Thoracic Wall and Pleura Flashcards
what are the boundaries of the thoracic cage?
- thoracic vertebrae
- ribs and intercostal m.
- sternum
- thoracic outlet
what is the thoracic inlet?
- T1 vertebra and longus colli m.
- first pair ribs
- manubrium
what structures pass through the thoracic inlet?
- esophagus
- trachea
- external jugular vv.
- common carotid aa.
- vagosympathetic trunks
- recurrent laryngeal nn.
- roots of phrenic nn.
what are the thoracic outlet boundaries?
- last thoracic vertebrae
- last pair of ribs and costal arch
- xiphoid
closed by the diaphragm
which intercostal muscles help with inspiration?
- external intercostal muscles
which intercostal muscles help with expiration?
- internal intercostal mm.
which direction do external intercostal mm. run?
- caudalventral
which direction do internal intercostal mm. run?
cranialventral
where are the external intercostal mm located, insertion/origin, action?
- ICS up to CCJ
- insert on cranial rib, origin on caudal rib
- inspiratory
where are the internal intercostal mm., origin/insertion, action?
- ICS up to sternum
- origin on cranial rib, insertion on caudal rib
- expiratory
what are all of the inspiratory muscles?
- external intercostal mm
- scalenus m.
- diaphragm
- rectus thoracis
- serratus dorsalis cranialis m.
- all fibers go caudoventral to drag ribs cranial, besides diaphragm which retracts caudally
what are the expiratory muscles?
- internal intercostal mm.
- serratus dorsalis caudalis m. (not clinically important)
- transversus thoracis
- abdominal muscles also aid in expiration
What is 2?
- serratus doralis cranialis
what is 3?
scalenus
what is 4?
rectus thoracis
what is 1?
external intercostal mm.
what is 1?
internal intercostal mm.
what is 3?
- transversus thoracis m
what are the attachments of the inspiratory mm?
- muscle fiber direction: caudoventral
- insertion on ribs is caudoventral to origin
what is the action of inspiratory mm?
- pull ribs cranialdorsal
- widen thoracic cavity
what is the innervation of the inspiratory and expiratory mm?
ventral branches of thoracic spinal (intercostal) nn.
what are the attachments for expiratory mm?
- fibers run cranioventral from cranial border of ribs to insert on caudal border of rib in front
what is action of expiratory muscles?
act to decrease volume within thoracic cavity by drawing ribs caudally
what is the clinical significance of intercostal V.A.N.?
- they run in the ICS caudal to each rib, so only insert any needle in middle of ICS because ventrally at cartilage also have a cranial portion of artery
what vein do dorsal intercostal veins drain into?
azygous v.
what vein do ventral intercostal veins drain into?
- internal thoracic v.
how do you properly do an intercostal nerve block?
- block a min of two to three adjacent nerves due to overlapping nerve supply (cranial and caudal to incision site)
what is the endothoracic fascia?
- connective tissue lining thoracic wall outside parietal pleura
- forms C.T. of mediastinum and surrounds nerves, vessels, and other structures within mediastinum
- in middle mediastinum becomes more dense to form fibrous pericardium around heart
what is the clinical important of endothoracic fascia?
- continuous with deep fascia of neck so an infection in neck could spread to thoracic cavity
what innervates the diaphragm?
phrenic nerve (C7, C6, and C5)
what body parts are adjacent to diaphragm cranially?
- lungs, thoracic wall, and heart
what body parts adjacent to diaphragm caudally?
- liver and stomach
what is the most cranial part of diaphragm?
cupula
what are the parts of the diaphragm?
- tendinous center (V-shaped)
- muscle (periphery) - lumbar (R&L cura), costal, sternal
what are the openings in the diaphragm called?
- aortic hiatus
- esophageal hiatus
- caval foramen
what goes through the aortic hiatus?
- aorta, azygous v., thoracic duct
what goes through the esophageal hiatus?
- esophagus, ventral and dorsal vagal trunks
what runs through the caval foramen?
- caudal vena cava
what part is the top green blank?
lumbar part (R and L crura aka crus single)
what is the top pink blank on right side of picture (not anatomically)?
- aortic hiatus
what is the bottom pink blank on right side (not anatomically)?
esophageal hiatus
what is the left pink blank (not anatomically)?
caval foramen (in tendinous center)
what part is the top green blank on left pointing?
central tendon
what part is the bottom green blank?
- sternal part
what is the green blank in the middle on left side (not body)?
costal part
what occurs in traumatic diaphragmatic rupture?
- usually occurs in dog and cats after car accident, usually involves costal part and has a high mortality
what is a hiatal hernia?
- stomach prolapses into thoracic cavity (congenital or acquired)w
where is the pleura?
thorax
where is the pericardium?
surrounding heart
where is the peritoneum?
abdominal and pelvic cavities
where is the vaginal tunic?
surrounds testicles and scrotum
where is the visceral pleura?
covers lungs
where is the parietal pleura?
- costal pleura: lines ribs and intercostal muscles
- diaphragmatic pleura: covers diaphragm
where is mediastinal pleura?
covers mediastinum aka space between lungs
where is pericardial pleura?
part mediastinal pleura on either side of pericardium
what is special about the mediastinal pleura?
- caudal mediastinal pleurae of left and right ventral to esophagus are fused (can communicate)
- pneumothorax of one lung may lead to collapse of other
- fragile in horse, dog, cat, and sheep
- substantial in ox
what is special about pleural cupulae?
- cup-shaped bubbles of pleura at cranial extent of each lung, protrude a short distance through thoracic inlet
- forms due to parietal pleurae extending further than visceral pleura
- can be injured in penetrating wounds resulting in pneumothorax and lung collapse
what is special about pleural cupulae?
- cup-shaped bubbles of pleura at cranial extent of each lung, protrude a short distance through thoracic inlet
- forms due to parietal pleurae extending further than visceral pleura
- can be injured in penetrating wounds resulting in pneumothorax and lung collapse
where is the pulmonary ligament?
- between caudal lung lobe and caudal end of hilus
how does pulmonary ligament form?
- double fold of pleurae where mediastinal pleura reflects to become pulmonary pleura
what is the plica venae cavae?
- fold of mediastinal pleura on right side surrounds caudal vena cava and right phrenic n. extending into diaphragm
what is the mediastinal recess?
- small pleural space medial to plica venae cavae
- occupied by accessory lobe
what are the contents of cranial mediastinum?
- dorsal: esophagus, trachea, great vessels (brachiocephalic trunk and cranial vena cava) and their branches
- middle and ventral: thymus, internal thoracic aa and vv, cranial mediastinal lymph nodes
what is in the middle mediastinum?
- dorsal: esophagus, tracheal bifurcation, root of lung, tracheobronchial lymph nodes, aortic arch
- middle and ventral: heart and pericardium, folds of pleura
what is in the caudal mediastinum?
- dorsal: esophagus, aorta, R azygous v.
- middle: caudal vena cava
- ventral: potential space between layers of pleura
what is line of pleural reflection?
- costal pleura reflects onto diaphragm forming costodiaphragmatic recess
- goes from 8th CC to last rib
what is important about costodiaphragmatic recess?
- safe area for thoracic puncture
what is important about superficial thoracic “spur” vein?
- good landmark to denote CCJ
- insert needle above vein and in middle of ICS
what is hydrothorax?
- excess serous fluid in pleural cavity
what is haemothorax?
- excess blood in cavity
what is pyothorax?
- pus in pleural cavity
what is chylothorax?
- chyle in pleural cavity due to ruptured thoracic duct
what is pneumothorax?
- air in pleural cavity
- externally: penetrating injury
- internally: lung trauma and damage to pulm pleura
