Developments

Question 1

4th Week - Limb buds become visible as outpocketings from the

Answer 1

ventrolateral body wall

Question 2

Forelimb first, hind limb-1-2 days later.

Answer 2

T

Question 3

During 7th week of gestation upper limb rotates——— placing the extensor muscles on lateral and posterior surface, thumbs lie laterally.

Answer 3

90o laterally

Question 4

Lower limb rotates————–placing the extensor muscles on———- surface and big toe medially. •

Answer 4

90o medially

anterior

Question 5

Initially limb bud consists of————— derived from——————- mesoderm

Answer 5

mesenchymal core

parietal (somatic) layer of the lateral plate

Question 6

Bones and connective tissue develop of this mesenchymal tissue. From

Answer 6

parietal (somatic) layer of the lateral plate mesoderm

Question 7

Three components of the limbs-

Answer 7

Styopod

Zeugopod

autopod

Question 8

Ectoderm covering the limb bud at the distal border of the limb thickens to form

Answer 8

apical
ectodermal ridge(AER)

Question 9

AER exerts inductive influence on adjacent mesenchyme causing it to remain
→

Answer 9

undifferentiated-Undifferentiated zone

Question 10

Fingers and toes develop when

Answer 10

cell death in apical ectodermal ridge (AER) separates

this ridge into five parts.

Question 11

Mesenchymal tissue in the limb buds begin

to condense and these cells differentiate into

Answer 11

chondrocytes.

Question 12

Joints are formed in the cartilaginous

condensations when

Answer 12

chondrogenesis is arrested and a joint interzone is induced.

Question 13

Joint cavity is formed by

Answer 13

cell death

Question 14

Cells surrounding the joint differentiate into

Answer 14

Joint capsule

Question 15

Mesenchymal bone-

Answer 15

Condensation of mesenchymal tissue in the limb buds- 5th week

Question 16

hyaline cartilaginous bone-

Answer 16

Chrondrification of mesenchymal bone model to form hyaline cartilaginous bone- 6th week

Question 17

Endochondral ossification -begins at

Answer 17

t the end of embryonic period (8th week)

Question 18

Primary center of ossification in all long bones appear by ——week (They form the——)

Answer 18

12th

diaphysis of the
bone

Question 19

Secondary centers of ossification begin to appear at

Answer 19

the ends of the long bones after birth. They form

the epiphyses of the bone.

Question 20

Epiphyseal plate (growth plate) -

Answer 20

cartilaginous plate between diaphysis and epiphysis

Question 21

When the bone acquired its full length, the ————- disappear, and epiphyses unites with
shaft (diaphysis) of the bone.

Answer 21

epiphyseal plates

Question 22

small-long bones (phalanges)- epiphyseal plate

Answer 22

only at one end.

Normally the distal end of the bone

Question 23

Irregular bone-

Answer 23

One or more primary centers of ossification and usually several secondary centers.

Question 24

The ectoderm is towards——-
endoderm is towards——— and
mesoderm between ectoderm and endoderm.

Answer 24

amniotic cavity,

yolk sac

Question 25

Mesoderm can be differentiated into

Answer 25

paraxial (close to developing notochord) and lateral | plate mesoderm, with intermediate mesoderm in between.

Question 26

Paraxial mesoderm differentiates into —— arranged——-

Answer 26

somites. These somites are arranged cranio-caudally.

Question 27

Limb muscles are developed from

Answer 27

myoblasts surrounding the developing bones in the limbs.

Question 28

With elongation of the limb buds,

Answer 28

muscle tissue first splits into flexor and extensor | components

Question 29

Digit amputations resulting from

Answer 29

amniotic bands

Question 30

Congenital hip dislocation

Answer 30

Underdevelopment of acetabulum and head of the femur

Question 31

Congenital joint contracture (Arthrogryposis

Answer 31

synostosis

Question 32

osteogenesis imperfecta-

Answer 32

shortening, bowing and hypomineralization long bones

Question 33

Transverse limb deficiency

Answer 33

caused disruption to AER or by vascular | abnormalities

Question 34

Congenital Anomalies appendicular skeleton

Answer 34

Achondroplacia Gigantism Acromegaly

Question 35

Achondroplacia

Answer 35

Defective endochondral ossification of epihyseal bones (dwarfism) Autosomal dominant disorder Early fusion of epiphyseal cartilage

Question 36

Gigantism

Answer 36

– Excessive height and body proportions | - Due to congenital infantile hyper pituitarism( incrased secretion of growth hormone.

Question 37

Acromegaly

Answer 37

Enlargement of bones of hand and foot

Question 38

Development of Vertebral Column

Answer 38

Cells of the sclerotome proliferate and surround the notochord and neural tube Sclerotome will condense around notochord and neural tube

Question 39

notochord

Answer 39

axial support of the embryo)

Question 40

neural tube (which develops

Answer 40

into brain and spinal cord).

Question 41

Ossification of Vertebra

Answer 41

1) Mesenchymal vertebra 2) chondrification to form cartilaginous vertebra 3) Cartilaginous vertebra ossifies by primary and secondary centers of ossification to form bony vertebra

Question 42

primary centers of ossification

Answer 42

3 | One for centrum (initially two joined to form one), one for each vertebral arch

Question 43

secondary center of ossification

Answer 43

5 One for tip of the spinous process, one for tip of each transverse process, two annular epiphysis:1-for superior and 1- for inferior vertebral body

Question 44

Sclerotome of each segment has caudal compactly arranged zone and cranial less compactly arranged zones.

Answer 44

T

Question 45

Each myotome has——- from the spinal cord.

Answer 45

segmental innervation

Question 46

Arteries are in the

Answer 46

inter segmental plane.

Question 47

Caudal half of sclerotome (compact) part fuses with cranial part (less dense) of the next (caudal) somite. The central part of sclerotome becomes less compact and developed into ——of intervertebral disc.

Answer 47

anulus fibrosus

Question 48

Notochord | within body of the vertebra degenerates, and within the intervertebral disc it forms——

Answer 48

nucleus pulposus.

Question 49

Vertebral body will be in——— like the segmental arteries Nerves will be in the—-

Answer 49

inter segmental plane, segmental plane

Question 50

Muscles are attached to adjacent vertebra- so they can help in movement of the spine

Answer 50

T

Question 51

Congenital Anomalies of Vertebral column

Answer 51

Chondroma Spina Bifida Hemivertebra Cervical rib

Question 52

Chondroma

Answer 52

Tumor of notochord | - Occur at the base of the skull, in the lumbosacral region

Question 53

Spina Bifida:

Answer 53

Failure of fusion of vertebral arches

Question 54

Open spina bifida-

Answer 54

covered by thin membrane

Question 55

Closed spina bifida | spina bifida occulta

Answer 55

covered by thick membrane or skin

Question 56

Spina bifida cystica-

Answer 56

involves spinal cord and meninges

Question 57

Cervical rib -

Answer 57

Develops from costal elements in cervical vertebra results in compression of subclavian vessels

Question 58

Hemivertebra

Answer 58

Due to failure of one half of vertebral centrum to ossify | - This leads to scoliosis- lateral curvature.