PT 0500 Thorax and Viscera Update PDF

1 PT 0500 Human Anatomy Thoracic Viscera 1. Review of the Thorax A. Function i. Protect thoracic or...

1 PT 0500 Human Anatomy Thoracic Viscera 1. Review of the Thorax A. Function i. Protect thoracic organs ii. Resist negative pressure during inhalation iii. Provide attachment and support for UE joints and muscles B. Superior Thoracic Aperture (Thoracic Inlet) i. Bounded by T1 vertebra, First ribs and Manubrium ii. Trachea, esophagus, nerves and vessles to/from head, neck and UEs pass through C. Inferior Thoracic Aperture (Thoracic Outlet) i. Bounded by T12 vertebra, 11th and 12th ribs (posterolaterally), Subcostal border (costal cartilage of R7-R10, anterolaterally), xiphisternal joint (anteriorly) D. Internal Spaces i. Right and Left pulmonary cavities ii. Mediastinum (see below for details) Section 1  2 2. The Mediastinum (central thoracic compartment b/t pulmonary cavities) A. Superior i. Superior thoracic aperture to level of T4-T5 (and sternal angle) ii. Contains: thymus, great vessels and branches, SVC, trachea, esophagus, thoracic duct, vagus n, phernic n, cardiac plexus, recurrent laryngeal nn, brachiocephalic v B. Posterior (Inferior Mediastinum) i. Contains: thoracic aorta, thoracic duct, lymph nodes, azygous and hemi-azygous vv, esophagus, sympathetic trunks and splanchnic nn C. Middle (Inferior Mediastinum) i. Contains pericardium, heart, roots of great vessels, root (hilum) of lungs, phrenic n D. Anterior (Inferior Mediastinum) i. Contains: loose connective tissue, part of thymus gland Section 1  3 3. CardioVascular System A. Heart i. Chambers and Specialized Features a. Right and Left Atrium 1) Lined with pectinate muscles 2) Separated by interatrial septum 3) Fossa Ovalis in interatrial septum Right Atrium Section 2  4 b. Right and Left Ventricles 1) Trabeculae carneae: muscles in walls of ventricles 2) Interventricular septum: separates ventricles 3) Papillary muscles: anchor chordae tendinae to ventricular walls. Contract to prevent prolapse of AV valves during systole 4) Conus arteriosus (infundibulum): smooth walled portion of R ventricle leading into pulmonary trunk 5) Septomarginal Trabecula (moderator band): in R ventricle, muscular bundle that carries part of the right branch of AV bundle toward anterior papillary muscle Right Ventricle ii. Valves a. AV Valves 1) Chordae tendinae: anchor tricuspid (right) and mitral (left) valves to papillary muscles b. Pulmonic Valve (semilunar valve, 3 cusps) c. Aortic Valve (semilunar valve, 3 cusps) Section 2  5 iii. Order of blood flow through the heart a. Deoxygenated blood returns to the heart from the superior and inferior vena cava b. Right atrium c. Tricuspid valve d. Right ventricle e. Pulmonary semilunar valve (pulmonic valve) f. Pulmonary trunk  Left and right pulmonary arteries g. Lungs h. Pulmonary veins i. Left atrium j. Bicuspid valve (Mitral valve) k. Left ventricle l. Aortic valve (aortic semilunar valve) m. Aorta -> takes oxygenated blood to the body Section 2  6 iv. Fibrous Skeleton a. Connective tissue rings that support the AV and semilunar valves b. Provides attachment for the valves and myocardium c. Electrically insulates the ventricles from the atria v. External Structure of the Heart a. Apex: Inferolateral portion of left ventrical b. Base: Posterior (formed by left atrium and part of right atrium) c. Coronary Sulcus: marks separation of atria and ventricals d. Anterior and Posterior Interventricular Sulci: grooves separating Right and Left Ventricals e. Surfaces 1) Anterior (sternocostal) 2) Diaphragmatic (inferior) 3) Right Pulmonary 4) Left Pulmonary Section 3  7 vi. Conducting System a. SA node: inherent rhythm 60-100 BPM b. Atrial walls c. AV node: inherent rhythm 40-60 BPM d. AV Bundle: inherent rhythm 15-40 BPM, run through fibrous septum between atria and ventricles e. AV Bundle branches: split and spread conduction downward into each ventricle f. Moderator Band (Septomarginal Trabecula): part of R A-V bundle carried in trabeculae carneae muscle from IV septum twd papillary muscle g. Purkinje Fibers: small branches off AV bundle branches h. Ventricular Walls vii. Innervation to the Heart a. Cardiac Plexus 1) Sympahtetic cardiopulmonary splanchnic nerves   HR b. Parasympathetic via vagus nerves   HR Section 3  8 viii. Pericardium a. Fibrous Pericardium 1) Dense connective tissue continuous with adventitia (outer covering) of great vessels superiorly and connected to central tendon of diaphragm inferiorly b. Serous Pericardium 1) Parietal layer: lining fibrous pericardium a) Creates a continuous sac with visceral pericardium 2) Visceral layer is the epicardium (see layers below) c. Neurovascular Supply to Pericardium 1) Arterial supply: Pericardiophrenic artery (off internal thoracic) 2) Innervation: Phrenic nerves, Vagus nerves, Sympahtetic trunk (vasomotor) Section 4  9 ix. Heart: 3 Layers of tissue a. Epicardium: Connective tissue covering. Thin layer of mesothelium. (visceral layer of serous pericardium) b. Myocardium: cardiac muscle tissue 1) Striated 2) Single central nuceus 3) Intercalated discs, branching cells c. Endocardium i. simple squamous epithelium ii. Basal Lamina iii. Subendocardium Loose connective tissue, elastic fibers, collagen fibers In contact with myocardium Contains blood vessels and nerve and conducting system of the heart Section 4  10 x. Coronary Blood Supply a. Right Coronary Artery 1) Supplies R atrium and ventricle and parts of the L ventricle a) In most people also supplies SA node (60%) and AV node (80%) 2) Major Branches a) Marginal a b) Posterior interventricular (descending) 3) Dominance: dominance in the heart refers to which coronary artery supplies the posterior interventricular. In ~70% of people the R is dominant. b. Left Coronary Artery 1) Larger than R, supplies most of L ventricle and atrium, the IV septum and some R ventricle 2) Branches a) Anterior Interventricular (Left Anterior Descending) b) Circumflex c. Cardiac Veins 1) Great Cardiac Vein (follows LAD) 2) Middle Cardiac Vein (follows post interventricular a) 3) Small Cardiac Vein (follows Marginal a) 4) Coronary Sinus: drainage from all main cardiac vessels  empties into R atrium a) Anterior Cardiac veins empty into auricle of R atrium Section 5  11 B. Surface Projections of the Heart i. Apex: 5th L intercostal space ii. Aortic area (ausculatatory area) R second intercostal space iii. Pulmonic area: L second intercostal space iv. Tricuspid area: 4th L intercostal space v. Mitral area: 5th L intercostal space Section 5  12 C. Major Arteries in the Thorax i. Aorta (in posterior mediastinum) a. Ascending 1) Coronary Arteries b. Arch 1) R Brachiocepalic (branches to R subclavian and R common carotid) 2) L Common Carotid 3) L Subclavian a) Internal thoracic artery branches off c. Descending Thoracic Aorta (key branches) 1) Bronchial aa 2) Posterior intercostal aa  anastamose with anteiror intercostal aa d. Abdominal Aorta (to be covered with abdomen) e. Blood supply to the superficial thorax (external to the ribs) comes off the axillary artery (continuation of the subclavian) More on this later. Section 6  13 D. Major Veins i. Superior Vena Cava a. Venus return from all structures superior to diaphragm (excluding heart and lungs) ii. Inferior Vena Cava iii. Azygous (R), Hemiazygous and Accessory Hemiazygous (L) a. Drain posterior thoracic and abdominal walls and viscera of the mediastinum b. Drain into SVC (accessory joins hemi which then drains into azygous  SVC) Section 6  14 E. Orientation of Vessels and Nerves i. Superior Mediastinum a. Thymus (lymphoid organ)  replaced by fat after puberty b. Superior vena cava and tributaries c. Arch of the aorta and branches 1) Ligamentum arteriosum (fetal remnant of what?) d. Vagus Nerves 1) Left recurrent laryngeal nerve hooks around arch of aorta e. Phrenic nerves 1) Run anterior to the root of the lungs f. Trachea and Esophagus g. Thoracic duct and lymphatic trunks ii. Posterior Mediastinum a. Thoracic Aorta 1) Posterior to root of L lung and esophagus 2) Pierces diaphragm at level of T12 b. Esophagus c. Thoracic duct and lymphatic trunks d. Azygos veins e. Thoracic sypmathetic trunks and lower thoracic splanchnic nerves Section 6  15 4. Pulmonary System A. Overview of the Lungs i. Apex (superior) and Base ii. Surfaces of the Lungs a. Costal Surface: Smooth and convex b. Mediastinal Surface: Concave, grooved for passing vessels c. Diaphragmatic Surface: Base of the lung iii. Boarders a. Anterior: where costal and mediastinal surfaces meet b. Inferior: b/t diaphragmatic and costal/mediastinal surfaces c. Posterior: where costal and mediastinal surfaces meet posteriorly iv. Roots of the Lung and Hilum a. Root of the Lung 1) Pulmonary artery 2) Pulmonay veins (superior and inferior) 3) Main bronchus b. Hilum 1) Wedge-shaped area on mediastinal surface (where the root enters the lung) Section 7  16 v. Right Lung a. Lobes/Segments 1) Superior: apical, posterior, anterior 2) Middle: lateral, medial 3) Inferior: superior, anterior basal, posterior basal, medial basal, lateral basal b. Fissures 1) Oblique 2) Horizontal c. Impressions 1) Groove for inferior vena cava 2) Groove for superior vena cava 3) Groove for arch of azygos vein 4) Groove for esophagus Section 7  17 vi. Left Lung a. Lobes/Segments 1) Superior: apicoposterior, anterior, superior lingular, inferior lingular 2) Inferior: superior, anteromedial basal, lateral basal, posterior basal b. Fissure 1) Oblique c. Impressions 1) Cardiac impression 2) Groove for descending aorta 3) Groove for subclavian artery Section 7  18 B. Pleura (connective tissue covering lung tissue) i. Parietal Pleura a. Lines pulmonary cavities b. Parts 1) Costal Part 2) Mediastinal Part 3) Diaphragmatic Part 4) Cervical Peura (what is the cupola?) ii. Visceral Pleura a. Adherent to lung tissue (cannot be separated) b. Continuous with parietal pleura at hilum of lungs iii. Pleural Cavity a. Potential space b/t parietal and visceral b. Filled with serous fluid (small amount) c. Allows pleura to slide over each other during movement d. What is pleurisy? Section 7  19 C. Vasculature of the Pleura and Lungs i. Bronchial Arteries and Veins: supply nutrition to the lungs and visceral pleura (also supply upper esophagus) ii. Pulmonary Lymphatic Plexus: primarily drain into thoracici duct and right lymphatic duct (upper cervical pleura may drain into axilary) D. Innervation of the Lungs i. Symphathetic (from paravertebral ganglia of sympathetic trunks) a. Bronchodilation, vasoconstriction, and inhibitory to glands ii. Parasympathetic (from vagus nerve) a. Bronchoconstriction, vasodilation, secretomotor to galnds iii. Visceral afferents a. Reflexive responses (coughing) b. Blood pressure and blood gas c. Nociception iv. Sensory receptors in parietal pleura (touch and pain) a. from intercostal nerves and phrenic nerves Section 7  20 E. Trachea i. Extends from C5-C6 to T4-T5 ii. Extends from larynx to carina (bifurcation at T4-T5 level) F. Bronchi (primary, secondary, tertiary) i. Right primary bronchus is angled more vertically  greater risk of aspiration into R than L ii. Enter the lungs at the hilum (as part of the root) of the lung and branch into lobar (secondary) bronchi Section 8  21 iii. Lobar bronchi branch into segmental (tertiary) bronchi. Each segmental bronchus serves one segment of the lung. A segmental bronchus and its associated segment of the lung are known as a bronchopulmonary segment. a. Lobes of the lungs 1) Right: superior, middle, inferior 2) Left: superior, inferior iv. Bronchopulmonary Segment: a. Largest subdivision of a lobe b. Separated from adjacent segments by connective tissue c. Supplied independently by tertiary branch of pulmonary artery and segmental bronchus d. Surgically respectable v. Segments of the lungs (do NOT memorize these!!) a. Right Lung 1) Superior lobe: apical, anterior, posterior 2) Middle lobe: lateral, medial 3) Inferior lobe: superior, anterior basal, medial basal, lateral basal, posterior basal b. Left Lung 1) Superior lobe: Apicoposterior, anterior, superior lingular, inferior lingular 2) Inferior lobe: superior, anteromedial basal, lateral basal, posterior basal Section 8  22 G. Terminal Bronchioles i. Less than 1mm diameter ii. Simple cuboidal epithelium iii. Lack cartilage, have smooth muscle in their walls iv. Contain Clara cells (immune function) Section 8  23 H. Acini: chief functional unit of the lung. Respiratory Zone: where gas is exchanged between blood and air. i. Respiratory bronchioles: conduct air, but can also contribute to gas exchange ii. Alveolar ducts: an abundance of alveoli along iii. Alveoli: primary site of gas exchange a. Lined with simple squamous epithelium for easy diffusion Section 8  24 I. Muscles of Ventilation i. Inspiration a. Diaphragm 1) Attachments a) Posterior xiphoid process and sternum (anterior) b) Internal surface inferior 6 costal cartlilages/ribs (lateral) c) Superior lumbar vertebrae (posterior) d) Inferior surface fibrous pericardium via central tendon 2) Innervation: a) Phrenic Nerve (C3-C5) 3) Action a) Descends with inspiration 4) Has openings for major vessels/ structures a) Caval opening (IVC) at T8 b) Esophageal hiatus at T10 c) Aortic hiatus at T12 b. External intercostals (see back muscles notes) c. Accessory (more on these with the neck) 1) SCM 2) Scalenes ii. Expiration a. Quiet breathing = passive recoil b. Active expiration 1) Internal intercostals (more with back muscles) c. Forces expiration 1) Abdominals (more on these in the next lecture) Section 9  25 iii. Mechanics of Veniltation a. Upper Ribs lift antero-superior with inspiration b. Middle/lower ribs list supero-lateral with inspiration Section 9  26 J. Surface Anatomy of Lungs i. Apices for lungs: in supraclavicular fossa (posterior and superior to clavicle), just lateral to SCM (projects above level of first rib) ii. Oblique Fissure: SP T2  6th costal cartilage anteriorly (if arm is elevated, follow medial boarder of scapula) iii. Horizontal Fissure: from oblique fissure posteriorly along 4th rib anteriorly iv. Inferior border of lungs: 6th costal cartilage at sternum (4th on L)  6th costal cartilage at MCL  8th rib at MAL  10th rib at SL  SP of T10 Section 10  27 K. Referred Pain Patterns for the Pulmonary System i. Diaphragm and mediastinal pleura: C3-C5  (neck and shoulder) ii. Pleura: dermatomal along thoracic and abdominal walls iii. Innervated by intercostal nerves and phrenic nerve iv. Can be substernal or chest region (over the involed portion of lung) Section 10