general and musculoskeletal system Flashcards
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.
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.
what type of bone is immediately below the cartilage in a joint?
subchondral bone
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.
red
fat
yellow
yellow
what type of fibres connect the periosteum to the compact bone?
sharpey fibres
what layer is between the medullary cavity and the compact bone?
endosteum
what type of ossification occurs in flat bones?
intramembraneous
what is the main types of ossification in growing long bones?
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
in flat bones, what is the type of bone called that is between the 2 layers of compact bone?
spongy bone, sometimes called diploe in the skull
what is the main function of sesamoid bones?
to protect tendons at planes where the greatest friction occurs
bone is derived from:
a) ectoderm
b) neuroectoderm
c) endoderm
d) mesoderm
D
which cells are responsible for synthesising matrix and osteoid in bones?
a) osteoblasts
b) osteoclasts
c) osteocytes
A
which cells are most numerous in bone?
a) osteoblasts
b) osteoclasts
c) osteocytes
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
which cells are responsible for bone resorption?
a) osteoblasts
b) osteoclasts
c) osteocytes
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)
what is an apophysis
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
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
B
put these zone of the physis in order:
cell growth or proliferation zone
resting zone
ossification zone
hypertrophy zone
provisional calcification zone
epiphysis- resting zone (immature cells), cell growth and proliferation zone, hypertrophy zone, provisional calcification zone, ossification zone- diaphysis
which is the weakest zone of the physis?
a) cell growth or proliferation zone
b) resting zone
c) hypertrophy zone
d) provisional calcification zone
C
what is the zone of ranvier in the physis?
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
how do bones grow in diameter (process name)?
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.
which type of bone is the odd one out?
a) cancellous bone
b) trabecular bone
c) compact bone
d) spongy bone
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.
see page 9 adriannas notes for table of closure of physes in dogs.
continue from page 11 blood supply to long bones
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
C. there are also small metaphyseal arteries and extensive periosteal blood supply to help intramembranous ossification
is the physis vascular or avascular?
avascular, it receives blood from the nutrient foramen (metaphyseal side- majority) and the epiphyseal joint capsule
in immature bones where is the most common site of haematogenous osteomyelitis and why?
metaphysis- largest blood supply
how do vertebral bodies receive blood supply?
the body has a central nutrient foramen, the epiphyses has small vessels
in mature long bones, how is the epiphysis vascularised?
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
which vessels enlarge to accommodate fracture healing in bones?
mainly periosteal arteries
most nerves in bone are:
a) motor
b) sensory
c) sympathetic
d) parasympathetic
B
the main nutrient artery of a bone is in the:
a) epiphysis
b) metaphysis
c) diaphysis
d) physis
C
why is the femoral head highly susceptible to vascular insult in dogs?
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.
why are young foals more likely to get osteomyelitis and septic arthritis, than your dogs, in relation to bone anatomy and physiology
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
where do dogs and cats get vitamin d from?
diet
how is vitamin d turned in to the active form in the body?
metabolised by enzymes in the liver and kidneys
which hormone inhibits bone resorption?
a) calcitonin
b) PTH
c) calcitriol
d) 25- hydroxycholecalciferol
A
where are calcitonin and PTH produced
pth- parathyroid gland
calcitonin- thyroid
fracture healing- see thrall
cartilage growth development and repair??
what is the fundamental unit/ smallest functional unit of contraction in a muscle?
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.
which ion is most important for muscle contraction?
A) K+
B) P+
C) Ca2+
D) Na+
C
