Anatomy Flashcards
What are the functions of the bony pelvis
Support of the upper body when sitting and standing
Transfers weight from single vertebral column to bilateral femurs
Attachment for muscles of locomotion and abdominal wall
Attachment for external genitalia
Protection of pelvic organs, their blood & nerve supplies, their venous and lymphatic drainage
Passage for childbirth
Which bones form the bony pelvis
2 hip bones - made up of ilium, ischium and pubis
Sacrum
Coccyx
What forms the sub-pubic angle
The joins of the two pubic bones
Creates an arch which creates the angle
What forms the pelvic inlet
sacral promontory
ilium
superior pubic ramus
pubic symphysis
What forms the pelvic outlet
pubic symphysis ischiopubic ramus ischial tuberosities sacrotuberous ligaments coccyx
Where is the pelvic cavity found
Sits within bony pelvis between pelvis inlet and pelvic floor
Continuous with the abdominal cavity above
What is found in the pelvic cavity
The pelvic organs and supporting tissues
Where can you palpate the ischial spines
On internal examination of a female
At the 4 and 8 o’clock positions
Used to measure station in labour
Which parts of the pelvis are palpable
On deep palpation can feel pubic symphysis and tubercle
Iliac crests are palpable
Ischial tuberosity can be felt when sitting down
Ischial spines palpable internally
What joints are found in the pelvis
Sacroiliac joints - synovial
Hip joint - synovial
Pubic symphysis - secondary cartilaginous
What happens to the pelvic ligaments in pregnancy
They relax
This is due to the hormones - relaxin
Name the two main ligaments of the pelvis
Sacrotuberous ligament (sacrum to ischial tuberosity) Sacrospinous ligament (sacrum to ischial spine)
What are the functions of the pelvic ligaments
Help to stabilise pelvis joint during weight bearing
Ensure the sacrum isn’t pushed superiorly when weight is transferred vertically - jumping etc
Describe the relationship between the pelvic ligaments and the sciatic foramen
The 2 ligaments divide it into the greater and lesser sciatic foramen (important for passage of nerves/vessels into lower limb/perineum)
Describe the structure and contents of the obturator foramen
It is entirely covered by ligament except for tiny area that has obturator canal
The obturator nerve and vessels pass through here to supply the medial thigh
What is the main concern with a fractured pelvis
The potential damage to the structures held within it - can lead to life threatening haemorrhage
less concern about the bones themselves
The pelvis usually fractures in multiple places - true or false
True
Bony pelvis is a ring, so must fracture in multiple places (minimum 2)
Or it is combined with joint dislocation
Which blood vessels can be damaged in pelvic trauma
External and internal iliac artery/veins with their branches
If damaged this can cause a life threatening haemorrhage - lot of blood in the pelvis
List the differences between the male and female pelvis
Female has bigger openings (inlet and outlet)
Pubic arch and subpubic angle much bigger in female
Pelvic cavity is more shallow in women
Female is more rounded and male is more love heart
All to prep for childbirth
What is meant by moulding of the foetal skull
When the bones are able to move over one another to allow the head to pass in labour
What are the fontanels
2 diamond shaped areas - anterior and posterior - which are gaps between the skull bones
Just covered by a membrane - called the soft spot
Also have mastoid and sphenoid ones that are less clinically relevant
What is the vertex of the skull
Seen in the foetal skull
Diamond shaped area between the2 parietal eminences (bulges) and the anterior and posterior fontanelles
Describe the dimeters of the foetal skulls
The occipital frontal dimeter is the longest
Skull is longer than it is wide
Which diameter of the female pelvis is greatest
Transverse diameter in female greater than AP diameter
How should the baby enter the pelvic cavity
Should be facing either left or right so that the OP diameter of their skull matches the transverse diameter of the pelvis (2 largest ones)
How do you measure the station of labour
Palpate the distance of the foetal head from the ischial spines
If above spines = negative station
If below its a positive station
How should the baby pass through the pelvis
Enter the pelvic cavity facing to the side (transverse)
As it descends the head should rotate and be flexed
At the pelvic outlet the AP diameter becomes widest so the head needs to be vertical (OA) so that they line up
Foetal head should be extended on delivery
There is further rotation to deliver the shoulders
Which parts of the female reproductive system are found in the pelvic cavity
Ovaries
Uterine tubes
Uterus
Superior part of vagina
Which parts of the female reproductive system are found in the perineum
Inferior part of vagina Perineal muscles Bartholin's glands Clitoris Labia
What is the primary organ of female reproduction
Ovary
All others are considered secondary or accessory
What separates the pelvic cavity and perineum in women
The levator ani muscle (forms the pelvic floor)
What is the peritoneum
Peritoneum is a very thin, serous membrane layer that covers the abdominal organs and entire pelvis
It forms the floor of peritoneal cavity and is a roof over pelvic organs
What pouches are formed by the peritoneum in women
vesico-uterine
recto-uterine (pouch of Douglas)
What is the clinical importance of the pouch of Douglas
It is usually the most inferior part of the peritoneal cavity Therefore excess (abnormal) fluid within the peritoneal cavity tends to collect here
How can you drain fluid from the pouch of Douglas
By inserting a needle through the posterior fornix of the vagina
Which part of the female reproductive tract is intraperitoneal
The uterine tubes
As the peritoneum drapes over the uterine tube it will come back down the other side so it is completely surrounded
What is the broad ligament of the uterus
A double layer of peritoneum that extends between the uterus and the lateral walls and floor of the pelvis
Formed by peritoneum draping over the uterine tubes and coming together underneath
What is contained within the broad ligament of the uterus
contains the uterine tubes and the proximal part of the round ligament
What is the function of the broad ligament of the uterus
helps maintain the uterus in its correct midline position
What is the round ligament of the uterus
Round ligament is the embryological remnant of the gubernaculum – thought to help guide the ovaries from the posterior abdominal wall to their correct position
Sometimes called the ligamentum teres
Where does the round ligament of the uterus run
Attaches to the lateral aspect of the uterus
It passes through the inguinal canal (via the deep ring) and down into the labia
What are the 3 layers of the uterus
perimetrium
myometrium - thick muscular layer
endometrium - shed in menstruation
Where does implantation of an embryo occur
In the body of the uterus
What is an ectopic pregnancy
Implantation of an embryo anywhere other than the body of the uterus
The foetus will not survive
Why is ectopic pregnancy a medical emergency
A rupture will lead to a big haemorrhage that will kill mum
Where can ectopic pregnancies occur
Most ectopic pregnancies will occur in the uterine tubes
Some can occur in the abdomen
What holds the uterus in position
number of strong ligaments - e.g. uterosacral
Endopelvic fascia
Muscles of the pelvic floor (e.g. levator ani)
What happens if the support structures of the uterus are weakened
If any of these supports are weakened you become prone to prolapse
Uterus descends down into the vagina
What is the normal position of the uterus
Anteverted and anteflexed
Anteverted means the cervix is tipped anteriorly relative to the axis of the vagina
Anteflexed mean the uterus is tipped anteriorly relative to the axis of the cervix (the mass of the uterus lies over the bladder)
What is a retroverted uterus
cervix is tipped posteriorly relative to the axis of the vagina
No effect really just a normal variation
What area is samples during a cervical smear
Have to sample the transformation zone of the cervix – where you move from internal part of cervix to external (cell type changes)
This is the most common area for dysplasia
How do the vaginal walls usually sit
Walls of the vagina are usually collapsed and touching each other
This is why you need to insert the speculum for smears
Where does fertilisation occur
Ampulla of the uterine tube
What is the term for removal of the tubes and ovaries
bilateral salpingo-oophrectomy
Are the abdominal cavity and genital tract connected
Yes
There is a direct communication as the fimbriated end of the tubes open directly into the peritoneal cavity
What is the clinical significance of the connection between the abdomen and reproductive tract
Any genital infections can spread up and cause peritonitis
Ectopic pregnancies can develop in the abdomen
Where are the ovaries found
Ovary are found on the lateral wall of the pelvic cavity (in ovarian fossa)
Moved here by round ligament
Describe the blood supply to the ovaries
The arterial, venous and lymphatics supply of the ovaries come from the posterior abdominal wall as this is where they originate
What are the vaginal fornices
Small spaces at the top of the vagina around the cervix
It has 4 parts anterior, posterior and 2x lateral
Where can the ischial spines be palpated
Inside the vagina
Laterally at the 4 and 8 o’clock positions
How can you palpate the uterus
Bimanual palpation
One hand in vagina other on abdomen
If felt it is anteverted
How can you palpate the adnexae (ovaries and tubes)
place examining fingers into lateral fornix
press deeply with other hand in the iliac fossa of the same side
repeat on other side
What is the perineum
Shallow area between the pelvic floor and the perineal skin
Split into 2 triangles – urogenital and anal
Contains the openings of the pelvic floor
Describe the levator ani muscle
It is made up of smaller muscles and makes up most of the pelvic floor
Its skeletal so under voluntary control
What is the function of the levator ani muscle
Provides continual support for the pelvic organs - always tonically contracting
Will reflexively contract if there is an increase in pressure such as sneezing, coughing, lifting weights to prevent incontinence
What supplies the levator ani muscle
Nerve to the leavtor ani - S3,4,5
Some supply from pudendal nerve as well
What is the perineal body
Bundle of collagenous and elastic tissue into which the perineal muscles attach
Just deep to the skin
Important to pelvic floor strength
When might the perineal body get damaged
During childbirth
It will massively impact pelvic floor strength
Try and protect it from tears etc
What are the bartholins glands
Glands found in the perineum which secrete mucus to lubricate the entrance to the vagina
Very painful when infected
Where are the female breasts found
From ribs 2-6
From lateral border of sternum to mid-axillary line
Lies on the deep fascia of the pecs
HAs an axillary tail
What makes up the breast
Fatty tissue and non-lactating lobules all around the breast
In later stages of pregnancy the lobules become lactating – fill up with milk
What is the retromammary space
Space between the fascia of the pec and the breast
It allows the breast to move against the muscles
What attaches the breast to the skin
Firmly attached via suspensory ligaments
How do you assess a breast lump
Position described in relation to the 4 quadrants - upper/lower outer/inner
Have to assess whether the lump is fixed to underlying tissue or not
Both the axilla and supraclavicular area should be assessed
Where does lymph from the breasts drain
Most lymph drains to axillary nodes on the same side and then to the supraclavicular nodes
However lymph from inner breast quadrants can drain to the parasternal lymph nodes - can cross side
Lower quadrants can drain to abdominal nodes
What structures are found in the axilla
brachial plexus branches
axillary artery and axillary vein (& their branches)
axillary lymph nodes
all embedded in axillary fat
Describe the levels of axillary node clearance
Level I – inferior and lateral to pectoralis minor
Level II – deep to pectoralis minor
Level III – superior and medial to pectoralis minor
What is the blood supply of the breast
Most blood supply comes from internal thoracic artery (branches off the subclavian)
Some from axillary
Which general type of nerves supply the structures of the pelvis
sympathetic, parasympathetic and visceral afferent
Which general type of nerves supply the structures of the perineum
somatic motor and somatic sensory
What types of nerves carry pain from the adnexae, uterus and vagina
Visceral afferents
Lower vagina (perineal section) is somatic sensory
What type of nerve carry pain from the perineum
Somatic sensory
What type of nerve is responsible for pelvic floor contraction
Somatic motor
What type of nerve is responsible for uterine cramping and contraction
hormonal Sympathetic/parasympathetic
Where do the visceral afferents of the superior pelvic organs (touching peroneum) enter the spinal cord
Run alongside sympathetic fibres
Enter spinal cord between levels T11-L2
Where is pain from the superior pelvic organs felt
Suprapubic
Where do the visceral afferents of the inferior pelvic organs enter the spinal cord
Run alongside parasympathetic fibres
Enter spinal cord at levels S2, S3, S4
Where is pain from the inferior pelvic organs felt
Pain perceived in S2, S3, S4 dermatome (perineum)
Describe the sympathetic supply to the pelvis
Sacral sympathetic trunks
From T11-L2
Superior hypogastric plexus
Describe the parasympathetic supply to the pelvis
Sacral outflow (S2, 3, 4)
Pelvic splanchnic nerves
Emerge from spinal roots
Mixes with sympathetics in inferior hypogastric plexus
Which two spinal levels will pain from the reproductive system go to
T11-L2 and S2-S4
T = visceral afferents from uterine tubes, uterus and ovaries
S - visceral afferents from cervix and superior vagina and the pudendal nerve
What structures are supplied by the pudendal nerve
inferior vagina, perineal muscles, glands, skin.
Sensory to external genitalia, anus and perineum
Motor to the muscles
What are the roots of the pudendal nerve
S2-4
What are the options for labour anaesthesia
Spinal anaesthetic
Epidural anaesthetic
Pudendal nerve block
At what level do you inject the anaesthetic for a spinal or epidural
The L3-4 region
AT what level does the subarachnoid space end
S2
At what level does the spinal cord become the cauda equina
Level of the L2 vertebrae
List the layers the needle for an epidural must pass through
Skin supraspinous ligament interspinous ligament ligamentum flavum epidural space (fat and veins)
List the layers the needle for an spinal anaesthetic must pass through
Skin supraspinous ligament interspinous ligament ligamentum flavum epidural space (fat and veins) dura mater arachnoid mater finally reaches subarachnoid space (contains CSF)
At what spinal levels do the sympathetic nerves exit the spinal cord
T1-L2
How do sympathetic signals reach below the level of L2
sympathetic ganglia receive fibres from L2 level via the sympathetic chain and distribute them via connections with lumbar, sacral and coccygeal spinal nerves
What are the side effects of a spinal anaesthetic
Vasodilation of all arterioles of the lower limb
Skin looks flushed, is warm and has reduced sweating
Can lead to hypotension
Headache if there is a CSF leak
Which nerves are affected by a spinal anaesthetic
All spinal nerves and their named nerves containing sympathetic fibres
including femoral, sciatic, obturator, pudendal
Describe the path of the pudendal nerve
Exits pelvis via greater sciatic foramen
Passes posterior to sacrospinous ligament
Re-enters pelvis/perineum via lesser sciatic foramen
Travels in pudendal canal ( in obturator fascia)
Branches to supply structures of the perinuem
What passes through the pudendal canal
Pudendal nerve
Internal pudendal artery and vein
Nerve to obturator internus
What can a pudendal nerve block be used for
During labour - forceps delivery, painful vaginal delivery or for an episiotomy
Before perineal suturing post tear
How do you find the pudendal nerve for a block
The ischial spine can be used as a landmark - feel inside vagina
Inject over lateral aspect of sacrospinous ligament
This is found medially to the spines
What are the effects of a perineal tear
Weakened pelvic floor and faecal incontinence could result
What is an episiotomy
Posterolateral (mediolateral) incision made into the ischioanal fossa
Done to avoid an uncontrolled tear and try and protect the anus and rectum
What forms the lateral pelvic wall
Ilium makes up most of the lateral pelvic wall
Small contribution from pubis and ischium
Obturator membrane (with obturator canal), sacrotuberous and sacrospinous ligaments
Describe the arteries of the pelvis
Majority of arteries of pelvis and perineum arise from internal iliac artery Exceptions: Gonadal arteries (ovaries/testes) come from abdominal aorta (L2) Superior rectal for rectum comes from abdominal aorta
There are lots of anastomoses
What is the blood supply to the penis
Dorsal artery (corpus spongiosum + glans) Deep artery (corpus cavernosum – most of blood during an erection)
Both are branches of the internal pudendal artery
What are the branches of the internal pudendal artery in men
Perineal artery
Dorsal artery
Deep artery
Where does the uterine artery come from
Comes from the anterior division of the internal iliac
This comes from the common iliac
Where does the vaginal artery come from
Branches from the uterine artery
What does the uterine artery anastomose with
Vaginal artery and the ovarian artery
Where does blood from the pelvis drain to
Some will drain via superior rectal into hepatic portal system
Some will drain via lateral sacral veins into internal vertebral venous plexus
List the major lymphatic groups of the pelvis
Pararectal Deep inguinal Superficial inguinal Internal iliac External iliac Common iliac Sacral Inferior mesenteric Lumbar
Which lymph nodes do the superior pelvic organs drain to
external iliac to common iliac to aortic then thoracic duct
Which lymph nodes do the inferior pelvic organs drain to
Internal iliac nodes to common iliac to aortic then to thoracic
Where does lymph from the ovaries/testes drain to
Lumbar nodes
Where does lymph from the clitoris and penis drain to
Deep Inguinal
What makes up the pelvic floor
3 layers (inner to outer)
Pelvic diaphragm - deepest layer which includes 2 muscle groups, levator ani and coccygeus
Muscles of perineal pouches
Perineal membrane - superficial layer
What is the function of the pelvic floor
Separates pelvic cavity from perineum
Plays important role in providing support to pelvic organs - tonically contracted
Actively contracts during sneezing or coughing
Plays an important role in maintaining continence - both urinary and faecal
Which muscles make up the pelvic diaphragm
Levator ani and the coccygeus
Coccygeus is located inferiorly
Where does the levator ani attach
Pubic bones, ischial spines and tendinous arch of levator ani
Perineal body, coccyx and walls of organs in midline
Which muscles make up the levator ani
Puborectalis
Pubococcygeus
Iliococcygeus
What innervates the levator ani
The pudendal nerve (S2,3,4) and nerve to levator ani
What is found in the deep perineal pouch
Contains part of the urethra Vagina in females Bulbourethral glands in male Neurovascular bundle for penis/clitoris Extensions of the ischioanal fat pads Smooth muscles External urethral sphincter and compressor urethrae
Where is the deep perineal pouch found
Lies below the fascia covering the inferior aspect of the pelvic diaphragm
Lies above the perineal membrane
Describe the structure of the perineal membrane
Thin sheet of tough, deep fascia found superficial to the deep perineal pouch
Attaches laterally to the sides of the pubic arch, closing the urogenital triangle
Openings for the urethra (and vagina in females)
It provides an area of attachment for the external genitalia
What is found in the superficial perineal pouch in men
It contains the root of the penis and the spongy urethra
What is found in the superficial perineal pouch in women
Contains female erectile tissue and associated muscle:
Clitoris and crura – corpus cavernosum
Bulbs of vestibule
Associated muscles
Branches of internal pudendal vessels and pudendal nerve
Also contains greater vestibular glands,
superficial transverse perineal muscle
What can cause injury to the pelvic floor
Pelvic floor trauma and denervation
- Pregnancy
- Childbirth
- Previous injury to pelvis/pelvic floor
- Previous surgery
- Congenital issues
Increased intra-abdominal pressure
- Chronic constipation
- Obesity
- Heavy lifting
- Chronic cough or sneeze
- Abdominal mass
Connective tissue disorders - Menopause (oestrogen deficiency) - Age related - Congenital or acquired connective tissue disorders, - Drug related: e.g. steroids
What is a vaginal prolapse
Herniation of urethra, bladder, rectum or rectouterine pouch through supporting fascia
Presents as a lump in vaginal wall
How does a uterine prolapse present
dragging sensation
feeling of ‘lump’
urinary incontinence
How can you repair a uterine prolapse
Pessaries
Physio
Sacrospinous fixation -sutures placed in sacrospinous ligament
Performed vaginally
What can cause urinary incontinence
Sphincter incompetence (stress)
Detrusor instability (urge)
Retention
Functional
What are the risk factors for urinary incontinence
Being female (pregnancy, childbirth, menopause, short urethra)
Age (more likely the older you are)
Weight (being overweight increases pressure on bladder)
Smoking (chronic cough)
Diabetes and kidney disease
What is considered abnormal urinary frequency
More than 8 times per day is abnormal
How can you treat an overactive bladder
Lifestyle advice Bladder drill Pelvic floor exercises Drugs (anticholinergics) Botox Neuromodulation Reconstructive surgery
What is the first line drug for an overactive bladder
Pteridine
When is urodynamics indicated
Indicated for hesitancy, voiding difficulty, neuropathy, history of retention
What is urodynamics
- Test done to determine why the bladder is leaking
Measure the volume of urine expelled from the bladder each second (tells you the flow rate)
What are the degrees of uterine prolapse
1st = in vagina 2nd = at the introitus (the opening) 3rd = outside the vagina (over 1cm beyond interoitus) 4th = all outside with the uterus (procidentia)
If the fontanelle is sunken, what does it suggest
Dehydration
If the fontanelle is swollen, what does it suggest
Hydrocephalus
When do the fontanelles close
From 18 months to 2 years
What type of nerve fibres does the pudendal nerve contain
Somatic motor and sensory
Sympathetic
What is a cystocele
Hernial protrusion of the bladder into the vaginal wall
What structures are found in the spermatic cord
Vas deferens Testicular artery Pampiniform venous plexus Lymphatics Sympathetic and genital nerves
Are uterine contractions affected by a pudendal nerve block
No as the uterus is not supplied by the pudendal nerve
This allows labour to progress
What is a normal testicular volume/size
15-25ml is normal volume
5cm in size
What is the clinical relevance of the ischioanal fossa
Usually just filled with fatty tissue but infection can easily spread through it
Abscesses can form in here
What is the risk of sacrospinous fixation in prolapse repair
Risk of injury to pudendal neurovascular bundle and sciatic nerve
What is meant by trans-peritoneal spread
When disease can penetrate through the peritoneal layer and disseminate into the peritoneal cavity
The peritoneal layer is only a single cell epithelium so aggressive cancer or infection can penetrate it
Describe how the vagina is supported vertically - level 1 support
Vertical suspension of the uterus, cervix and
vagina provided by the uterosacral and cardinal
ligaments
At the apex and lower third of the vagina
Describe how the vagina is supported laterally - level 2 support
Lateral attachment of the vagina in its middle
third, provided by connective tissue known as
paravaginal fascia
It connects the vagina to the ‘white line’ or arcus
tendineus fascia pelvis (ATFP) - part of the origin of
levator ani.
Describe how the vagina is supported in its lower 3rd - level 3 support
Lower third of the vagina is supported by the
fusion of the vaginal endopelvic fascia to the perineal
body posteriorly, the levator ani muscles laterally and
urethra anteriorly.
What is both the somatic and autonomic supply to the vagina
Somatic nerve supply: S2-4.
Autonomic nerve supply: Inferior hypogastric plexus.
Failure of level 1 (vertical) vaginal support causes which type of prolapse
uterine or vault prolapse
Can also cause incontinence
Failure of level 2 (lateral) vaginal support causes which type of prolapse
Cystocele
Failure of level 3 vaginal support causes which type of prolapse
Rectocele
Also causes urethral mobility and stress incontinence
What triggers the micturition reflex
As bladder fills it stimulates sensory receptors in wall - pass impulses to S2-4, which ascend to
higher centers via the lateral spinothalamic tracts.
The descending impulses inhibit detrusor contraction
First sensation to void occurs when bladder is around half full
The impulses continue as volume increases until acceptable
place to void is found - detrusor still inhibited
Describe the initiation phase of the micturition reflex
The pelvic floor relaxes -simultaneous relaxation of extrinsic
and intrinsic striated muscle,
Then there is suppression
of descending inhibitory impulses leading to detrusor
contraction.
The parasympathetic system inhibits
the resting tone of the urethral smooth muscle,
resulting in relaxation
stimulated
parasympathetic fibres from S2-4 via the hypogastric
nerve, release acetylcholine which binds to M2 and
M3 muscarinic receptors in bladder, resulting in
detrusor contraction.
Detrusor overactivity results in which medical condition
Urge incontinence
Describe the voiding phase of micturition
Rising intravesical pressure and falling urethral pressures
equate leading to urine flow and bladder emptying
As intravesical pressure falls toward end of
micturition , the pelvic floor and urethral muscles
contract, causing urethral closure and interruption of
flow, finalising the cycle.
Which muscles provide urinary continence
External urethral sphincter
Compressor urethrae
Levator ani
Which muscles provide faecal continence
Contraction of puborectalis muscle
The normal state of the pelvic diaphragm muscle is contracted - true or false
True
They must relax to
release urine and faeces
Which nerves innervate the detrusor muscle
Parasympathetic nerves derived from the pelvic splanchnics, S 2, 3, 4
Which urogenital organs can prolapse
Can involve the bladder (cystocele), uterus, vagina
and/or rectum (rectocele)
