Development of Skelton and Muscles Flashcards
Bones of the face.
Viscerocranium
Bones protecting the brain.
Neurocranium
Skeleton develops from…
Paraxial mesoderm= bones of face, skull and vertebra
Neural crest cells= bones of face and skull
Lateral plate (parietal) mesoderm= sternum, pelvic and shoulder girdles, limbs
Somites and somitomeres arise from…
paraxial mesoderm
Somites differentiate into…
Sclerotome, myotome, dermatome
Cells of sclerotome are mesenchymal that become…
fibroblasts, chondroblasts, osteoblasts
Intramembranous ossification process
Mesenchymal cells- osteoblasts- ossification center- osteoid secreted- calcification
Endochondral ossification process
Mesenchymal cells- hyaline cartilage- ossification center-
Neurocranium formed from both intramembranous and endochondral ossification. What do each form?
Intramembranous= flat skull bones
Endochondral= basal skull bones ie sphenoid, ethmoid
Name the fontanelles and what they become.
Anterior- Bregma
posterior- Lambda
posterolateral/mastoid- Asterion
anterolateral/sphenoidal- Pterion
When do each fontanelle close?
Posterior- 1-2 months old
anterolateral/sphenoidal- 6 months old
posterolateral/mastoid- Between 6 months and 18 months old
Anterior- 18 months old
First two pharyngeal arches form…
viscerocranium
Where do pharyngeal arches originate from?
Paraxial and lateral plate mesoderm and neural crest cells
What does the Meckel cartilage give rise to?
Malleus and incus
What do the pharyngeal arches give rise to?
First=Maxilla, zygomatic and part of temporal bone. Mandible
Second= hyoid, Stapes, Styloid process and stylohyoid ligament
Clinical Condition: Skull never forms leaving brain tissue exposed
Anencephaly
Clinical Condition: Small head due to brain failed to grow to normal size. Often from alcohol durring gestation.
Microcephaly
Clinical Condition: Early closure of cranial sutures.
Craniosynostosis
Clinical Condition: Early closure of sagittal suture
Scaphocephaly
Clinical Condition: Early closer of both coronal sutures
Brachycephaly
Clinical Condition: Early closure of coronal suture on one side.
Plagiocephaly
Caudal and cranial somites combining, myotomes bridging the intervertebral discs=
Resegmentation processes
Primary and secondary spinal curvatures
Primary= Thoracic and sacral
Secondary= cervical and lumbar
When do limb buds form?
4th week/1 month
What do limb buds consist of?
Mesenchymal core and ectodermal covering
Apical ectodermal ridge (AER)
Terminal end of limb bud. Send signal to prevent differentiating to allow elongation.
Stylopod=
humerus and femer
Zeugopod=
radius/ulna tibia/fibula
Autopod=
carpals, metacarpals, tarsals, metatarsals
Schematic of human hands occurs due to programed cell death. What are the two areas and times in which this happens?
48 days= cell death in plate creates separate ridges for digits
51 days= cell death in interdigital spaces produce separation of digits
Where does skeletal muscle arise from?
paraxial myotome
Where does cardiac muscle arise from?
visceral and splanchnic mesoderm
Where does smooth muscle differentiate from?
Visceral/ splanchnic mesoderm, ectoderm, and neural crest cells.
Head muscles are derived from?
somitomeres
Head muscles are derived from, where skeletal muscles are derived from…
somitomeres
somites
What are myofibrils made of?
Actin and myosin
When do cross-striations appear in myofibrils?
End of 3rd month
Purkinje fibers are modified myoblasts? T or F
True
Name the only structures derived from the ectoderm.
Sphincter and dilator muscles of pupil
muscle tissue in mammary and sweat glands
Smooth muscle development can be organized into what three categories?
Dorsal aorta/large arteries
Coronary arteries
Gut and its derivatives
Clinical Condition: Pectoralis minor and par of major are missing (on left side)
Poland sequence
Clinical Condition: Partial or complete absence of abdominal musculature.
Can also have urinary bladder or urethral malformation.
Prune belly syndrome
