Anatomy Flashcards
Female repro structures found in pelvic cavity
Ovaries
Uterine tubes
Uterus
Superior part of vagina
Female repro structures found in perineum
Inferior part of vagina
Perineal muscles
Bartholin’s glands
Clitoris
Labia
Muscle making up most of pelvic floor
Levator ani
Where is parietal peritoneum in females?
- floor of peritoneal cavity
- roof over pelvic organs
- covers superior aspect of organs
- forms pouches (vesico-uterine, rector-uterine/Pouch of Douglas)
Where does fluid collect in an unright female abdomen?
Pouch of Douglas
- recto-uterine
- collections of pus/blood
- can drain through caldocentesis
Describe the broad ligament
Double layer of peritoneum
(formed by peritoneum draping up and back over uterine tubes)
Extends from uterus to lateral pelvis
Helps maintain uterus in correct midline position
Describe round ligament
Embryological remnant
Attaches anteriorly to lateral uterus
Passes through deep inguinal ring and attaches to superficial tissue of female perineum (labia)
Pain in preg as uterus grows
3 layers of uterus
perimetrium
myometrium (contracts during preg)
endometrium (thickens during menstrual cycle)
- implantation of zygote in body of uterus
Position of uterus
Anteverted
- cervix tipped anteriorly relative to the axis of the vagina (vagina goes posterior and cervix goes forward)
Anteflexed
- uterus tipped anteriorly relative to the axis of the cervix (uterus sits on top of bladder)
Normal variations of uterine position
Retroverted
- cervix tipped posteriorly relative to the axis of the vagina
Retroflexed
- uterus tipped posteriorly relative to the axis of the cervix
3 supports of uterus
number of strong ligaments (e.g. uterosacral ligaments)
endopelvic fascia
muscles of the pelvic floor (e.g. levator ani)
Travel of ovum during ovulation
Ovary -> fimbrae of tube -> infundibulum -> ampulla (fertilisation) -> isthsmus -> uterus
WHat do you see in hysterosalpingogram (HSG)?
Radiopaque dye spilling out of the end of the uterine tube and into the peritoneal cavity
- shows tubes are open at the ends
Describe the ovaries
Almond sized and shaped, located laterally in the pelvic cavity (ovarian fossa)
Develop on the posterior abdominal wall
Secrete oestrogen and progesterone
Which ant pituitary hormones act on the ovaries?
FSH and LH
Describe the structure of vagina
Muscular tube whose walls are normally in contact
- except superiorly where the cervix holds them apart forming a fornix (around the cervix).
- fornix = anterior, posterior, 2x lateral
What is sampled in cervical screening?
Squamo columnar junction (transformation zone)
- brush is inserted into the external cervical os with firm pressure and rotated
What structures are palpated on vaginal digital exam?
Uterus position - bimanual palpation
Adnexae, masses/tenderness - using fornices
Ischial spines - laterally, 4 and 8 oclock
Describe levator ani
Skeletal muscle - voluntary, normally tonically contracted
Majority of pelvic diaphragm
Nerve to levator ani (S3, 4, 5), dual supply
Describe shape of perineum
shallow space between pelvic diaphragm and the skin
diamond shaped
openings in pelvic floor
- passage of distal parts of alimentary, renal and reproductive tracts from pelvis to perineum
Describe the perineal body
bundle of collagenous and elastic tissue into which the perineal muscles attach
VERY important to pelvic floor strength
can be disrupted during labour
located just deep to skin
What is a Bartholin/greater vestibular gland?
Secrete lubricating mucus to opening of vagina
Enlarged gland due to cyst/infection
Structures in the vestibule
EXt urethral orifice
Vaginal orifice
Anatomy of breast
From ribs 2-6
- lateral border of sternum to mid-axillary line
- lies on deep fascia covering pec major/serratus anterior
- firmly attach to skin via suspensory ligaments
Where is retromammary space?
Between fascia and breast
- means breast tissue should be able to move freely
- if immobile/fixed, means tissue has extended into pec major (clinically worrying)
Where does lymph from breast drain?
ipsilateral axillary lymph nodes
- then to the supraclavicular nodes
inner quadrant lymph can spread to contralateral parasternals
lower quadrant lymph can drain to abdo lymph nodes
Describe clearance of axillary nodes
Level I – inferior and lateral to pectoralis minor
Level II – deep to pectoralis minor
Level III – superior and medial to pectoralis minor
Blood supply to breast
Axillary artery
Internal thoracic (internal mammary)
Venous drainage mimics above (mostly axillary)
Phases of ovarian cycle
Follicular phase
Ovulation
Luteal phase
Phases of uterine cycle
Menstrual phase
Proliferative phase
Secretory phase
Function of primitive streak in embryo
Develops the body axis
Found on the caudal end
- embryo knows which way is up and down
What is gasrtulation?
Change form a bilaminar disc to trilaminar disc with a mesoderm layer
(two to three layers)
Cells invaginate int primitive streak and spread back out to form 3rd layer
Origin of repro system and genitals
Intermediate mesoderm
How does the indifferent gonad develop?
- Migration of PGCs from yolk sac to intermediate mesoderm
- Coelomic epithelium proliferates and thickens to form genital ridges.
- This prolif epi forms somatic supports which envelop PGCs
- This forms primitive sex cords (indifferent)
Structures forming genital ducts in embryo’s ambisexual phase
Embryo has both types
Mesonephric (Wollfian) duct
= male
Paramesonephric (Mullerian) duct
= female
Female development from germ cells in absence of SRY
Germ cells differentiate into oogonia and then into primary oocytes
Somatic support cells differentiate into granulosa cells and surround the primary oocytes
This forms primordial follicles in the ovary
WHy are thecal cells important in female development?
They help to produce part of oestrogen which stimulates formation of the female external genitalia and development of paramesonephric ducts.
What structures does paramesonephric tube give rise to?
Uterine tubes
Uterus
Superior vagina
3 parts of paramesonephric duct
CRANIAL portion which opens up into the coelomic cavity
HORIZONTAL portion which crosses the mesonephric duct
CAUDAL portion which fuses with the paramesonephric duct on the opposite side
Male development from germ cells in presence of SRY
Somatic support cells develop into Sertoli cells
Primary sex cords form testis/medullary cords, which engulf the PGC’s
Rete testis connect the mesonephric tubules to the testis cords
Tthickened layer of connective tissue forms the tunica albuginea.
How are Leydig cells significant in terms of male development?
They are stimulated to form by Sertoli cells and secrete testosterone.
This induces formation of epididymis, vas deferens, seminal vesicles
Dihydrotestosterone then induces male spec genitalia and prostate
Describe persistent Mullerian duct syndrome
Mullerian (paramesonephric) ducts fail to regress
Present with:
- Uterus, vagina and uterine tubes
- Testes in ovarian location
- Male external genitalia
Function of gubernaculum in testes deveopment
Pulls gonads down from T10 caudally down in scrotum
Failure = cryptorchidism
3 male accessory glands
develop near the junction of mesonephric duct and urethra, during week 10.
- prostate gland
- bulbourethral gland
- seminal vesicle
Development of male external genitalia
Spongy urethra forms by proximal to distal ‘zipping’ of urethral groove
Ectodermal ingrowth at tip of the glans penis, which meets spongy urethra
- Prepuce (foreskin) is formed by circular ingrowth of ectoderm around the periphery of the glans
Describe pres of hypospadias
- External urethral opening lies in an abnormal position along the ventral aspect of the penis
- Occurs with varying degrees of severity.
Where does inguinal ligament run?
Between ASIS and pubic tubercle
Where do 3 hamstrings attach?
Ischial tuberosity
Describe tendinous arch of levator ani
Thickened fascia of levator ani
When does externa iliac artery become femoral?
When it passes under the inguinal ligament
Where do gonadal arteries originate?
Abdo aorta at L2 ish
(this is where ovaries/testes originate)
Two divisions of internal iliac artery
Anterior = visceral
Posterior = parietal (mainly body wall)
Medial umbilical ligament is remnant of
Umbilical cord
(obliterates away as redundant)
Where does anterior scrotal artery originate from?
External iliac artery
What is in place of inferior vesicle arteries in females?
Superior vesicle arteries
Vaginal arteries, also sends branches to bladder
Where do ovarian and uterine artery anastomose?
Ovarian and tubal branches of ovarian artery come down the uteris and anastomose with uterine artery at neck of uterus/cervix
Uterine also anastomoses with vaginal artery lateral to ureter
Anatomical relationship between ureter and uterine artery
Water passes under the bridge
- ureter under uterine artery
Tell the diff because ureter wiggles when touched
Where does venous blood in the pelvis drain to?
Mainly to iliac vein
- some via superior rectal to hepatic portal
- some via lateral sacral veins into internal vertebral venous plexus (aka epidural venous plexus)
How are the epidural venous plexuses significant in terms of pelvic mass?
They are valveless and allow positional travel of blood, no regulation
Can follow metastatic pathway into epidural space etc
Which nerve in pelvic lateral wall doesn’t originate from sacral plexus?
Obturator nerve
S2, 3, 4
Keeps the poo off the floor
Where does lymph from superior pelvic viscera drain to first?
external iliac nodes
THEN common iliac, aortic, thoracic duct, venous system
Where does lymph from inferior pelvic viscera and deep perineum drain to first?
internal iliac nodes
THEN common iliac, aortic, thoracic duct, venous system
Where does lymph from superifical perineum drain to first?
superficial inguinal nodes
Where does gonadal lymph drain to?
Para-aortic/lumbar/caval
(because this is where they originated)
3 bones fusing to form hip bone
ilium
ischium
pubis
Muscle that sits in iliac fossa
Iliacus
Attachment of inguinal ligament
ASIS to pubic tubercle
Muscles attaching to ischial tuberosity
3 true hamstrings
Borders of pelvic inlet
sacral promontory
ilium
superior pubic ramus
pubic symphysis
Borders of pelvic outlet
pubic symphysis
ischiopubic ramus
ischial tuberosities
sacrotuberous ligaments
coccyx
Where are ischial spines palpable?
On vaginal examination: approx. 4 and 8 o’clock positions
Clin significance of pubic symphysis in obstetrics
Constant point from which to measure fundal height
Type of joint pubic symphysis
Secondary cartilaginous
- not much movement
- can loosen during pregnancy, may cause pain
- can lead to PS dysfunction, sort of dislocated
Attachments of
sacrotuberous ligament, sacrospinous ligament
sacspin - sacrum and ischial spine
sactub - sacrum and ischial tuberosity
Function of pelvic ligaments
Protection against sudden weight transfer
- these ligaments relax later in pregnancy
Foraminae of pelvic formed by ligaments
Greater sciatic foramen
Lesser sciatic foramen
- formed by attachments of ligaments to sciatic notches
Name for deep fascia of obturator internus
Tendinous arch
- where levator ani attaches
Key differences between male and female pelvis
the AP and transverse diameters of the female pelvis are larger than the male, both at the pelvic inlet and outlet
the subpubic angle (and pubic arch) in the female is wider than the male
the pelvic cavity is more shallow in the female
Define moulding
the movement of one bone over another to allow the foetal head to pass through the pelvis during labour
When do fontanelles close?
Ant - 18-24 months
Post - 12-18 months
What is the vertex of foetal skull?
area outlined by the anterior and posterior fontanelles and the parietal eminences
Diameters of foetal skull
occipitofrontal diameter is longer than the biparietal diameter (i.e. the foetal head is longer than it is wide)
What is the station during childbirth?
The distance of the foetal head from the ischial spines is referred to as the station.
Negative number means the head is superior to the spines
Positive number means the head is inferior to the spines
Position of baby during delivery
Baby flexed with chin on chest
Leave pelvic cavity in OA position
During delivery baby’s head should be in extension
Foetal head position in childbirth
at the pelvic inlet, the foetal head should be transverse
as it descends through the pelvic cavity, the foetal head should rotate and it should be flexed
at the pelvic outlet, the foetal head should ideally lie occipitoanterior (OA) and extension of the head on the neck should occur
further rotation after baby’s head is delivered to allow delivery of shoulders
Type of nerve supplying pelvis
Body cavity
sympathetic, parasympathetic and visceral afferent
Type of nerve supplying perineum
Body wall
somatic motor and somatic sensory
Superior part of pelvic organ/if painful pelvic organ is touching peritoneum, visceral afferents run alongside…
Sympathetic fibres
- enter spinal cord at T11-L2
- pain felt as suprapubic
- e.g. uterine tubes, uterus, ovaries
Inferior part of pelvic organ/if painful pelvic organ is not touching peritoneum, visceral afferents run alongside…
Parasympathetic fibres
- enter spinal cord at S2, 3, 4
- pain perceived in the dermatome, perineum
- e.g. cervix, sup vagina
If structure crosses pelvis to perineum and is above levator ani, visceral afferents are carried with…
parasympathetic fibres
- spinal cord levels S2, S3 and S4
If structure crosses pelvis to perineum and is below levator ani, visceral afferents are carried with…
somatic sensory (pudendal nerve)
- spinal cord levels S2, S3 and S4
- localised pain within perineum
How do visceral afferents get to their correct spinal level from pelvis/peritoneum?
Mesh and travel with hypogastric plexuses
Easy version of pelvic/perineal innervation
Perineum - pudendal, S2,3,4
Superior - touching peritoneum, T11-L2
Inferior - touching peritoneum, S2,3,4
Anaesthetic injected into what region in spinal/epidural block?
L3-4 (sometimes up to L5)
- cauda equina L2, dural sac continues to S2
- lie pt on side and drape over pillow
How to find L3-L4 space for spinal anaesthetic?
Find intercrystal plane (line between most superior points on iliac crests) and vertebrae superior should be L4
Space above L4 vertebrae is where anaesthetic should be injected
WHat makes the pop sound during an epidural?
Needle piercing ligamentum flavum before it reaches epidural space
Why is epidural slower acting than spinal?
Anaesthetic has to find its way through fat to anaesthetise spinal cord
Spinal goes directly into CSF and is very close to cord and rootlets
Why is it important spinal anaesthetic is balanced?
Blocks sympathetic fibres of all arterioles and organs in area
- causes vasodilation
- skin looks flushed and warm
- reduced sweating
RISK OF HYPOTENSION
Route of 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 (alcock’s)
Branches to supply structures of the perineum
How is pudendal nerve block given?
Palpate ischial spine with vaginal examination at 4 and 8 oclock
Inject anaesthetic from skin to sacspin ligament
At ninewells, they put in sheathed needle with hand and then unsheath and inject to nerve from within
Degrees of perineal tears
1st degree: skin
2nd degree: skin and perineal muscle
3rd degree: nvolved anal sphincter
4th degree: through anal sphincter and bowel mucosa
Incision made in episiotomy
Posterolateral (mediolateral) incision (down and out)
- incises fatty space
- reduces risk of tearing to anus
- easier to stitch up
Attachments of external oblique
Attach between lower ribs and iliac crest, pubic tubercle and linea alba
Fibres run in same direction as external intercostals
Attachments of internal obliques
Attach between lower ribs, thoracolumbar fascia, iliac crest and linea alba
Fibres run in same direction as internal
intercostals
Attachments of transversus abdominus
Attach between lower ribs, thoracolumbar fascia, iliac crest and linea alba
What is the linea alba?
Formed by the interweaving of the muscle aponeuroses
Runs from the xiphoid process to the pubic symphysis
(the vertical line in 6 pack)
What are tendinous intersections of rectus abdominus?
divide each rectus abdominis
3 or 4 smaller muscles
(horizontal lines in 6 pack)
What is the significance of the arcuate line?
Superior
- aponeuroses completely enclose rectus abdominus
- results in ant and post rectus sheath
Inferior
- aponeuroses only cover anterior rectus abdominus
- results in anterior rectus sheath
Clin significance of rectus sheath
When undertaking a suprapubic incision i.e. LSCS, rectus sheath will be incised anteriorly
Where is transversalis fascia found?
Between extraperitonal fat and transversus abdominus
Nerve supply to anterolateral abdominal wall
enter from lateral direction
7th-11th intercostal nerves
become thoracoabdominal nerves
subcostal (T12)
iliohypogastric (L1)
ilioinguinal (L1)
Blood supply to anterior abdominal wall
superior epigastric arteries
- continuation of internal thoracic
- emerges at superior aspect of abdominal wall
inferior epigastric arteries
- branch of the external iliac artery
- emerges at inferior aspect of abdominal wall
- just medial to inguinal ring
Blood supply to lateral abdominal wall
intercostal and subcostal arteries
- continuations of posterior intercostal arteries
- emerge at lateral aspect
How should you cut through muscle?
Incise in same direction as muscle
How is the incision made in LSCS?
Rectus muscles not cut, they are separated form each other in a lateral direction, moves them closer to their nerve supply
Layers incised when opening abdo for CS
Skin and fascia
(anterior) Rectus sheath
Rectus abdominis (separated not cut)
Fascia and peritoneum
Retract bladder
Uterine wall
Amniotic sac
Layers stitched closed in CS
Uterine wall with visceral peritoneum**
Rectus sheath
Skin
Layers incised and stitched in laparotomy
Layers when opening:
- Skin and fascia
- Linea alba
- Peritoneum
Layers to stitch closed:
- Peritoneum & Linea alba
- Fascia Skin
Risk of midline incision
Relatively bloodless incision
- not great blood supply to aid healing
- increases the chance of wound complications e.g. dehiscence, incisional hernia
Which artery do you need to watch out for with a lateral port in laparoscopy?
Inferior epigastric artery
- ensure you stay lateral
Route of inferior epigastric artery
branch of the external iliac artery
emerges just medial to the deep inguinal ring
then passes in a superomedial direction posterior to the rectus abdominis
Where is deep inguinal ring?
Between ASIS and pubic tubercle
How to differentiate between ureter and uterine artery in hysterectomy etc?
- the ureter passes inferior to the artery (“water
under the bridge”) - the ureter will often “vermiculate” when touched
Structure of secretory tissue of breast
15-25 lobes
- tubulo acinar gland, drains to nipple
Fibrous tissue adjacent to lobes
Adipose surrounds fibrous tissue
Anatomical position of breast
2nd/3rd rib to 6th rib
Sternal edge to midaxillary line
Describe structures of mammary bed
SUP
Deep pectoral fascia, lies on pec major and serratus anterior
INF
External oblique and aponeurosis
Function of submammary space
Allows degree of breast movement on deep pectoral fascia
Anatomical features of nipple
4th IC space in nulliparous women
15-20 lactiferous ducts
Circular/longitudinal smooth muscle
Define tubercles of Montogomery
Sebaceous glands on outer margin of areola
Enlarge in pregnancy and lactation
Function of 3 tissue types of breast
Glandular tissue: Tubulo-alveolar type and arranged in lobes
Fibrous tissue: Supports lobes and forms numerous septa.
Interlobar fatty tissue: makes the organ rounded in contour
Drainage of glandular tissue of breast
15-20 pyradmidal lobes
-> lactiferous duct
-> dilates to form lactiferous sinus
-> segmental duct system
-> terminal ducts
-> pouches out like bunch of grape (acinar)
Describe suspensory ligaments of Cooper
Fibrous structures that extend from dermis of skin to deep pec fascia overlying ant chest wall
Most pronounced in upper breast
Support breast tissue
Describe function of TDLU
basic functional secretory unit of the breast
Cells lining acini of sec lobule
secretory epithelial cells
- columnar and cuboidal
surrounded by myoepithelial cells
- contractile, surrounded by BL
Outer layer of nipple
Keratinised stratified squamous epithelium
(skin hahahha)
Mammary gland changes in pregnancy
1st trim
- elongation/branching of smalller ducts
- prolif of epi cells of glands and MEps
2nd trim
- continues to develop/differentiates secretroy alveoli
- plasma/lymphocytes infiltrate connective tissue
3rd trim
- alveoli mature
- development of extensive roughER
Adipose/connective tissue decr
Changes to mammary gland in luteal phase
Epithelial cells get taller
Duct lumen enlarge
Small vol of secretion in ducts
Hormones responsible for prolif of secretrory tissue in breasts in pregnancy
Oestrogen and progesterone
Antibodies in breast milk
IgA
Types of secretion in breat milk
Apocrine
- lipid droplets with small vol of cytoplasm surrounded by membrane
Merocrine
- exocytosis
- protein packaged by Golgi and secreted via vesicles, merge with apical membrane to release contents
Effecct of menopause on mammary gland
secretory cells of the TDLU’s degenerate leaving only ducts
fewer fibroblasts, reduced collagen in connective tissue
Blood supply of breast
Lateral Mammary branches from Lateral Thoracic a.
Medial Mammary branches from Internal Thoracic a.
All from subclavian
Venous drainage of breast
Medial and Lateral Mammary vein
(mostly medial)
Lymphatic drainage of breat
75% to axillary nodes
Subareolar plexus
Parasternal (also opposite sides, may drain to abdo)
Innervation of breast
Branches of IC nerves 4-6
- sensory and symp efferent
Nipple
- ant branch of lateral cutaneous branch of T4
Describe Paget’s disease of breast
Pre-cancerous changes eating into duct and epidermis of nipple and areolar, nipple first then areola
