introduction to MSK anatomy and embryology Flashcards
When does development of limbs begin
end of 4th week
What limbs develop first
upper limbs - lower limbs begin 1-2 days after
What induces the development of the limbs
Activation of group of mesenchymal cells in the somatic plate mesoderm
What is the apical ectodermal ridge
A multilayered, thickened ectoderm at the apex of the limb bud
What induces the apical ectodermal ridge
Paracrine growth factor FGF-10 which produces FGF-8 (fibroblast growth factor) - interacts with underlying mesoderm causing mitosis to promote limb growth
What is the role of the mesodermal cells that aggregate at the base of each limb bud
signalling centres
What expresses the sonic hedgehog genes
Zone of polarizing activity
What is the function of sonic hedgehog genes
Control the normal patterning of limbs along the anterio-posterior axis
It also activates Bone morphogenic protein gene and Hoxd genes
What is the function of bone morphogenetic protein gene
Forms FGF-10
What is the function of HOX genes
Determine what skeletal element is formed
Which limb bud is larger
upper limb
At what level does the upper limb develop
Opposite the caudal cervical segments - C4-T2
At what level do the lower limbs develop
Upper sacral segments - L2-S2
What are digits
fingers and toes
What happens in the upper lim on the 6th week
digital rays form in the hands
What happens in week 7 for the lower limb
Digital rays and digits form in foot
What happens in the 8th week in the limbs
Separate digits - fingers and toes - form by apoptosis of the loose mesenchymal tissue between the digit rays
What is the shape of the upper limb handplate
Paddle shaped
What is the shape of the lower limb footplates
flipper shaped
What causes elongation of the limb buds
mesenchymal prolliferation
What forms the vasculature and skeletal components of the limbs
The lateral plate mesoderm migrating into the limb buds and condensing along the central axis
What forms all the bones in the limbs
Lateral plate mesoderm
What bones in the limb only undergo endochondral ossification
All of them except the clavicle which undergoes membranous ossification as well as endochondral
What is the first bone to ossify in the human body
clavicle
What occurs at week 7-9 in the upper limb
Primary ossification centres form in the clavicle, humerus, radius and ulna
What occurs at week 9 in the upper limb
Primary ossification centres form in the metacarpals and the phalanges
What occurs in week 7-9 in the lower limbs
Primary ossification centres form in the femur and tibia
What occurs at week 9 in the lower limbs
Primary ossification centres form in the ilium, ischium, pubis, calcaneus, talus, metatarsals and phalanges
What happens in the 5th week in terms of musculature for the limbs
Mesoderm from the dermomyotome regions of the somites migrate into the limb bud, condense and differentiate into myoblasts which form anterior and posterior condensations which eventually differentiate into the musculature commonly seen in the limbs
What are myoblasts
Muscle cell precursors
What does the dorsal (posterior) condensation in the upper limb form
Extensors and supinators muscles
What does ventral (anterior) condensation form in the upper limbs
Flexors and pronator muscles
What does the dorsal (posterior) condensation in the lower limbs
Extensors and abductors
What does ventral (anterior) condensation form in the lower limbs
flexors and adductors
What does the 4th aortic arch form
The right subclavian artery
What does the 7th intersegmental artery form
Distal part of right subclavian artery and whole left subclavian artery
What does the subclavian artery divide into
The axis artery that then goes into the common interosseous artery and then the median artery and then the radial and ulnar artery
When a vessel has common in the name what does it normally mean
That the vessel will divide
What does the axis artery persist as
Axillary artery, brachial artery, anterior interosseous artery and the deep palmar arch
What does the terminal plexus form
Palmar arches
What does the umbilical artery produce
It produces the axis artery of the lower limb and ends as the terminal plexus
What does the axis artery produce
anterior tibial artery , posterior tibial artery
What does the anterior tibial artery continue as
dorsalis pedis
What does the posterior tibial artery terminate as
Medial and lateral plantar arteries
What does the external iliac artery produce
The femoral artery
What does the axis artery in the lower limb persist as in the adult
Inferior gluteal, sciatic, proximal part of popliteal and distal part of the peroneal artery
What does the femoral artery produce
The profunda femoris artery (deep)
What supplies the bulk of the muscles in the thigh
The profunda femoris artery
What does the terminal plexus form
Deep plantar arch
What does C5-C7 form
musculocutaneous nerve
What does C8-T1 form
Ulnar nerve
What does C5-8 and T1 form
median nerve
What does the anterior divisions of the lower limb buds branch into
Tibial (L4-S3) and obturator (L2-L4)
What does the posterior division of the lower limb bud branch into
Superior gluteal (L4-S1), inferior gluteal (L5-S2), femoral (L2-L4) and common fibular (L4-S2)
What way does the upper limb rotate in week 7
90 degrees laterally
What way does the lower limb rotate in week 7
90 degrees medially
What is a dermatome
Area of skin supplied by a single spinal nerve and its ganglion
What is a cutaneous nerve area
Area of skin supplied by a peripheral nerve
What is amelia
Loss of limbs
What is meromelia
partial loss of limbs
What is hemimelia
Loss of one limb
What is phocomelia
Loss of proximal part of limb
What is syndactyly
Webbed digits
What is brachydactyly
loss of digits
What is polydactyly
Excess number of digits
What is bifurcate hand
forked hand
What is talipes equinovarus
club foot - twisted foot in way where sole of foot cannot be placed flat on the ground
What gender is congenital hip dysplasia more common in
females
