Thorax Lectures Flashcards
what are the 5 boundaries of the thorax?
cranially = thoracic inlet (approx at level of 1st rib)
caudally = diaphragm
sides = ribs (muscle / subcutaneous tissues and skin)
dorsally = mostly vertebral column, epaxial muscles and skin
ventrally = sternum, muscles and skin
is the area of the ribs equal to the area of the lungs?
nope, some other abdominal organs are also under the ribs
what are the collective functions of thoracic muscles
-mechanical and infection protection
-thermodynamics
-hydration
-respiration (inspiration is causative effect; expiration is predominatly recoil)
-locomotion (syncarcosis for formation, union of parts by skeleton muscle)
what are the extrinsic muscles that are part of thoracic wall and involved in the synsarcosis (8)
cutaneous trunci, trapezius, rhomboideus, latissimus dorsi, serratus group of muscles, brachiocephalicus, omotransversarius, pectorals
what serratus muscle isnt really present in the dog
serratus dorsalis caudalis
what muscles do you have to remove to see the serratus dorsalis
serratus ventralis cervical and thoracic portion
origin, insertion and action of the serratus ventralis cervicus
origin = fascia serrata of the scapula
insertion = transverse processes of the last five cervical ribs
action= support of the trunk, carry trunk forward and backward, carry the shoulder forward and backward with respect to the limb
origin, insertion and action of the serratus ventralis thoracic
origin = fascia serrata of the scapula
insertion = transverse processes of the first five ribs
action = support of the trunk, carry trunk forward and backward, carry the shoulder forward and backward with respect to the limb
origin, insertion and action of the serratus dorsalis cranialis
origin = the thoracic fascia and spines of the first six to eighth thoracic vertebrae
insertion = cranial border and lateral surfaces of ribs two to ten
action = lift the ribs for inspiration
origin, insertion and action of the serratus dorsalis caudalis
origin = thoracolumbar fascia
insertion = caudal border of last three to eight ribs
action = draws the last three or more ribs caudally for inspiratoin
direction of fibers for external intercostal muscles, and action
runs craniodorsal to caudoventral
pulls ribs cranially, assists in inspiration
direction of fibers for external intercostal muscles, and action
runs caudodorsal to cranioventral
where is the transversus thoracis (parasternal) muscle located and what is its action
located inside the rib cage, from sternum to costochondral junction
pulls costal cartilage inward; assists in expiration
what are the epaxial muscles
spinalis thoracis
longissimus
iliocostalis thoracis
what does the retractor costae do, where is it
keeps ribs in place, looks like it is on the start of the lumbar spine and last rib?
where is the rectus thoracis
on the first to fourth rib
where does the levator costae muscles run, what do they do
runs from the tip of the transverse process of vertebrae cranially to upper aspect of rib caudally
they anchor the rib to the next vertebrae
thoracic wall nerves - what are they (4) and what are they part of
dorsal cutaneous nerves = dorsal primary branches of spinal nerves
lateral cutaneous nerves = ventral primary branches of spinal nerves
lateral thoracic nerve = contribution from brachial plexus
intercostobrachial = some part of brachial plexus and some part of intercostals
what is behind each rib and where do you never cut
intercostal vein, artery and nerve
always cut cranial to the rib, never caudal or else you will cut into them
what is the pleural cavity and pleura
pleural cavity is the body cavity that holds the lungs
pleura is the serous membrane that folds onto itself to form a two layered membrane
what does the costal parietal pleura cover
elevated thoracic wall
what does the diaphagmatic parietal pleura cover
diaphragm
what does the mediastinal parietal pleura cover
mediasteinum, including heart
what does the visceral (pulmonary) pleura cover
caudal, middle, cranial lobes of the right lung
what is revealed when the right lung is reflected
phrenic nerve, thymus, azygos vein, internal thoracic artery
what species have a left azygous vein
ruminants
what animal doesnt have a pleural sac
elephants
what does visceral vs parietal pertain to
visceral is pertaining to the organs
parietal is pertaining to the wall
why is there a “danger area” past the first rib
because the pleural sacs can extend cranially past the 1st rib so its not fully protected, be careful if cutting into this area as it can cause air to enter and possibly collapse lung
what is the parietal pleura divided into
costal pleura, mediastinal pleura, diaphragmatic pleura,
what is the importance of the costodiaphragmatic recess
its the space the lungs can use, but dont in normal circumstances
what is the line of pleural reflection
where the diaphragmatic portion of pleura connects with costal portion of pleura (i think this is where the recess is?)
where is the cardiac notch of the left lung in horses
3 through 6 intercostal spaces
line of pleural reflection in horses
extends along the 8th and 9th costal cartilages, crosses the costochondral junction of the 9th rib and passes caudodorsally in a gentle curve at a progressively increasing distance from the costocondral junctions of the succeeding ribs
it reaches the middle of the cranial border of the last rib and turns craniomedially ending at the vertebral end of the last (17th) intercostal space
bovine cardiac notch
ventral one-third of the 3rd and 4th intercostal space
bovine line of pleural reflection
extends from the knee of the 7th or 8th rib, through a point ventral to the middle of the 11th rib to the angle of the last rib at the lateral border of the muscles at the back
what is the diaphragm
its a dome shaped musculo-tendinous separation between the thoracic and abdominal cavities
what are the parts of the diaphragm
right and left costal parts
sternal part
right and left crura (tendinous)
central tendon
what are the openings of the diaphragm
aortic hiatus
esophogeal hiatus
caval foramen
lesser apertures (for nerves like the vagus nerve)
where do the crura attach
to the ventral surfaces of the bodies of the third and fourth lumbar vertebrae
what is the most susceptible organ in trauma cases
diaphragm
thoracic duct - what does it carry and where is it located
carries chyle, a liquid containing both lymph and emulsified fats, rather than pure lymph
located ONLY ON THE LEFT SIDE. extends fromthe abdomen, crosses diaphragm through aortic hiatus and then empties into jugular vein or the cranial vena cava near the heart
important nerves of the thorax
vagus, right recurrent laryngeal, phrenic, vagosympathetic trunk, sympathetic trunk, cervicothoracic ganglion
where does the vagus nerve split and into what
after crossing the heart splits into dorsal and ventral branches
what does the phrenic nerve innervate
diaphragm
recurrent laryngeal nerves (left and right)
left one makes a loop around the aortic arch and finally innervates laryngeal muscles (lateral cricoarytenoid)
**if this is damaged it can cause roaring in the horse
right one curves around the right subclavian artery
what is the vagosympathetic trunk
combined vagus and sympathetic trunk in the neck collectively, they separate at the thoracic inlet
sympathetic trunk (chain)
cervicothoracic ganglion
sympathetic trunk is the series of connected ganglia on either side of the vertebral column
cervicothoracic ganglion = an important sympathetic ganglion located close to the head of the first rib; sympathetic innervation to the head passes through this ganglion (also call stellate or star ganglion)
blood supply to the thoracic wall - what are the segmental intercostal arteries and segmental intercostal veins and where do they go
arteries:
-dorsal intercostals = directly off aorta
-ventral intercostals = off the internal thoracic
veins:
-dorsal veins to azygous vein (paired in ruminants, only on R side otherwise)
-ventral veins to internal thoracic vein
what vessels anastamose and where
Dorsal intercostals directly off the aorta and the ventral intercostals come off of the internal thoracic but they anastomose (meet together) somewhere in the middle of the ribs
what does the trachea do and where is it
passes the air from the larynx to the lungs and vice versa
it starts from the cricoid cartilage (larynx) and ends at the roots of the lungs where it bifurcates (called “carina”; dorsal to the heart, by 4th-6th ribs)
structure of the trachea
composed of incomplete cartilage rings (open dorsally)
trachealis muscle is attached to the inside cartilages and covers the gap
has some glands that secrete mucus (has cilia that sweeps the tiny particles and mucus towards the larynx)
trachea branching
trachea –> primary bronchi (goes to each lung lobe) –> segmental bronchi (secondary and tertiary) –> broncioles (no cartilage) –> alveoli (gas exhange)
respiratory surface = sum of the alveoli
lung lobes of the dog
left lung = cranial lobe (cranial and caudal part), caudal lobe
right lung = cranial lobe, middle lobe, caudal lobe, accessory lobe
horse lung lobe differences
no middle lobe on the right lung
on the left, there are no cranial and caudal parts of the cranial lobe. its all one
cow lung lobe differences
the right cranial lobe has cranial and caudal parts
horse aortic arch
one branch out of the aorta is the brachiocephalic trunk.
then branches into left subclavian, right subclavian, and above that is thr bicarotid trunk that splits into the common carotids (2)
dog aortic arch
two branches off the aorta
1 = left subclavian
2 = brachiocephalic trunks that goes into the right subclavian and common carotids cranially
what does the left subclavian artery turn into
axillary artery
what arteries branch off of the left subclavian in dogs
vertebral artery
costocervical trunk
internal thoracic artery
superficial cervical artery
branching of left subclavian in horse
vertebral, deep cervical, costocervical trunk, superficial cervical, internal thoracic
and left subclavian turns into axillary
branching in sheep
brachiocephalic trunk turns into left subclavian… branching is costocervical trunk, superficial cervical, internal thoracic, vertebral and the left subclavian turns into axillary
extent of the heart within the thoracic cavity for different species, and how it sits in situ
ruminants = 2nd intercostal space to 5th IS
horse = 2nd IS to 6th IS
dog = 3rd rib to 6th IS
cat = 3rd IS to 6-7th rib
in situ the right ventricle sits more cranially
pericardium - types and consequences of fluid accumulation in it
fibrous pericardium (strength)
partietal and visceral pericardium (liquor pericardii)
consequence is cardiac tamponade and pericarditis
heart ligaments - names, location and what they do
steropericardial ligament; between heart (pericardium) and sternum. it maintains the apex of the pericardial sac in relatively fixed position near the sternum
phrenicopericardial ligament: between the heart and the diaphragm. it maintains the apex of the pericardial sac in relatively fixed position with the diaphragm
what is an auricle, what does it have and what does it do
its a blind pocket of each atrium, is has pectinate muscles
adds to the size of the atrium and decreases the turbulence
what is a moderator band, and what does it do
also called septomarginal band or trabeculae
its a band between the septum and the outer wall of the ventricle (right side I think?)
conducting pulses
what is the plica vena cava
very thin membrane connecting vena cava to diaphragm
what is the name for the ligamentum arteriosum in fetus’
ductus anteriosum
does the tricuspid or bicuspid valve come first? where is it
tricuspid, right atrium to right ventricle
location of the heart, angles in different species
middle mediastinum, mostly (60%) at the left side. has base (dorsal) and apex (ventral)
cat = ~30 degrees
dog = ~45 degrees
cow = ~75 degrees
horse = ~90 degrees
what is a puncta
a point or small area
what are the punctas, where are they and what can you hear in each
EQUINE
-puncta maxima
- right AV valve (tricuspid). its on the right side, low in 3rd or 4th IC space (THIS IS ONLY ON THE RIGHT SIDE….. THE OTHERS ARE ON THE LEFT)
- aortic valve. high in 4th IC space below horizontal line through shoulder joint
- left AV valve (bicuspid). low in 5th IC space caudodorsal to olecranon
- pulmonary valve. low in IC space 3 above costochondral junction
what is the order to hear the different valves with a stethescope
PAM
pulmonary - 3rd low
aortic - 4th high
mitral - 5th low
anatomical zones to differentiate between heart murmurs - what for the left vs right
the left chest wall is typically divided with respect to point of maximum intensity into two positions:
-left heart base (includes both the pulmonic valve and aortic valve areas)
-left heart apex (mitral value area)
the right chest wall is typically divided with respect to point of maximum intensity into two positions:
-mid heart (tricuspid valve area)
-sternal border (typical of a ventral septal defect
BOVINE punctas
aortic valve - high in 4th IC space below horizontal line through shoulder joint
pulmonary valve - low in IC space 3 above costochondral junction
left AV valve (bicuspid). low in 4th IC space dorsal to olecranon
right AV valve (tricuspid). its on the right side, low in 3rd or 4th IC space (THIS IS ONLY ON THE RIGHT SIDE….. THE OTHERS ARE ON THE LEFT)
what is a common cause of sudden death is horses from
cordae tendinae that arent working properly
what do cordae tendinae come off of
papillary muscles (its an extension of heart muscle, finger like projections)
coronary arteries - where do they arise from and what do they turn into
arise at the beginning of the aorta, just proximal to aortic valve
left coronary artery (bigger one); bifurcates into paraconal (descending) and circumflex (encircling) heart
right coronary artery; gives rise to subsinousal branch
how does the blood get nutrition from the heart
aortic sinuses
coronary veins - what does cardiac vein return, termination of main coronary vein
cardiac veins returns deoxygenated blood to the right atrium as a single vessel (great cardiac vein)
the termination of the main coronary vein (great cardiac vein) in the right atrium is called the coronary sinus
cardiac innervation - what is included and where does it come from, beating rate
receives both sympathetic and parasympathetic fibers
-sympathetic from sympathetic trunk = increases heart rate
-parasympathetic from vagus nerve (CNX) = slows heart rate
fossa ovalis - what is it, what connects
its an open hole (foramen ovale) in the fetus
connects right and left sides, similar to the function of the ductus arteriosus
what is a ventral septal defect, where does it occur and what happens
VSD is a hole in the heart, its a congenital defect
the hole occurs in the interventricular septum
this allows blood to pass from the left to the right side of the heart. the oxygen rich blood then gets pumped back to the lungs instead of out to the body causing the heart to work much harder
what is the tetralogy of fallot
VSD, pulmonary stenosis, hypertrophy of right ventricle and overriding aorta all happen at once
