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Define the thoracic inlet and outlet
Think that the "flow" is going with gravity
- Inlet: 1st rib end
- -contains: major arteries from aorta, major veins to SVC, esophagus, trachea, phrenic n, vagus n
- Outlet: bottom ribs end
- -IVC, descending aorta, esophagus, sympathetic nn, vagus nerve plexus
What is the clinical significance of having a cervical rib?
- Think about what is close to the normal 1st rib.
- -T1 and C8 ribs
- -subclavian artery and veins
These could all get compressed
Where is a rib most often fractured?
The angle of the rib
Label the neck, tubercle, shaft, costal groove, and head of the rib
What is the anatomical significance of the sternal angle (angle of Louis)?
Listening posts for the aortic and pulmonary valves, second rib attaches here, inferior border of sup. mediastinum, T4/T5 level
What are the 5 types of intercostal muscles and where are they?
- from outside the inside:
- -external intercostal mm (hands in front pockets)
- -from costovertebral to costochondral joint
- -Internal intercostal muscles (hands in back pockets)
- -from sternocostal joint to 5cm from costovertebral
- -(costal VAN here)
- -Innermost intercostal muscles
- -lateral aspect of ribcage
- -Subcostal muscles (span 2 ribs)
- -close to vertebrae
- -transverse thoracic
- -rib to sternum
What are the layes of the paricardium?
- visceral: closest to the heart
- parietal: visceral reflects back on itself and forms the pericardial cavity
- fibrous: tough and designed to protect the heart
What is the significance of the pericardial cavity? The transverse sinus?
Pericardial cavity: friction free movement of the heart
Transverse sinus: can clamp the the great vessels via this sinus during heart surgery
What are the surfaces of the heart?
- Anterior: Rt Atrium, Ant. I/V groove, Rt vent
- Posterior: Lt Atrium
- Inferior: Lt Vent, Post. I/V groove, (heart sits on this)
- Apex: Lt vent
What are the borders of the heart?
- Right: Rt atrium (area b/n SVC and IVC; 3rd to 6th ribs)
- Left: Lt Ventricle (+lt atrium) (5th rib apex->2nd rib)
- Inferior: Right ventricle (along 5th intercostal space)
- Superior: roots of the aorta/pulmonary artery/SVC (2nd rib)
Identify where the auricle, pectinate muscles, fossa ovalis, SA node, and AV node, coronary sinus, Rt AV orifice are.
- 8 - auricle
- 7 - pectinate muscles
- 3 - fossa ovalis
- 6 - SA node
- 5 - AV node
- 2 - coronary sinus
- 4 - Rt AV orifice
Where are the trabeculae carnae, conus arteriosus, moderator band, papillary muscles
- 1 - trabeculae carne
- 7 - moderator band
- 5 - Conus arteriosus (smooth to pulm. artery)
- 2 - Papillary muscles (septal, anterior, posterior)
Describe the location of the mitral valve
lateral to the aorta. 1 papillary muscle on anterior wall, 1 papillary muscle on posterior wall.
What are the three compnents of the 2 AV valves
- 1) leaflets - the flaps that close
- 2) papillary muscles - contract to hold the leaflets closed during contraction
- 3) chordae tendinae - attach the papillary muscles to the leaflets
What is stenosis and regurgitation of the valves?
- stenosis: narrowing of the opening (causes ventricular hypertrophy and murmers (turbulent flow)
- regurgitation: dilation of affected chamber, increased backpressure, murmers
Where are the 4 main listening posts for auscultation
- right second I/C space: aorta
- left second I/C space: pulmonary artery
- Right 4th I/C space: tricuspid valve
- left 5th I/C space (midclavicular line): mitral valve
What are the 4 coronary arteries coming off the LHS of the aorta?
- -Left Coron. a: All others branch off of this
- -LAD: branches off of LCA, supplies anterior I/V septum, supplies part of R and L vents
- -Circumflex: continues in coronary groove to posterior heart, supplies Lt vent and atrium
- -Left marginal artery: off of circumflex and supplies left border of heart
What are the 4 arteries coming off of the right side of the aorta?
- Right coronary artery: all others rise off of this
- Right marginal artery: along inferior border, supplies rt ventricle
- Post. I/V artery: post. I/V groove to apex, supplies Av node, post 1/3 of I/V septum, can come off circumflex if LD
- SA nodal a: off RCA near its origin (can come off left coronary in 40% of people)
What arteries accompany the following veins: great cardiac vein, middle cardiac vein, small cardiac vein
- -great CV: travels with LAD and is continuous with coronary sinus
- -middle CV: travels with posterior I/V
- -small CV: first travels with right marginal, then with right coronary and drains into coronary sinus. drains RV
Describe the flow of electrical potential in the heart
- -SA node (70-80BPM): sets the rhythm of the heart, conducts through innternodal pathways and Bachmann's bundles to contract atria and stimulate
- -AV node (40-60BPM): in septum, supplied by posterior I/V a
- -AV bundle: membranous portion of I/V septum
- -R and L bundle branches: down I/V septum
- -Purkinje fibres: from apex to rest of ventricular wall.
Describe the parasympathetic and sympathetic innervation of the heart.
sympathetic: from T1-6; throughout heart; increase contractility, vasodilation of C aa, increased HR
parasympathetic: from Vagus n; decreased HR and contractility, vasoconstriction
How does referred pain work in cardiac ischemia?
The visceral sensory fibres are close to the somatic sensory fibres, causing them to fire and making it feel like you have pain in areas where T1-4 have somatic sensory innvervation (shoulder, chest, etc)
What are the borders of the superior mediastinum?
- Anterior: manubrium
- Poster.: T1-T4 vertebrae
- superior: Thoracic inlet
- inferior: angle of Louis to T4/5
What are the contents of the superior mediastinum? List any important relationships?
- -Thymus (beneath sternum)
- -Brachiocephalic veins: unite to make SVC, left is longer in goes behind manubrium (all nn tuck behind this)
- -SVC: right lung is aterior (think SVC syndrome), ascending aorta is medial
- -aorta: ascending and arch, behind the brachiocephalic veins,
- -ligamentum arteriosum (between pulmonary artery and aorta)
- -phrenic nerves (C3-C5):
- -vagus nerves (cranial): parasympathetic of cardiac, pulmonary, esophagus plexi.; recurrent laryngeal nerves off of these
- -trachea: behind all these vessels
- -esophagus: behind the trachea
Describe the course and list the main branches/tributaries of the:
- Brachiocephalic veins
- Superior vena cava
- Vagus nerve
What are the boundaries of the posterior mediastinum?
- superior: T4/5
- inferior: diaphram
- anterior: heart
- posterior: T5-12
What are the contents of the posterior mediastinum? Important relationships
- -Thoracic aorta
- -thoracic duct: between azygos and aorta
- -azygos and hemiazygos veins: hemiazygos flows into azygos which connects to both IVC and SVC
- -esophagus: innervated by the vagus nn plexus
- -thoracic sympathetic trunk: run parallel to the spine, sympathetic inn to cardiac, pulmonary, and esophgeal plexuses
- -vagus nerve plexus
Where does the thoracic duct drain?
- everything below diaphram
- Left thorax and left upper limb
- head and neck
What goes through and at what level are the diaphramatic apertures?
- Vena caval hiatus - T8 - IVC
- Esophageal hiatus - T10 - esophagus, vagus nn
- Aortic hiatus - T12 - Aorta, thoracic duct, azygous