Human Development Flashcards
Male vs female pelvis
Female = larger and wide Female = more flared iliac crests Male = sharper pubic arch Females = wider more oval pelvic inlet Males = coccyx angled more forwards Males = ischial bones closer giving narrower pelvic outlet
Sacrotuberous ligament
Sacrum –> ischial tuberosity
Sacrospinous ligament
Sacrum –> ischial spine
Sacroiliac ligament
sacrum –> ilium
Greater sciatic foramen
Formed by sacrotuberous and sacrospinous ligaments
Piriformis, sciatic nerves, superior and inferior gluteal vessels and nerves, internal pudendal nerve and vessels
Lesser sciatic foramen
Former by sacrospinous ligaement superiorly and sacrotuberous inferiorly
Obturator internus, internal pudendal nerve (re-entering the pelvis)
Parts of levator ani from anterior to posterior
Levator prostate/sphincter vaginalis
Puborectalis - pubic bone around rectum
Pubococcygeus - pubis –> anococcygeal body
Iliococcygeus - ilium –> sanococcygeal body and coccyx
Coccygeus
Ischial spines –> lateral sacrum and coccyx
Function of pelvic floor
Support and maintain pelvic viscera is position
Maintain continence
Resisting abdominal and intra-pelvic pressure
Folic acid in preventing birth defects
400mg per day
Could prevent around 75% of neural tube defects
Embryonic vs foetal period
Embryonic = 3-8 weeks Foetal = 8 weeks --> term
Major vs minor congenital defects
Major = require medical or surgical intervention or causes significant handicap
Anencephaly
Malformed head and brain
Failure of anterior neuropore to close
Spina bfida
Herniation of spine and contents in the lower back
Failure of posterior neuropore to close
Hypospadias
Male urethra opens out in unusual place
Cleft lip
Failure of maxillary and medial nasal prominences to fuse
Cleft palate
Failure of palatine shelves to fuse
Holoprosencephaly
Loss of midline structures
Omphalocele
Abdominal contents do not correctly return from umbilical cord
Gastrochisis
Abdominal contents herniate through defect in anterior abdominal wall
Phocemelia
Limb abnormalities
Syndactylyl
Digits fused together
Polydactyly
Extra digits
Ankyloglossia
Tongue tie
Unusually thick and short frenulum
Hydatiform male
Diploid cells but genetic material purely from father
Sirenomelia
Lower body parts fused
Epiblast cells stop invaginating too early
Situs invterus
Reversal of left and right axis of the body
Atrial septal defect
Blood can flow between two atria
Ventricular septal defect
Blood can flow between two ventricles
AV canal
Lack of AV septum
Coarctation of aorta
Aortic narrowing where ductus arteriosus inserts
Transposition of the great vessels
Vessels connect to incorrect heart chamber
Truncus arteriosus
Aorta and pulmonary trunk fail to fully separate
Tetralogy of Fallot
Overriding aorta that can take blood from left heart
Pelvic kidney
Kidney that failed to migrate up to posterior abdominal wall
Horseshoe kidney
Kidneys fused inferiorly
Vitelline duct abnormality
Meckel’s diverticulum
Small pocket of vitelline duct remains in the ileum
Tracheo-oesophageal fistula
Failure of trachea and oesophagus to fully divide
Hirschprung’s disease
Loss of enteric nervous system ganglion cells in the gut
Female vs male primitive genital tubes
Female = Mullerian ducts
Male = Wolffian ducts
Mullerian ducts more lateral
When do gonadal ridges begin to form?
5th week of gestation
Where does the gubernaculum attach?
To the gonadal ridge and the labioscrotal swellings (future scrotum or labia majora)
Contents of spermatic cord
Gubernaculum, vas deferens, testicular vessels, nerves and lymphatics
What is the tunica vaginalis?
Portion of peritoneum that was pulled down into the scrotum with the descent of the testicles
When does testicular descent occur?
Around the 26th week
Inguinal canal structure
4cm long
2mm above inguinal ligament
Starts at deep inguinal ring
Ends at superficial inguinal ring
What passes through the inguinal canal
Ilioinguinal nerve
Round ligament in females
Spermatic cord in males
Testicular blood supply
Bia testicular arteries from L2 of AA
Venous drainage via testicular veins to the IVC on the right and left renal vein on the left
Vas deferens length
45cm
Vas deferens course
From the epididymis in the scrotum
Up into the pelvis through the spermatic cord
Crosses external iliac vessels
Passes around the lateral walls of the pelvis
Crosses ureter posterior to the bladder
Joined by seminal vesicle to empty into the ejaculator duct in the prostate
Indirect inguinal hernia
Herniation of abdominal contents through the deep inguinal ring
Processes vaginalis fails to close
Hydrocele
Accumulation of peritoneal fluid in the scrotum
Processes vaginalis still slightly open
Ovarian ligament
Cranial gubernaculum remains
Ovary –> uterus
Round ligament
Caudal gubernaulum remains
Uterus –> labia majora
Broad ligament
Double fold of peritoneum overlying uterus
Suspensory ligament
Peritoneum overlying ovarian vessels
Ovarian blood supply
From AA
Venous drainage to AA on the right and left renal vein on the left
Peritoneal pouches
Vesicouterine = between bladder and uterus
Rectouterine (pouch of Douglas) = between uterus and rectum
Fluid can accumulate here
Support of the uterus
Levator ani
Transverse cervical ligaments
Pubocervical ligaments
Sacrocervical ligaments
Vagina fornices
Anterior
Posterior
2 lateral
Ureter course in females
Pass over pelvic prim at common iliac bifurcation
Pass under ovarian arteries
Run of lateral pelvic walls and pass anterior to reach the bladder passing either side of the cervix
Ectoderm
Skin, hair, nails, nervous system
Mesoderm
Muscles, skeleton, heart, connective tissue
Endoderm
GI system, lungs, liver, pancreas, GU system
Foregut
Pharynx –> superior duodenum
Midgut
Superior duodenum –> 2/3 of transverse colon
Hindgut
1/3 of transverse colon –> rectum
Urogenital triangle borders
Pubic symphysis anteriorly
Inferior pubic rami laterally
Line between ischial tuberosities posteriorly
Anal triangle borders
Line between ischial tuberosities anteriorly
Sacrotuberous ligaments laterally
Coccyx posteriorly
Pudendal canal
Contains pudendal vessels and nerve
Lies within the fascia of the obturator internus in the lateral walls of the ischioanal fossa
Branches of internal pudendal artery
Dorsal artery of the clitoris/penis
Perineal artery
Inferior rectal artery
Pudendal nerve
S2-4
Leaves pelvis through greater sciatic foramen
Re-enters pelvis to reach the perineum through lesser sciatic foramen
Branches to give the dorsal nerve of penis/clitoris, perineal and inferior rectal
Deep perineal pouch contents
External urethral sphincter Deep transverse perineal Vagina Proximal female urethra Membranous male urethra Male bulbourethral gland
Superficial perineal pouch contents
Crura of penis/clitoris Bulb of penis/clitoris Bulbospongiosus Ischiocavernosus Superficial transverse perineal Bartholin's gland in females
Superficial perineal fascia layers
Membranous (Colles’) - thin, strong layer binding muscles of the root of the penis
Fatty (Camper’s) - continuous with fascia of the thigh
Erection
Parasympathetic outflow via inferior hypogastric plexus
Nitric oxide release
Vasodilation and engorgement
Ejaculation
Sympathetic fibres cause contraction of the epididymis, vas deferens, seminal vesicles and prostate
Bladder sphincter contracts to prevent retrograde ejaculate flow
Bulb of vestibule
Divided by vagina
Superficially covered by bulbospongiosus
Crura of clitoris
Attaches to pubic arch and rami and pubis and ischium
Superficially covered by ischiocavernosus
Bartholin’s gland
Found posterior to the bulbs of vestibule
Secrete lubricating mucous into the vaginal orifice
Blockage of ducts can lead to Bartholin’s cyst
Muscles attaching to perineal body
Levator ani
External anal sphincter
Bulbospongiosus
Superficial transverse perineal
Genitofemoral nerve
L1-2
Skin of scrotum/labia majora
Cremaster muscle
Lumbosacral trunk
L4-5
Emerges medial from psoas major
Joins sacral plexus
Anatomical orientation of the uterus
Anteverted with respect to the vagina
Anteflexed with respect to the cervix
Process of gastrulation
Formation of primitive streak in epiblast
Epiblast cells invaginate to displace the hypoblast to become endoderm
Cells that do not invaginate become the ectoderm
Cells between the layers become mesoderm
What do neural crest cells form?
Cranial –> bones of the skull, pia and arachnoid mater, cranial nerves components
Trunk –> melanocytes, Schwann cells, dorsal root ganlia, parasympathetic nerves