Thorax prosection questions

Question 1

How many ribs are there in the dog?

Which tissues are these composed of?

Answer 1

13 ribs

Bone dorsally and cartilage ventrally

Question 2

What are the limits of the thorax?

Answer 2

Cranial - thoracic inlet
Caudal - Diaphragm 
Ventral - Sternum
Dorsal - thoracic vertebrae 
Lateral - ribs and intercostal muscles

Question 3

How many sternebrae are there in the dog and what are the names of the first and last of them?

Answer 3

8
1st = manubrium
8th = Xiphoid process

Question 4

The heart sits between ribs … and …?

Answer 4

3 and 6

Question 5

In the live animal, which rib spaces would you expect to be associated with each of the following valves: pulmonary, aortic, mitral and tricuspid?

Answer 5

Left side:
P = 3rd
A = 4th
M = 5th
Right side
T = 4th or 5th

Question 6

Which ribs contribute to the costal arch?

Answer 6

10-13

Question 7

Which dorsal structures limit the area of the lungs that can be ausculated?

Answer 7

Epaxial muscles

Question 8

Which lymph nodes would you normally palpate in the neck and thorax area in a normal dog?

Answer 8

Mandibular
Superficial cervical
Axillary
Accessory axillary

Question 9

Where would you occlude the jugular vein in order to raise it for blood sampling?

Answer 9

Base of the neck

Question 10

What is the term used for the joint between the atlas and the skull?
When would a vet want to access the space between these two bones?

Answer 10

Atlanto-occipital joint.

To sample CSF from the subarachnoid space

Question 11

Can you name the cartilages of the larynx from cranial to caudal?

Answer 11

Epiglottis, thyroid, arytenoid, cricoid

Question 12

What is the joint between the mandible and the skull called?

Answer 12

Temporomandibular joint

Question 13

What actions will contraction of the sternocephalicus muscle and brachiocephalicus muscle cause?

Answer 13

• Sternocephalicus: Movement of the head from side to side

- Brachiocephalicus: Advances the forelimb, extends shoulder, lateral movement of the head.

Question 14

Cranially each sternothyrohyoideus muscle divides into a ventromedial … and dorsolateral … component.

Answer 14

sternohyoideus

sternothyroideus

Question 15

Are the tracheal cartilage rings open on the ventral aspect or the dorsal aspect?

Answer 15

Dorsal

Question 16

From which major vessel does the common carotid arise?

Answer 16

Brachiocephalic trunk

Question 17

Which 2 muscles insert on the caudal ribcage?

Answer 17

• Rectus abdominis

- External abdominal oblique

Question 18

Which nerve arises from C5 with contributions from C6?

Answer 18

Phrenic nerve

Question 19

From which major vessel does the axillary artery arise?

Answer 19

Subclavian artery

Question 20

Which major vessel will the axillary vein drain into?

Answer 20

Subclavian vein

Question 21

Which major forelimb nerves arise from the brachial plexus?

Answer 21

Subscapular, suprascapular, musculocutaneous, axillary, radial, median and ulnar nerves

Question 22

Which organ does the phrenic nerve supply?

Answer 22

Diaphragm

Question 23

What is achieved when the phrenic nerve fires?

Answer 23

The diaphragm contracts, flattening caudally and therefore increasing the size of the thorax.
This reduced the pressure in the alveoli, resulting in inspiration

Question 24

In which direction do the internal and external intercostal muscle fibres run?

Answer 24

Internal run cranioventrally

External run caudoventrally

Question 25

What are the functions of the internal and external intercostal muscles?

Answer 25

External = respiration
Internal = active expiration

Question 26

The thoracic cavity is under negative pressure. What would happen if the pleura is ruptured?

Answer 26

• air into thorax
• collapse of lungs
• ribcage moves outwards as pressure equalises
• pressure inside pleural sac is lower than atmospheric pressure

Question 27

What differs in the thymus between young and adult animals?

Answer 27

In adults the thymic tissue is replaced by adipose tissue

Question 28

In the caudal extent of the pleural cavity you would find a recess, what is this called?

Answer 28

Costodiaphragmatic recess - where the pleura reflects from the ribs onto the diaphragm

Question 29

In the dog, what are the first two systemic branches arising from the aorta?

Answer 29

Brachiocephalic trunk

Left subclavian artery

Question 30

Name one difference between the aortic arch of the dog vs the cow.

Answer 30

L and R subclavian arteries both arise from the brachiocephalic trunk in the cow

Question 31

What does the thoracic duct contain, in life, and where does it originate and terminate?

Answer 31

• Contains lymph, called chyle when it has high conc of chylomicrons
• Runs from the cisternal chyli
• Drains into the major veins in the thoracic inlet

Question 32

Where do sympathetic fibres exit the central nervous system?

Answer 32

Thoracolumbar segments

Question 33

What are the left and right lung lobes in the dog?

Answer 33

Left = Cranial and caudal 
Right = Cranial, middle, caudal, accessory

Question 34

In which chamber of the heart do the cranial and caudal vena cavae empty?

Answer 34

Right atria

Question 35

Name one species in which there is both a left and right azygous vein

Answer 35

Ruminants and pigs

Question 36

What is the name of the fold of mediastinum in which the caudal vena cava travels to the diaphragm?

Answer 36

Plica vena cava