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21 Cards in this Set
- Front
- Back
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When and wear do the limb buds start to form? |
- Appear at the end of week 4 of development. - On ventrolateralbody wall. |
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From where to they originate? |
- Mesenchymal core from mesoderm. - surrounded by epithelial ectoderm |
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What does the eptihelial ectoderm develop into, and what does it do? |
- apical ectoderm ridge - induces surrounding mesenchymeto form the progress zone (PZ) of un-differentiated, rapidly proliferating cells. |
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How are congenital abnormalities screened for? What is the purpose of screening? |
- antenatal ultrasound - specialist delivery, genetic counseling, termination of pregnancy |
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How are congenital abnormalities graded? |
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Define teratogen |
an agent or factor which causes malformation of an embryo. |
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List 3 intrinsic risk factors and 5 extrinsic risk factors |
Intrinsic: - Chromosomal abnormalities - Inherited - Sporadic Extrinsic: - Teratogens(e.g. thalidomide) - Nutrient deficiency (e.g. folate) - Infections (VACTERL) - Failed abortion - Removal of intrauterine device(IUD) |
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At what stage do teratogens pose the most risk to development? |
4-5 weeks |
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List 6 teratogens |
- thalidomide - warfarin - Phenytoin - Valproic Acid - Alcohol - Cocaine |
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What is thalidomide? What are the consequences of its use? |
- Anti-emetic once used in pregnancies from 1957-1962. Use returned for treatment of AIDS and cancer. - Syndrome of limb defects, intestinal atresia (passage/orifice abnormally closed) and cardiac anomalies. |
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When does rotation of the limbs occur? |
week 7 |
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Give 7 examples of types of congenital anomalies affecting the limbs |
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Define the following; amelia meromelia phacomelia sirenomelia hemihypertrophy micromelia |
amelia: complete absence of one or more limbs. meromelia: partial absence of one or more limbs. phacomelia: type of meromelia. absence of long bones, rudimentary hands and feet attached to the trunk. sirenomelia: fusion of limbs hemihypertrophy: one side of the body or a part of one side of the body is larger than the other to an extent considered greater than the normal variation. micromelia: abnormally small and imperfectly developed extremities |
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What is constriction band syndrome? What causes it? |
- entrapment of fetal parts (usually a limb or digits) in fibrous amniotic bands while in utero - Adhesions between amnion and foetal structures or tears in the amnion that separate and surround part(s) of the foetus |
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List 7 presentations of Marfan's syndrome
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- Tall stature - long thin digits (arachnodactyly) - long thin limbs, - hyperextensiblejoints - a high arched palate - dislocation (usually upwards) of the lenses of the eyes - severe myopia |
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What is the pathology of Marfan's syndrome? |
- caused by mutations in the fibrillin-1 (FBN1) gene on chromosome 15 - encodes for the glycoprotein, fibrillin. - Fibrillin is a major building block of microfibrils, which constitute the structural components of the suspensory ligament of the lens and serve as substrates for elastin in the aorta and other connective tissues. |
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What is developmental dysplasia, and what is its complications? |
- Poorly developed acetabulum and head of femur, in-utero. - Dislocation commonly occurs after birth (congenital hip dislocation). - Complication: avascular necrosis of femoral head. |
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What are the clinical presentations of developmental dysplasia? |
- Barlow’s manoeuvre: posterior dislocation. - Ortolani’s manoeuvre: relocation on abduction. - Asymmetry of skin folds at hip (Galeazzi sign). - Shortened affected limb. |
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How is developmental dysplasia treated? |
- Pavlik harness - surgery if detected late |
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Define the following congenital anomalies of the the hands and feet ectrodactyl syndactyly polydactyly macrodactyly brachydactyly |
- ectrodactyl: failure of formation - syndactyly: failure of differentiation - polydactyly: duplication (mirror hand) - macrodactyly: overgrowth - brachydactyly: undergrowth |
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What is club foot (aka talipes equinovarus)? How is it treated? |
- hypoplasia of limb muscles - Ponseti method |
