Dinosaur Fingers Flashcards
Syndactyly
webbed
Brachydactyly
short
Symbrachydactyly
short, webbed
Synostosis
fused
Symphalangism
stiff
Polydactyly
too many
Camptodactyly
bent
clinodactyly
slanted
macrodactyly
large
Arachnodactyly
spider like
limb differences
upper limb more common than lower limb
unilateral– most on right side
associated anomalies: about half of cases, esp. with radial defects
Words we don’t use
hand deformities
hand abnormalities
good hand/ bad hand
normal hand/ abnormal hand
words we do use
hand difference
Big hand/ little hand
Right hand/ left hand
Hand formation
Day 27- arm bud begins to develop
Day 28-30 well formed arm bud
- upper bud precedes lower by 48 hours
Day 34-38 hand paddle has formed
Matureation of the hand
Week 6- ossification centers obvious
Week 7- fingers completelly separate-(- syndactyly)
Week 8- Joint spaces begin to develop - pre-programmed cell death (apoptosis). (Synostosis occurs here)
Limb development
mesenchymal core,
ectodermal covering
Apical ectodermal ridge (AER)
- removal of AER yields shortened extremity
Zone of polarizing activity (ZPO)- posterior border of AER.
Error here yields mirror hand.
Vascular system development
Capillary network forms marginal sinus under the AER
Gradual development of discreet venous and lymphatic channels
During 4th week of gestation vessels migrate into the limb bud
Vascular maturation
median artery is first to form
Radial and ulnar arteries outgrow the median and interosseous arteries
Timing is everything
During vascular maturation:
- vertebral formation
- kidney formation
- cardiac formation
- Tracheal and esophageal formation
- Gut formation
If the process is immature, it may go awry
48 hours later, all is well and the lower limb develops normally
Multifactorial influences
Most limb deficiencies do not have a genetic basis
Vascular origins
- vasoconstriction (chorionic villus sampling)
- hemorrhage
- Thrombosis
- Embolization
Most cases are sporadic, but here are some syndromes
VATER, VACTERL
TAR (thrombocytopenia absent radius)
FANCONI’s ANEMIA
Some cases of familial inheritance
a thumb issue
delta phalanx triphalangeal thumb
cleft hand inheritance
autosomal dominant
self esteem: how we can set the stage
I was born like this
It does make some stuff harder but,
I’m good at figuring stuff out
