Lecture 4 1/31/24

Question 1

What are the characteristics of the mediastinum?

Answer 1

-midline partition of thoracic cavity
-two serous membranes with supportive connecting tissue
-cranial, middle, and caudal parts
-caudal part is fenestrated

Question 2

What are the characteristics of the equine heart?

Answer 2

-more vertical compared to the canine heart
-medial to intercostal spaces 2 through 6
-occupies ventral 2/3 of middle mediastinum

Question 3

How does the coronary vessels of the equine differ from that of the bovine/canine?

Answer 3

-bovine and canine have both paraconal and subsinuosal branches arising from left coronary artery
-equine has paraconal branch arising from left coronary artery and subsinuosal branch arising from right coronary artery

Question 4

Where are the various valves located within the equine heart?

Answer 4

pulmonary valve: low left 3rd IC space
aortic valve: high left 4th IC space
left AV valve: low left 5th IC space
right AV valve: low right 3rd/4th IC space

Question 5

What is the single branch off the aortic arch in the equine heart?

Answer 5

brachiocephalic trunk

Question 6

What is the first branch off the equine brachiocephalic trunk?

Answer 6

left subclavian artery

Question 7

What does the equine brachiocephalic trunk terminate into?

Answer 7

-right subclavian artery
-bicarotid trunk

Question 8

Which vessels branch off the bicarotid trunk?

Answer 8

-left common carotid a.
-right common carotid a.

Question 9

Which two vessels branch off the equine costocervical trunk?

Answer 9

-dorsal scapular artery: supplies withers
-supreme intercostal artery: supplies first few intercostal spaces

Question 10

What is supplied by the deep cervical artery?

Answer 10

deep regions of the neck

Question 11

What are the characteristics of the right azygous vein?

Answer 11

-found in all species
-drains into cranial vena cava

Question 12

What are the characteristics of the left azygous vein?

Answer 12

-found in ruminants and pigs only
-drains into coronary sinus

Question 13

What are the characteristics of the thoracic duct?

Answer 13

-carries lymph from cisterna chyli to great veins cranial to the heart
-sits near left side of esophagus

Question 14

What is the stellate ganglion?

Answer 14

the combination of the cervical thoracic and middle cervical ganglia

Question 15

What is the recurrent laryngeal n.?

Answer 15

branch off the vagus n. that innervates the muscles of the larynx and keeps the airway open during respiration

Question 16

What is the importance of the left recurrent laryngeal n.?

Answer 16

-left-sided nerve loops around the back of the aortic arch before running up along trachea
-thought that heart pumping activity leads to nerve damage over time
-nerve damage can lead to unilateral atrophy of laryngeal muscles and trouble breathing

Question 17

Where are the tracheobronchial lymph nodes found?

Answer 17

at the site of tracheal bifurcation

Question 18

Where are the pulmonary lymph nodes found?

Answer 18

lying along the bronchi within the lungs

Question 19

Which structures are drained by the tracheobronchial and pulmonary lymph nodes?

Answer 19

-lungs
-trachea
-heart

Question 20

Where do the tracheobronchial and pulmonary lymph nodes drain into?

Answer 20

cranial (and sometimes middle) mediastinal lymph nodes

Question 21

What are the characteristics of the cranial mediastinal lymph nodes?

Answer 21

-drain into caudal deep cervical lymph nodes
-boundary is first rib

Question 22

What are the characteristics of the caudal mediastinal lymph nodes?

Answer 22

-very large in bovine/sausage-looking
-small in equine
-drains into tracheobronchial lymph nodes