Thoracic Cage and Cavity PDF

CVP 112 Thorax, Thoracic Cage and Thoracic Cavity Olena Bolgova, MD, PhD Professor of Gross Anatomy @ Dr. Olena, 2024  OBJECTIVES: By the end of this lecture students should be able to describe: Surface a...

CVP 112 Thorax, Thoracic Cage and Thoracic Cavity Olena Bolgova, MD, PhD Professor of Gross Anatomy @ Dr. Olena, 2024  OBJECTIVES: By the end of this lecture students should be able to describe: Surface anatomy of the thoracic wall Bones and joints of the thorax Clinical cases: Thoracic outlet syndrome (TOS) Sternal puncture and median sternotomy Rib fracture Cervical rib @ Dr. Olena, 2024  THORAX It is the superior part of the trunk between the neck and the abdomen: Thoracic cage Thoracic cavity @ Dr. Olena, 2024  Thoracic cavity The thoracic cavity is subdivided into 3 compartments: Mediastinum (median compartment) contains, among others, the heart and great vessels 2 Pleural cavities (one each on both sides of the mediastinum) contain the lungs @ Dr. Olena, 2024  Thoracic cage Framework of the wall of the thorax Protects the lungs and heart Provides attachment for the muscles of the thorax, upper limbs, back, and abdomen Communicates superiorly with the neck via the thoracic inlet Separated from the abdomen by the respiratory diaphragm @ Dr. Olena, 2024  Surface anatomy of the thoracic wall The anterior median (midsternal) line (AML): a vertical line passing through the midpoint of the sternum Parasternal line: a vertical line running along the lateral border of the sternum Midclavicular line (MCL): a vertical line passing through the midpoints of the clavicle @ Dr. Olena, 2024  Surface anatomy of the thoracic wall Anterior axillary line (AAL): a vertical line running along the anterior axillary fold that is formed by the pectoralis major as it spans from the thorax to the humerus Midaxillary line (MAL): a vertical line running from a point midway between the anterior and posterior axillary lines Posterior axillary line (PAL): a vertical line running along the posterior axillary fold that is formed by the latissimus dorsi and teres major muscles as they span from the back to the humerus @ Dr. Olena, 2024  Surface anatomy of the thoracic wall Scapular line (SL): a vertical line passing through the inferior angle of the scapula Paravertebral line: a vertical line running along the lateral border of the vertebral column Posterior median (midvertebral) line (PML): a vertical line passing through the tips of the spinous processes of the vertebrae @ Dr. Olena, 2024  Boundaries of the thoracic wall Anterior – sternum and costal cartilages Lateral – ribs and intercostal spaces Posterior – thoracic vertebrae and their IV discs Superior – suprapleural membrane Inferior – respiratory diaphragm @ Dr. Olena, 2024  Thoracic inlet (superior thoracic aperture) It is a superior opening of the thoracic cavity and communicates with the root of the neck Boundaries: Anterior – superior border of the manubrium of the sternum Lateral – medial borders of the first ribs and their costal cartilages Posterior – T1 It serves for the passage of the esophagus, trachea, and many vessels and nerves @ Dr. Olena, 2024  Thoracic outlet (inferior thoracic aperture) It is an inferior opening of the thoracic cavity and communicates with the abdomen It is closed by the respiratory diaphragm Boundaries: Anterior – xiphisternal joint Lateral – costal margins Posterior – T12 It serves for the passage of the esophagus, aorta, IVC, and many vessels and nerves, all of which pierce the respiratory diaphragm @ Dr. Olena, 2024  Different approaches: Anatomists refer to the superior thoracic aperture as the thoracic inlet because non-circulating substances (air and food) may enter the thorax only through this aperture. When clinicians refer to the superior thoracic aperture as the thoracic outlet, they are emphasizing the artery and T1 spinal nerve that emerge from the thorax through this aperture to enter the lower neck and upper limbs. @ Dr. Olena, 2024  Thoracic outlet syndrome (TOS) It is the compression of neurovascular structures in the thoracic outlet causing a combination of pain, numbness, tingling, or weakness and fatigue in the upper limb caused by pressure on the brachial plexus (lower trunk or C8 & T1) by a cervical rib or pancoast tumor. A cervical rib may also compress the subclavian artery in the thoracic outlet, resulting in ischemic muscle pain in the upper limb. @ Dr. Olena, 2024  STERNUM Manubrium superior part of the sternum articulates with the clavicles and the costal cartilages of ribs 1 & 2 lies opposite T3 & T4 Body of the sternum articulates superiorly with the manubrium (manubriosternal joint) and inferiorly with the xiphoid process (xiphisternal joint) notched on the sides for articulation with the costal cartilages of ribs 2-7 Xiphoid process thin plate of hyaline cartilage it becomes ossified in adult life @ Dr. Olena, 2024  Sternal angle (of Louis) It is formed by the junction of the manubrium and the body of the sternum It lies at the level of the costal cartilage of the 2nd rib just opposite the T4/T5 IV disc It serves as a clinical guide for the accurate numbering of ribs and intercostal spaces The horizontal line which comes through the sternal angle divide the superior and inferior mediastinum border Level of bifurcation of Trachea, start, and end of the arch of aorta @ Dr. Olena, 2024  Sternal Puncture and Median Sternotomy The sternum is a common site for bone marrow biopsy because it possesses hematopoietic marrow throughout life and because of its breadth and subcutaneous position. The sternum may be split in the median plane (median sternotomy) to allow the surgeon to gain easy access to the lungs, heart and great vessels. @ Dr. Olena, 2024  RIBS 12 pairs of flat bones, all attached posteriorly to the thoracic vertebrae True ribs: first seven ribs connected anteriorly to the sternum by their costal cartilages False ribs: ribs 8-10 - each one connected anteriorly by its costal cartilage to the costal cartilage of the rib superior to it Floating ribs: ribs 11-12 - their costal cartilages end in the muscles of the abdominal wall @ Dr. Olena, 2024  Typical ribs Typical ribs are 3 - 9. Each of which has a head, neck, tubercle, and body. The head articulates with the corresponding vertebral bodies and IV disks and supra-adjacent vertebral bodies The tubercle articulates with the transverse processes of the corresponding vertebrae, with the exception of ribs 11 & 12  Costal groove that follows the inferior and internal surface of a rib and lodges the intercostal vessels and nerves @ Dr. Olena, 2024  Rib fractures Rib fractures usually result from blows or from crushing injuries. The weakest part of a rib is just anterior to its angle; however, direct violence may fracture a rib anywhere, and its broken end may injure internal organs such as a lung and/or the spleen. Rib fractures are painful because the broken parts move during respiration, coughing, laughing, and sneezing. X-ray image is commonly used to confirm the diagnosis of rib fractures. @ Dr. Olena, 2024  Atypical ribs Atypical ribs are 1, 2, 10, 11 & 12 Rib 1 – shortest, flattest, broadest, most curved. It has a scalene tubercle for the insertion of the anterior scalene muscle and two grooves for the subclavian artery and vein Rib 2 – has two articular facets on its head, which articulate with the bodies of the first and second thoracic vertebrae Rib 10 - has a single articular facet on its head, which articulates with the T10. Rib 11 & 12 - have a single articular facet on their heads. They have no neck or tubercle. @ Dr. Olena, 2024  Cervical rib Mesenchymal or cartilaginous elongation of the transverse process of the seventh cervical vertebra. It may have a free anterior end, or be connected to the rib 1 by a fibrous band It is present in ~0.5% of persons It can cause pressure on the lower trunk of the brachial plexus (pain down the medial side of the forearm and hand and atrophy of the intrinsic hand muscles) and subclavian artery– TOS. @ Dr. Olena, 2024  Typical thoracic vertebrae T2-T9 Costal demifacets on the body articulate with the head of the corresponding rib and rib below. Costal facet of the transverse process articulates with the tubercle of the corresponding rib. @ Dr. Olena, 2024  T1, T10-T12 T1 Complete facet on superior body articulates with the entire head of rib 1. Demifacet on the inferior body articulates with the superior part of the head of rib 2. T10-T12 Only complete facets are on bodies for articulation with the entire head of the corresponding rib. @ Dr. Olena, 2024  Articulation of a typical rib @ Dr. Olena, 2024  Please take the practice quiz: @ Dr. Olena, 2024  References Gray's anatomy for students by Richard L. Drake, Wayne Vogl, Adam W. M. Mitchell; Churchill Livingstone; 2 edition; ISBN-13: 978-0443069529, ISBN-10: 0443069522 Clinically Oriented Anatomy by Keith L. Moore, Arthur F. Dalley, A. M. R. Agur; Lippincott Williams & Wilkins; 7th edition; ISBN- 13: 978-1451119459; ISBN-10: 1451119453 Langman's Medical Embryology by Thomas W Sadler; Lippincott Williams & Wilkins; 12th edition; ISBN-13: 978-1451113426; ISBN-10: 1451113420 Netter's Clinical Anatomy by John T. Hansen, David R. Lambert, Frank H. Netter; ICON Learning Systems; ISBN13: 9781929007714 @ Dr. Olena, 2024