Ch. 16 Fetal Musculoskeletal System Flashcards
By what gestational age can most bones be imaged?
15-16 weeks
Which bone is longer, the radius or ulna?
The ulna is on the pinky side and it is longer than the radius which is on the thumb side
Which bone is larger, the tibia or the fibula?
The tibia is located medially and it is larger than the fibula which is thinner and located laterally.
What bones make up the axial skeleton?
Cranium, facial bones, pelvis and spine
Shortening of the proximal segment of an extremity (ie Humerus and femur)
Rhizomelia
Shortening of the middle segment of an extremity (ie rad/ulna and tib/fib)
Mesomelia
Shortening of the distal segment of an extremity (ie hand or foot)
Acromelia
Term for shortened extremities
micromelia
term for an absent segment of an ext
phocomelia
Term for the complete absence of an entire ext
Amelia
Presence of more than five digits
Polydactyly
Soft tissue or bony fusion of the digits
Syndactyly
Term for when a long bone measures more than 4 SD below the mean for gestational age
Severe micromelia
Severely hypoplastic thorax is aka
“bell-shaped” thorax in a coronal plane
“champagne cork sign” in sagittal
Thoracic circumference that is less than the —– for GA is indicative of a lethal defect
5th percentile
What is the most common LETHAL skeletal dysplasia
Thanatophoric dysplasia (the name is derived from the Greek word thanatophoros which means “death bearing”)
Sono finds of Thanatophoric skeletal dysplasia
“CLOVERLEAF” skull aka KLEEBLATTSCHADEL
bowed femurs (“TELEPHONE RECEIVERS”
severe micromelia
hypoplastic thorax
platyspondyly
mild hypomineralization
Poly
A rare and lethal form of short-limbed dysplasia
Achondrogenesis
Sono finds of achondrogenesis
lack of vertebral ossification
severe micromelia
hypoplastic thorax
large head + or - decreased cranial ossification
poly
associated cleft lip/palate micrognathia
A rare bone demineralization disorder resulting from low levels of serum and tissue alkaline phosphatase
Congenital Hypophosphatasia
Sono finds of Congenital Hypophosphatasia
decreased mineralization of bones
severe micromelia with possible bowing of long bones
A condition in which there are abnormally fragile bones with decreased mineralization, fractures in utero resulting in severe micromelia and irregularity of bones
Osteogenesis imperfecta Type II
Osteogenesis imperfecta type II is familial in what way
Autosomal recessive
Sono finds of osteogenesis imperfecta type II
Presence of FRACTURES or “thick” bones due to callus formation
severe micromelia
hypoplastic thorax
multiple rib fractures
severe hypomineralization of the skull
A rare lethal dysplasia characterized by polydactyly and an extremely small thorax (death is a result of respiratory insufficiency)
Short-Rib polydactyly Syndrome
Sono finds of Short-rib syndrome
polydactyly
narrowed thorax with short ribs
micromelia
other anomalies (cardiac, renal, clefts, other)
Asphyxiating thoracic dystrophy is aka
Jeune syndrome
Rare autosomal recessive disorder that shares many of the features of short rib poly syndrome, the main prenatal feature being a small and narrow thorax
Asphyxiating thoracic dystrophy aka JEUNE SYNDROME
Skeletal dysplasia that is characterized by short bent or bowed bones
Campomelic dysplasia
Sono finds of campomelic dysplasia
“bent” long bones, especially the lower ext bones
narrow thorax
associated CNS and renal anomalies
Sono finds of the lethal short-limbed dysplasia Homozygous Dominant Achondroplasia
Rhizomelia
TRIDENT HAND - short fingers with separation between 3rd and 4th fingers
small thorax with pulmonary hypoplasia
large cranium, possible cloverleaf
What is the most common form of genetic skeletal dysplasia
Achondroplasia
What type of osteogenesis imperfecta is the most common
Type I
What type of OI is not detected prenatally
Type IV
Term for more than the normal number of digits on the hand or foot
Polydactyly
Skeletal dysplasia that is associated with deformation of the joints
Arthrogryposis
Hypoplasia or aplasia of the radius
Radial ray abnormalities
Permanent curvature of the 5th digit (secondary to hypoplastic middle phalanx)
Clinodactyly (associated with TRISOMY 21)
Fusion of digits, either soft tissue or bony fusion
Syndactyly
Another term for clubfoot is
Talipes equinovarus
What two factors contribute to talipes
Genetics and environmental
What two factors contribute to talipes
Genetics and environmental (Oligo, amniotic band syndrome, uterine tumors)
Term for when the bottom of the foot convexes outward. This defect is associated with trisomy 18
Rocker bottom foot
Term for fusion of the lower ext and abnormal or absent foot structures
Sirenomelia
What is another name for Sirenomelia
Mermaid syndrome
Sono finds of sirenomelia
single femur or two femurs constantly seen side by side
associated bilateral renal agenesis
oligo
