HUB105 Practical 16-18 Thorax PDF

HUB105 PRACTICALS 16, 17 & 18 THORAX DR CS OPUWARI  Thoracic wall The thoracic wall is covered externally by the skin and muscles attaching the shoulder girdle to the trunk. It is lined internally by endothoracic fascia. It extends between the superior and...

HUB105 PRACTICALS 16, 17 & 18 THORAX DR CS OPUWARI  Thoracic wall The thoracic wall is covered externally by the skin and muscles attaching the shoulder girdle to the trunk. It is lined internally by endothoracic fascia. It extends between the superior and inferior thoracic apertures. Superficial thoracic muscles You must dissect out the more superficial muscles before the thoracic wall is removed  Boundary of thoracic wall Posteriorly - Thoracic part of the vertebral column Anteriorly - Sternum and costal cartilages Laterally - Ribs and intercostal spaces Superiorly - Suprapleural membrane Inferiorly - Diaphragm  Superior thoracic aperture Bounded by: ▪1st Thoracic vertebra (posteriorly) ▪1st rib (laterally) ▪manubrium of sternum (anteriorly)  Inferior thoracic aperture Bounded by: 12th thoracic vertebra (posteriorly) 11th and 12th pairs of ribs (laterally) Costal cartilages of ribs 7-10 and xiphisternal joint (anteriorly)  The thoracic cage Not ossified until ~ age 40 Note all the joints associated with the rib cage. The thoracic cage Intercostal space A. Anterolateral view  Intercostal space … B. Details of an intercostal space and its relationships. Intercostal space … C. Transverse section.  What is the difference between: The rib cage and the thoracic wall? The anterior and posterior thoracic walls What dissection procedures happen prior to the “butterfly cut” usually done to remove the anterior thoracic wall? Name the muscles that form the thoracic wall. The posterior view of the anterior thoracic wall The posterior view of the anterior wall shows blood vessels, muscles and nerves. This part is often covered by the endothoracic fascia (what is this?) What functions do transversus thoracis muscles perform? Arterial supply to thoracic wall https://www.youtube.com/watch?v=wHgXHqK2E2M Venous drainage of thoracic wall https://www.youtube.com/watch?v=Gk8CORE_vEE Veins drain into: Azygos/hemiazygous veins >>SVC Or 8th Internal thoracic veins >> brachiocephalic veins Left side Posterior ICVs: supreme; 2,3,4 veins >>> left superior ICVs >>> left BCV. 9th Right side Posterior ICVs: supreme >> right BCV; 2,3,4 veins >>> right superior ICVs >>>> azygos vein. FIRST FOUR ICVs Azygos System of veins that drains the thoracic wall – video 1 Azygos System of veins that drains the thoracic wall – video 2 Intercostal Nerves The intercostal nerves are the anterior rami of the first 11 thoracic nerves. ▪ The first 6 intercostal nerves are distributed within their intercostal spaces. ▪ The 7th- 9th intercostal nerves leave the anterior end of their intercostal space by passing deep to the costal cartilage to enter the anterior abdominal wall. ▪ The 10th and 11th intercostal nerves pass directly into the abdominal wall. ▪ The 12th intercostal nerve runs lies in the abdomen and runs forward in the abdominal wall as the subcostal nerve. Typical intercostal nerves (3-6)  Atypical intercostal nerve (1) T1 divides into a large superior and a small inferior part. ▪ The superior part joins the brachial plexus (= to the lateral cutaneous branch of a typical intercostal nerve). ▪ The inferior part becomes the 1st intercostal nerve and there is no anterior cutaneous branch. The 1st intercostal nerves course on the internal surface of the 1st rib, instead of along the inferior margin in costal grooves. Atypical intercostal nerves (2) The 2nd intercostal nerve is joined to the medial cutaneous neve of arm by the intercostobrachial nerve (= lateral cutaneous branch of the typical nerve); it emerges from the 2nd intercostal space at the MAL. ▪ Supplies the skin of the axilla and the upper medial side of the arm. The 2nd intercostal nerves course on the internal surface of the 2nd rib, instead of along the inferior margin in costal grooves. Typical intercostal nerves (3-6) The lymphatic drainage of thoracic wall To axillary lymph nodes To parasternal lymph nodes (to thoracic duct (left) and bronchomediastinal trunk (right)). To intercostal lymph nodes (to thoracic duct).  Lymphatic drainage Thoracic duct drains the lower limbs, pelvic cavity, abdominal cavity, left side of thorax, head and neck and arm. Right lymphatic duct only drains lymph from the right arm, thorax, head and neck. The thoracic cavity 26 This is what you see after removing the anterior thoracic wall Heart in the mediastinum (what does this mean?) Lungs on both sides Blood vessels entering and leaving heart and lungs Connective tissue coverings of the lungs and heart (name these) Normally, this space is very tightly packed and you will need to carefully remove the lungs first, before the heart. The mediastinum The Pleura and Lungs 1. Provide the labels 2. What differences do the lungs have at their hilum? 3.Describe the pleura (visceral and parietal layers).  The heart The beating heart Read up these: Provide the labels Heart coverings Heart blood vessels Heart valves Heart chambers Heart blood supply Heart venous drainage  The diaphragm Respiratory muscle; active in inspiration; raises abdominal pressure. 3 Parts: Sternal part, Costal part and Vertebral part 1. Sternal part- posterior surface of the xiphoid process 2. Costal part- deep surfaces of the lower six ribs and their costal cartilages 3. Vertebral (lumbar) part- vertical columns or crura and from the arcuate ligaments. Insertion: All 3 parts unite in the central tendon. Nerve supply: ▪ Motor- left and right phrenic nerves (C3-C5)- motor ▪ Sensory- phrenic nerves (parietal pleura and peritoneum covering the central surfaces of the diaphragm)and lower six intercostal nerves (periphery of the diaphragm). Crus = elongated part of an anatomical structure, especially one which occurs in the body as a pair. Vena caval foramen Lumbar Part, Sternal right crus medial part Esophageal part A hiatus Costal part Aortic foramen A B Central tendon P The diaphragm and abdominal muscles (A) viewed from below and (B) viewed from in front The diaphragm: parts, openings, innervation Caval foramen (T8, in the central tendon) - right and left crura of the central tendon ▪ Inferior vena cava, right phrenic nerve and few lymphatics Esophageal hiatus is in the lumbar muscular part (T10) – ▪ Oesophagus, anterior and posterior vagal trunks, left gastric arteries and veins, lymphatic vessels Aortic hiatus, left of midline (T12) ▪ Aorta, thoracic duct, azygos vein and hemi-azygous vein Innervation: Phrenic nerve; from the cervical plexus (C3-C5) A