Pelvis Flashcards
Label these bony parts of the hip bone.
Label these parts of the ilium.
Label these parts of the ischium.
Label these parts of the pubis.
Label the ligaments of the pelvis.
What is the purpose of the sacrospinous and scarotuberous ligaments?
They ensure the inferior part of the sacrum is not pushed superiorly when weight is suddenly transferred vertically through the vertebral column (e.g. when jumping or during late pregnancy)
Which foraminae does the presence of the sacrospinous and sacrotuberous ligaments create in the pelvis?
The greater and the lesser sciatic foramen
What bones make up the pelvic inlet?
- sacral promontory
- ilium
- superior pubic ramus
- pubic symphysis
What structures make up the pelvic outlet?
- pubic symphysis
- ischiopubic ramus
- ischial tuberosities
- sacrotuberous ligaments
- coccyx
What organs of the female reproductive system lie within the pelvic cavity?
- Ovaries
- Uterine tubes
- Uterus
- Superior part of vagina
What organs of the female reproductive system are found in the perineum?
- Inferior part of vagina
- Perineal muscles
- Bartholin’s glands
- Clitoris
- Labia
Label these structures.
What is the broad ligament and where is it found?
A double layer of peritoneum that extends between the uterus and the lateral walls and floor of the pelvis
What structures are contained within the broad ligament?
Uterine tubes
Proximal part of the round ligament
Decribe the bony attachments of the sacrospinous ligament.
Sacrum to ischeal spine
Describe the bony attachments of the sacrotuberous ligament.
Sacrum to ischeal tuberosity
How does the male pelvis differ from the female pelvis?
More prominent sacral promontory
More curved coccyx
Narrower, taller pelvic cavity
Narrower pelvic inlet and outlet
Thicker, more robust bones
When may it be necessary to palpate bony landmarks of the pelvis?
Ischeal spines (internally) - landmark to guide pudendal nerve block (S2,3,4)
Pubic symphysis - to measure symphysis fundal height
Describe the relationship between the ischial spine and the pudendal nerve.
Travels from the sacrum through the greater sciatic formen, and loops around the sacrospinous ligament before reentering the pelvis through the lesser sciatic foramen
Which structures does the pudendal nerve innervate and which spinal cord levels does the nerve originate from?
S2, 3, 4
Supplies: clitoris and other perineal structures
How can fluid collection in the pouch of Douglas be drained?
Via needle aspiration passed through the posterior fornix of the vagina
What are the attachments of the round ligament?
Attaches to the lateral aspect of the uterus, and then passes through the deep inguinal ring to attach to the superficial tissue of the female perineum
What are the three layers of the uterus?
perimetrium
myometrium
endometrium
What are the three layers of support that hold the uterus in place?
- ligaments (e.g. uterosacral ligaments)
- endopelvic fascia
- muscles of the pelvic floor (e.g. levator ani)
What is the most common position of the uterus?
Anteverted and anteflexed
What does anteverted mean?
Uterus tipped anteriorly relative to the axis of the vagina
What does anteflexed mean?
Uterus tipped anteriorly relative to the axis of the cervix (the mass of the uterus lies over the bladder)
Where do the ovaries develop and what structure moves them to their final position?
Develop on the posterior abdominal wall and move onto the lateral wall of the pelvis
Round ligament of the uterus
What is the nerve supply of the levator ani?
Nerve to levator ani, S3, 4, 5 sacral plexus
What is the perineal body?
A bundle of collagenous and elastic tissue into which the perineal muscles attach
What is this structure?
Bartholins gland
What are the muscles labelled?
What is the rectus sheath?
A strong fibrous layer immediately deep to the superficial fascia, consisting of the combined aponeuroses of anterolateral abdominal wall muscles
What muscles does the rectus sheath surround?
Rectus abdominis muscles
What is the difference in the rectus sheath above and below the umbilicus?
Above the umbilicus there is an anterior and posterior rectus sheath
Below the umbilicus there is only anterior
Which level do the iliohypogastric and ilioinguinal nerve come from and in which direction do they travel?
L1
Travel in plane between internal oblique and transversus abdominis
Which artery is the suprior epigastric artery a continuation of and where can it be found?
Internal thoracic artery
Lies posterior to rectus abdominus
Which artery is the inferior epigastric artery a branch of?
External iliac artery
What layers must be opened to perform a lower section cesarean section (LSCS)?
- Skin and fascia
- (anterior) Rectus sheath
- Rectus abdominis – separate the muscles laterally
- Fascia and peritoneum
- Retract bladder (a urinary catheter is usually already inserted)
- Uterine wall
- Amniotic sac
What layers must be stitched closed following an LSCS?
- Uterine wall with visceral peritoneum
- Rectus sheath
- (Fascial layer if increased BMI)
- Skin
What artery must be avoided when inserting a lateral port during laparoscopy?
Inferior epigastric artery
How can the inferior epigastric artery be avoided during laparoscopy?
Artery emerges just medial to the deep inguinal ring (located half way between ASIS and pubic tubercle)
Insert port laterally to this
What kind of nerve supply does the pelvis have?
Sympathetic, parasympathetic and visceral afferent
What kind of nerve supply does the perineum have?
Somatic motor and somatic sensory
What is the sensory supply to the superior part of the pelvis, and what defines this?
Superior part defined as ‘touching the peritoneum’
Visceral afferents run alongside sympathetic fibres
What level of the spinal cord do the visceral afferents from the superior pelvis enter?
T11-L2
What is the sensory nerve supply of the inferior aspect of the pelvic organs?
Visceral afferents running alongside parasympathetic fibres
Which level of the spinal cord do the visceral afferents supplying the inferior part of the pelvic organs enter?
S2, S3 and S4
At what level does the subarachnoid space end?
S2
At what level does the spinal cord become the cauda equina?
L2
What level is the anaesthetic injected in a spinal/epidural procedure?
Subarachnoid space of L3-L5
What structures does the needle pass through to administer a spinal anaesthetic??
- supraspinous ligament
- interspinous ligament
- ligamentum flavum
- epidural space (fat and veins)
- dura mater
- arachnoid mater
How may a mediolateral episiotomy reduce the risk of faecal incontinence developing after a difficult vaginal delivery?
Tear can be directed away from the anus
What is the mahjor structure incised during a median episiotomy and what potential issues are faced if further tearing occurs?
Perineal body
Urgence, flatulence, faecal incontinence
Which nerve block could be performed to abolish sensation from the anterior aspect of the perineum?
Ilioinguinal
Posterior cutaneous femoral nerve
How does a spinal anaesthetic differ from an epidural anaesthetic?
Epidural injected into epidural space and acts on the rootlets passing through rather than the cord itself
Spinal anaesthetic injected into the subarachnoid space
What are the potential side effects of a spinal or epidural anaesthetic?
Temporary paralysis/immobility
Dural headache
Hypotension
What is the pudendal canal?
A passageway within the obturator fascia
Contains the pudendal nerve, internal pudenal artery and vein and the nerve to obturator internus
Into which structure is an episiotomy incision made?
Ischioanal fossa
What are the three layers of the pelvic floor?
pelvic diaphragm
muscles of perineal pouches
perineal membrane
What muscles make up the levator ani?
Puborectalis
Pubococcygeus
Iliococcygeus
Label these muscles.
What nerves innervate the levator ani?
Pudendal nerve
Nerve to levator ani
What is this structure?
Tendinous arch of levator ani
What muscle forms the tendinous arch of levator ani?
Obturator internus
What is the origin and insertion of the piriformis muscle?
Origin: pelvic surface of sacrum
Insertion: superior aspect of greater trochanter
What is the origin and insertion of the obturator internus muscle?
Origin: ischiopubic ramus & obturator membrane
Insertion: medial aspect of the greater trochanter
What is the obturator membrane?
The obturator membrane is a thin fibrous sheet, which almost completely closes the obturator foramen
Label these structures.
Where is the deep perineal pouch located?
Lies below the fascia covering the inferior aspect of the pelvic diaphragm
Lies above the perineal membrane
What is contained in the deep perineal pouch?
Contains part of the urethra and vagina in females
Bulbourethral glands in male
Neurovascular bundle for penis/clitoris
Extensions of the ischioanal fat pads and muscles
What is the difference between the deep transverse perineal muscle in males and females?
In females this is smooth muscle
In males this is skeletal muscle
Label these structures.
What structures are the last passive support for the pelvic organs?
Perineal body
Perineal membrane
What is the perineal membrane?
Thin sheet of touch, deep fascia located superficially to the deep perineal pouch
Where does the perineal membrane attach laterally?
Pubic arch
What structures are contained in the superficial perineal pouch of the male?
Root of penis:
Bulb – corpus spongiosum
Crura – corpus cavernosum
Associated muscles – bulbospongiosus and ischiocavernosus
Proximal spongy (penile) urethra
Superficial transverse perineal muscle
Branches of internal pudendal vessels and pudendal nerve
Label these structures.
Label these structures.
Label these structures.
Label these arteries.
The majority of arteries of the pelvis and perineum arise from the internal iliac, with the exception of which two arteries?
Gonadal
Superior rectal
What arteries arise from the posterior division of the internal iliac artery?
Gluteal
What arteries arise from the anterior divison of the internal iliac artery?
Obturator artery
Superior vesical arterie
Inferior vesical artery/vaginal artery
Internal pudendal artery
Most arteries in the male perineum arise from the internal pudendal artery, with the exception of which artery?
Anterior scrotal artery - comes from external iliac
What is the significant anastamosis in the female pelvis and why?
Anastamosis between uterine and ovarian artery
Uterine artery comes from internal iliac
Ovarian artery comes from abdominal aorta
Why might prostate cancers spread to the cranial cavity?
Venous drainage of prostate occurs through lateral sacral veins, which have no valves
Describe the venous drainage of the pelvis.
Drain mainly to internal iliac vein:
- some will drain via superior rectal into hepatic portal system
- some will drain via lateral sacral veins into internal vertebral venous plexus
What is the drainage of the gonadal veins?
Right - drains directly into IVC
Left - into left renal vein
Why does ureter damage in females during surgery more commonly occur on the left than the right?
The right usually crosses the external iliac, the left is more medial and crosses common iliac
Where does lymph from the superior pelvic viscera drain?
- external iliac nodes
- common iliac, aortic, thoracic duct
- ,venous system
Where does lymph from the inferior pelvic viscera drain?
- deep inguinal
- internal iliac nodes
- common iliac, aortic, thoracic duct, venous system
Where does lymph from the superficial perineum drain??
Superficial inguinal nodes
