Exam 2: Lecture 13: Horse Thoracic Cavity Flashcards
What is different about the diaphragm in horses than in dogs?
-Diaphragm in horses is a very oblique muscle
-Diaphragm is between the very delicate lungs & the very healthy digestive organs (so the digestive organs could put pressure on the lungs)
What part of the diaphragm is represented by “C” and what does it do?
-Costal parts
-Attached to the cartilages of the ribs
What part of the diaphragm is represented by “S” and what does it do?
-Sternal part
-Dorsal surface of xiphoid cartilage
What part of the diaphragm is represented by “L” and what does it do?
-Lumbar parts
-Right & left crura: lumbar vertebrae & ventral longitudinal ligament
Where is the aortic hiatus located on the diaphragm?
-Between the two crura
Where is the esophageal hiatus located on the diaphragm?
-Perforates the right crus near its junction with the central tendon
Where is the cava foramen located on the diaphragm?
-Courses through central tendon toward the right side
How is the mediastinum divided in horses?
-Divided into cranial and caudal mediastinum (both touch each other)
What is important about the caudal mediastinum?
-It is fenestrated in horses
What is this?
-Caudal mediastinum
What is the cupula pleura?
-Cranial extend of the pleural cavity
-Extends cranial to the first rib, is larger on the right side
What is the costodiaphragmatic recess?
-Space not occupied by lungs even when they are fully inflated
What is the capacity (in liters) of the horse lungs?
-55 liters
What are the lobes of the left and right lungs?
-Left lung = cranial & caudal
-Right lung = cranial, caudal & accessory
What is indicated by the star (both blue arrows)?
-Cardiac notch of the right lung
What is the hilus of the lung?
-Wedge-shaped region in the middle of each lung
-Where the main structures of the lung enter & exit (like bronchi, pulmonary arteries, veins, nerves, and lymphatic)
What is indicated by the arrow (dashed blue lines)?
-Impression of the caudal vena cava
What side is the accessory lobe on?
-Right lung
-Comes from the right side, but has a tendency to lay on the left if we draw a line dividing the lungs in half
What is important about the cardiac notch on the left lung?
-It is much larger than the right
-Takes up 3 intercostal spaces (3rd, 4th, 5th)
-(b/c apex of the heart is more oriented on the left)
What is different about the equine trachea compared to dogs?
-Tracheal muscles are attached internally (to the internal walls of the trachea)
Where is the carina located?
-Located at the level of T4-T5
What is the sympathetic effect on the trachea?
-Relax everything to make it more expanded
What is indicated by the yellow arrow?
-Pulmonary ligament
What are the borders of the lungs?
-Dorsal region of the 16th rib
-Middle of the 11th rib
-Costochondral junction of the 6th rib
What are the borders to auscultate the lungs in a horse? (Where do you want to put your stethoscope)
-Caudal angle of scapula
-Dorsal end of the 16th rib
-Point of elbow (olecranon)
How much does an equine heart weigh?
-Around 0.7% of the horse weight
-Average adult horse has a 3.6 kg (7.9 lb) heart
The average pulse is _____ bpm in a mature horse, but it can reach more than _____ bpm during maximum exertion
-Pulse is 28-45 bpm, can each more than 250 bpm
The left face of the heart is also called the
-Auricular face
The right face of the heart is also called the
-Atrial face
Which side of the heart?
-Auricular face (left)
Which side of the heart?
-Atrial face (right)
99% of venous blood that is returning through the heart goes through what structure?
-Coronary sinus
What is an important structure of the heart that should be checked during necropsy?
-Fossa ovalis
What artery of the heart is much larger in horses than in dogs?
-Right coronary artery
What is the top arrow indicating?
-Coronary sinus
What is the bottom arrow indicating?
-Great cardiac vein
What is indicated by the arrow on the left?
-Coronary sinus
What is indicated by the pink circle?
-The opening of the coronary sinus into the right atrium
What is indicated by the arrow on the right?
-Middle cardiac vein
What does the middle cardiac vein join?
-Joins coronary sinus to open into the right atrium
Where would you auscultate the pulmonary valve?
-Left side, 3rd or 4th intercostal space, craniodorsal to the olecranon
Where would you auscultate the aortic valve?
-Left side, 4th intercostal space, ventral to the shoulder joint
Where would you auscultate the left atrioventricular valve?
-Left side, 5th intercostal space, caudodorsal to the olecranon
Where would you auscultate the right atrioventricular valve?
-Right side, 4th intercostal space, caudodorsal to the olecranon
What is different between horses and dogs when talking about the branching of the aortic arch?
-Horses only have one big branch (the brachiocephalic trunk)
What is indicated by the blue star?
-Brachiocephalic trunk
What is indicated by the blue star?
-Left subclavian a.
What is indicated by the blue star?
-Right subclavian a.
What is indicated by the blue star?
-Bicarotid trunk
Another difference between horses than dogs (this is not in dogs)
What is indicated by the blue star?
-Left common carotid a.
What is indicated by the blue star?
-Right common carotid a.
What is the first branch off the left subclavian a?
-Costocervical trunk
What is the artery indicated by the star?
-Costocervial trunk
What is important about the costocervical trunk?
-Will go up & provide branches to thoracic limb and to at least 4 intercostal arteries
What is the second branch off the left subclavian a?
-Deep cervical a.
What artery is indicated by the blue star?
-Deep cervical a.
Where does the deep cervical a. come form and where is it located?
-Comes from costocervical trunk on the right side subclavian a. on the left side
-Runs at level of T1 and goes immediately deep & medial in the neck -> very close to nuchal ligament
What does the deep cervical a. supply?
-Courses to head to supply cervical structures & musculature in the caudal neck region
What artery and vein needs to be carefully avoided in small horses?
-Deep cervical a. & v.
What artery is indicated by the blue star?
-Vertebral a.
What is the third branch off the left subclavian a.?
-Vertebral a.
What artery courses cranially through the transverse foramen of cervical vertebrae and courses through the alar foramen & lateral vertebral foramen of the atlas and enters the vertebral canal?
-Vertebral a.
What artery and vein is shown here?
-Vertebral a. & v.
What artery lives in the area known as the jugular fossa and runs just past the thoracic inlet to the outside?
-Superficial cervical a.
What artery is indicated by the blue star?
-Superficial cervical a.
What does the superficial cervical a. supply?
-Supplies structures in the craniolateral shoulder region
What artery is indicated by the blue star?
-Internal thoracic a.
What are the branches of the internal thoracic a.?
-Ventral intercostal aa. (supply ventral part of thoracic wall)
-Cranial epigastric a. (supplies ventral abdominal wall)
What artery is indicated by the blue star?
-Axillary a.
What artery is indicated by the blue arrow? (and what does it branch into?)
-Bronchoesophageal a. (branches into bronchial a. & esophageal a.)
What artery is indicated by the blue star?
-Descending thoracic aorta
What artery is indicated by the blue star?
-Dorsal intercostal aa.
What is different between the dog and cat venous branching near the cranial vena cava?
-Dog = both brachiocephalic veins join together to form the cranial vena cava
-Horse = have bijugular trunk, then 2 subclavian vv., then cranial vena cava
What thorax view can you see veins?
-Right
What thorax view can you see arteries?
-Left
What vein is indicated by the blue star?
-Caudal vena cava
What vein is indicated by the blue star?
-Cranial vena cava
What vein is indicated by the blue star?
-Superficial cervical v.
What vein is indicated by the blue star?
-Vertebral v.
What vein is indicated by the blue star?
-Costocervical v.
What vein is indicated by the blue star?
-Right azygous v.
What part of the GVE sympathetic nervous system is indicated by the blue star?
-Ansa subclavia
What part of the GVE sympathetic nervous system is indicated by the blue star?
-Cervicothoracic ganglion
What part of the GVE sympathetic nervous system is indicated by the blue star?
-Vertebral n.
What part of the GVE sympathetic nervous system is indicated by the blue star?
-VagoSympathetic trunk
What part of the GVE sympathetic nervous system is indicated by the blue star?
-Middle cervical ganglion
What part of the GVE sympathetic nervous system is indicated by the blue star?
-Rami communicantes
What part of the GVE sympathetic nervous system is indicated by the blue star?
-Sympathetic trunk
What part of the GVE sympathetic nervous system is indicated by the blue star?
-Major splanchnic n.
What part of the GVE parasympathetic nervous system is indicated by the blue star?
-Recurrent laryngeal n.
What part of the GVE parasympathetic nervous system is indicated by the blue star?
-VagoSympathetic trunk
What part of the GVE parasympathetic nervous system is indicated by the blue star?
-Vagus n.
What part of the GVE parasympathetic nervous system is indicated by the blue star?
-Recurrent laryngeal n.
What part of the GVE parasympathetic nervous system is indicated by the blue star?
-Ventral vagal branch
What part of the GVE parasympathetic nervous system is indicated by the blue star?
-Ventral vagal trunk
What part of the GVE parasympathetic nervous system is indicated by the blue star?
-Dorsal vagal trunk
What part of the GVE parasympathetic nervous system is indicated by the blue star?
-Dorsal vagal branch
