Horse Thorax Lecture

Question 1

How many pairs of ribs does a horse have?

-Describe orientation

Answer 1

18 pairs of ribs that form a caudally prolonged rib cage.

-Last rib is close to coxal tuber

Question 2

How is scapula orientated w/ribs?

Answer 2

Caudal angle of scapula lies over upper end of the 7th rib

Question 3

Where is the point of the elbow on the horse?

Answer 3

Lowest part of the 5th rib or 5th intercostal space

Question 4

What can restrict clinical access to the cranial part of the thorax?

Answer 4

Triangle between scapula and humerus that is occupied by the triceps muscle.

Question 5

Common sites for thoracocentesis on horse?

-What should you be careful of?

Answer 5

Lower=7th IC space
Upper=13th IC space

Careful to avoid spur v around 7th IC space

Question 6

What is the vertex of the thorax?

Answer 6

6th IC space of rib

Question 7

What does the line of pleural reflection show clinical access to?

Answer 7

Craniodorsal=pleural cavity

Caudoventral=peritoneal cavity

Question 8

T/F Diaphragm of horse is less oblique thatn in other domestic species?

Answer 8

F

More obilque

Question 9

Define line of pleural reflection

Answer 9

Where the pleura that covers the diaphragm reflects on itself to become the costal pleura that lines the ribs

Question 10

Ribs associated w/line of pleural reflection

Answer 10

Starts at 8th and 9th costochondral jxn and continues caudodorsally to 17th rib.

Question 11

Importance of line of pleural reflection

-When aspirating, where should needle be placed?

Answer 11

Landmark separating pleaural and peritoneal cavities. When aspirating pleural fluids for clinical evaluation, the needle should be placed cranial to line of pleural reflection

Question 12

Define costodiaphragmatic recess

Answer 12

Craniodorsal to the line of pleural reflection, diaphragmatic and costal pleura are separated by this potential space

Question 13

Basal border of the lung for L and R

Answer 13

Ribs

6,11,16

Question 14

Cardiac Notch for L and R

Answer 14

L=Ribs 3-6

R= 3rd rib and 4th IC space

Question 15

Parts of the left lung

Parts of right lung

Answer 15

L=Cranial and caudal lobe

R=Cranial, caudal, accessory

Question 16

When lung is moderately expanded, the base of each lung reaches

Answer 16

To a line passing through the upper part of the 16th rib, middle of 11th rib, and costochondral jxn of 6th rib

Question 17

Which lung allows for extensive contact w/chest wall and why?

Answer 17

L due to deep cardiac notch which allows pericardium extensive contact w/chest wall btw 3rd-6th ribs.

Question 18

Where is pleural tap done most safely and when?

Answer 18

Lower part of 7th IC space, ventral to margin of lung

-Introduce needle during full expiration

Question 19

Define cupula pleurae

Answer 19

Cranial outpouching of right pleural sac beyond first rib and is vulnerable to penetrating wounds

Question 20

Landmarks for auscultation of the lungs

Answer 20

Triangle defined by caudal angle of scapula (7th rib), point of elbow (5th rib), and upper end of the 16th rib.

Cranial and dorsal sides of the triangle are more or less straight but the caudoventral side, hypotenuse, is slightly bowed

Question 21

Describe mediastinum of thorax

Answer 21

Thin and delicate and fenestrated at caudal portion

Question 22

What can sits in the cephalic groove and easily damaged if horse runs into fence

Answer 22

Cephalic v and deltoid branch of superficial cervical a

Question 23

What goes through aortic hiatus

Answer 23

Aorta
R azygous v
Thoracic duct

Question 24

What goes through esophageal hiatus

Answer 24

Vagosympathetic trunk

Esophagus

Question 25

What goes through caval foramen

Answer 25

Caudal vena cava

Question 26

What are the bony boundaries of the thoracic inlet

Answer 26

1st rib (lateral)
Manubrium (ventral)
Body of T1 (dorsal)

Question 27

Give important structures that pass through thoracic inlet

Answer 27

Trachea
Esophagus
Common carotid a
External jugular v
Tracheal ducts
Vagosympathetic trunks
Recurrent larynegel n
phrenic n

Question 28

The heart is attached to sternum via

Answer 28

Sternopericardiac ligament

Question 29

Left side heart sounds

Answer 29

Pulmonary valve- low 3rd IC space
Aortic valve- high 4th IC space
Left AV valve- low 3rd IC space

Question 30

Right side heart sounds

Answer 30

Right AV valve- 3rd and 4th IC space