Skeletal System

Question 1

The somite that the skeletal system starts from

Answer 1

Medial Ventral Somite

Question 2

What is the structure that is on either side of the somite?

Answer 2

Paraxial Mesoderm

Question 3

What are the two parts that the somites divide into?

Answer 3

Dermamyotome and Sclerotome

Question 4

What forms from the Dermamyotome?

Answer 4

Dermatome and Myotome nerves

Question 5

What forms from the Sclerotome?

Answer 5

Skeleton

Question 6

What is the dividing somite made up of?

Answer 6

Mesenchyme

Question 7

What develops from Mesenchyme?

Answer 7

Bone and Cartilage

Question 8

What are the two kinds of bone growth/ossification?

Answer 8

Inter-carilagenous (intermembrounous) and Endochondral

Question 9

What allows the bones to grow rapidly as the fetus grows?

Answer 9

The Cartilage state of developing bones

Question 10

What to the vascularization point cells become?

Answer 10

Osteoblasts

Question 11

What is the function of osteoblasts?

Answer 11

Deposit osteiod tissue that will become ossification centers

Question 12

What is deposited at the ossification centers?

Answer 12

Bone matirx

Question 13

What do spicules become?

Answer 13

Lamellae

Question 14

What to the lamelle develop around and what do they form?

Answer 14

Blood vessels, Develop osteons

Question 15

What to the spicules grow to become?

Answer 15

Trabecullae

Question 16

What are the two types of development for the skull?

Answer 16

Neurocranium and splanchnocranuim

Question 17

What is the Nuerocranium?

Answer 17

The bone that forms from mesenchyme that surrounds the brain

Question 18

What are the two kinds of neurocranium development?

Answer 18

Neurochondrocranium and neuromembranocranium

Question 19

Where does the neurochondocranium develop? When does it start ossification?

Answer 19

The base of the neurocranium. Starts at about 8 weks

Question 20

What develops from the neurochondrocranium at 6 weeks

Answer 20

• two pairs of nasels
• one pair of prechonreals/trabecula
• one pair of orbitals
• one pair of temborals
• one single hypophysial
• one single parachonral
• one pair of otics
• for single occipitals

Question 21

What is formed from the neuormembranocranium and how is it formed?

Answer 21

the sides and the roof of the neurocranium. formed by intramembranous ossification

Question 22

What are the subdivisions that are formed from the neuromembranocranium?

Answer 22

• Two Frontals
• Two parietals
• one vomer
• two nasels
• two lacrimals

Question 23

what are the large fibrous areas of the skull formed from the neuromembranocranium?

Answer 23

Fontanelles or soft spots

Question 24

The fetal life bones are separated by connective tissue membranes known as what?

Answer 24

Sutures

Question 25

The largest fontanelle and when it closes

Answer 25

Anterior fonenelle. closes by the end of the second year

Question 26

Which two fontanelles are closed at about the 2nd or 3rd month after birth?

Answer 26

Posterior and Anterolateral

Question 27

When does the posteriolateral fonetanelle close?

Answer 27

by the end of the first year after birth

Question 28

T/F: The fetal skull can undergo changes during the birth process due to the softness of the fontanelles and sutures.

Answer 28

True

Question 29

Waht are some of the characteristics of the fetal skull

Answer 29

- bones are very thin - very large in proportion to the body - hard for baby to hold the head up when first born

Question 30

What are the three arches of the splanchondrocranium?

Answer 30

Visceral, Pharyngeal, and Bracheal arches

Question 31

How many arches have and how many do we start with?

Answer 31

have 5, start with 6

Question 32

What forms from the 1st arch?

Answer 32

Palate and Maxilla, Meckl's cartilage, Incus and Malleus

Question 33

Forms from the 2nd arch?

Answer 33

States, Cranial 1/2 of the hyoid bone, lesser horn

Question 34

forms from the 3rd arch?

Answer 34

caudal 1/2 of the hyoid bone, greater horn

Question 35

forms from the 4th and 6th arches?

Answer 35

cartilage of the layranx

Question 36

What structure is eventually replaced by the vertebral column?

Answer 36

Notocord

Question 37

What does the vertebral column form from?

Answer 37

somite mesenchyme scerotome

Question 38

When does chondrification begin to appear?

Answer 38

in the 7th week of development

Question 39

What does intersegmental development give the vertebra?

Answer 39

muscle attachment and nerve emergence

Question 40

When do the vertebral arches unite to form the spinous process?

Answer 40

3rd month AFTER BIRTH

Question 41

When does ossification of the vertebra begin?

Answer 41

9 weeks of development

Question 42

all ossification centers are present int eh fetus at the 5th month except...

Answer 42

Sacral and coccyx region

Question 43

How many ossification centers does each vertebra have and where are they in development?

Answer 43

3. One in the centrum (body) and one at each half of the vertebral arch

Question 44

How many ossification centers are in the pubescent vertebra?

Answer 44

5. one at tip of spinous process, one at the tip of each transverse process, and two of the rim of the epiphysical center

Question 45

what does the sternum develop from?

Answer 45

Mesenchymal sternal bands (bars)

Question 46

When does the upper and lower limbs first appear as buds?

Answer 46

upper-4th week | lower-5th week

Question 47

Which way dose the upper limb rotate to allow the elbow to face posterior?

Answer 47

laterally

Question 48

Which way does the lower limb rotate to allow the knee to face anterior?

Answer 48

medially

Question 49

What is the first bone to ossify in the human body?

Answer 49

Clavicle