Embryology - Muscles, Somites, Limbs, Lung

Question 1

A somite starts off as mesenchymal cells. they then differentiate into ___, ___, and ___

Answer 1

sclerotome, dermatome, and myotomes (sometimes the last two are combined : dermomyotome)

Question 2

Sclerotome cells surround ___

Answer 2

the notochord and neural tube

Question 3

__sclerotomes split and recombine to form __

Answer 3

segmental; intersegmental vertebral rudiments and ribs

Question 4

What are somites made from? What do they establish?

Answer 4

paraxial mesoderm; segmental org. of the body

Question 5

paraxial mesoderm is from what?

Answer 5

the intraembryonic mesoderm lateral to the notochord and neural tube

Question 6

what embryonic tissue forms cartilage

Answer 6

mesenchyme

Question 7

what are the two embryonic types of connective tissue that form bone

Answer 7

mesenchyme and cartilage

Question 8

embryonic intramembranous ossification ossifies_____.

Answer 8

mesenchyme

Question 9

embryonic intracartilaginous ossification ossifies ___.

Answer 9

cartilage

Question 10

synovial joints are made from what? What about the joint capsule and synovial membrane?

Answer 10

interzonal mesenchyme located between developing bones. the other parts are also interzonal mesenchyme

Question 11

cartilagenous joints are made from what?

Answer 11

interzonal mesenchyme that differentiates into hyaline or fibrocartilage

Question 12

fibrous joints are made from what?

Answer 12

interzonal mesenchyme that differentiates into fibrous connective tissue

Question 13

during the 4th week, mesenchymal cells from somites are found in the ____, ____, and ___.

Answer 13

surrounding notochord, surrounding the neural tube, and in body wall.

Question 14

limb buds appear from ____.

Answer 14

lateral plate mesoderm

Question 15

each limb bud contains what two things?

Answer 15

apical ectodermal ridge and mesenchyme

Question 16

what is the apical ectodermal ridge? what is a possible modulator?

Answer 16

it is a thickening of ectoderm at the apex of a limb bud. It is possibly modulated by retinoic acid

Question 17

which muscle is NOT from mesoderm

Answer 17

iris muscles

Question 18

developmental tissues leading to muscle

Answer 18

mesenchyme > myoblasts > muscle

Question 19

each myotome splits into two structures?

Answer 19

dorsal epimere and ventral hypomere

Question 20

visceral muscles (iris, sweat gland muscles etc) are from what?

Answer 20

spanchnic mesoderm

Question 21

Cardiac muscle is from what? Are purkinje fibers from that as well?

Answer 21

splanchnic mesoderm. NO. Purkinje fibers are from a different dvpmntal pathway

Question 22

Name the 5 things that are derived from sclerotomes

Answer 22

vertebral bodies, vertebral arches, annulus fibrosis, costal processes, sternum/sternal bars

Question 23

what 3 things are derived from costal processes?

Answer 23

Ribs, transverse processes, and sacral mass

Question 24

Epimeres give rise to___

Answer 24

deep epaxial m of back

Question 25

Hypomeres give rise to what muscles

Answer 25

lateral and ventral body wall: intercostals, abdominal girdle muscles and rectus abdominus

Question 26

In the limb, what makes the bones, tendons, ligaments and vasculature?

Answer 26

Lateral plate mesoderm

Question 27

appendicular skeleton is formed with what type of ossification?

Answer 27

endochondral

Question 28

Which bones appear in weeks 7-12

Answer 28

Clavicle> upper limb> lower limb> scapula and ilium> phalanges> ischium and pubis> tarsals and carpals (basically starts with arm and alternates from arm to legs, going distally)

Question 29

the upper limb rotates ___(direction) so that the extenors are on the __ and __ aspects

Answer 29

laterally; lateral; dorsal

Question 30

the lower limb rotates ___(direction) so that the extenors are on the __ aspect

Answer 30

medially; ventral

Question 31

lung buds develop as ___ from the ventral portion of ___, caudal to the ____

Answer 31

endodermal envagenations; foregut; pharynx

Question 32

what is the larynx made from?

Answer 32

cranial portion of the laryngo-tracheal tube and surrounding mesoderm

Question 33

What is the trachea made from? Which parts of it are from splanchnic mesoderm?

Answer 33

middle portion of the laryngo-tracheal tube; cartilage, CT, and muscle

Question 34

What makes the bronchopulmonary (lung) buds? What do the original parts of the lung buds turn into?

Answer 34

terminal end of the laryngo-tracheal tube; stem (primary) bronchi and the lobar bronchi

Question 35

What are the five stages of lung development?

Answer 35

embryonic, pseudoglandular, canalicular, terminal sac, and alveolar

Question 36

Pseudoglandular period of lung development (5-17 weeks): epithelium type? survival?

Answer 36

cuboidal epithelium, no respiratory surfaces so no survival

Question 37

Canalicular period of lung development (17-25 weeks) what three things develop? survival?

Answer 37

vascularization, respiratory bronchioles, and terminal sacs develop; survival with exceptional medical help

Question 38

terminal sac period of lung development ( 24 weeks- birth) What matures? What develops?

Answer 38

terminal sacs, respiratory epithelium mature; surfactant becomes present

Question 39

alveolar period of lung development ( 30 weeks- birth) what matures?

Answer 39

alveoli from terminal sacs. **Note: you only have about 12-15% of your potential alveoli formed at birth.

Question 40

the parietal pleura is formed from ____ of the body wall

Answer 40

somatic mesoderm

Question 41

what is a fistula

Answer 41

abnormal passage or connection btn two internal organs

Question 42

what is an atresia

Answer 42

closure

Question 43

what is agenesis

Answer 43

failure to form

Question 44

Fun fact:

Answer 44

1 in 2000 babies are born with teeth (natal teeth)

Question 45

Fun lung fact:

Answer 45

fresh and healthy neonatal lung tissue will float when placed in water because of trapped air. Lungs of a stillborn will sink in water because they are filled with fluid