final exam skeletal system Flashcards
each somite divides into 2 parts:
dermamyotome- derma and myo
sclerotome- skeleton
what forms the somites?
mesoderm
dividing somite is made up of mesodermal cells that give rise to?
mesenchyme
condensation of mesenchyme gives rise to formation of
bone models and selective gene activity begins
3 areas of mesenchymal development
paraxial-> somite-> lateral mesoderm
cartilage bones
replace provisional cartilage and are remaining bones of body
membrane bones
make up the face and cranial roof and develop from skeletal mesenchyme
what is the cartilaginous vertebral body that replaces notochord
centrum- 2 CHONDRIFICATION CENTERS
vertebral arches do not unite to form spinous processes until
3rd month after birth
when does ossification of vertebra begin?
9th week, all centers present by 5th month except sacral and coccyx
what are the ossification centers at puberty?
5: 1 at tip of spinous processes
1 at each tip of transverse processes
2 on rim of epiphyseal center
mesenchymal bands= sternal bars of?
sternum
chondrification of limbs start at?
5th and 6th week
upper limbs rotate
laterally
lower limbs rotate
medially
which bone ossifies before any other bone in the body?
clavicle
congenital malformations of the skeleton
chondrodystrophies- abnormal development of cartilage
cartilage stage in these bones can grow rapidly to match growth of fetus
inter-cartilagenous or endochondral
2 types of neurocranium development
neurochondrocranium
neuromembranocranium
neurochondrocranium at 6 weeks
nasals, orbitals, temporals
neuromembranocranium- fontanelles and sutures**
2 parietals, 2 frontals, 1 vomer, 2 nasals, 2 lacrimals
closure times of fontanelles
anterior- end of second year, largest
anterolateral- 2-3 mo
posterolateral- end of 1st year
splanchochondrocranium- bones of the face
visceral, pharyngeal, brachial arches
1st visceral arch
mandibular
1st arch
palate, maxilla, meckels cartilage, incus, malleolus
2nd arch
stapes, cranial half of hyoid, lesser horn
3rd arch
caudal half of hyoid, greater horn
4 and 6 arch
cartilage of larynx
vertebral column comes from
somite mesenchyme sclerotome
intersegmental development gives the vertebra:
1 muscle attachment
2 nerve emergence
chondrification begins in
7th week in cranial vertebra and follows down
slow growth of cartilage and bone ossification is called
achondroplasia syndrome
3 characteristics of achondroplasia syndrome
1 small stature
2 megalocephaly
3 skeletal issues
hypochondroplasia syndrome is
a mild form of achondroplasia
clavicle agenesis or no clavicle
cleidocranial dysostosis
2 type of spina bifida
occulta- can’t see
cystica- can see, meninges only
2 types of congenital scoliosis
1 numerical variations
2 morphological variations
all sutures closing prematurely and symmetrically
oxycephaly
metatopic suture- triangle looking
trigonocephaly
when sutures close asymmetrically
plagiocephaly
when sagittal sutures close prematurely
scaphocephaly
coronal sutures- large wide short
acrocephaly
complete absence of limbs
amelia
absence of reduction of proximal part of limbs
phocomelia
absence of reduction of distal part of limbs
meromelia
hypoplasia and fusion of lower limbs
sympodia
duplication of distal part of limbs
dichiria
presence of extra digits
polydactyly
fusion of digits
syndactyly
shortness of digits
brachydactyly
long digits with extra phalanges
hyperphalangism
