Anatomy Summaries PDF

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ANATOMY SUMMARIES ctjoiiAl. gtj- 7a ~J~ -4--i. —f. \ /, i / s \ '- ~ -An^r-. _....^7 julsLuUjl-^. 0bipny a j-a --- Tht 6 r 0| I n I “lobe” Anatomy!  C I MCfl&zJ k DECLARATION Please note that these summaries are compiled from the following sources 1. Drake, R., Vogl, A.W. and Mitchell, A.W., 2010. Gray's anatomy for students 2nd Edition. 2. Elsevier Health Sciences. Netter, F., 2011. Atlas of Human Anatomy 5th Edition. Elsevier. 3. http://teachmeanatomv.info/ 4. Crossman, A.R. and Neary, D., 2010. Neuroanatomy: An Illustrated Colour Text. Elsevier Health Sciences. I do not own the information used to compile the summaries. All copyrights belong to their respective authors. These summaries are for educational purposes only and may not be reproduced. Furthermore, these summaries are intended to supplement, not replace, the abovementioned sources for the purpose of anatomy training. 3 BASICS In this region: Top tips Anatomical position Anatomical planes Anatomical terms of location Anatomical terms of movement Joints  Top tips On osteology r ' ssxsa“* - ~ „ ,«,a sulcus of humerus = attachment of pectoralis major P ' for examP|e< fallal hp of intertubercular / ^lain|featfUreS °f b°nes maY be asked during spot tests. Know classification & siding of bone. On muscles ^ Muscles are important for PT/OT's thprpfnro.. Muscle origins & insertions for the'head & intrinsic m^scleTS^ especially for the limbs. Jnnervations are also very important for PT/OT's especial* whentr»"t V°U*°n0' have t0 studV- but identify, innervations of muscles well. ' P y when Seating physical patients. Therefore, know the y Study muscles with a picture as well. S Thh mu^l. ta. S The general rule for muscles is that if "2 , & “,nserts on the ™*t°id process. S Muscle fibers tell you in which direction it conTrlc^conTra'T ^ ^ ’* SUpplies ib an idea of the movements they bring forth. Therefore the or*Vthi* ^ould give you SSSKSl S Sh°Uld produca movement a, both thus producing movement at the shoulder & elbow joints. S * °n he scapula & lnsert olecranon, On blood vessels ✓ specific vessels can be studied,bX^y oft^clp/tess spmPf' ^ SUPP'ieS the faCe' from there' , Know the origin of arteries & where veins drain into ? Un'eSS indicated t0 bp Recife ✓ passingthroughCtheaedductorcla,nalUbutdor/t'spend' Ribs 11 & 12 have no anterior connection with other ribs / sternum — floating ribs. Structure: Curved shaft Anterior end: continuous with costal cartilage Posterior end: articulates with vertical column, characterised by head, neck & tubercle » Head Expanded 2 articular surfaces separated by crest. Superior.surface = smaller, articulates with inferior costal facet of body of vertebra above. Inferior surface = larger, articulates with superior costal facet of own vertebra. Neck r Short, flat region of bone. | Separates head from tubercle. Tubercle Projects posteriorly from junction of neck with small shaft. ! Articular part = medial, has oval facet for articulation with corresponding facet on transverse process of associated vertebra. r Non-articular part = raised, roughened by ligament attachments. I Shaft Thin. Flat with internal & external surfaces. Superior margin smooth & rounded. Inferior margin is sharp. Shaft bends forward laterally to tubercle at angle. Has gentle twist around longitudinal axis. Inferior margin of internal surface marked by distinct costal groove.. Unique ribs: Rib 1 * Flat in horizontal plane. Broad superior & inferior surfaces. * Slopes inferiorly from articulation with vertebra T1 to attachment with manubrium of sternum. Head articulates with body of vertebra T1 (only one articular surface). Tubercle has facet for articulation with transverse process. Scalene tubercle (distinct tubercle on superior surface) separates 2 grooves that cross rib midway along shaft. 47  Anterior groove caused by subclavian vein. Posterior groove caused by subclavian artery. * Anterior & posterior to grooves, shaft is roughened for attachment of muscles / ligaments. Rib 2 Like rib 1. * Flat, but 2x as long. Articulates with vertical column in normal way. Rib 10 Head has single facet for articulation with own vertebra. Ribs 11 & 12 Articulate only with bodies of own vertebrae, no transverse process. No tubercles / necks. Short, little curve (12 has none), pointed anteriorly. Sternum1 - p. (Netter) Structure: 3 major elements: Manubrium Part of bony framework of neck & thorax. Superior surface = expanded laterally, bears distinct & palpable notch, jugular notch, in midline. Either side of notch = large oval fossa for articulation with clavicle. Inferior to fossae, on each lateral surface of ma_nubrium - facet for attachment of 1st costal cartilage. Lower end of lateral border - demi facet for articulation with upper half of anterior end of 2nd costal cartilage. ~ Body Anterior surface = marked by transverse ridges that represent lines of fusion between segmental elements called sternebrae. Lateral margins = articular surfaces for costal cartilages. Superiorly = lateral margin has demi facet for articulation with inferior aspect of 2nd costal cartilage. Inferior to facet = 4 facets for articulation with costal cartilages of ribs 3-6. * Inferior end of body = demi facet for articulation with upper demi facet on 7th costal cartilage. Inferior end attached to xiphoid process. Xiphoid process Smallest part of sternum. Shape is variable. Begins as cartilaginous structure, becomes ossified as adult. On each side of upper lateral margin = demi facet for articulation with inferior end of 7th costal cartilage. 48 Joints1 Costovertebral joints See back notes. Costotransverse joints See back notes. Sternocostal joints - p. 184 (Netter) B/w upper 7 costal cartilages & sternum. 1st joint between rib 1 & manubrium not synovial, has fibrocartilaginous connection. 2nd -7th joints are synovial, have thin capsules, reinforced by sternocostal ligaments. 2nd joint divided into 2 compartments by intraarticular ligament (ligament attaches to 2nd costal cartilage to junction of manubrium & body of sternum). Interchondral joints - p. 184 (Netter). B/w costal cartilage of adjacent ribs (mainly ribs 7-10, but also 5-6). Provide indirect anchorage to sternum & contribute to formation of smooth inferior costal margin. Usually synovial. Fibrous capsules reinforced by interchondral ligaments. Manubriosternal & xiphisternal joints - p. 183 (Netter) B/w manubrium & body of sternum. B/w body & xiphoid process of sternum. Usually symphyses. Slight angular movements in manubriosternal during respiration. Xiphisternal becomes ossified with age. Manubriosternal easily palpated. Sternal angle lies on horizontal plane that passes through intervertebral disc of vertebrae T4 & T5. 49 Thoracic wall1 Components Skeletal = sternum, ribs & thoracic vertebrae. Muscles. Intercostal spaces. Superior thoracic aperture Angled anteroinferiorly. Borders: Posteriorly = body of vertebra Tl. Laterally = medial margin of rib 1 on each side. Anteriorly = manubrium. Contents / structures passing through: Trachea Oesophagus Thoracic duct Other lymph nodes & vessels Apexes of lungs Phrenic..Qgjye:- ,* Vagus nerve " Recurrent laryngeal nerve Sympathetic trunk Left & right common carotid arteries Left & right subclavian arteries Internal jugular veins Brachiocephalic vein Subclavian vein Inferior thoracic aperture Angled posteroinferiorly, closed off by diaphragm. Borders: Posteriorly = body of vertebra T12. Posterolaterally = rib 12 & distal end of rib 11. Anterolaterally = distal cartilaginous ends of ribs 7-10 which unite to form margin. Anteriorly = xiphoid process. Contents / structures passing throuRh: Inferior vena cava Branches of right phrenic nerve Oesophagus Vagus nerves Lymphatics Oesophageal branches of left gastric vessel 50  Aorta Thoracic duct Azygos veins Sympathetic trunks Least splanchnic nerves Intercostal spaces - p. 187 -189 (Netter) B/w adjacent ribs. Lavers: From superficial to deep Skin Superficial fascia Ribs + muscle attaching to external surface External intercostal m. \\\ Internal intercostal m. /j/ Neurovascular.structures Innermost intercostal m. / J J Endothoracic fascia Parietal pleura Pleural cavity Visceral pleura Lung 51 Neurovascular contents: Lie in costal groove (see rib osteology); 12 ribs, 11 intercostal arteries, vein & nerves, 12th set = subcostal artery, vein & nerves. Vein (superior) Artery (middle) Nerve (inferior) =outside costal groove, most at risk. Small collateral branches of major intercostal nerves & vessels present superior to rib below. Endothoracic fascia: Deep to intercostal spaces & ribs. Separating structures from underlying pleura. Layer of loose connective tissue. Contains various amounts of fat. Muscles: Muscle Origin Insertion Innervation Action External intercostal Inferior margin of rib Superior margin of Intercostal nerves Tl- Most active: above rib below Tll inspiration Supports intercostal space Moves ribs superiorly Internal intercostal Lateral edge of costal Superior margin of Intercostal nervesTl- Most active:' groove of rib above rib below deep to Tll expiration attachment of Supports intercostal related external space intercostal Moves ribs inferiorly Innermost Medial edge of costal Internal aspect of Intercostal nerves Tl- Acts with internal intercostal groove of rib above superior margin of Tll intercostal muscles rib below Subcostales Internal surface (near Internal surface of Related intercostal May depress ribs angle) of lower ribs 2nd/3rd rib below nerves Transversus thoracis Inferior margins and Inferior aspect of Related intercostal Depress costal internal surfaces of deep surface of body nerves cartilages costal cartilages of of sternum, xiphoid 2nd - 6th ribs process & costal cartilages ribs 4-7 Arterial supply: Anterior intercostal arteries = 6 arise from interna! thoracic a. & other 6 from terminal branch thereof (musculophrenic a.). Posterior intercostal arteries = arise from thoracic / descending aorta. Venous drainage: Drain into 2 directions Anteriorly = internal thoracic veins. Posteriorly = azygos system & brachiocephalic veins. Innervation: 52 Intercostal nerves = anterior rami of spina! nerves ofTl -Til. 2 branches Lateral cutaneous branch * Collateral branch Diaphragm1 See p. 191 -192 (Netter) Fibromuscular structure b/w abdominal & thoracic cavity. Attachments: Xiphoid process of sternum Costal margin of thoracic wall Ends of ribs 11 & 12 Ligaments that span across structures of posterior abdominal wall Vertebrae of lumbar region From peripheral attachments muscle fibers converge to join central tendon. Pericardium attached to central tendon Structures piercing diaphragm: Hiatus Location Contents Vena cava hiatus foramen T8 - central tendon Inferior vena cava Branches of right phrenic nerve Oesophageal hiatus T10 - muscular part, just left to Oesophagus midline Vagus nerves Lymphatics Oesophageal branches of left gastric vessel Aortic hiatus T12 - behind posterior attachment Aorta Thoracic duct Azygos veins Other structures outside posterior attachments of diaphragm lateral to aortic hiatus: Sympathetic trunks Least splanchnic nerves (greater & lesser penetrate crura) Arterial supply: Vessels that arise superiorly & interiorly to it From above Pericardiophrenic arteries (internal thoracic a.) Musculophrenic arteries (internal thoracic a.) Superior phrenic arteries (thoracic aorta) Small branches from intercostal arteries From below Inferior phrenic arteries (abdominal aorta) Venous drainage: Generally parallel arteries. Veins drain into * Brachiocephalic veins in neck Azygos system of veins Abdominal veins (left suprarenal & inferior vena cava) Innervation: 54 Penetrate diaphragm, innervate from abdominal surface. Motor = phrenic n. (C3-C5) Sensory = phrenic n. (centrally), T5 - Til intercostal n. (peripherally), subcostal n. Muscle: Muscle Origin Insertion Innervation Action Diaphragm Xiphoid process Converge into central Phrenic nerve Draws central tendon Lower 6 costal tendon down & forward cartilages during inspiration L1-L3 vertebrae 55 Pleural cavities1 Pleural cavity - p. 195 (Netter) Potential space enclosed between visceral & parietal pleurae. 2 major types of pleura (depending on location) Parietal pleura = pleura associated with walls of pleural cavity. Visceral pleura = pleura that reflects from medial wall onto surface of lung (adheres to & covers lung). Contain thin layer of serous fluid. Function = allows surface of lung covered by visceral pleura to directly oppose & freely slide over parietal pleura attached to wall. Parietal pleura Names of pleura correspond with parts of wall associated with Costal part: related to ribs & intercostal spaces. Diaphragmatic part: covering diaphragm. Mediastinal part: covering mediastinum. Cervical pleura / dome of pleura / pleura! cupola: dome-shaped layer lining cervical extension of pleural cavity. Suprapleural membrane Covering superior surface of cervical pleura. Dome-like layer offascia. -.-.. _ Provides apical support for pleural cavity in root of neck;T ' - - - ~ v rr::. Attached laterally to medial margin of rib 1 & behind transverse process of C7; * ' /"... Superiorly membrane receives muscle fibres from some deep muscles of neck (scalene muscles) - keeps membrane taut. Region of T5 & T7 mediastinal pleura reflects off mediastinum as tubular, sleeve-like, covering for structures passing between lung & mediastinum, sleeve & structures = root of lung. Root Joins medial surface of lung at hilum of lung. Mediastinal pleura continuous with visceral pleura here. Peripheral reflections Mark extent of pleural cavities. - Superiorly = pleural cavity projects as much as 3-4cm above 1st costal cartilage, not above neck of rib 1 (limitation caused by inferior slope of rib 1 to its articulation with manubrium). - Anteriorly = cavities approach each other posterior to upper part of sternum. - Inferiorly = costal pleura reflects onto diaphragm above costal margin. - Midclavicular line = pleural cavity extends inferiorly to rib 8, from here to vertebral column inferior boundary can be approximated by a line that runs between rib 8-10 & vertebra T12. - Midaxillary line = extends to rib 10, from here inferior margin courses horizontally crossing ribs 11-12 to reach vertebra T12. Visceral pleura: * Continuous with parietal pleura at hilum of each lung. Firmly attached to surface of lung including both opposed surfaces of fissures that divide lungs into lobes. Parietal pleura Visceral pleura 56  Blood supply Posterior intercostal a. Bronchial a. Internal thoracic a. Superior intercostal a. Superior phrenic a. Innervation 2nd - 12th intercostal n. Sympathetic fibres from T2 - T5 Sensory fibres only Phrenic n. Lymphatic drainage Adjacent lymph nodes on thoracic Drain into nodes at hilum of lungs wall (axillary nodes) Pleural recess: Lungs don't fill anterior / posterior inferior regions of pleural cavities. Recess in which 2 layers of parietal pleura becomes opposed. Expansion of lungs into spaces occurs only during forced inspiration. Function: provides potential spaces in which fluids can collect & from which fluids can be aspirated. Costomediastinal recesses - Anteriorly on each side. - Costal pleura opposed to mediastinal pleura. - Largest on left, in region overlying heart. Costodiaphragmatic recesses - Largest. - In each pleural cavity, between costal pleura & diaphragmatic pleura. Regions between inferior margin of lungs & inferior margin of pleural cavities. - Deepest after forced expiration & shallowest after forced inspiration. - During expiration inferior margin of lung rises, costodiaphragmatic recess becomes larger. 57 Lungs1 See p. 196 - 200 (Netter) Organs of respiration. Lie on either side of mediastinum, surrounded by left & right pleural cavities. Air enters & leaves lungs via main bronchi (branches of trachea). Structure Half-cone shape. Base = sits on diaphragm. Apex = projects above rib 1 into root of neck. 2 surfaces Costal surface = Immediately adjacent to ribs & intercostal spaces of thoracic wall. Mediastinal surface = lies against mediastinum anteriorly & vertebral column posteriorly & contains comma-shaped hilum of lung. 3 borders Inferior border = sharp, separates base from costal surface. Anterior & posterior borders = separate costal from medial surface (anterior is sharp, posterior is smooth & rounded). Lungs lie directly adjacent to & are indented by structures contained in overlying area. Heart & major vessels form bulges in mediastinum - indents medial surfaces of lung. "v- Ribs indent costal surfaces. Root & hilum: Root Short tubular collection of structures, together attaches lung to structures in mediastinum. Covered by sleeve of mediastinal pleura that reflects onto surface of lung as visceral pleura. Hilum Region outlined by this pleural reflection on medial surface of lung. Structures enter & leave here. Pulmonary ligament Thin blade-like fold of pleura. Projects interiorly from root of lung. Extends from hilum to mediastinum. Function = may stabilise position of inferior lobe, may accommodate up-and-down translocation of structures in root during breathing. In mediastinum Vagus nerve posterior to roots of lungs. Phrenic nerves anterior to roots of lungs. Contents of root & hilum Pulmonary artery = superior. 2 pulmonary veins = inferior. Main bronchus = posterior. Bronchial vessels. Nerves. Lymphatics. On right = lobar bronchus to superior lobe branches from main bronchus in root. On left = lobar bronchus to superior lobe branches in lung itself & superior pulmonary artery. 58  Right lung _ Left lung__ Roughly pyramidal Roughly pyramidal Sharp anterior edge Sharp anterior edge Overlapping pericardium to a degree Overlapping pericardium to a degree Convex lateral surface Convex lateral surface Bluntly round posterior surface Bluntly round posterior surface Shorter & wider Longer & thinner Size Larger Smaller___ Fissures 1 horizontal 1 oblique 1 oblique Superior Superior Middle Inferior Inferior Cardiac impression Lesser indentation Larger indentation to accommodate heart & pericardium_ Anterior margin Straight Cardiac notch_ Hilum 2 bronchi 1 bronchus Pulmonary artery & vein Pulmonary artery & vein Bronchial artery Bronchial artery_ Heart Heart Oesophagus Oesophagus Azygos vein Aortic arch SVC Descending aorta IVC ' - - Left subclavian artery & vein Right subclavian artery & vein Differences At cardiac notch can listen to heart without lung interference Lingula is an extension of superior lobe inferior to cardiac notch Bronchial tree: Trachea Flexible tube. Extends from vertebral level C6 in lower neck to T4/5 in mediastinum. Bifurcates into left & right main bronchus. Held open by C-shaped transverse cartilage rings embedded in waif open part facing posteriorly. Lowest tracheal ring has hook-shaped structure - carina - projected backwards in midline between origins of main bronchi. Posterior wall = smooth muscle = trachealis. * Each main bronchus enters root of lung & passes through hilum into lung. Right / left main bronchus “ Right main bronchus is wider, takes more vertical course through root & hilum than left main bronchus. Divides into lobar bronchi in lungs. Lobar / secondary bronchi Each supplies a lobe. On right: lobar bronchus to superior lobe originates within root of lung. * Further divide into segmental bronchi. Segmenta I / tertiary bronchi Supply bronchopulmonary segments. Bronchopulmonary segments 59  * Within each, segmental bronchi give rise to multiple divisions and ultimately to bronchioles. Bronchioles Further subdivide. Supply respiratory surfaces. Walls of bronchi held open by discontinuous elongated plates of cartilage, but not bronchioles. Bronchopulmonary segments: Area of lung supplied by segmental bronchus & accompanying pulmonary artery branch. Tributaries of pulmonary vein pass intersegmentaiiy between & around margins of segments. Each bronchopulmonary segment is shaped like irregular cone with apex at origin of segmental bronchus & base projected peripherally onto surface of lung. Bronchopulmonary segment is smallest, functionally independent region of a lung & smallest area of lung that can be isolated & removed without affecting other regions. 10 bronchopulmonary segments in each lunch (some fuse in left lung). Blood supply Pulmonary arteries: Right & left originate from pulmonary trunk. Carry deoxygenated blood to lungs from right ventricle of heart. Bifurcation of pulmonary trunk occurs to left of midline, inferior to T4/5, anteroinferioriy to left of bifurcation of trachea.. Right pulmonary artery ‘ - Longer than left. - Passes horizontally across mediastinum. - Passes anteriorly & slightly inferiorly to tracheal bifurcation & anteriorly to right main bronchus. - Passes posteriorly to ascending aorta, superior vena cava & upper right pulmonary vein. - Right pulmonary artery enters root of lung & gives off large branch to superior lobe of lung. - Main vessel continues through hilum, gives off second branch to superior lobe. - Divides to supply middle & inferior lobes. Left pulmonary artery - Shorter than right. - Anterior to descending aorta. - Posterior to superior pulmonary vein. - Passes through root & hilum & branches within lung. Pulmonary veins: On each side a superior pulmonary vein & inferior pulmonary vein carries oxygenated blood from lungs to heart. Begins at hilum of lung, pass through root of lung, drain into left atrium. Bronchial arteries & veins: Constitute nutritive vascular system of pulmonary tissues. Interconnect within lung with branches of pulmonary arteries & veins. Bronchial arteries originate from thoracic aorta / one of its branches 1 right bronchial artery = arises from 3rd posterior intercostal artery (sometimes upper left bronchial artery). * 2 left bronchial arteries = arise from anterior surface of thoracic aorta - superior left bronchial artery from T5 & inferior left bronchial artery from inferior to left bronchus. Bronchial arteries run on posterior surfaces of bronchi & ramify in lungs to supply pulmonary tissues. Bronchial veins drain into 60  Pulmonary veins / left atrium. Azygos vein on right / superior intercostal vein / hemiazygos vein on left. Innervation Structures of lung & visceral pleura supplied by = visceral afferents & efferents distributed through anterior pulmonary plexus & posterior pulmonary plexus. Interconnected plexuses lie anteriorly & posteriorly to tracheal bifurcation & main bronchi. Anterior plexus much smaller than posterior plexus. Branches of plexuses originate from = sympathetic trunks & vagus nerves. Distributed: along branches of airway & vessels. Visceral efferents from Vagus nerves constrict bronchioles. Sympathetic system dilates bronchioles. Lymphatic drainage Superficial / subpleural & deep lymphatics of lung drain into tracheobronchial nodes. Tracheobronchial nodes Around roots of lobar & main bronchi. Along sides of trachea. As group = extend from within lung, through hilum & root, into posterior mediastinum. Efferent vessels from these nodes pass superiorly along trachea to unite with parasternal nodes & JL brachiocephalic nodes = right & left bronchomediastinal trunks. TaS. Trunks drain directly into deep veins at base of neck / right iymphatic trunk / thoracic duct. 61 Superior mediastinum1 See p. 208 (Netter) Posterior to manubrium & anterior to bodies of first 4 thoracic vertebrae. Borders Superior boundary = oblique plane passing from jugular notch upward & posteriorly to superior border of Tl.. Inferior boundary = transverse plane passing from sternal angle to intervertebral disc between T4/5 separates it from inferior mediastinum. Lateral boundary = bordered by mediastinal part of parietal pleura on each side. Continuous with neck superiorly & inferior mediastinum interiorly. Contents Thymus Right & left brachiocephalic vein Left superior intercostal vein Superior vena cava Arch of aorta with 3 large branches Trachea Oesophagus S Phrenic nerves -Vagus nerves Left recurrent laryngeal branch of left vagus nerve Thoracic duct Other small nerves, blood vessels & lymphatics Thymus Most anterior component of superior mediastinum. Lying posterior to manubrium. Asymmetric, bi-lobed structure. Upper extent can reach into neck as high as thyroid gland. Lower portion extends into anterior mediastinum over pericardial sac. Involved in early development of immune system. Child = large, adult: variable sizes, old age = barely identifiable as organ, mostly fatty tissue arranged as 2 fatty lobulated fatty structures. Arterial supply Small branches originating from internal thoracic arteries. Venous drainage Into left brachiocephalic vein & possibly into internal thoracic veins. Lymphatics Returns to multiple groups of nodes " - Parasternal {along internal thoracic arteries) - Tracheobronchial (at tracheal bifurcation) - In root of neck Right & left brachiocephalic veins: Located posterior to thymus. 62  Form on each side at junction between internal jugular & subclavian veins. Left vein crosses midline & joins with right vein to form superior vena cava. Right brachiocephalic vein - Begins posterior to media! end of right clavicle. “ Passes vertically downward forming superior vena cava when joined by left. - Venous tributaries x Vertebral veins x 1st posterior intercostal x Internal thoracic veins x Possibly = inferior thyroid & thymic veins Left brachiocephalic veins - Begins posterior to medial end of left clavicle. - Crosses to right moving in slightly inferior direction. - Joins with right to form superior vena cava posterior to lower edge of right 1st costal cartilage, close to right sternal border. - Venous tributaries "s x Vertebral veins x 1st posterior intercostal x Left superior intercostal x Inferior thyroid x Internal thoracic veins x Possibly: thymic & pericardial..... Left superior intercostal vein: Receives 2nd, 3rd sometimes 4th posterior intercostal veins. Usually left bronchial veins. Sometimes left pericardiophrenic vein. Passes over left side of aortic arch, lateral to left vagus nerve & medial to left phrenic nerve. Then enters left brachiocephalic vein. Inferiorly may connect with accessory hemiazygos vein (superior hemiazygos vein). Superior vena cava: Vertically oriented. Origins = posterior to lower edge of right 1st costal cartilage - where right & left brachiocephalic veins join. Terminates = lower edge of right 3rd costal cartilage -where it joins the RA. Lower half in of SVC within pericardial sac & contained in middle mediastinum. Receives Azygos vein = before entering pericardial sac (may also receive pericardial & mediastinum veins). Arch of aorta: Thoracic portion divided into 3 parts. Ascending aorta. B Arch of aorta.. * Thoracic (descending) aorta Only arch in superior mediastinum. Origin = ascending aorta emerges from pericardial sac. Courses upward & backward & to left as passes through superior mediastinum. Terminates = left side at vertebral T4/5. Highest extension = midlevel of manubrium of sternum. 63  Arch initially anterior then lateral to trachea. * 3 branches arise from superior border of arch of aorta {at origins all 3 crossed anteriorly by left brachiocephalic vein) 1st branch = brachiocephalic trunk - Beginning on right. - Largest of three. - At origin behind manubrium, slightly anterior to other 2 branches. - Ascends slightly posterior & to right. _ - At level of upper edge of right sternoclavicular joint divides into 2 x Right common carotid x Right subclavian - Supply: x Right side of head & neck, x Right upper limb. - Occasionally small branch - thyroid artery x Contributes to supply of thyroid gland. 2nd branch = left common carotid — Origin = arch immediately to left & slightly posterior to brachiocephalic trunk. - Ascends through superior mediastinum along left side of trachea. - Supplies x Left side of head & neck. 3rd branch = left subclavian artery o Origin = arch immediately to left of, slightly posterior to left common carotid artery, o Ascends through superior mediastinum along left side of trachea, o Supplies x Left upper limb. Ligamentum arteriosum: In superior mediastinum. NB in embryonic circulation, when it is a patent vessel (ductus anteriosus). Connects pulmonary trunk with arch of aorta = allows blood to bypass lungs during development. Vessel closes soon after birth & forms ligamentous connection. Trachea & oesophagus: Trachea Midline structure. Palpable in jugular notch as enters superior mediastinum. Oesophagus Posterior to trachea.. Anterior to vertebral column. Significant mobility in vertical positioning as pass through superior, mediastinum - swallowing & breathing cause positional shifts. As pass through superior mediastinum, crossed laterally by azygos vein on right side & arch of aorta on left. Trachea divides into right & left main bronchi inferior to transverse plane between sternal angle & vertebral level T4/5. Oesophagus continues into posterior mediastinum. Nerves of the superior mediastinum: Vagus nerves CN X. 64  Pass through superior & posterior divisions of mediastinum on way to abdominal cavity. As pass through thorax provide parasympathetic innervation to - Thoracic viscera. - Carry visceral afferents from thoracic viscera - info about normal physiological processes, not pain. Right vagus nerve - Enters superior mediastinum. - Lies between right brachiocephalic vein & brachiocephalic trunk. - Descends in posterior direction toward trachea. - Crosses lateral surface of trachea & passes posteriorly to root of right lung, crossed by arch of azygos vein, then reaches oesophagus. - Gives branches to x Oesophagus x Cardiac plexus x Pulmonary plexus Left vagus nerve - Enters superior mediastinum posterior to left brachiocephalic vein. - Between left common carotid & left subclavian arteries. - Passes into superior mediastinum - lies just deep to mediastinal part of parietal pleura & crosses left side of arch of aorta. - Descends in posterior direction & passes posterior to root of lung to reach oesophagus in posterior mediastinum. -V'^Sives branches to ;........ -v™. x Oesophagus. x Cardiac plexus x Pulmonary plexus - Gives rise to x Left recurrent laryngeal nerve - at inferior margin of arch of aorta lateral to ligamentum arteriosum.. x Passes inferior to arch of aorta before ascending on medial surface. x Entering groove between trachea & oesophagus, nerve continues superiorly to enter neck & terminate in larynx. Phrenic nerves Origin = cervical region (3rd, 4th, 5th cervical spinal segments). Descend through thorax to supply - Motor & sensory innervation of diaphragm & associated membranes. - Somatic afferent fibers to mediastinal pleura, fibrous pericardium, parietal layer of serous pericardium. Right phrenic nerve - Enters superior mediastinum lateral to right vagus nerve & lateral, slightly posterior to beginning of right brachiocephalic vein. — Continues inferioriy along right side of this vein & right side of SVC. - Entering middle mediastinum, nerve descends along right side of pericardial sac, within fibrous pericardium, anterior to root of right lung. - Pericardiophrenic vessels accompany along most of course in thorax. - Leaves thorax by passing through diaphragm with IVC. Left phrenic nerve - Enters superior mediastinum similarly to right phrenic nerve. - Lateral to left vagus nerve & lateral, slightly posterior to beginning of left brachiocephalic vein. - Continues to descend across left lateral surface of arch of aorta. 65  - Passes superficially to left vagus nerve & left superior intercostal vein. - Entering middle mediastinum, nerve follows left side of pericardial sac, within fibrous pericardium, anterior to root of left lung. - Accompanied by pericardiacophrenic vessels. - Leaves thorax by piercing diaphragm near apex of heart. Thoracic duct in superior mediastinum: Major lymphatic vessel. Passes through posterior portion of superior mediastinum. Enters superior mediastinum inferiorly, slightly to left of midline, having moved to position just before leaving posterior mediastinum opposite vertebral level T4/5. Continues through superior mediastinum, posterior to arch of aorta & initial portion of left subclavian artery, between oesophagus & left mediastinal part of parietal pleura. Anterior mediastinum1 See p. 208 {Netter) Posterior to body of sternum & anterior to pericardial sac. Borders Superior = transverse plane passing from sternal angle to intervertebral disc between vertebra T4 & T5, separating it from superior mediastinum. Inferior = diaphragm. Laterally = mediastinal part of parietal pleura on either side. Contents Portion of thymus Fat Connective tissue Lymph nodes Mediastinal branches of internal thoracic vessels Sternopericardial ligaments (pass from posterior surface of body of sternum to fibrous pericardium). Middle mediastinum1 See p. 209 (Netter) Centrally located in thoracic cavity within pericardial sac. Contents Pericardium Heart Origins of great vessels Various nerves Smaller vessels Pericardium Fibroserous sac surrounding heart & roots of great vessels. 2 components Fibrous pericardium = tough CT outer layer, defines boundaries of middle mediastinum. Serous pericardium = thin, 2 parts. ~ Parietal layer = lines inner surface of fibrous. - Visceral layer (epicardium) = adheres to heart & forms outer covering. 2 layers a ^continuous at roots of great vessels. - Pericardialxavity - narrow space between 2 laye refilled with fluid to allow for uninhibited movement of heart. Fibrous pericardium Base attached to central tendon of diaphragm & small muscular area of diaphragm on left side. Attached to posterior surface of sternum by sternopericardial ligaments. Apex continuous with adventitia of great vessels. Serous pericardium Parietal layer = continuous with visceral layers around roots of vessels. Reflections occur in 2 locations - Superiorly = surrounding arteries, aorta & pulmonary trunk. - Posteriorly = surrounding veins, superior& inferior vena cava & pulmonary veins. 2 zones of reflection = oblique pericardial sinus & transverse pericardial sinus. Passage between 2 sites of reflected serous pericardium is transverse pericardial sinus 68 Heart1 Cardiac orientation Shape of pyramid that has fallen over, resting on one side. Apex projects forward, downward & to left. Base opposite apex, faces posterior direction. Surfaces Base Quadrilateral & directed posteriorly. Consists of - Left atrium. - Small portion of right atrium. - Proximal parts of great veins. x Pulmonary veins = right & left sides of left atrium, x Vena cavae = upper & lower ends of right atrium. Base of heart fixed posteriorly to pericardial wall opposite bodies of vertebrae T5-T8. Oesophagus lies immediately posterior to base. From base, heart projects forward, downward & to left, ending in apex. - Apex Formed by inferolateral part of left ventricle, positioned deep to left 5th intercostal space, 8-9 cm from midsternal line. _: : ' Anterior - — Faces anteriorly. Consists mostly of right ventricle, some right atrium on right & some of left ventricle on left. Diaphragmatic Rests on & consists of left ventricle & small portion of right ventricle, separated by posterior interventricular groove. Faces interiorly, rests on diaphragm. Separated from base of heart by coronary sinus. Extends from base to apex of heart. Left pulmonary surface Faces left lung. Broad & convex. Consists of left ventricle & portion of right atrium. Right pulmonary surface Faces right lung. Broad & convex. Consists of right atrium. Margins & borders Right & left margins - Same as right & left pulmonary surfaces of heart. Inferior margin - Sharp edge between anterior & diaphragmatic surfaces of heart. - Formed mostly by right ventricle & small portion of left ventricle near apex. Obtuse margin - Separates left & anterior pulmonary surfaces. - Round & extends from left auricle to cardiac apex. 69  - Formed mostly by left ventricle & superiorly by small portion of left auricle. External sulci Internal partitions divide heart into 4 chambers - Coronary sulcus x Circles heart, separating atria from ventricles. x Contains = right coronary artery, small cardiac vein, coronary sinus & circumflex branch of left coronary artery. - Anterior & posterior interventricular sulci x Separate 2 ventricles. x Anterior interventricular sulcus = on anterior surface of heart, contains anterior interventricular artery & great cardiac vein. x Posterior interventricular sulcus = on diaphragmatic surface of heart, contains posterior interventricular artery & middle cardiac vein. * Sulci are continuous inferiorly, just to right of apex of heart. Cardiac chambers Heart consists of 2 pumps separated by partition. Right pump receives deoxygenated blood from body, pumps to lungs. Left pump receives oxygenated blood from lungs, pumps to body. Each pump consists of atrium& ventricle separated by valve Thin walled atria receive blood. " ^ ^Tlrfck walled ventricles pump blood out. ^ 1 Left ventricle thicker than right, pumps blood to entire body. - Interatriral, interventricular & atrioventricular septa separate four chambers of heart. Right atrium: Right border of heart formed by right atrium. Receives venous blood from SVC IVC Coronary sinus Main cavity extends into right auricle Forms a conical muscular pouch. * Projects from RA to increase capacity. Interior Smooth, thin walled posterior. Rough anterior wall. - Pectinate muscles. - Primitive chamber. Smooth & rough parts separated by vertical groove. - Sulcus terminalis = external name. - Christae terminalis = interna! name. Openings * Atrioventricular orifice = tricuspid valve. - 3 cusps. - Base of each cusp secured to fibrous ring that surrounds atrioventricular orifice. - Fibrous ring helps maintain shape of opening. x Anterior cusp, x Posterior cusp. 70  x Septal cusp. - Free margins attached to chordae tendinae, which arise from tips of papillary muscles. * Opening of coronary sinus - Receives blood from most of cardiac veins & opens medially to opening of inferior vena cava. Openings of smallest cardiac veins (foramina of venae cordis minimae) - Numerous small openings. - Scattered along walls of RA. - Small veins that drain myocardium. Interatrial septum: Separates right & left atrium. Depression just above orifice of inferior vena cava = fossa ovalis, with prominent margin, limbus fossa ovalis. Fossa ovalis marks embryonic foramen ovale — prominent part of foetal circulation J Rteht ventricle: Forms most of anterior surface & portion of diaphragmatic surface. ™: Outflow tract of RV = leads to pulmonary trunk = conus arteriosus (infundibulum) = has smooth walls. Inflow tract = numerous muscular, irregular structures called trabeculae carneae Trabeculae carneae (papillary muscles) - Only one end attached to ventricular surface, other end point of attachment for tendon-like fibrous cords (chordae tendineae), which connect to free edges of cusps of tricuspid valve - 3inRV r x Anterior papillary muscle = largest, most constant, arises from anterior wall. [“ x Posterior papillary muscle = 1/2/3 structures, some chordae tendineae arising directly from ventricular wall. |" x Septal papillary muscle = most inconsistent papillary muscle, small / absent, chordae i tendineae emerging directly from septal wall. - Septomarginal trabecula (moderator band) x Specialised trabeculum. x Forms bridge between lower portion of interventricular septum & base of anterior papillary muscle. x Carries portion of cardiac conduction system - right bundle of atrioventricular bundle to anterior wall of RV. Pulmonary valve f At apex of infundibulum, outflow tract of RV, opening of pulmonary trunk closed by pulmonary valve. | 3 semilunar cusps. Free edges projecting upward into lumen of pulmonary trunk. - Left semilunar cusp. - Right semilunar cusp. - Anterior semilunar cusp. r x Cusps form pocket-like sinus (dilation in wall of initial portion of pulmonary trunk), after contraction, recoil of blood fills pulmonary sinuses, forces cusps closed = prevent RV from refilling. Left atrium: Forms most of base / posterior surface of heart. 2 halves. * Posterior half / inflow portion: receives 4 pulmonary veins, has smooth walls, derives from proximal parts of pulmonary veins. 71  Anterior half: continuous with left auricle, contains musculi pectinate, no distinct structure separate 2 components of LA. Mitral valve Left atrioventricular orifice opens into posterior side of superior LV. Closed during ventricular contraction by mitral / left atrioventricular valve / bicuspid valve. - Anterior cusp. - Posterior cusp. Bases of cusps secured to fibrous ring surrounding opening. Coordinated action of papillary muscles & chordae tenideae described for RV. Left ventricle: Contributes to anterior, diaphragmatic & left pulmonary surfaces of heart & forms apex. Chamber is conical, longer than RV, has thickest layer of myocardium. Outflow tract (aortic vestibule) = posterior to infundibulum on RV, has smooth walls. Trabeculae carneae in LV are fine & delicate - ridges & bridges the same to RV. Papillary muscles & chordae tendineae similar to RV. 2 papillary muscles. Anterior papillary muscle. Posterior papillary muscle. Aortic valve Outflow tract / aortic vestibule of LV, continuous superiorly with ascending aorta. Opening between aorta & LV closed by aortic valve. Valve has similar structure to pulmonary valve. - Free edge projecting upward into lumen of ascending aorta. - Between cusps & wall of aorta are pocket-like sinuses. x Right aortic sinus = right coronary artery originates here, x Left aortic sinus = left coronary artery originates here. x Posterior aortic sinus = (& cusp) sometimes referred to as non-coronary sinus & cusp. Interventricular septum: Forms anterior wall & some wall on right side. Septum has 2 parts Muscular part = thick & forms major part of septum. Membranous part = thin & upper part of septum. (Atrioventricular part) = positioned above septal cusp of tricuspid valve, between LV & RA. Arterial supply 2 coronary arteries. Arise from aortic sinuses in initial portion of ascending aorta. Supply muscle & other tissues of heart. Circle heart in coronary sulcus. Right coronary artery Originates = right aortic sinus of ascending aorta Branches * Atrial branch > sinu-atrial nodal branch. Right marginal branch. * Posterior interventricular branch. Supplies 72  RA RV * Sinu-atriai Atrioventricular node interatrial septum Portion of LA Posteroinferior one third of interventricular septum Portion of posterior part of LV Left coronary artery - ' Origin = left aortic sinus of ascending aorta. Branches Anterior interventricular branch > diagonal branches. Circumflex branch > left marginal artery. Supplies LA LV Most of interventricular septum Atrioventricular bundle & branches Variations of distribution patterns of coronary arteries 73  I Venous drainage Cardiac veins.. Coronary sinus receives 4 major tributaries. Great cardiac vein/anterior interventricular vein.,. - Origin: apex of heart. “r' * Middle cardiac vein / posterior interventricular vein. - Origin: near apex of heart. Posterior cardiac vein. Small cardiac vein. - Origin: lower anterior section of coronary sulcus between RA & RV Other cardiac veins. Anterior veins of RA / anterior cardiac veins. Venae cordis minimae / veins of Thebesius. Cardiac conduction system Musculature of atria & ventricles capable of contracting spontaneously. This system initiates & coordinates contraction. Consists of nodes & networks of specialised cardiac muscle cells organised into 4 basic components. Sinu-atrial node. Atrioventricular node. Atrioventricular bundle with right & left bundle branches. , Subendocardial plexus of conduction cells (Purkinje fibers). j Unique distribution pattern of cardiac conduction system establishes an important unidirectional pathway of excitation / contraction........ Throughout course, large branches are insulated from surrounding myocardium by CT - tends to decrease inappropriate stimulation & contraction of cardiac muscle fibers. Number of functional contracts between conduction pathway & cardiac musculature greatly increases in subendocardial network. 1 Unidirectional wave of excitation & contraction is established - moves from papillary muscles & apex of ventricles to atrial outflow tracts. , * i i 74 '  Sinu-atrial node " Impulses begin here —cardiac pacemaker. Collection of cells located at superior end of crista terminalis at junction of superior vena cava & RA. Also junction between parts of RA derived from embryonic sinus venosus & atrium proper. Excitation signals generated here spread across atria, causing muscle to contract Atrioventricular nodes Wave of excitation in atria stimulates atrioventricular node. Located near opening of coronary sinus, close to attachment of septal cusp of tricuspid valve & within atrioventricular septum. It is a collection of specialised cells that forms beginning of elaborate system of conducting tissue - atrioventricular bundle - extends excitatory impulse to all ventricular musculature. Atrioventricular bundle * Direct continuation of atrioventricular node. Follows along lower border of membranous part of interventricular septum before splitting into right & left bundles. - Right bundle branch x Continues on right side of interventricular septum toward apex of RV. x From septum enters septomarginal trabecula to reach base of anterior papillary muscle, x Here, divides and is continuous with final component of cardiac conduction system - subendocardial plexus of ventricular conduction cells / Purkinje fibers, x Network of specialised cells spread throughout ventricle to supply ventricular musculature including papillary muscle ' — Left bundle branch _ x Passes to left side of muscular interventricular septum, descends to apex of LV. x Along course, gives off branches that become continuous with subendocardial plexus of conduction cells / Purkinje fibers. x At right side, network of specialised cells spread excitation impulses throughout LV. Cardiac conduction system: 75 Cardiac innervation Cardiac plexus Superficial part. Deep part. Tributaries Parasympathetic = right & left cardiac branches of vagus nerve. Sympathetic = sympathetic trunk T4-T5. * Visceral afferents = vagal cardiac fibers (vagus n.) & cardiac fibers (cervical / thoracic portions of sympathetic trunk). Posterior mediastinum1 Posterior to pericardial sac & diaphragm & anterior to bodies of mid & lower thoracic vertebrae. Borders Superior transverse plane passing from sternal angle to intervertebral disc between vertebrae T4 & T5 Inferior = diaphragm. Lateral = mediastinal part of parietal pleura on either side. Superior = continuous with superior mediastinum. Contents Oesophagus & associated neve plexus. Thoracic aorta & branches. Azygos system of veins. Thoracic duct & associated lymph nodes. Sympathetic trunks. Thoracic splanchnic nerves. Muscular tube. Between: pharynx in neck & stomach in abdomen. ‘ ' ". Origin: inferior border of cricoid cartilage/ opposite vertebra C6. Terminates: cardiac opening of stomach, opposite vertebra Til. Descends on anterior aspect of bodies of vertebrae, in midline position as moves through thorax. As approaches diaphragm, moves anteriorly & to left, crossing from right side of thoracic aorta to assume position anterior to it. Passes through oesophageal hiatus at vertebral level T10. Slight anterior to posterior curvature that parallels thoracic portion of vertebral column. Secured superiorly by attachment to pharynx. Secured interiorly by attachment to diaphragm. Relationships to other structures in posterior mediastinum Right side covered by part of parietal pleura. Posterior to oesophagus = thoracic duct on right side inferiorly, but crosses to left more superiorly also on left is thoracic aorta. Anterior to oesophagus = below tracheal bifurcation level is right pulmonary artery & left main bronchus, oesophagus then passes posterior to LA, separated from it by pericardium. * Inferior to atrium = oesophagus related to diaphragm. Other structures posterior = portions of hemiazygos veins, right posterior intercostal veins near diaphragm the thoracic aorta. Flexible muscle tube can be compressed / narrowed by surrounding structures at places - Junction of oesophagus with pharynx in neck. - In superior mediastinum where oesophagus is crossed by arch of aorta. In posterior mediastinum where oesophagus compressed by left main bronchus. - In posterior mediastinum at oesophageal hiatus in diaphragm. Arterial supply & venous & lymphatic drainage « Oesophageal arteries origin = thoracic aorta, bronchial arteries & ascending branches of left gastric artery in abdomen. 77  Venous drainage = small vessels to azygos vein, hemiazygos vein & oesophageal branches to left gastric vein in abdomen. * Lymphatic drainage = returns to posterior mediastinal & left gastric nodes. Innervation Oesophageal branches origin: vagus nerves & sympathetic trunk. Striated muscle fibers in superior portion originate: branchial arches & are innervated by branchial efferents from vagus nerves. Smooth muscle fibers: innervated by components of parasympathetic part of ANS, visceral efferents from vagus nerves (preganglionic fibers that synapse in myenteric & submucosal plexuses of enteric nervous system in oesophageal wall. Sensory innervation: visceral afferent fibers originating in vagus nerves, sympathetic trunks & splanchnic nerves. Visceral afferents from vagus nerves relay info back to CNS about normal physiological processes & reflexes, not pain recognition. Visceral afferents passing through sympathetic trunks & splanchnic nerves primary participants in detection of oesophageal pain & transmission of info to various levels of CNS. Oesophageal plexus After passing posterior to root of lungs, right & left vagus nerves approach oesophagus. As reach oesophagus, each nerve divides into several branches that spread over structure, forming oesophageal plexus. Mixing of fibers from vagus nerves as plexus continues inferiorly on oesophageal toward diaphragm. Above diaphragm, fibers of plexus converge to form 2 trunks _ Anterior vagal trunk = on anterior surface of oesophagus, mainly from fibers originally in left vagus nerve. ~ _ ‘ - Posterior vagal trunk = on posterior surface of oesophagus, mainly fibers originally in right vagus nerve. *. Vagal trunks continue on surface of oesophagus as passes through diaphragm into abdomen. Thoracic aorta: Origins = at lower edge of vertebra T4, where is continuous with arch of aorta. Terminates = anterior to lower edge of vertebrae T12, where passes through aortic hiatus posterior to diaphragm. Situated to left of vertebral column superiorly, approaches midline inferiorly, lying directly anterior to lower thoracic vertebral bodies. Throughout course, gives off number of branches Branches Origin & course Pericardial branches Few small vessels to posterior surface of pericardial sac Vary in number, size & origin Bronchial branches Usually: 2 left bronchial arteries from thoracic aorta & 1 right bronchial artery from 3r posterior intercostal artery / superior left bronchial artery 4 / 5 vessels from anterior aspect of thoracic aorta - Form continuous anastomotic chain Oesophageal Anastomotic connections include: branches Oesophageal branches of inferior thyroid artery superiorly Oesophageal branches of left inferior phrenic & left gastric arteries inferiorly Several small branches supplying lymph nodes, vessels, nerves & areolar tissue in posterior Mediastinal branches mediastinum 78  Posterior intercostal Usually 9 pairs of vessels branching from posterior surface of thoracic aorta arteries Usually supply lower 9 intercostal spaces (1st 2 supplied by supreme intercostal artery - branch of costocervical trunk) Superior phrenic Small vessels from lower part of thoracic aorta supplying posterior part of superior surface of diaphragm arteries Anastomose with musculophrenic & pericardiacophrenic arteries Subcostal artery Lowest pair of branches from thoracic aorta located inferior to rib 12 Azygos system of veins: Consists of series of longitudinal vessels on each side of body that drain blood from body wall & move it superiorly to empty into SVC. Blood from thoracic viscera may also enter system - anastomotic connections with abdominal veins. May or may not be continuous & are connected to each other from side to side at various points throughout course. Function = important anastomotic pathway capable of returning venous blood from lower part of body to heart if IVC is blocked. Major veins in system Azygos vein on right. Hemiazygos vein & accessory hemiazygos vein on left. Significant variations in origin, course, tributaries, anastomoses & termination of vessels. Azygos vein Origin = opposite vertebra LI / L2 at junction between right ascending lumbar vein & right subcostal vein or direct branch of IVC, which is joined by common trunk from junction of right ascending lumbar vein & right subcostal vein. Enters thorax through / posterior to right crus of diaphragm. * Ascends through posterior mediastinum, usually to right of thoracic duct. Level T 4, arches anteriorly over root of right lung to join superior vena cava before SVC enters pericardial sac. Tributaries of azygos vein - Right superior intercostal vein (single vessel formed by junction of 2nd, 3rd & 4th intercostal veins) - 5th - 11th right posterior intercostal veins - Hemiazygos vein - Accessory hemiazygos vein - Oesophageal veins - Mediastinal veins - Pericardial veins - Right bronchial veins Hemiazygos vein (inferior hemiazygos vein) Origin = junction between left ascending lumbar vein & left subcostal vein or either of these veins alone & often has connection to left renal vein. Enters thorax through left crus of diaphragm or aortic hiatus. * Ascends through posterior mediastinum on left side to level T9, here crosses vertebral column posterior to thoracic aorta, oesophagus & thoracic duct to enter azygos vein. Tributaries - Lowest 4/5 left posterior intercostal veins - Oesophageal veins — Mediastinal veins Accessory hemiazygos vein (superior hemiazygos vein) 79  Descends on left from superior portion posterior mediastinum to level T8, here crosses vertebral column to join azygos vein / ends in hemiazygos vein / connection with both. Connection superiorly to left superior intercostal vein. Tributaries _ 4th-8th left posterior intercostal veins - Sometimes left bronchial veins Thoracic duct in posterior mediastinum: Main channel through which lymph from most of body is returned to venous system. Origin = confluence of lymph trunks in abdomen, sometimes forming saccular dilation - cisterna chyli (chyle cistern) - which drains abdominal viscera & walls, pelvis, perineum & lower limbs. Extends from L2 - root of neck. Enters thorax posterior to aorta through aortic hiatus of diaphragm. Ascends through posterior mediastinum to right of midline between thoracic aorta on left & azygos vein on right. Lies posterior to diaphragm & oesophagus & anterior to bodies of vertebra. At level T5, duct moves to left of midline & enters superior mediastinum & into neck. After being joined by left jugular trunk (drains left side of head & neck) & left subclavian trunk, (drains left upper limb), thoracic duct drains into junction of left subclavian & left internal jugular veins. Tributaries Confluence of lymph trunks in abdomen. Descending thoracic lymph trunks draining lower 6/7 intercostal spaces on both sides. - "**& Upper intercostal lymph trunks draining upper left 5/6 intercostahspaces..... : ^ Ducts from posterior mediastinal nodes. :i-........... Ducts from posterior diaphragmatic nodes. Sympathetic trunks: PartofANS. Component of posterior mediastinum as pass through thorax. This portion of 2 parallel cords punctuated by 11 / 12 ganglia. Ganglia connected to adjacent thoracic spinal nerves by white & gray rami communicantes & are numbered according to thoracic spinal nerve with which are associated. In superior portion of posterior mediastinum, trunks anterior to neck of ribs. Interiorly become more medial in position until lie on lateral aspect of vertebral bodies. Leave thorax by passing posterior to diaphragm under medial arcuate ligament / through crura of diaphragm. Throughout course = trunks covered by parietal pleura. Branches from ganglia Branches from upper 5 ganglia - Mainly postganglionic sympathetic fibers. - Supply various thoracic viscera. - Branches relatively small, contain visceral afferent fibers. Branches from lower 7 ganglia - Mainly preganglionic sympathetic fibers. - Supply various abdominal & pelvic viscera. - Braches are large, carry visceral afferent fibers. - Branches form 3 thoracic splanchnic nerves. x Greater splanchnic nerve x Lesser splanchnic nerve x Least/lower splanchnic nerve 80  HEAD & NECK In this region: Osteology Joints Face Scalp Orbit Ear Temporal & infratemporal fossae Neck Pharynx Larynx Oesophagus Trachea & bronchial tree Oral cavity Nose & nasal cavities Tips: ^ Study all the osteological landmarks of the skull, by directly studying the pictures in Netter as indicated by page numbers. \ ' - S Foramina in the skull are important, including their contents..... 81 Osteology see p. 4-10 (Netter) 22 bones excluding ossicles. Bones of skull attached to one another by sutures (except mandible). Sutures are immobile (synarthrosis). Forms cranium which can be divided into 3. Calvaria = upper domed part, covers cranial cavity containing brain. Base = floor of cranial cavity. Viscerocranium / facial skeleton = lower anterior part. Mandible not part of cranium or viscerocranium. Calvaria Base Viscerocranium Temporal Parts of: Nasal Parietal Sphenoid Palatine Pa rts of: Temporal Lacrimal Frontal occipital Zygomatic Sphenoid Maxillae occipital Inferior nasal conchae Vomer Paired & unpaired bones of skull Paired Unpaired Temporal Frontal Parietal Occipital Zygomatic Sphenoid Maxilla Ethmoid Lacrimal Vomer Nasal Mandible Palatine Inferior nasal conchae Cranial Cavity1- see p. 9-10 (Netter) Roof of cranium: Comprised of 3 bones: Frontal Parietal Occipital Sutures: Coronal = b/w frontal & parietal. Sagittal = b/w parietals. * Lambdoid = b/w parietal & occiptital. Visible junctions where sutures meet: * Bregma - coronal + sagittal. Lambda - lambdoid + sagittal. Base of the cranium:  Comprised of 6 bones: * Frontal Sphenoid Ethmoid * Occipital Parietal Temporal Cranial fossae1 - see p. 11-13 (Netter) 3 hollows on internal aspect of base of cranium in which brain rests. Anterior cranial fossa: Consists of 3 bones Frontal bone Ethmoid bone Sphenoid bone Boundaries Anteriorly & laterally = frontal bone. Midline = ethmoid bone. Posteriorly = 2 parts of sphenoid bone, body (midline) & lesser wings (laterally). Features Frontal bone marked in midline by body ridge, known as frontal crest - projects upwards, acts as site of attachment for falx cerebri (a sheet of dura mater that divides the two cerebral hemispheres). In midline of ethmoid bone, crista galli is situated - upwards projection of bone, which acts as another point of attachment for falx cerebri. On either side of crista galli is cribriform plate - sheet of bone which contains numerous small foramina (transmit olfactory nerve fibres (CN I) into nasal cavity). * It also contains two larger foramina - Anterior ethmoidal foramen: transmits anterior ethmoidal artery, nerve & vein. - Posterior ethmoidal foramen: transmits posterior ethmoidal artery, nerve & vein. Anterior aspect of sphenoid bone lies within anterior cranial fossa. From central body, lesser wings arise - rounded ends of lesser wings are known as anterior clinoid processes (serve as place of attachment for tentorium cerebelli, a sheet of dura mater that divides cerebrum from cerebellum). Foramen Structures passing through Foramen cecum Emissary veins to nasal cavity Olfactory foramina in cribriform plate Olfactory nerves (1) Middle cranial fossa: Consists of 3 bones * Sphenoid bone 2 temporal bones * Boundaries Anteriorly & laterally = lesser wings of sphenoid bone, (two triangular projections of bone that arise from the central sphenoid body). Anteriorly & medially = limbus of sphenoid bone (limbus is bony ridge that forms anterior border of chiasmatic sulcus, a groove running between the right and left optic canals). Posteriorly & laterally = superior border of petrous part of temporal bone. 83  * Posteriorly & medially = dorsum sellae of sphenoid bone (large superior projection of bone that arises from sphenoidal body). Floor - body & greater wing of sphenoid & squamous & petrous parts of temporal bone. Features Consists of a central portion, which contains pituitary gland & two lateral portions, which accommodate temporal lobes of brain. Both parts of fossa are marked by numerous bony landmarks. Central Part... - Formed by body of sphenoid bone. - Contains sella turcica which is a saddle-shaped bony prominence. - Acts to hold & support pituitary gland, and consists of 3 parts. x The tuberculum sellae (horn of the saddle). ° Vertical elevation of bone. ° Forms anterior wall of sella turcica & posterior aspect of chiasmatic sulcus (a groove running between the right and left optic canals), x The hypophysial fossa or pituitary fossa (seat of the saddle). ° Sits in middle of sella turcica. ° Depression in body of sphenoid, which holds the pituitary gland, x The dorsum sellae (back of the saddle). ° Forms posterior wall of sella turcica. ° Large square of bone, pointing upwards & forwards. ° Separates middle cranial fossa from posterior cranial fossa. - ~The sella turcica is surrounded by anterior & posterior clinoid processes. - Anterior clinoid processes arise from sphenoidal lesser wings, while posterior clinoid processes are superolateral projections of dorsum sellae. - They serve as attachment points for tentorium cerebelli, a membranous sheet that divides brain. Foramen Structures passing through Optic canal Optic nerve (II) Ophthalmic artery Superior orbital fissure Oculomotor nerve (III) Trochlear nerve (IV) Ophthalmic division of trigeminal nerve (VI) Abducent nerve (VI) Ophthalmic veins Foramen rotundum Maxillary division of trigeminal nerve (V2) Foramen ovale Mandibular division of trigeminal nerve (V3) Lesser petrosal nerve Foramen spinosum Middle meningeal artery Hiatus for greater petrosal nerve Greater petrosal nerve Hiatus for lesser petrosal nerve Lesser petrosal nerve Posterior cranial fossa: Comprised of 3 bones Occipital bone 2 temporal bones Boundaries ' Anteriorly & medially = dorsum sellae of sphenoid bone (large superior projection of bone that arises from body of sphenoid). 84  * Anteriorly &laterally = superior border of petrous part of temporal bone. " Posteriorly = internal surface of squamous part of occipital bone. Floor = mastoid part of temporal bone and squamous, condylar & basilar parts of occipital bone. Features Temporal Bone - Internal acoustic meatus is oval opening in posterior aspect of petrous part of temporal bone. - Transmits the facial nerve (CVII), vestibulocochlear nerve (CN VIII) and labrynthine artery. Occipital Bone - Large opening, foramen magnum, lies centrally in floor of posterior cranial fossa. - Largest foramen in skull. - Anteriorly an incline, known as clivus, connects foramen magnum with dorsum sellae. - Jugular foramina are situated either side of foramen magnum. - Immediately superior to anterolateral margin of foramen magnum is the hypoglossal canal. — Posterolaterally to foramen magnum lies cerebellar fossae. - These are bilateral depressions that house the cerebellum - divided medially by a ridge of bone, the internal occipital crest. _Structures passing through End of brainstem / beginning of spinal cord Vertebral arteries Spinal roots of accessory nerve Meninges_ Facial nerve (VII) Vestibulocochlear nerve (VIII) Labyrinthiheartery. Glossopharyngeal nerve (IX) Vagus nerve (X)