~ ~ ~ THORAX ~ ~ ~ Dr. Cunningham
Ann Nguyen -- NYUCD 2008 D1 Anatomy Notes -- Spring '05
st
- located b/t the diaphragm and 1 rib - surrounded by a musculoskeletal wall - contains the organs of circulation (heart) and respiration (lungs) - functions… ○ breathing ○ protection ○ conduit – especially the mediastinum - thorax is divided into… ○ right pleural cavity ○ left pleural cavity ○ mediastinum • Superior Thoracic Aperature (opened) = rib1 + vertebra1 + manubrium of the sternum • Inferior Thoracic Aperature (closed by the diaphragm) = rib11-12 + costal cartilage of rib7-10 + xyphoid process + T12 vertebra SKELETON ● Sternum • manubrium • body • xiphoid process • jugular notch = palpable indentation on the top of the manubrium • lateral notches = articulates w/ clavicles & rib1 costal cartilage • sternal angle = symphysis joint b/t manubrium + body; palpable articulation w/ rib2 (important landmark) - articulates w/ costal cartilages of rib1 – rib7 ● 12 Ribs • head = articulates w/ T-vertebra body • tubercle = articulates w/ T-vertebra transverse process • neck • shaft • angle = the ribs slope anteriorly & inferiorly • costal groove = internal, inferior border where the intercostal BV-N’s run ○ true ribs (rib1 – rib7) = directly articulates w/ sternum via their own costal cartilages ○ false ribs (rib8 – rib10) = indirectly articulates w/ sternum via fusion to costal cartilage of rib7 ○ floating ribs (rib11 – rib12) = do not articulate w/ sternum at all ○ rib1
- shorter, flatter, higher than the rest of the ribs • subclavian groove = through which the subclavian vein runs • scalene tubercle = for attachment of the scalenus anterior muscle • roughened area = for attachment of the scalenus medius muscle
○ rib dislocation = between the sternum + costal cartilage ○ rib separation = between the rib + costal cartilage ○ rib fracture = commonly at the angle; immobilization is usually not required ● 12 Thoracic Vertebrae • body = unique heart-shape - have demifacets for rib articulation - each rib articulates w/ its own vertebra body + the vertebra above - except rib1, rib10, rib11, rib12 that have their own single body facet • spinous processes = long, slender • transverse processes = have facets for rib articulation ● Joints • Costovertebral joints (synovial) - between rib heads + vertebra body - between rib tubercles + vertebra transverse processes • Sternocostal joints (synovial) - between sternum + costal cartilages of true ribs • Costochondral joints (synchondrosis) - between each rib + its own costal cartilage
Compiled for you by:
Ann Nguyen -- NYUCD 2008 D1 Anatomy Notes -- Spring '05
MUSCLES ● Extrinsic Thoracic Muscles ○ Back Muscles • erector spinae ○ Upper Limb • trapezius • latissimus dorsi • rhomboid major & minor • levator scapulae • pectoralis major & minor • serratus anterior ○ Anterior Abdominal Wall • rectus abdominus • transverse abdominus • external & internal oblique ● Intercostal Muscles
• External Intercostals - run obliquely anteroinferiorly from ribtop to ribbottom -- extends only as far as the cartilage margin - elevates ribs during inspiration the rest is just membrane covering the cartilage • Internal Intercostals - run vertically, perpendicular to the External Intercostals -- extends all the way the sternum - depresses ribs during expiration • Innermost Intercostals - run in the same direction as the Internals - depresses ribs during expiration - separated from the Internals by BV-N’s ○ Posterior Intercostal Arteries = branch in pairs off the descending aorta ○ Anterior Intercostal Arteries = branch off the internal thoracic artery, which branched off the subclavian artery ○ Posterior Intercostal Veins = empty into the azygos & hemiazygos vein ○ Anterior Intercostal Veins = empty into the internal thoracic vein ○ Intercostal Nerves = arise from the ventral primary rami ● Diaphragm - this is the most important muscle involved in respiration - innervated by Phrenic Nerve (venral primary rami of C3, C4, C5) -- runs bilaterally down neck to mediastinum - contraction = diaphragm lowers to increase vertical dimension of the thorax for inspiration ● Back Muscle of Respiration • levator costarum = elevates ribs during inspiration ● Accessory Neck Muscles of Respiration • sternocleidomastoid = elevates the sternum’s manubrium during forced inspiration • scalenus anterior, posterior, medius = elevates rib1 and rib2 during forced inspiration - innervated by thoracic spinal nerves (posterior primary rami) MECHANICS OF BREATHING - lungs are innervated by the Vagus Nerve - sympathetic innervation = bronchodilation - parasympathetic innervation = bronchoconstriction ○ Active Quiet Inspiration - increasing transverse diameter = intercostal muscles raise the ribs at costosternal & costovertebral joints - increasing anteroposterior diameter = raising the R & L ribs as a unit at the costovertebral joints - increasing vertical diameter = diaphragm contracts downward ○ Active Forced Inspiration - sternocleidomastoid + scalene muscles - serratus anterior + pectoral muscles ○ Passive Quiet Expiration = elastic recoil of lung tissue forces the air out ○ Forced Expiration = abdominal muscles contract to ↑↑↑ intraabdominal pressure to forcefully expel the air out • Emphysema = increased distance b/t alveoli and capillaries causes insufficient gas exchange • Pneumothorax / Hemothorax = air / blood in pleural cavity causes lungs collapse • Asthma = spasming in the smooth muscles of the bronchial tree, inflammation of respiratory mucosa
Compiled for you by:
LUNGS & PLEURA
Ann Nguyen -- NYUCD 2008 D1 Anatomy Notes -- Spring '05
● Pleura • parietal pleura = lines the walls of the pleural cavity - costal pleura = lines the inner aspect of the rib cage - diaphragmatic pleura = lines the superior aspect of the diaphragm - mediastinal pleura = lines the mediastinum - cervical pleura = bulges up into the neck as the “cupola” / apex of the parietal pleura • visceral pleura = lines the lungs and cannot be separated • pleural cavity = the space in between the 2 pleura • reflections = where the parietal + visceral pleura meet w/ eo (continuous at the root of the lung) • recesses = where the pleura come in contact w/ other pleura (costodiaphragmatic & costomediastinal) ● Lung Surfaces • apex = bulges up thru the thoracic inlet (superior thoracic aperature) • diaphragmatic base = touches the diaphragm • mediastinal surface = touches the heart • costal surface = touches the ribs ● Lung Fissures & Lobes • oblique fissure in left lung = divides into superior & inferior lobes • oblique fissure in right lung = divides into middle & inferior lobes • horizontal fissure in right lung only = divides into superior & middle lobes • cardiac notch + lingula = superior lobe of left lung only ● Hilum • pulmonary artery = carries de-oxygentated blood from the right ventricle to the lungs • pulmonary vein = carries oxygenated blood from the lungs to the left atrium • R & L bronchi = carries O2 in, CO2 out ~ ~ ~ (R) bronchus is located higher than in the (L) called the “Epiarterial Bronchus” ~ ~ ~ • bronchial artery = comes from the thoracic descending aorta • autonomic nerves • lymphatics ● Bronchial Tree • Trachea - 20 C-shaped cartilaginous rings - fibrous tissue & involuntary smooth muscle in the opened part of the rings - upper segment = thyroid gland - lower segment = thymus gland • Carina = where the trachea branches into the R & L primary bronchi (T5-level) • 2 Primary Bronchi ~ ~ ~ right side = wider, shorter, more vertical = more likely for aspirated objects to be lodged here ~ ~ ~ • 2 Left Secondary (Lobar) Bronchi • 3 Right Secondary (Lobar) Bronchi - superior 2° bronchi branches off before entering the lung’s hilum goes to superior lobe - middle & inferior 2° bronchi branches off inside the lung’s hilum goes to middle & inferior lobes • 10 Tertiary (Segmental)Bronchi - supplies each of the 10 independently-functioning bronchopulmonary segments • Bronchioles - very thin smooth muscle walls w/o any cartilage support - smooth muscle spasms = asthma • Terminal Bronchioles - ends in 1-cell thick alveolar sacs surrounded by capillaries for gas exchange ● Blood Supply & Nerves • bronchial arteries branch from the descending aorta and follows and branches along the bronchial tree • innervation= Vagus Nerve
Compiled for you by:
MEDIASTINUM ○ heart + great vessels ○ esophagus + trachea + bronchi ○ vagus nerve + phrenic nerve ○ thoracic duct ○ thymus gland
Ann Nguyen -- NYUCD 2008 D1 Anatomy Notes -- Spring '05
MIDDLE MEDIASTINUM ● Pericardial Sac • parietal pericardium - outer fibrous layer - inner serous layer • visceral pericardium / epicardium = the serous lining of the heart • pericardial cavity = the space between the 2 membranes ● Walls of the heart • epicardium = aka: visceral pericardium = the serous outermost layer • myocardium = the muscular middle layer • endocardium = the inner layer lined by endothelium ● Surface Anatomy of the heart - superior border = located at sternal angle th - inferior border = ends in an apex at rib6 / 5 intercostal space - right border = runs parallel to the sternum - left border = runs obliquely from apex to the sternal angle - sternocostal surface = this is the anterior aspect - diaphragmatic surface = rests on the diaphragm below, but not adherent to it - posterior surface / base = consists mainly of the LA + LV th - apex = located at the left 5 intercostal space 10cm from midline - the entire heart rotates counterclockwise during development so that the… right side of the heart lies anterior left side of the heart lies posterior RA = forms the entire right border 2 RV = forms /3 of the inferior border; occupies most of the anterior aspect LA = located entirely on the posterior aspect LV = forms all of the left border • atrioventricular sulcus / coronary sulcus = runs horizontally, dividing the atria from ventricles • interventricular sulcus = runs vertically, dividing the R & L ventricles ● Entrances & Exits of the heart • 1 Superior Vena Cava = returns de-oxygenated blood from head, upper limbs, thorax back to the RA • 1 Inferior Vena Cava = returns de-oxygenated blood from lower limbs & abdomen back to the RA • 1-R&L Pulmonary Arteries = sends de-oxygenated blood from LV to the lungs for gas exchange • 2-R&L Pulmonary Veins = returns oxygenated blood from the lungs after gas exchange to the LA • 1 Aorta = sends oxygenated blood from the LV to the systemic circulation in the rest of the body ● Valves of the heart ○ Atrioventricular Valves • tricuspid valve = between RA + RV to prevent backflow into the RA • bicuspid / mitral valve = between LA + LV to prevent backflow into the LA ○ Semilunar Valves (3 cusps) • pulmonary valve = located in the RV + pulmonary artery • aortic valve = located in the LV + aorta ○ Auscultation of valves closing - the valves are located too close together, so we listen to the disseminated sounds of the valves closing in the flow of blood where the blood deflects off the borders of the heart • tricuspid valve = lower left sternal border • bicuspid valve = apex nd • pulmonary valve = upper left sternal border, 2 intercostal space nd • aortic valve = upper right sternal border, 2 intercostals space Compiled for you by:
Ann Nguyen -- NYUCD 2008 D1 Anatomy Notes -- Spring '05
● Right Atrium
- receives de-oxygenated blood from the SVC + IVC + coronary sinus • right auricle = embraces the aorta’s base • SVC orifice = has no valve • IVC orifice = has a small rudimentary valve • coronary sinus orifice = cardiac venous drainage • crista terminalis = vertical ridge b/t SVC & IVC, dividing the rough anterior wall & smooth posterior wall • pectinate muscles = radiating outward from the crista terminalis • fossa ovalis = represents the remnants of the fetal foramen ovale that shunted blood b/t the R & L atria • SA & AV nodes = inconspicuous areas of specialized muscle tissue; plays a role in the innervation of the heart ● Right Ventricle - pumps de-oxygenated blood to the lungs for gas exchange • trabeculae carneae = ridges of muscle giving it a roughened appearance • chordae tendinae = attaches the valve cusps to papillary muscles • papillary muscles = attaches the chordae tendinae to the heart wall to ensure valve closure ● Left Atrium = receives oxygenated blood coming back from the lungs thru the 2 pulmonary veins ● Left Ventricle = has markedly thickened walls to forcefully pump oxygenated blood out to the systemic circulation st
● Coronary Arteries = these are the 1 to branch off the ascending aorta • right coronary artery = runs along the anterior coronary sulcus right marginal branch = runs along the oblique inferior border of the heart posterior descending branch = runs along the posterior interventricular sulcus anastomoses w/ the left coronary artery’s LAD branch terminal branch = continues along the posterior coronary sulcus anastomoses w/ left coronary artery’s circumflex branch • left coronary artery = runs between the left atrium and pulmonary trunk left anterior descending branch (LAD) = runs along the anterior interventricular sulcus towards apex anastomoses w/ right coronary artery’s posterior descending branch circumflex branch = continues along the posterior coronary sulcus anastomoses w/ right coronary artery’s terminal branch left marginal branch ● Coronary Veins • coronary sinus = runs along the posterior coronary sulcus and enters the RA the various smaller cardiac veins collectively dump their de-oxygenated blood into this vessel great cardiac vein = runs along the anterior coronary sulcus & interventricular sulcus adjacent to the LAD oblique vein = drains the LA posterior vein = drains the LV middle cardiac vein = drains the RA; runs along the posterior interventricular sulcus ● Intrinsic Innervation • SA Node = this is the “pacemaker” where the electrical impulse for heart beat is initiated located b/t the SVC and RA • AV Node = this is the relay station that starts to spread the electrical impulse Bundle of His Purkinje Fibers located in the AV septum ● Extrinsic Innervation • parasympathetic efferent fibers from the Vagus Nerve = bradycardia = slows down heart beat • sympathetic efferent fibers from the Sympathetic Trunk = tachycardia = speeds up heart beat • cardiac plexus - a collection of both parasympathetic preganglionic + sympathetic post-ganglionic fibers - located on the inferior aortic arch border
Compiled for you by:
ANTERIOR MEDIASTINUM - fat, connective tissue, lymph nodes… nothing of particular interest
Ann Nguyen -- NYUCD 2008 D1 Anatomy Notes -- Spring '05
SUPERIOR & POSTERIOR MEDIASTINUM - trachea & bronchi - thymus gland - esophagus ● Esophagus - located posterior to the trachea, anterior to the vertebrae and descending aortic arch - extends from C6 – T11 - parasympathetic innervation by branches of the Vagus Nerve in the neighboring region as it descends - sympathetic innervation by the sympathetic ganglia in the neighboring region as it descends - has 3 segments… • cervical = picks up blood supply from the laryngeal arteries • thoracic = picks up blood supply from the branches off the descending aorta • abdominal = picks up blood supply from branches off the gastric arteries - has 2 sphincters… • pharyngeal / “cricopharyngeus” = to prevent swallowing of air • abdominal / “cardiac” = to prevent regurgitation of stomach contents - has 4 constrictions… • at the pharyngeal end in the beginning • at the aortic arch in the superior mediastinum • at the tracheal bifurcation • at its puncture through the diaphragm • Esophageal Plexus = a collection of branches off the R & L Vagus Nerves ● Aorta
st
• Ascending = R & L coronary arteries are the 1 to branch off here from the aortic sinuses (bulges) • Arch = between C2 and T4 st brachiocephalic artery is the 1 to branch off here right common carotid artery = enters the neck right subclavian artery = enters the upper arm left common carotid artery = enters the neck left subclavian artery = enters the upper arm • Descending - visceral branches (unpaired) = supplies the thoracic viscera (lungs, esophagus, diaphragm, pericardium) - somatic branches (paired) = supplies the thoracic wall - becomes the abdominal aorta after passing thru the diaphragm ● Inferior Vena Cava = drains the lower limbs + abdomen ● Superior Vena Cava = drains the upper limbs + head & neck R & L brachiocephalic veins internal jugular vein subclavian vein ● Azygous / Hemiazygous Veins = drains the thoracic walls • drainage of all (R) intercostals veins Azygos Vein SVC • drainage of the highest (R) intercostal vein Superior Intercostal Vein Right Brachiocephalic Vein SVC • drainage of (L) upper intercostal veins Superior Intercostal Vein Left Brachiocephalic Vein • drainage of (L) middle intercostal veins Superior Hemiazygos Vein, connects to Azygos Vein on the other side • drainage of (L) lower intercostal veins Inferior Hemiazygos Vein Left Ascending Lumbar Vein ○ Right Ascending Lumbar Vein becomes the Azygos Vein after it passes thru the diaphragm ○ Left Ascending Lumbar Vein becomes the Inferior Hemiazygos Vein ● Thoracic Duct • Cisterna Chyli = a small sac in the abdomen where the duct originates receives drainage from the lower extremities, pelvis, abdomen - enters the thorax from the abdomen thru the diaphragm - ascends in the thorax b/t aorta & azygos vein - drains into the (L) internal jugular and subclavian veins ● Thymus Gland - rudimentary in the adult b/c it atrophied after puberty - produces T-lymphocytes
Compiled for you by:
NERVES OF THE THORAX
Ann Nguyen -- NYUCD 2008 D1 Anatomy Notes -- Spring '05
● Intercostal Nerves - originate in the spinal cord from anterior primary rami of spinal nerves T1 – T12 - innervates the musculature of the thoracic walls - receives skin sensation of the chest wall & upper anterior abdominal wall ● Phrenic Nerve - originates in the neck from anterior primary rami of spinal nerves C3, C4, C5 - carries both afferent + efferent fibers to and from the diaphragm - runs along scalenus anterior muscle enters thoracic inlet descends lateral to mediastinum diaphragm ● Vagus Nerve – CN10 - exits the skull thru the Jugular Foramina descends thru the neck enters thoracic inlet • (R) Vagus Nerve passes the (R) subclavian artery (R) Recurrent Laryngeal Nerve returns to larynx • (L) Vagus Nerve passes the aortic arch (L) Recurrent Laryngeal Nerve returns to larynx - both Vagus Nerves descend posteriorly to the root of the lung… Pulmonary Plexus = found at the root of the lungs • sympathetic fibers = come from cardiac plexus bronchodilation • parasympathertic fibers = come from Vagus bronchoconstriction Cardiac Plexus = found below the aortic arch, anterior to tracheal bifurcation • sympathetic fibers = come from cervical sympathetic ganglia vasodilation • parasympathetic fibers = come from Vagus vasoconstriction Esophageal Plexus Anterior & Posterior Vagal Trunks in the abdomen ● Sympathetic Trunk
Compiled for you by: