Development of muscular and skeletal system

Question 1

What is the precursor for somites?

Answer 1

The paraxial mesoderm

Question 2

What do the somites divide into?

Answer 2

The somite form next to the neural tube and will divide into a ventromedial and dorsolateral part

Question 3

What does the ventromedial part of the somite become?

Answer 3

The sclerotome which will be the axial skeleton

Question 4

What does the dorsolateral part of the somite become?

Answer 4

The dermatome (dermis) or myotome (muscle)

Question 5

What is the process of a somite differentiating?

Answer 5

The somite will split into its two separate parts then the cells will migrate down and surround the notocord and the neural tube

Question 6

What are the cells that form from the sclerotome?

Answer 6

mesenchyme cells which will form the embryonic connective tissue

Question 7

What are the two processes of the bone formation?

Answer 7

intramembranous ossification and endochondral ossification

Question 8

What does intramembranous ossification form?

Answer 8

face/skull bones and clavicle-

mesenchyme to bone

Question 9

What does the endochondral ossification form?

Answer 9

The long bones and the pelvis

mesenchyme to cartilage to bone

Question 10

What does the vertebral column form from?

Answer 10

The notochord and sclerotome

Question 11

what is the process of the vertebral column formation?

Answer 11

1/2 of the caudal dense from section a and 1/2 of the cephalic loose from section b will fuse and form a bone

Question 12

What are the two sections of the sclerotome in the vertebral region called?

Answer 12

caudal dense and cephalic loose

Question 13

What part of the vertebra does the caudal dense form?

Answer 13

The articulating processes

Question 14

What part of the vertebra does the cephalic loose form?

Answer 14

part of the vertebral body

Question 15

Where do the intervertebral disc come from?

Answer 15

The notochord and sclerotome

Question 16

What are the two portions of the intervertebral disc?

Answer 16

The nucleus pulposus and the annulus fibrosis

Question 17

What does the nucleus pulposis form from?

Answer 17

It is the mucoid center of intervertebral disc that is globbing up of the notochord

Question 18

What does the annulus fibrosus form from?

Answer 18

It is fibrous tissue that forms from sclerotome that surrounds the notochord

Question 19

What do the ribs form from?

Answer 19

The sclerotome

Question 20

How do the ribs form?

Answer 20

They grow out of the thoracic vertebra and the costal cartilage forms at the same time

Question 21

How does the sternum form and from what?

Answer 21

The sternum will start as sternal bars that will grow out then slowly fuse together to form the sternum- this originates from somatic lateral plate mesoderm

Question 22

What is a cervical rib?

Answer 22

a rib will form up in the upper cervical region and will lead to thoracic outlet syndrome

Question 23

What is pectus carinatum?

Answer 23

Also known as pigeon chest- there is a sternal protrusion- no significant health problems- unsure why it forms

Question 24

What is pectus excavatum?

Answer 24

Sternal depression also known as funnel chest
This will compress the heart and cane shift it more to the over. This will lead to decreased lung space- pts have SOB, exercise intolerance and greater fatigue

Question 25

What are HOX genes?

Answer 25

they are genes that signal the control of body plan along the cranial/caudal axis- they will determine the shape/size/characteristics of vertebra

Question 26

What is a gain of function in HOX genes?

Answer 26

This is when a hox gene influences sections that they are not suppose to. Also called caudalization- the vertebra will tend to look more like the vertebra below it.

Question 27

What is a loss of function HOX gene?

Answer 27

This is when a hox gene is lost so the resulting levels will begin to look more like the vertebra above it. This is also known as cranialization

Question 28

What two layers does the myotome divide into?

Answer 28

the epimere and hypomere

Question 29

What does the epimere develop?

Answer 29

It forms the epiaxial muscles- the true muscles of the back- they are innervated by dorsal rami

Question 30

What does the hypomere develop?

Answer 30

It forms the hypaxial muscles- all other muscles of the body- innervated by the ventral rami

Question 31

What are the hypaxial divisions?

Answer 31

The cervical myotome- scalene, geniohyoid, infrahyoid the thoracic myotome- flexor (abdominal) muscles of spine lumbar myotome- quadratus lumborum sacrococcygeal myotome- pelvid diaphragm

Question 32

What is Poland syndrome?

Answer 32

Failure of the hypaxial muscles to migrate to the chest. Results in the absence of the pec major and minor so there is ipsilateral breast hypoplasia. Could also result in loss of ribs 2-4 or syndactyly

Question 33

What is Prune-Belly syndrome?

Answer 33

The partial or complete loss of abdominal musculature due to hypaxial muscles not migrating to the correct area. associated with cryptochidism or malformation of the urinary tract