general and musculoskeletal system

Question 1

what is the cut back zone, seen in some radiographs of immature dogs?
a) In the metaphysis the wide physeal region is modelled to the narrower diaphyseal bone by means of active subperiosteal osteoclastic activity.
b) In the epiphysis the wide physeal region is modelled to the narrower epiphyseal bone by means of active subperiosteal osteoclastic activity.
c) responsible for growth in length of the bone towards the diaphysis.

Answer 1

A

Craniocaudal view of the elbow
of a 31/2-month-old Boxer. The hollow white arrowheads delineate the
distal humeral physis. It is common for both the medial and lateral
aspects of the physis to be irregular with broad regions of lucency. The
solid white arrow is the lateral aspect of the proximal radial physis. The
cortical irregularity distal to this is normal, known as the cutback zone,
which reflects a region of rapid osseous remodeling.

Question 2

what type of bone is immediately below the cartilage in a joint?

Answer 2

subchondral bone

Question 3

in the medullary cavity of bones ______ (red/yellow) marrow (present first) is very vascular with hemopoietic properties – produces red &
white granular cells. Eventually infiltrated with ______ – _____ (red/yellow) marrow - whose hemopoietic potential is dormant.
(red/ yellow) marrow has a reduced opacity compared with the cortex, although the opacity is still usually greater
than that of surrounding soft tissues.

Answer 3

red
fat
yellow
yellow

Question 4

what type of fibres connect the periosteum to the compact bone?

Answer 4

sharpey fibres

Question 5

what layer is between the medullary cavity and the compact bone?

Answer 5

endosteum

Question 6

what type of ossification occurs in flat bones?

Answer 6

intramembraneous

Question 7

what is the main types of ossification in growing long bones?

Answer 7

endochondral, but both endochondral and intramembraenous occur. they begin with a primary center of ossification in the cartilage model and grow by intramembranous ossification, then secondary sites of ossification grow, then endochondral ossification occurs. but growth is complicated and both can occur at the same time

Question 8

in flat bones, what is the type of bone called that is between the 2 layers of compact bone?

Answer 8

spongy bone, sometimes called diploe in the skull

Question 9

what is the main function of sesamoid bones?

Answer 9

to protect tendons at planes where the greatest friction occurs

Question 10

bone is derived from:
a) ectoderm
b) neuroectoderm
c) endoderm
d) mesoderm

Answer 10

D

Question 11

which cells are responsible for synthesising matrix and osteoid in bones?
a) osteoblasts
b) osteoclasts
c) osteocytes

Answer 11

A

Question 12

which cells are most numerous in bone?
a) osteoblasts
b) osteoclasts
c) osteocytes

Answer 12

C
As the osteoblast lays down osteoid, it loses its ability to produce osteoid and becomes an osteocyte surrounded by mineralized matrix
Osteocytes are connected by a system of tunnels called canaliculi

Question 13

which cells are responsible for bone resorption?
a) osteoblasts
b) osteoclasts
c) osteocytes

Answer 13

B
Calcium and phosphorus are released with bone breakdown and absorbed by the osteoclast (maintain homeostasis)
Osteoclasts and osteoblasts work as a unit (the basic multicellular unit)

Question 14

what is an apophysis

Answer 14

Other secondary ossification centre that contributes to the shape of the bone but not bone growth (e.g. the greater trochanter of the femur)
Located in areas of ligamentous or tendinous attachment
These areas will ultimately fuse to the associated bone

Question 15

which zone of the physis is closest to the epiphysis?
a) cell growth or proliferation zone
b) resting zone/ reserve zone
c) hypertrophy zone
d) provisional calcification zone

Answer 15

B

Question 16

put these zone of the physis in order:

cell growth or proliferation zone
resting zone
ossification zone
hypertrophy zone
provisional calcification zone

Answer 16

epiphysis- resting zone (immature cells), cell growth and proliferation zone, hypertrophy zone, provisional calcification zone, ossification zone- diaphysis

Question 17

which is the weakest zone of the physis?
a) cell growth or proliferation zone
b) resting zone
c) hypertrophy zone
d) provisional calcification zone

Answer 17

C

Question 18

what is the zone of ranvier in the physis?

Answer 18

The zone of Ranvier is a groove in the growth plate of a bone that allows for the bone to grow in width. It’s made up of cells, fibers, and a bony lamina

Question 19

how do bones grow in diameter (process name)?

Answer 19

appositional growth
growth in diameter can continue even after longitudinal growth ceases. This growth by adding to the free surface of bone is
called appositional growth. Appositional growth can occur at the endosteum or periosteum where osteoclasts resorb old bone that lines the medullary cavity, while osteoblasts produce new bone
tissue.

Question 20

which type of bone is the odd one out?
a) cancellous bone
b) trabecular bone
c) compact bone
d) spongy bone

Answer 20

C

all the others are synonyms for each other
cancellous bone, light, porous bone enclosing numerous large spaces that give a honeycombed or spongy appearance. The bone matrix, or framework, is organized into a three-dimensional latticework of bony processes, called trabeculae, arranged along lines of stress. The spaces between are often filled with marrow and blood vessels.

Question 21

see page 9 adriannas notes for table of closure of physes in dogs.

Question 22

continue from page 11 blood supply to long bones

Question 23

in the immature long bone where does the epiphysis and metaphysis get blood supply from?
a) both get blood from the nutrient foramen
b) both get blood from the joint capsule
c) the metaphysis get blood from the nutrient foramen and the epiphysis gets blood from the joint capsule

Answer 23

C. there are also small metaphyseal arteries and extensive periosteal blood supply to help intramembranous ossification

Question 24

is the physis vascular or avascular?

Answer 24

avascular, it receives blood from the nutrient foramen (metaphyseal side- majority) and the epiphyseal joint capsule

Question 25

in immature bones where is the most common site of haematogenous osteomyelitis and why?

Answer 25

metaphysis- largest blood supply

Question 26

how do vertebral bodies receive blood supply?

Answer 26

the body has a central nutrient foramen, the epiphyses has small vessels

Question 27

in mature long bones, how is the epiphysis vascularised?

Answer 27

Long bones receive blood supply from multiple sources, including the central nutrient artery and metaphyseal arteries, at the physeal scar they likely anastomose with periosteal vessels and supply the epiphysis. some of the blood leaves via the nutrient foramen, but some also leaves via small veins that perforate the compact bone near the articular surfaces at the extremities of the bone. the compact bone is supplied by the periosteal arteries and medullary blood. at fascial attachment sites the outer cortex is often supplied by arterioles extending from the fascia

Question 28

which vessels enlarge to accommodate fracture healing in bones?

Answer 28

mainly periosteal arteries

Question 29

most nerves in bone are: a) motor b) sensory c) sympathetic d) parasympathetic

Answer 29

B

Question 30

the main nutrient artery of a bone is in the: a) epiphysis b) metaphysis c) diaphysis d) physis

Answer 30

C

Question 31

why is the femoral head highly susceptible to vascular insult in dogs?

Answer 31

Because all arteries of the intracapsular and intraosseous networks propagate from the extraosseous vessels via a single extracapsular vascular ring, the blood supply to the femoral neck and head is highly susceptible to vascular insult. Extraosseous vessels include, from the most to the least significant, the lateral and medial circumflex femoral, caudal and cranial gluteal, and iliolumbar arteries he lateral and medial circumflex femoral and caudal gluteal arteries coalesce to form an extracapsular vascular ring that lies at the base of the femoral neck. The intracapsular arteries develop from this ring, penetrate the joint capsule at its distal attachment, and subsequently ascend toward the epiphysis. These arteries remain subsynovial as they rise and lie along the craniodorsal aspect of the femoral neck. Near the capital physis they anastomose to form an intracapsular vascular ring, encircling the neck. Branches of this ring then penetrate the physis and give rise to an intraosseous, arcuate network that supplies the epiphysis and proximal neck (see Figure 61-7). The artery of the ligament of the femoral head does not contribute to the epiphyseal blood supply in dogs. This is in contrast to cats, which may explain why fewer cases of avascular necrosis of the femoral head and neck are seen in this species.

Question 32

why are young foals more likely to get osteomyelitis and septic arthritis, than your dogs, in relation to bone anatomy and physiology

Answer 32

foals have transphyseal vessels which also communicate with the joint synovium, these start to regress at 14 days of age and disappear by 45d ish. the connected blood supply makes septic arthritis more likely

Question 33

where do dogs and cats get vitamin d from?

Answer 33

diet

Question 34

how is vitamin d turned in to the active form in the body?

Answer 34

metabolised by enzymes in the liver and kidneys

Question 35

which hormone inhibits bone resorption? a) calcitonin b) PTH c) calcitriol d) 25- hydroxycholecalciferol

Answer 35

A

Question 36

where are calcitonin and PTH produced

Answer 36

pth- parathyroid gland calcitonin- thyroid

Question 37

fracture healing- see thrall

Question 38

cartilage growth development and repair??

Question 39

what is the fundamental unit/ smallest functional unit of contraction in a muscle?

Answer 39

sarcomere, made of actin and myosin Each muscle comprises multiple tissues, including blood vessels, lymphatics, contractile muscle fibers, and connective tissue sheaths. The outermost sheath of connective tissue covering each muscle is called epimysium. Each muscle is made up of groups of muscle fibers called fascicles surrounded by a connective tissue layer called perimysium. Multiple units of individual muscle fibers within each fascicle are surrounded by endomysium, a connective tissue sheath. The two most essential myofilaments that make up the contractile elements of the muscle fiber are actin and myosin. They are arranged distinctively in a striated pattern to form the dark A band, the light I band, and the fundamental unit of contraction, also referred to as a sarcomere.

Question 40

which ion is most important for muscle contraction? A) K+ B) P+ C) Ca2+ D) Na+

Answer 40

C