or the urethra
Where is the ductus deferens?
Passes through the inguinal canal then over and behind the ureter to enter the urethra through the prostate
Where are the seminal vesicles?
On the back of the bladder, they open into the ductus deferens between the ampulla and ejaculatory duct
What needs to be considered when inserting a male catheter?
- The catheter needs to negotiate the first bend of the urethra as it passes from the perineum to the pelvis
- Can also be lodged in the prostatic utricle
- The second bend can be flattened by lifting up the penis
What percentage of secretions of the ductus deferens are from seminal vesicles and prostate?
- 60% seminal vesicles
- 40% prostate
Compare the organisation of the internal urethral sphincter in males and females
- In males it is better organised
- This is because it needs to be closed in males during ejaculation to prevent reflux of the ejaculatory fluid
List the parts of the male urethra
- Preprostatic part (1.5cm)
- Prostatic part (2.5cm)
- Membranous part (2cm)
- Spongy part (15cm)
Describe the arterial supply of the male pelvis
- Internal iliac artery splits into an anterior and a posterior branch
- Inferior vesical artery supplies the prostate, bladder and ductus deferens
- The prostatic branch of the inferior vesical artery goes to the prostate
- Superior vesical arteries supplies the bladder and ductus deferens
- Pensi supplied by internal pudendal artery from the internal iliac
Describe the anatomy of the perineum
- Diamond shaped area between the pubic symphysis, iscial tuberosities and coccyx
- Split into an anterior (urogenital region) and posterior (anal triangle)
Describe the structure of the posterior compartment
- Ischio-anal fossae (fat filled spaces separating the anal canal and levator ani from pelvic muscles
Describe the structure of the anterior triangle
- Divided into superficial and deep parts by the perineal membrane
- Perineal membrane attached to the pubic arch, with a small gap and a free posterior margin
- Deep peritoneal space is above the perineal membrane, but below the fascia of the pelvic diagram
- The superficial perineal space is below the perineal membrane and perineal fascia
- Spaces are potential
Describe the superficial perineal structures of the male
- Glans of the penis
- Body of the penis
- Suspended from the falciform ligament
- Two crus of the penis, either side, with two ischiocavernosus muscles (corpus cavernosum) attached to ischiopubic rami
- Bulb of the penis in the middle, with the bulbospongiosus muscle/corpus spongiosum
- Meet to form the shaft and head of the penis/clitoris
List the deep perineal structures of males
- External urethral sphincter (skeletal muscle)
- Two bulbourethral glands and ducts open into urethra below the perineal membrane
List the arteries supplying the rectum and anal canal
- Superior rectal artery, middle rectal artery and inferior rectal artery
- One from inferior mesenteric, two from internal iliac artery
What are the iscioanal fossae?
- Fat filled spaces in the anal triangle which allow recto-anal and vaginal expansion
- Lateral wall contains the pudendal neurovascular bundle
List the contents of the spermatic cord
- Testicular artery and pampiniform plexus of vein
- External spermatic fascia (external oblique aponeurosis)
- Internal spermatic fascia (transversalis fascia)
- Cremasteric fascia (from internal oblique)
Describe the nerve supply of the pelvis
- Supplied by autonomic nerves only
- Sympathetic nerves from lower thoracic and upper lumbar segments via hypogastric plexus (superior and inferior)
- Parasympathetic from S2-4 outflow
- Pain referred to the suprapubic region
List the sensory and motor functions of the pudendal nerve
- Sensory - dorsal nerve, sensory to the penile skin and flans, lower urethra, lower rectum and anal canal
- Motor - to perineal muscles, bulbospongiosus and ischicavernosus causing ejaculation and external urethral sphincter
List the functions of the parasympathetic nerves
- Vasodilation of arterioles in erectile tissue
- Secretion in prostate and bulbourethral glands
List the functions of the sympathetic nerves
- Contraction of smooth muscles of epididymis, vas deferens, seminal vesicles and prostate cause emission
- Contraction of internal urethral sphincter
Where does the pudendal nerve arise?
From the lumbosacral plexus (S2-S4)
List the female pelvic organs
- Ovary, uterine tubes
- Uterus and cervix
- Vagina
- Ureter bladder and urethra
- Rectum, caecum and appendix, parts of sigmoid colon and ileum
- Vessels nerves and lymphatics
Why do females get UTIs more easily than males?
They have a shorter urethra
Describe the peritoneum in females
- Does not go to the pelvic floor
- Uterine tubes enveloped by the broad ligament
- Ovaries are suspended by mesovarium from posterior of broad ligament
- Pelvic fascial condensations form ligaments supporting viscera (cervix and vagina)
What are the important contents of the broad ligaments
Uterine tubes and uterine arteries
What anchors the cervix in position?
- The vervical ligaments
- Prevent the uterus from prolapsing into the vagina
- Pubocervical ligament
- Transverse cervical ligament (very important, also called the cardinal ligament - it is the strongest)
- Uterosacral ligament
List the parts of the uterus and uterine tube
- Uterus has fundus, body, lower part and cervix
- Uterine tubes have infundibulum, ampulla, isthmus and uterine parts
What is the fornix?
The border between the cervix and the vaginal cavity, where the cervix curves into the vagina
List the openings of the cervix and the cell types that line it
- A fibromuscular cylinder with internal os and external ox (os meaning opening)
- Canal is lined by simple columnar epithelium, with the vaginal surface covered in stratified squamous non-keratinised epithelium
What does a smear test identify?
If the squamous cells of the vaginal part of the cervix has become keratinised
What is the angle of anteversion?
Angle between the axis of the vagina and the axis of the cervix (90 degrees)
What is the angle of anteflexion?
Angle between the axis of the cervix and the axis of the uterine body
Where is the posterior fornix?
- Between the vagina and the rectum
- From here a pelvic abscess can be drained and eggs can be collected
Describe the relationship between the urethra and vaginal wall
They are fused - attached very tightly
List the structures palpable from the vaginal wall
- Cervix
- Ischial spine
- Sacral promontory
- Uterine artery pulse
- Ovary
List the arteries supplying the female pelvis
- Superior vesical, uterine and middle rectal
- Walls of the pelvis supplied by sacral, gluteal and obturator branches
- Pudendal arteries supplies the perineum and recto anal region via inferior rectal branch
- The vaginal artery is the equvalent to the inferior vesiclal artery in males
Where does the uterine artery supply?
- Main blood supply to the uterus
- Enlarges during pregnancy
- Crosses the ureter 1cm from the cervix
- Runs close to the uterus in the broad ligament, with ascending (body of uterus and tube) and descending branches (vagina)
What supplies blood to the ovary?
- Ovarian artery from the abdominal aorta
- Descending branch supplies the vagina
What do you need to be wary of in hysterectomy?
When stopping the blood supply the ureters could accidentally be tied off
What is the lithotomy position?
Lying supine with the knees flexed
List the deep perineal structures in the female
- Exit for urethra and external urethral sphincter (responsible for incontinence)
- Sphincter urethrovaginalis (around vagina and urethra)
- Opening for vagina
- Anal opening
Describe the formation of the clitoris
- Median erectile mass (corpus spongiosum) divides to form vestibular bulbs which forms the glans of the clitotis)
- Lateral erectile tissue (corpora cavernosa) paired cylinders attached to the ischiopubic rami, forming the body of the clitoris
- Erectile tissues are surrounded by skeletal muscle
List the contents of the superficial perineal pouch
- Vulva
- Labia majora
- Mons pubis
- Labia minora
- Clitoris
- Vestibule of vagina
- Vestibular bulbs (under the labia majora)
- Vestibular glands (lesser on either side of the urethra, greater either side of the vaginal opening)
What is another name for the lesser vestibular glands?
Skenes glands
What is another name for the greater vestibular glands?
Bartholins glands
List the nerves supplying the female pelvis
- Only autonomic
- Sympothetic T10-L2 hypogastric plexus
- Parasympathetic S2-4
- Anterior labial nerve (from iliolingual)
- Perineal branch of postcutaneous nerve of thigh
- Pudendal nerve (clitoris, vagina, labia minora, rectum)
Where does lymph drain in the pelvis?
- Pelvic organs drain to external and internal iliac nodes
- Ovary and testes drain to para-aortic nodes
- Perineum and external genitalia drain to superficial inguinal nodes below the inguinal ligament
