Flashcards in Block 2 - Musculoskeletal Embryology II Deck (10):
What is arthrogryposis? How is it caused in a developing fetus? What do the synovial joints fill with instead of a capsule?
Genetic condition where little/no movement occurs around a synovial joint in utero, causing abnormal formation of synovial joints
Due to muscle deficit or problem with amniotic sac
Joint fills in with fibrous connective tissue
What is Poland Syndrome? What is absent?
Unilateral absence of pectoralis major muscle.
Abnormalities in skin and anterior axiallary fold.
Affecting more males than females
What are the 4 differences between abaxial and primaxial?
Abaxial - myogenic cells from hypomere, induced by lateral plate mesoderm, innervated by ventral ramus, CT framework derived from lateral plate
Primaxial - myogenic cells from hypomere and epimere, induced by neural tube and notochord, innervated by dorsal and ventral rami, CT framework derived fom somite
What is Duchenne Muscular Dystrophy?
Most common muscular dystrophy
X-linked mutation encoding for dystrophin, a scaffolding protein
Lack of strength/coordination of muscles leads to death in late teens
(Becker Muscular Dystrophy is milder, mutation in same gene, but does not onset until early adulthood)
Describe the cause and symptoms of the mirror hand defect
If ZPA breaks down, no anterior posterior differentiation. Both side of the hand thinks it is the pinky side.
What is truncated limb syndrome? What is it caused by?
Disruption of the apical ectodermal ridge causes truncation of limb when the ridge is disrupted. Limb appears normal proximal to disruption.
What causes cutaneous syndactyly?
Apoptosis does not occur after the APE splits into 5 ridges, so webbing is seen
What causes osseous syndactyly?
The bones of the hand/foot fuse as the APE breaks up
What causes abnormalities resulting in Cleft hand/foot and polydactyly vs cutaneous syndactyly and osseous syndactyly?
APE divisions vs. apoptosis after APE ridge divisions