Thoracic Anatomy Flashcards
components of the rib cage
vertebrae, ribs, sternum
margins of the thoracic cavity
cranial: thoracic inlet
caudal: diaphragm
dorsal: thoracic vertebrae
ventral: sternum
lateral: ribs, costal cartilage, intercostal muscles
thoracic inlet
cranial entry/exit point from the thorax
- located at the level of the first thoracic vertebrae/rib and manubrium sternum
what structures pass through the thoracic inlet
longus colli muscle
esophagus
trachea
arteries/veins of the head, neck, and thoracic limbs
vagosympathetic trunk
thoracic outlet
caudal entry/exit point from the thorax
- located at the level of the last thoracic vertebrae/rib, costal arch, last sternebrae, and xiphoid process
costal arch
lower edge of the thorax formed by the bottom edge of the ribcage
what structures pass through the thoracic outlet
descending aorta
azygous vein
sympathetic trunk
cisterna chyli/thoracic duct
esophagus
dorsal and ventral vagal trunks
caudal vena cava
what makes up the thoracic viscera
lungs, heart, trachea, esophagus, vessels, nerves
what structures are most visible on the left side
aorta
L subclavian
esophagus
what structures are most visible on the right side
cranial and caudal vena cava
azygous vein
axillary artery
plica vena cava
fold of pleura that surrounds the vena cava as it exits the mediastinum
phrenic nerve
innervates the diaphragm to control breathing
bilateral - there is a R and L phrenic nerve
ID by the largest nerve running across the heart
origination of the phrenic nerve
C3, C4, C5
cervicothoracic ganglia
stellate ganglia
connected to the middle cervical ganglia via ansa subclavia fibers
ansa subclavia
nerve fibers that connects the cervicothoracic ganglia to the middle cervical ganglia
modulates sympathetic input
middle cervical ganglia
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
vagus nerve
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
vago-sympathetic trunk
joint sympathetic and parasympathetic nerves within the same sheath
run together in the cervical region
mediastinum
middle space of the pleural cavity
contains almost all thoracic structures
what thoracic structures does the mediastinum not contain
lungs
part of the caudal vena cava
phrenic nerve
why is part of the caudal vena cava not in the mediastinum
caudal vena cava exits the mediastinum surrounded by plica vena cava
what forms the mediastinum
serosal linings
in some species: mediastinum is incomplete at birth –> has persistent fenestrations
how many thoracic serous sacs are there
three
1. pericardium
2. L pleural sac
3. R pleural sac
what are the two linings of each sac
fibrous and serous
fibrous lining
outermost side of each membrane/sac
“sticky” - attaches to the heart, lung, or fibrous lining of adjacent sac
serous lining
innermost side of each membrane/sac
“smooth” to rub against each other to allow movement of organs
visceral pleura/pericardium
inside wall of the sac that is in contact with the organ
has a serous (inner) and fibrous (outer) side of the membrane
parietal pleura/pericardium
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
pleural/pericardial cavity
potential space between the serous membranes of the visceral and parietal pleura/pericardium
what do pleural sacs surround
surround each lung
pulmonary visceral pleura
visceral pleura that is in contact with the lungs
costal parietal pleura
parietal pleura that is in contact with the ribs (lateral pleural cavity)
mediastinal parietal pleura
parietal pleura that is in contact with the mediastinum (medial pleural cavity)
diaphragmatic parietal pleura
parietal pleura that is in contact with the diaphragm (caudal pleural cavity)
what are pleural sacs lined with and why
mesothelial cells
produce a small amount of fluid to lubricate and allows serous linings to slide
what does the pericardium surround
surrounds the heart
parts of the pericardium
epicardium (visceral pericardium)
parietal pericardium
lines of reflections
occur where parietal pleura reflects from one wall of the thorax to another (or to the mediastinum)
- vertebral line of reflection
- sternal line of reflection
- diaphragmatic line of reflection
vertebral line of reflection
where the costal pleura becomes mediastinal pleura (dorsally)
sternal line of reflection
where the costal pleura becomes mediastinal pleura (ventrally)
diaphragmatic line of reflection
where the costal pleura becomes diaphragmatic pleura
costomediastinal recess
potential space in the ventral pleural cavity between the costal pleura and mediastinal pleura
costodiaphragmatic recess
potential space in the caudal ventral pleural cavity between the costal pleura and diaphragmatic pleura
