Development of Muscular System

Question 1

What structures come off the paraxial mesoderm?

Answer 1

Somites: myotome (muscle), sclerotome (axial skeleton), dermatome (dermis)

Question 2

What structures come off the intermediate mesoderm?

Answer 2

Urogenital: kidneys and gonads

Question 3

What structures come off the lateral plate mesoderm?

Answer 3

Connective tissue: Blood, lymph, mesenteries, cardiovascular

Question 4

Myotomes of the paraxial mesoderm form all of the muscles except what?

Answer 4

Eye muscles

Question 5

The ventromedial portion of the somite of the paraxial mesoderm gives rise to what?

The Dorsolateral portion of the somite of the paraxial mesoderm gives rise to what?

Answer 5

Ventromedial = sclerotome

Dorsolateral= dermatome and myotome

Question 6

What are the key components of the vertebral canal?

Answer 6

Notochord and paraxial mesoderm

Question 7

In the development of the vertebral column the scleretome is divided up in the caudal and cephalic portions.

Which is dense and which is lose?

What portion fuse together?

Answer 7

Caudal is dense

Cephalic is loose

1/2 of the dense Caudal portion fuses to 1/2 of the loose cephalic portion to form the vertebrae

Question 8

The nucleus pulposus of the intervertebral disc is formed by what?

Answer 8

Expanded notochord

or the left over part of the notochord

Question 9

Annulus fibrosis is formed by what structure?

Answer 9

Fibrous tissue of sclerotome and fibrocartilage

Question 10

What structures of the vertebrae actually form from the caudal dense portion?

Answer 10

Superior articular process

Pedicle

Transverse process

Question 11

What structures of the vertebrae actually form from the cephalic loose portion?

Answer 11

Inferior articular process

Question 12

What structures of the vertebrae are formed from both the caudal dense portion and cephalic loose portion?

Answer 12

Spinous process

Centrum (body)

Question 13

The intervertebral disk is formed from what germinal layer?

Answer 13

mesoderm

Question 14

Ribs and costal cartilage are derived from what structures?

Answer 14

Sclerotome

Question 15

The sternum develops in what embryonic structure?

Answer 15

Somatic layer lateral plate mesoderm

Question 16

Formation of the sternum and ribs happens around what week?

Answer 16

Week 5

Question 17

Cervical vertebrae are formed by what Hox?

Answer 17

Hox 4 and Hox 5

Question 18

Ribs are signaled by what Hox genes?

Answer 18

Hox 6

Question 19

What hox gene will give us floating ribs?

Answer 19

Hox 9

Question 20

Lumbar vertebrae are formed with what hox gene?

Answer 20

Hox 10

Question 21

Sacral vertebrae are formed by what hox gene?

Answer 21

Hox 11

Question 22

Gain of function for hox genes causes what abnormality?

Answer 22

Caudalization, where superior regions take on traits of the inferior (caudal) region

Question 23

Gain of function mutation of Hox 6 in the cervical region will lead to what?

Answer 23

The cervical region developing ribs and looking more thoracic

Question 24

Gain of function mutation of Hox10 leads to what in thoracic region?

Answer 24

Thoracic vertebrae will now look more like lumbar vertebrae

Question 25

Loss of function mutation of Hox genes causes what phenonmenon?

Answer 25

Cranialization where the inferior vertebrae take on traits of the region above it

Question 26

Loss of function mutation usually relate to what Hox genes?

What occurs?

Answer 26

Hox 4

cervical vertebrae look more like C1

Hox 5

cervical vertebrae look more like C2

Hox 10

lumbar vertebrae look more thoracic

Question 27

Hox 4 is normally expressed in what region?

C2-C5

Hox 5 is normally expressed in what region?

C3-T2

Question 28

Bilateral cervical ribs contributes to thoracic outlet syndrome where axillary arteries are compressed, and are formed through what disorder?

Answer 28

Gain of function of Hox 6

Question 29

Funnel chest, or pectus excavatum is when the sternum is depressed and the heart can be shifted. Some have exercise intolerance

Answer 29

Pectus Excavatum

Question 30

What are the two different regions the myotome become, and what structures does each give rise to?

Answer 30

Epimere

Epaxial muscles (dorsal side) innervated by dorsal rami

(erector spinal groups)

Hypomere

Hypaxial muscles innervated by ventral rami

(flexors of the trunk)

Question 31

Scalene, Prevertebral, geniohyoid, and infrahyoid muscles are from which of the following?

A. Hypaxial cervical myotome

B. Hypaxial thoracic myotome

C. Hypaxial lumbar myotome

D. Hypaxial Sacrococcygeal myotome

Answer 31

Hypaxial cervical myotome

Question 32

Lateral and ventral flexor muscles of the vertebral column are from which of the following?

A. Hypaxial cervical myotome

B. Hypaxial thoracic myotome

C. Hypaxial lumbar myotome

D. Hypaxial Sacrococcygeal myotome

Answer 32

Hypaxial thoracic myotome

Question 33

Quadratus lumborum are from which of the following?

A. Hypaxial cervical myotome

B. Hypaxial thoracic myotome

C. Hypaxial lumbar myotome

D. Hypaxial Sacrococcygeal myotome

Answer 33

Hypaxial lumbar myotome

Question 34

What is Poland syndrome?

What disease or disorder is it associated with?

What is the embryological mechanism associated with formation of Polands syndrome?

Answer 34

Absence of pectoralis major and sometimes absence of ribs

Syndactyly

Abnormal migration of hypaxial muscles, as in they did not migrate into the anterio chest

Question 35

What is Prune Belly-syndrome?

What 2 disorders is it also associated with?

What embryological mechanism is associated with Prune Belly syndrome?

Answer 35

Absence of abdominal musculature

Cryptorchidism (failure of testes to descend)

Urethral abstruction (malformation of urinary tract and bladder)

Abnormal migration of the hypaxial muscles into the abdomen