introduction

Question 1

how many ribs and thoracic vertebrae are in a dog

Answer 1

13

Question 2

describe the gross topography of the thorax

Answer 2

cranially the thoracic inlet
dorsally thoracic vertebra
laterally the ribcage
ventrally the sternum
caudally the diaphragm

Question 3

what is the dorsal 2/3 of the rib made of

Answer 3

bone

Question 4

what is the ventral 1/3 of the rib made of

Answer 4

cartilage

Question 5

what is the junction between the 2 tissues of the ribs called

Answer 5

costochondral junction

Question 6

where do the first 9 ribs join ventrally

Answer 6

the sternum

Question 7

what do the remainder of ribs join

Answer 7

each other to form the coastal arch

Question 8

what is the last rib called that is not connected ventrally

Answer 8

floating rib

Question 9

what bones and how many is the sternum made from

Answer 9

8 sternebrae

Question 10

what is the first sternebra called and where is it palpable

Answer 10

palpable cranially and is called the manubrium

Question 11

what is the last sternebra called and state where it is palpable

Answer 11

palpable caudally and is called the xiphoid process

Question 12

what is the cartilaginous extension of the xiphoid process called

Answer 12

xiphoid cartilage

Question 13

what is the diaphragm

Answer 13

a sheet of skeletal muscle which extends from the sternum, ribs and vertebrae and inserts on a central aponeuorotic tendon

Question 14

what is contained within the thorax

Answer 14

heart, distal airways and lungs, the thoracic oesophagus, the thymus, blood vessels, lymph nodes and lymphatic vessels.

Question 15

describe the anatomy of the lungs

Answer 15

lungs are divided into 2 sections called lobes.
each love is divided into lobules.
left lung has 2 lobes = cranial and caudal
the cranial lobe is further divided into a cranial and caudal portion.
the right lung has 4 lobes - cranial, middle, caudal and accessory.

Question 16

where does the heart sit in relation to the lungs?

Answer 16

ventral to the hilus (root) of the lungs and between the left and right lung.

Question 17

which mammal lacks the middle lobe of the right lung?

Answer 17

horse

Question 18

what is the pleura

Answer 18

series membrane that lines the thorax
invaginated sac consisting of 2 parts - visceral and parietal pleura.

Question 19

describe the anatomy of the heart

Answer 19

large muscular organ located in the thorax
base of the heart sits dorsally and cranially the apex.
main vessels entering and exiting the heart do so at the base.
the heart lines approx midline, angled caudoventrally with a slight deviation of its apex (points towards the head of the animal)
divided into 4 chambers - 2 atria, 2 ventricles

Question 20

describe the route blood takes to the heart

Answer 20

left atrium receives oxygenated blood from the lungs by pulmonary veins.
right atrium receives deoxygenated blood from the body via cranial and caudal vena cavae. The right ventricle pumps this blood into the pulmonary artery through the pulmonic valve. the pulmonary artery takes the this deoxygenated blood to the lungs for oxygenation.
left ventricle pumps oxygenated blood it receives from left atrium into the aorta via the aortic valve.
the aorta delivers this blood to all tissues of the body by means of many divisions into smaller arteries.

Question 21

what is the heart encapsulated and invested by?

Answer 21

serous membrane called the pericardium - out pouching of the pleura. has visceral and parietal layers with a few mm of serous fluid to allow ease of movement of the heart within its sac.

Question 22

what is the name of the inner layers the heart consists of

Answer 22

endocardium, muscular myocardium and the outer serosal epicardium which is confluent with the visceral pericardium.

Question 23

what are the 4 valves called

Answer 23

right and left Atrioventricular valves known as bicuspid or mitral on left and tricuspid on right
pulmonic valve
aortic valve

Question 24

what are the aortic and pulmonary valves also known as

Answer 24

semilunar valves

Question 25

what do the AV valves consist of and how many on each

Answer 25

fibrous cusps
bicuspid has 2
tricuspid has 3

Question 26

what is the thin muscular wall called that separates the atria

Answer 26

interatrial septum

Question 27

what is the very muscular wall called that separates the ventricles

Answer 27

interventricular septum - really part of the left ventricle

Question 28

what is the additional outpouching of the atria called

Answer 28

atrial appendage or auricle

Question 29

define systole

Answer 29

contraction phase
blood pumped out of chambers

Question 30

define diastole

Answer 30

relaxation phase
blood fills the chambers of the heart

Question 31

how is S1 heart sound generated and when does it occur?

Answer 31

AV valves close and blood which has passed into the ventricle rebounds off the closed valve and walls.
this is at the end of diastole and at the beginning of isovolumetric contraction. a contribution is made by the opening of the aortic valve and acceleration of the blood as it is squeezed into the aorta.

Question 32

outline the basic electrical pathway through the heart

Answer 32

initial electrical impulse in the normal heart is generated in cells in the wall of the right atrium called the sinoatrial node.
impulse travels from this node and moves cell to cell over the atria to stimulate them to contract.
electrical activity is passed through atrioventricular node located in the distal interatrial septum.
impulse then enters the AV bundle in the proximal interventricular septum.
bundle passes through annulus fibrosis and divides into 2 limbs - left and right bundle branch.
each limb continues distally within the septum then branches out to supply the ventricular muscle via purkinje fibres. the left bundle branch further divides into anterior and posterior fascicles.
one part of right bundle branch crosses to the free wall of the right ventricle in a band of tissue called the septomarginal band.

Question 33

what is meant by isovolumetric relaxation and isovolumetric contraction

Answer 33

volume remains the same

Question 34

how is the heart sound S2 generated

Answer 34

the pulmonary and aortic valves close and blood reverberates in the great vessels as it decelerates once the impetus of the ventricle is removed.
this marks end of systole.

Question 35

how is s3 generated and how audible is it

Answer 35

rarely audible except from in horses.
can be heard in dogs with heart failure.
caused by blood turbulence in the left ventricle as blood flows in from the atria under pressure. it reflects reduced compliance on the left ventricle in early diastole.

Question 36

how is S4 generated and how audible is it and what is it associated with in small animals?

Answer 36

audible in the horse.
associated with impaired relaxation of the ventricular wall in small animals
caused by increased force of contraction of the atria during atrial systole as it endeavours to overcome the slow relaxation of the ventricular wall.

Question 37

what do S1 and S2 mark

Answer 37

start and end of systole.

Question 38

when is S3 and S4 audible

Answer 38

during diastole

Question 39

when does s3 occur

Answer 39

just after s2

Question 40

when does s4 occur

Answer 40

before s1

Question 41

what is gallop rhythm

Answer 41

if s3 and/or s4 are audible on auscultation of the heart in dogs and cats.

Question 42

what is a murmur

Answer 42

sound generated by abnormal turbulence within the heart or great vessels

Question 43

what causes turbulence

Answer 43

anything that interferes with the normal flow of blood
eg a thickened heart valve, a too narrow valve (stenotic) an incompetent valve which allows the backflow of blood or a defect in the interventricular system.

Question 44

what is annulus fibrosis

Answer 44

fibrous plate that supports the valves.