Development of Skelton and Muscles

Question 1

Bones of the face.

Answer 1

Viscerocranium

Question 2

Bones protecting the brain.

Answer 2

Neurocranium

Question 3

Skeleton develops from…

Answer 3

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

Question 4

Somites and somitomeres arise from…

Answer 4

paraxial mesoderm

Question 5

Somites differentiate into…

Answer 5

Sclerotome, myotome, dermatome

Question 6

Cells of sclerotome are mesenchymal that become…

Answer 6

fibroblasts, chondroblasts, osteoblasts

Question 7

Intramembranous ossification process

Answer 7

Mesenchymal cells- osteoblasts- ossification center- osteoid secreted- calcification

Question 8

Endochondral ossification process

Answer 8

Mesenchymal cells- hyaline cartilage- ossification center-

Question 9

Neurocranium formed from both intramembranous and endochondral ossification. What do each form?

Answer 9

Intramembranous= flat skull bones
Endochondral= basal skull bones ie sphenoid, ethmoid

Question 10

Name the fontanelles and what they become.

Answer 10

Anterior- Bregma
posterior- Lambda
posterolateral/mastoid- Asterion
anterolateral/sphenoidal- Pterion

Question 11

When do each fontanelle close?

Answer 11

Posterior- 1-2 months old
anterolateral/sphenoidal- 6 months old
posterolateral/mastoid- Between 6 months and 18 months old
Anterior- 18 months old

Question 12

First two pharyngeal arches form…

Answer 12

viscerocranium

Question 13

Where do pharyngeal arches originate from?

Answer 13

Paraxial and lateral plate mesoderm and neural crest cells

Question 14

What does the Meckel cartilage give rise to?

Answer 14

Malleus and incus

Question 15

What do the pharyngeal arches give rise to?

Answer 15

First=Maxilla, zygomatic and part of temporal bone. Mandible
Second= hyoid, Stapes, Styloid process and stylohyoid ligament

Question 16

Clinical Condition: Skull never forms leaving brain tissue exposed

Answer 16

Anencephaly

Question 17

Clinical Condition: Small head due to brain failed to grow to normal size. Often from alcohol durring gestation.

Answer 17

Microcephaly

Question 18

Clinical Condition: Early closure of cranial sutures.

Answer 18

Craniosynostosis

Question 19

Clinical Condition: Early closure of sagittal suture

Answer 19

Scaphocephaly

Question 20

Clinical Condition: Early closer of both coronal sutures

Answer 20

Brachycephaly

Question 21

Clinical Condition: Early closure of coronal suture on one side.

Answer 21

Plagiocephaly

Question 22

Caudal and cranial somites combining, myotomes bridging the intervertebral discs=

Answer 22

Resegmentation processes

Question 23

Primary and secondary spinal curvatures

Answer 23

Primary= Thoracic and sacral
Secondary= cervical and lumbar

Question 24

When do limb buds form?

Answer 24

4th week/1 month

Question 25

What do limb buds consist of?

Answer 25

Mesenchymal core and ectodermal covering

Question 26

Apical ectodermal ridge (AER)

Answer 26

Terminal end of limb bud. Send signal to prevent differentiating to allow elongation.

Question 27

Stylopod=

Answer 27

humerus and femer

Question 28

Zeugopod=

Answer 28

radius/ulna tibia/fibula

Question 29

Autopod=

Answer 29

carpals, metacarpals, tarsals, metatarsals

Question 30

Schematic of human hands occurs due to programed cell death. What are the two areas and times in which this happens?

Answer 30

48 days= cell death in plate creates separate ridges for digits 51 days= cell death in interdigital spaces produce separation of digits

Question 31

Where does skeletal muscle arise from?

Answer 31

paraxial myotome

Question 32

Where does cardiac muscle arise from?

Answer 32

visceral and splanchnic mesoderm

Question 33

Where does smooth muscle differentiate from?

Answer 33

Visceral/ splanchnic mesoderm, ectoderm, and neural crest cells.

Question 34

Head muscles are derived from?

Answer 34

somitomeres

Question 35

Head muscles are derived from, where skeletal muscles are derived from...

Answer 35

somitomeres somites

Question 36

What are myofibrils made of?

Answer 36

Actin and myosin

Question 37

When do cross-striations appear in myofibrils?

Answer 37

End of 3rd month

Question 38

Purkinje fibers are modified myoblasts? T or F

Answer 38

True

Question 39

Name the only structures derived from the ectoderm.

Answer 39

Sphincter and dilator muscles of pupil muscle tissue in mammary and sweat glands

Question 40

Smooth muscle development can be organized into what three categories?

Answer 40

Dorsal aorta/large arteries Coronary arteries Gut and its derivatives

Question 41

Clinical Condition: Pectoralis minor and par of major are missing (on left side)

Answer 41

Poland sequence

Question 42

Clinical Condition: Partial or complete absence of abdominal musculature. Can also have urinary bladder or urethral malformation.

Answer 42

Prune belly syndrome