Mod 6 - Lecture 1 - Thoracic Wall PDF

Thoracic Wall Surface anatomy, bones, muscles, blood vessels, and nerves Learning Outcomes Describe the surface anatomy of the thoracic walls and its major landmarks. Identify and describe the bones that make the rib cage. Identify and describe the muscles of the thorax. Identify and...

Thoracic Wall Surface anatomy, bones, muscles, blood vessels, and nerves Learning Outcomes Describe the surface anatomy of the thoracic walls and its major landmarks. Identify and describe the bones that make the rib cage. Identify and describe the muscles of the thorax. Identify and describe the blood vessels of the thorax. Identify and describe the nerve supply of the thorax. Overview Of Thorax The Thorax is the part of the body between the neck and abdomen. The Chest is much more extensive than the thorax including shoulders and breasts. The Thoracic Cavity and its wall have the shape of a truncated cone, contains pleural cavity, pericardial cavity, and mediastinum.  Thoracic Wall Functions : Protect vital thoracic organs. Resist the negative pressures generated by inspiratory movements. Provide attachment for and support the weight of the upper limbs. Provide the anchoring attachment of many of the muscles that move and maintain the position of the trunk and upper limbs. The wall of the thoracic cavity is relatively thin, essentially made from the thoracic cage (rib cage), made by ribs and costal cartilages, sternum and thoracic vertebrae. The floor of the thoracic cavity is made by thoracic diaphragm. Ribs, Costal Cartilages, and Intercostal Spaces True (vertebrosternal) ribs (1st–7th ribs): They attach directly to the sternum through their own costal cartilages. False (vertebrochondral) ribs (8th, 9th, and usually 10th ribs): Their cartilages are connected to the cartilage of the rib above them; thus, their connection with the sternum is indirect. Floating (vertebral, free) ribs (11th, 12th, and sometimes 10th ribs): The rudimentary cartilages of these ribs do not connect even indirectly with the sternum; instead, they end in the posterior abdominal musculature. Ribs, Costal Cartilages, and Intercostal Spaces Typical ribs (3rd–9th) have the following components: Head: make a joint with bodies of two thoracic vertebrae Neck: between the head and tubercle Tubercle: located at the junction of the neck and body; articulates with the corresponding transverse process of the vertebrae Body (shaft): thin, flat, and curved, part. It has a costal groove paralleling the inferior border that provides some protection for the intercostal nerve and vessels. Ribs, Costal Cartilages, and Intercostal Spaces Atypical ribs (1st, 2nd, and 10th–12th): The 1st rib is widest and nearly horizontal, shortest, and most sharply curved. It has a single facet on its head and two transversely directed grooves crossing its superior surface for the subclavian vessels. The 2nd rib has articulation with the bodies of the T1 and T2 vertebrae; its main atypical feature is a rough area on its upper surface, the tuberosity for serratus anterior. The 10th–12th ribs, have only one facet on their heads and articulate with a single vertebra. They are short and have no neck or tubercle.  Thoracic Vertebrae Long, inferiorly slanting spinous processes. Bilateral costal facets (demifacets) on the vertebral bodies, for articulation with the heads of ribs. Costal facets on the transverse processes for articulation with the tubercles of ribs, except for the inferior two or three thoracic vertebrae.  The Sternum The sternum (G. sternon, chest) is the flat, elongated bone that forms the middle of the anterior part of the thoracic cage. consists of three parts: Manubrium Body Xiphoid process. jugular notch (suprasternal notch) The concave center of the superior border of the manubrium Clavicular notches receive clavicls forming the sternoclavicular (SC) joints  Thoracic Apertures The superior thoracic aperture is bounded as follows: Posteriorly, by vertebra T1, Laterally, by the 1st pair of ribs and their costal cartilages Anteriorly, by the superior border of the manubrium The inferior thoracic aperture, the anatomical thoracic outlet, is bounded as follows: Posteriorly, by the 12th thoracic vertebra, Posterolaterally, by the 11th and 12th pairs of ribs Anterolaterally, by the joined costal cartilages of ribs 7–10, forming the costal margins Anteriorly, by the xiphisternal joint Joints of Thoracic Wall Intervertebral (of vertebrae T1–T12) Costovertebral Joints of head of rib Costotransverse Costochondral Lateral end of costal cartilage with sternal end of rib Sternocostal Sternoclavicular Sternal end of clavicle with manubrium of sternum Manubriosternal Xiphisternal  Muscles of Thoracic Wall Interior Muscle Superior Attachment Innervation Main Action Attachment Serratus Nuchal ligament, 2nd–5th Superior borders posterior spinous processes of intercostal Proprioception (elevate ribs) of 2nd–4th ribs superior C7–T3 vertebrae nerves Serratus Inferior borders of Anterior rami to Spinous processes of posterior 8th–12th ribs near T9–T12 thoracic Proprioception (depress ribs) T11–L2 vertebrae inferior their angles spinal nerves Subjacent ribs Posterior Levator Transverse between tubercle primary rami of Elevate ribs costarum processes of C7–T11 and angle C8–T11 nerves External Elevate ribs during forced intercostal inspiration Internal Superior border of Interosseous part: intercostal Inferior border of ribs During active ribs below depresses ribs (forced) Innermost Interchondral respiration intercostal Intercostal part: elevates ribs nerve Internal surface of lower Superior borders of Probably act in same manner as Subcostal ribs near their angles 2nd or 3rd ribs below internal intercostal muscles Internal surface of Transversus Posterior surface of Weakly depress ribs costal cartilages thoracis lower sternum Proprioception? 2–6 Nerves of Thoracic Wall Arteries of Thoracic Wall Artery Origin Superior intercostal artery Posterior (intercostal spaces 1 and 2) intercosta and thoracic aorta ls (remaining intercostal spaces) Internal thoracic Anterior (intercostal spaces 1–6) intercosta and musculophrenic ls arteries (intercostal spaces 7–9) Internal Subclavian artery thoracic Subcostal Thoracic aorta  Veins of Thoracic Wall The posterior intercostal veins anastomose with the anterior intercostal veins (tributaries of internal thoracic veins) The intercostal veins accompany the intercostal arteries and nerves and lie most superior in the costal grooves Most posterior intercostal veins (4–11) end in the azygos/hemi-azygos venous system, which conveys venous blood to the superior vena cava (SVC) Any Questions?