7 Flashcards
from mesoderm or ectoderm proliferate and
aggregate;
Mesenchymeal (chondrogenic) cells
become round and enlarged and are now termed
Chondroblasts
secrete amorphous ground substance
Chondroblasts
to form the cartilage matreix
collagen
fibers
Originates from paraxial mesoderm, somatic mesoderm or ectomesenchyme
Bone
occurs in most bones of the axial skeleton and
appendicular skeleton.
Endochondral bone development
Cartilage model
ossification
chondroblasts secrete matrix to produce a cartilage model of the
future bone; the model is surrounded by
perichondrium
Addition of layers of bone matrix reduces the intertrabecular spaces and the cancellous
bone in the diaphysis is converted into a
Compact bone
creating
a smooth surface lubricated by
synovial fluid in the joint cavity
Osteoblasts also secrete calcium to the osteoid to
form
bone trabecula
me non-secretory and are now termed osteocytes.
Osteocytes present cytoplasmic processes that radiate into the matrix through tiny bone
channels called
Canaliculi
A bone with large intertrabecular spaces is classified as
cancellous or spongy bone
The intertrabecular spaces are occupied by blood-forming cells
(red bone marrow) and are also called
marrow spaces or marrow cavities
Joints must move during in utero and postnatal
development to prevent
ankylosis
Sclerotomal mesenchymal cells lateral to the thoracic vertebrae differentiates into
cartilaginous ribs
which are eventually destroyed and replaced by
bony ribs ( cancellous bone)
The sternum develops differently, from 2 longitudinal aggregations of somatic
mesaenchyme (somatic mesoderm) called
sternal bars
. The two (2) sterna bars fuse in the
ventral midline and become segmented to form
eight (8) sternebrae
lateral deviation of vertebral column
Scoliosis
sagittal deviation of vertebral column in a fixed position
Kyphosis
sagittal deviation of vertebral column in a fixed extended position.
Lordosis
abnormal twisting of the cervical vertebral column
Torticolis or wry neck
absence of vertebral arch
Spina bifida
spina bifida of several adjacent vertebrae.
Rachischisis
spina bifida covered by skin and subcutis.
Spina bifida occulta
The cartilaginous structures fuse and ossify to form the bones of the
floor of the skull.
does not ossify
Nasal capsule
ethmoid and bone around the pituitary gland
Prechordal cartilage
base of occipital
Parachordal cartilage
temporal bone
Otic capsule
Intramembranous bones articulate by means of fibrous joints called
Sutures
Widened
suture areas, at the corners of growing bones are called
Fontanels
develops from outward growth of ectomesenchymal tissue located rostral to the
cranium and pharynx.
Face
Ectomesenchymal cells around prosencephalon completely envelop the
prosencephalon to form the
frontonasal prominence
located between VC1 and VC2, becomes the external
auditory meatus.
VC1 or hyomandibular cleft
are overshadowed by the expanding hyoid arch and fuse to form a cervical
sinus that later disappears w/out a trace.
VC2 to VC4
cleft lip caused by failure of fusion of medial nasal and maxillary
processes.
Cheiloschisis
cleft palate caused by failure of medial palatine processes to fuse
Palatoschisis
no opening
Branchial cyst
opening to exterior
branchial sinus
Openings to interior and exterior
branchial fistula
Primordia of enamel organs
escape to the exterior and develop tooth structures anchored on the parietal bone or
base of the ear.
Heterotropic polyodontia
loss of a specific part of a limb
Limb reduction
presence of one or more extra digits.
Limb Duplication
inherited; systemic premature
ossification of physes of extremeties.
Achondroplasia (dwarfism; Dachshund)
complete absence of a limb.
Amelia
absence of a part of a limb.
Meroromelia
complete absence of limb.
Acromelia
Absence of half or one or more segments of a limb
Hemimelia
reduced size of a limb.
Micromelia
absence of one or more proximal segments, a consequence of
pregnant women taking thalidomide in the late 1950’s.
Phocomelia
fused digits
Syndactyly
shortened or stumpy digits.
Brachydactyly
absence of one or more digits.
Ectrodactyly
presence of one or more extra digits. This is common in pig and cat.
Limb Duplication
one or more extra digits
Polydactyly
partial or complete duplication of one limb
Bimelia
limb growing from the back of the animal
Notomelia (noto=back)
crooked limb. Gr. gryposis=crooked) - can results from
malformed joints, denervation, abnormal muscle tension, or impaired
mobility in utero.
Arthrogryposis
abnormal maturation of the hip joint that results in formation
of a shadow acetabulum and flattened femoral head.
Hip Dysplasia
permanent fixation of a joint caused by immobility of the fetus in
utero.
Ankylosis
