DEVELOPMENT OF THE MUSCULOSKELETAL SYSTEM

Question 1

Types of Muscle Cell (Myocyte)

Answer 1

Skeletal or striated or voluntary myocyte
Smooth or visceral or involuntary myocyte
Cardiac myocyte

Question 2

comprises 40 – 45 % of the total body weight.
➢ Long and cylindrical w/ many nuclei located at the periphery of the cell

Answer 2

Skeletal or striated or voluntary myocyte

Question 3

is found in the walls of tubular and visceral
organs.
➢ Spindle-shaped w/ one nucleus located in the middle of the cell

Answer 3

Smooth or visceral or involuntary myocyte

Question 4

comprises the myocardium of the heart.
➢ Branched w/ many nuclei located in the middle of the cell.

Answer 4

Cardiac myocyte

Question 5

Mesodermal cells of myotome of each somite/somitomere separate from dermatome and
sclerotome, and elongate to spindle-shaped that synthesize myosin and actin and
appear striated. Several myoblasts fuse to form multinucleated myotubes

Answer 5

myoblasts

Question 6

The myotubes, with
nuclei that migrate peripherally, present cross striations, and are now called .

Answer 6

skeletal myocytes

Question 7

After birth, the myocytes interact with motor nerves and differentiate into .

Answer 7

fast-twitch, slow-twitch
or intermediate myocytes

Question 8

Muscle development requires

Answer 8

innervations

Question 9

Also, muscles and tendons must be stretched by growing bone) in order to grow proper lengths

Answer 9

under
tension(

Question 10

Each anatomic muscle is
practically allocated a special number of myoblasts that is determined by the time of birth.
Thereafter, muscle cell growth is due solely to

Answer 10

cellular hypertrophy.

Question 11

Epimere becomes

Answer 11

epaxial muscles

Question 12

the hypomere becomes the

Answer 12

hypaxial muscles

Question 13

by delamination forms mesenchymal cells that elongate to
form myoblasts.

Answer 13

Splanchnic mesoderm

Question 14

for smooth muscles of blood vessels

Answer 14

Somatic mesoderm

Question 15

for smooth muscles of the iris.

Answer 15

Ectoderm (neural ectoderm of optic cup)

Question 16

that surrounds the epithelium of a structure or organ for other
smooth muscles.

Answer 16

mesenchyme

Question 17

Cardiac muscle cells are joined together by intercellular
connections called

Answer 17

intercalated discs.

Question 18

Types of Connective Tissues

Answer 18

1. Loose connective tissue - mesenchymal, mucoid, areolar adipose tissue, etc.
2. Dense connective tissue - tendons, ligaments.
3. Cartilage
4. Bone

Question 19

Mesenchymal cells from mesoderm (somite) or in case of head, from ectoderm (neural
crest) become stellate or spindle-shaped and are now termed .

Answer 19

fibroblasts

Question 20

There are two types of fibers secreted by fibroblasts:

Answer 20

collagenous and elastic.

Question 21

Blood vessels and osteogenic cells invade the calcified cartilage and form the

Answer 21

periosteal
bud

Question 22

The bone trabeculae interconnect to form .

Answer 22

cancellous bone

Question 23

is made possible through the epiphyseal plate, a plate of
cartilage between the diaphysis and epiphysis where the cartilage is continuously
formed and replaced during the growing years of the animal

Answer 23

Growth in length of long bone

Question 24

occurs by deposition of additional layers of bone
substance on the bone surface by osteoblasts in the periosteum of diaphysis and
destruction of bone and cartilage by osteoclasts and chondroclasts, respectively, in
the central portion of diaphysis to create a marrow canal or marrow cavity.

Answer 24

Growth in diameter of long bone

Question 25

Addition of layers of bone matrix reduces the intertrabecular spaces and the cancellous bone in the diaphysis is converted into a

Answer 25

compact bone

Question 26

Osteocytes present cytoplasmic processes that radiate into the matrix through tiny bone channels called

Answer 26

canaliculi

Question 27

The intertrabecular spaces are occupied by blood-forming cells (red bone marrow) and are also called

Answer 27

marrow spaces

Question 28

Common Malformations of the Vertebra Alignment Defects

Answer 28

Scoliosis Kyphosis Lordosis Torticolis or wry neck Spina bifida Rachischisis Spina bifida occulta

Question 29

- lateral deviation of vertebral column

Answer 29

Scoliosis

Question 30

- sagittal deviation of vertebral column in a fixed position

Answer 30

Kyphosis

Question 31

- sagittal deviation of vertebral column in a fixed extended position

Answer 31

Lordosis

Question 32

- abnormal twisting of the cervical vertebral column

Answer 32

Torticolis or wry neck

Question 33

- absence of vertebral arch (failure of vertebral arch to form dorsally over the vertebral foramen).

Answer 33

Spina bifida

Question 34

– spina bifida of several adjacent vertebrae

Answer 34

Rachischisis

Question 35

- spina bifida covered by skin and subcutis

Answer 35

Spina bifida occulta

Question 36

- does not ossify

Answer 36

Nasal capsule

Question 37

- ethmoid and bone around the pituitary gland

Answer 37

Prechordal cartilage

Question 38

- base of occipital bone

Answer 38

Parachordal cartilage

Question 39

- temporal bone

Answer 39

Otic capsule

Question 40

develops from outward growth of ectomesenchymal tissue located rostral to the cranium and pharynx.

Answer 40

Face

Question 41

Malformations of the Face

Answer 41

Cheiloschisis Palatoschisis Branchial cyst ( Heterotropic polyodontia -

Question 42

- cleft lip caused by failure of fusion of medial nasal and maxillary processes.

Answer 42

Cheiloschisis

Question 43

- cleft palate caused by failure of medial palatine processes to fuse

Answer 43

Palatoschisis

Question 44

(no opening)

Answer 44

Branchial cyst

Question 45

(opening to exterior)

Answer 45

branchial sinus

Question 46

(openings to interior and exterior).

Answer 46

branchial fistula

Question 47

- (dentigerous cyst, ‘ear teeth’). Primordia of enamel organs escape to the exterior and develop tooth structures anchored on the parietal bone or base of the ear.

Answer 47

Heterotropic polyodontia

Question 48

Types of Limb Malformations

Answer 48

Limb Reduction Limb Duplication Limb and Joint Deformities

Question 49

Type of Limb Reduction

Answer 49

Achondroplasia (dwarfism; Dachshund) Amelia Meroromelia Acromelia Hemimelia Micromelia Phocomelia Syndactyly Brachydactyly Ectrodactyly

Question 50

inherited; systemic premature ossification of physes of extremeties

Answer 50

Achondroplasia (dwarfism; Dachshund) -

Question 51

- complete absence of a limb.

Answer 51

Amelia

Question 52

- absence of a part of a limb.

Answer 52

Meroromelia

Question 53

– complete absence of limb.

Answer 53

Acromelia

Question 54

– absence of half or one or more segments of a limb

Answer 54

Hemimelia

Question 55

- reduced size of a limb.

Answer 55

Micromelia

Question 56

- absence of one or more proximal segments, a consequence of pregnant women taking thalidomide in the late 1950’s

Answer 56

Phocomelia

Question 57

- fused digits.

Answer 57

Syndactyly

Question 58

- shortened or stumpy digits

Answer 58

Brachydactyly

Question 59

- absence of one or more digits

Answer 59

Ectrodactyly

Question 60

Type of Limb Duplication

Answer 60

Polydactyly Bimelia Notomelia (noto=back

Question 61

- presence of one or more extra digits. This is common in pig and cat

Answer 61

Limb Duplication

Question 62

- one or more extra digits

Answer 62

Polydactyly

Question 63

- partial or complete duplication of one limb

Answer 63

Bimelia

Question 64

- limb growing from the back of the animal.

Answer 64

Notomelia (noto=back)

Question 65

Type of Limb and Joint Deformities

Answer 65

Arthrogryposis Hip Dysplasia Ankylosis

Question 66

- crooked limb. Gr. gryposis=crooked) - can results from malformed joints, denervation, abnormal muscle tension, or impaired mobility in utero.

Answer 66

Arthrogryposis

Question 67

- abnormal maturation of the hip joint that results in formation of a shadow acetabulum and flattened femoral head.

Answer 67

Hip Dysplasia

Question 68

- permanent fixation of a joint caused by immobility of the fetus in utero.

Answer 68

Ankylosis