Thoracic Anatomy

Question 1

components of the rib cage

Answer 1

vertebrae, ribs, sternum

Question 2

margins of the thoracic cavity

Answer 2

cranial: thoracic inlet
caudal: diaphragm
dorsal: thoracic vertebrae
ventral: sternum
lateral: ribs, costal cartilage, intercostal muscles

Question 3

thoracic inlet

Answer 3

cranial entry/exit point from the thorax
- located at the level of the first thoracic vertebrae/rib and manubrium sternum

Question 4

what structures pass through the thoracic inlet

Answer 4

longus colli muscle
esophagus
trachea
arteries/veins of the head, neck, and thoracic limbs
vagosympathetic trunk

Question 5

thoracic outlet

Answer 5

caudal entry/exit point from the thorax
- located at the level of the last thoracic vertebrae/rib, costal arch, last sternebrae, and xiphoid process

Question 6

costal arch

Answer 6

lower edge of the thorax formed by the bottom edge of the ribcage

Question 7

what structures pass through the thoracic outlet

Answer 7

descending aorta
azygous vein
sympathetic trunk
cisterna chyli/thoracic duct
esophagus
dorsal and ventral vagal trunks
caudal vena cava

Question 8

what makes up the thoracic viscera

Answer 8

lungs, heart, trachea, esophagus, vessels, nerves

Question 9

what structures are most visible on the left side

Answer 9

aorta
L subclavian
esophagus

Question 10

what structures are most visible on the right side

Answer 10

cranial and caudal vena cava
azygous vein
axillary artery

Question 11

plica vena cava

Answer 11

fold of pleura that surrounds the vena cava as it exits the mediastinum

Question 12

phrenic nerve

Answer 12

innervates the diaphragm to control breathing

bilateral - there is a R and L phrenic nerve

ID by the largest nerve running across the heart

Question 13

origination of the phrenic nerve

Answer 13

C3, C4, C5

Question 14

cervicothoracic ganglia

Answer 14

stellate ganglia

connected to the middle cervical ganglia via ansa subclavia fibers

Question 15

ansa subclavia

Answer 15

nerve fibers that connects the cervicothoracic ganglia to the middle cervical ganglia

modulates sympathetic input

Question 16

middle cervical ganglia

Answer 16

sympathetic ganglia

origination point of the vagosympathetic trunk (runs cranially)

sympathetic trunk originates from spinal cord –> runs cranially to middle cervical ganglia –> vago-sympathetic trunk to the head

vagus nerve originates from brainstem –> runs caudally in vago-sympathetic trunk to middle cervical ganglia –> runs caudally into abdomen as dorsal and ventral branches

Question 17

vagus nerve

Answer 17

parasympathetic innervation of the heart, lungs, and upper abdominal viscera

bilateral - L and R

branches from the middle cervical ganglia into dorsal and ventral branches

Question 18

vago-sympathetic trunk

Answer 18

joint sympathetic and parasympathetic nerves within the same sheath

run together in the cervical region

Question 19

mediastinum

Answer 19

middle space of the pleural cavity

contains almost all thoracic structures

Question 20

what thoracic structures does the mediastinum not contain

Answer 20

lungs
part of the caudal vena cava
phrenic nerve

Question 21

why is part of the caudal vena cava not in the mediastinum

Answer 21

caudal vena cava exits the mediastinum surrounded by plica vena cava

Question 22

what forms the mediastinum

Answer 22

serosal linings

in some species: mediastinum is incomplete at birth –> has persistent fenestrations

Question 23

how many thoracic serous sacs are there

Answer 23

three
1. pericardium
2. L pleural sac
3. R pleural sac

Question 24

what are the two linings of each sac

Answer 24

fibrous and serous

Question 25

fibrous lining

Answer 25

outermost side of each membrane/sac "sticky" - attaches to the heart, lung, or fibrous lining of adjacent sac

Question 26

serous lining

Answer 26

innermost side of each membrane/sac "smooth" to rub against each other to allow movement of organs

Question 27

visceral pleura/pericardium

Answer 27

inside wall of the sac that is in contact with the organ has a serous (inner) and fibrous (outer) side of the membrane

Question 28

parietal pleura/pericardium

Answer 28

outside wall of the sac that is in contact with adjacent sacs or body wall has a serous (inner) and fibrous (outer) side of the membrane

Question 29

pleural/pericardial cavity

Answer 29

potential space between the serous membranes of the visceral and parietal pleura/pericardium

Question 30

what do pleural sacs surround

Answer 30

surround each lung

Question 31

pulmonary visceral pleura

Answer 31

visceral pleura that is in contact with the lungs

Question 32

costal parietal pleura

Answer 32

parietal pleura that is in contact with the ribs (lateral pleural cavity)

Question 33

mediastinal parietal pleura

Answer 33

parietal pleura that is in contact with the mediastinum (medial pleural cavity)

Question 34

diaphragmatic parietal pleura

Answer 34

parietal pleura that is in contact with the diaphragm (caudal pleural cavity)

Question 35

what are pleural sacs lined with and why

Answer 35

mesothelial cells produce a small amount of fluid to lubricate and allows serous linings to slide

Question 36

what does the pericardium surround

Answer 36

surrounds the heart

Question 37

parts of the pericardium

Answer 37

epicardium (visceral pericardium) parietal pericardium

Question 38

lines of reflections

Answer 38

occur where parietal pleura reflects from one wall of the thorax to another (or to the mediastinum) 1. vertebral line of reflection 2. sternal line of reflection 3. diaphragmatic line of reflection

Question 39

vertebral line of reflection

Answer 39

where the costal pleura becomes mediastinal pleura (dorsally)

Question 40

sternal line of reflection

Answer 40

where the costal pleura becomes mediastinal pleura (ventrally)

Question 41

diaphragmatic line of reflection

Answer 41

where the costal pleura becomes diaphragmatic pleura

Question 42

costomediastinal recess

Answer 42

potential space in the ventral pleural cavity between the costal pleura and mediastinal pleura

Question 43

costodiaphragmatic recess

Answer 43

potential space in the caudal ventral pleural cavity between the costal pleura and diaphragmatic pleura