Thoracic Wall (Muscles & Vessels) - Mansoura National University PDF

Thoracic Wall (Muscles & vessels) Department of human Anatomy and Embryology Faculty of Medicine Mansoura National University, Egypt Edited by: Dr. Fikry shata  Intended Learning Outcomes (ILOs) 1. Identify the components of the Thoracic Wall. 2. Name the b...

Thoracic Wall (Muscles & vessels) Department of human Anatomy and Embryology Faculty of Medicine Mansoura National University, Egypt Edited by: Dr. Fikry shata  Intended Learning Outcomes (ILOs) 1. Identify the components of the Thoracic Wall. 2. Name the boundaries and structures passing through the thoracic inlet. 3. Name the boundaries and structures passing through the thoracic outlet. 4. Recognize the origin, insertion, nerve supply, extent, direction of fibers and action of intercostal muscles. 5. Mention the mechanism of respiration. 6. Identify the origin, features and branches of intercostal nerves 7. Recognize the origin, branches and termination of intercostal arteries 8. Recognize the origin, tributaries and termination of intercostal veins  Agenda 1. What are the components of the Thoracic Wall. 2. What are the boundaries and structures passing through the thoracic inlet? 3. What are the boundaries and structures passing through the thoracic outlet? 4. What is the origin, insertion, nerve supply, extent, direction of fibers and action of intercostal muscles? 5. What is the mechanism of respiration? 6. What is the origin, features and branches of intercostal nerves? 7. What is the origin, branches and termination of intercostal arteries? 8. What is the origin, tributaries and termination of intercostal veins?  OVERVIEW OF THORAX The thoracic cavity and its wall have the shape of a cone: narrow above and wide below. the floor of the thoracic cavity (the diaphragm) is pushed upward by the abdominal organs. The thorax includes the primary organs of the respiratory and cardiovascular systems.  Thoracic Wall The Thoracic Wall is composed of: Bones: Forming the thoracic cage Superiorly: Thoracic inlet Inferiorly: Thoracic Outlet Between the ribs: 11 intercostal spaces In the intercostal spaces: Intercostal muscles Intercostal nerves Intercostal arteries Intercostal veins Skeleton of Thoracic Wall (thoracic cage) Vertebral Column Sternum Ribs & Costal Cartilages Thoracic Apertures (openings)  Thoracic Inlet Trachea Oesophagus Thoracic duct Thoracic inlet (superior thoracic aperture) Right Common Boundaries: Carotid artery Left Anteriorly: suprasternal notch. Right subclavian brachiocephalic Posteriorly: 1st thoracic vertebra. artery vein On both sides: inner border of 1st rib and its costal cartilage. Structures passing: pierce the supra-pleural membrane (Sibson’s fascia) 1. Tubes: trachea and oesophagus. 2. Arteries: common carotid, subclavian, internal thoracic and superior intercostal. 3. Veins: right and left brachiocephalic, vertebral and inferior thyroid. 4. Nerves: phrenic, vagus, sympathetic chain and left recurrent laryngeal. Right internal 5. Lymphatic: thoracic duct thoracic artery  Upper border of the body of the first thoracic vertebra Inner border of the right first rib Inner border of the left first Thoracic inlet Left first costal cartilage Right first Manubrium Upper border of costal cartilage Sterni Manubrium Sterni  Thoracic Outlet Boundaries: Anteriorly: xiphoid process. Posteriorly: last thoracic vertebra and last 2 ribs. On both sides: costal margin (7th – 10th costal cartilages). Structures passing: it is closed by the diaphragm. It is crossed by the structures piercing the diaphragm.  Costal cartilages of 7th , 8th , 9th and 10th ribs Xiphoid (Costal Margin) Process Lower border of xiphoid process 12th Thoracic Vertebra Lower border of 12th 10th 12th Thoracic Vertebra 11th 11th and 12th ribs  Intercostal spaces Definition ❑The spaces which lie between adjacent ribs ❑11 spaces Number 1)3 layers of intercostal Contents muscles 2)Intercostal nerves 3)Intercostal arteries 4)Intercostal veins 5)lymphatics Thoracic Wall (intercostal muscles)  Intercostal Muscles 1. External intercostal 2. Internal intercostal muscles muscles Origin & From lower border of rib From costal groove of rib above Insertion above To upper border of rib below To upper border of rib below Direction of Downward and forward Downward and backward fibers and medial and lateral Extension From: tubercle of rib From: side of the sternum posteriorly anteriorly To: Costochondral junction To: approximately angle of the rib anteriorly posteriorly Completed Anterior overlapping Posterior by intercostal membrane intercostal membrane Action Elevation of ribs Depression of ribs (inspiration) (expiration) External Intercostal Muscle Anterior intercostal membrane External intercostal muscle Internal Intercostal Muscle Posterior intercostal membrane  Intercostal Muscles Transversus thoracis muscles It is subdivided into 3 parts: A. Sternocostalis: anteriorly (in the upper intercostal spaces). B. Subcostalis: Posteriorly (in the lower intercostal spaces). C. Intercostalis intimi (innermost intercostal): in the middle Transversus Thoracis muscles  Innermost intercostal (Intercostalis intimi) Direction of fibers Intermost Intercostal Muscle Downward and backward Extent ❑Along the middle two-fourth of the intercostal space Action depression of the ribs during expiration.  Sternocostalis Transversus thoracis (triangularis sternae) Direction of fibers Upwards and Laterally Origin body and xiphoid process of sternum Insertion costal cartilages of ribs 2-6 Action: move the ribs during forced breathing  Subcostalis Direction of fibers Downward and backward Origin from the inner surface of one rib near its posterior angle. Insertion to the inner surface of the second or third rib below its origin. Action Depress the ribs in forced exhalation Subcostalis  Intercostal Muscles 3. Transversus Thoracis muscles Sternocostalis muscle Innermost intercostal muscle Subcostalis muscle Origin Back of the lower 1/3 of Lower border of rib above Inner surface of the body of the sternum one rib medial to and xiphoid process the angle Insertion Inner surface of costal Upper border of rib below Inner surface of the cartilages from 2nd to 6th 2nd or 3rd rib below Site Anterior of the middle of the intercostal space posterior of the intercostal space intercostal space Direction Upwards and Laterally Downwards and Backwards Downwards and of fibers Medially Action Depression of the ribs during expiration  Quiz The anterior intercostal membrane is the continuation of what muscle? A) External Intercostal muscle B) Internal Intercostal muscle C) Subcostalis D) Sternocostalis E) Innermost intercostal muscle Answer: A Intercostal Arteries  Intercostal Arteries Each space contains one posterior and 2 anterior intercostal arteries. Anterior intercostal arteries Number: 2 arteries in each of the upper 9 spaces. Origin: The upper 6: branches from the internal thoracic artery. The lower 3 (7th, 8th and 9th): branches from the musculophrenic Termination: they anastomose with the posterior intercostal artery and its collateral branch.  Intercostal Arteries Posterior intercostal arteries Number: one artery in each of the 11 spaces. Origin: The 1st and 2nd: from the superior intercostal artery (branch from the costo-cervical trunk, which is a branch from the 2nd part of subclavian). The 3rd - 11th: from the descending aorta. Termination: by anastomosis with the upper anterior intercostal artery in each space. Branches: ❑ Dorsal branch: supplies the spinal cord, muscles and skin of the back. ❑ Muscular branches: to the intercostal muscles. ❑ Collateral branch: passes on the upper border of the rib below to anastomose with the lower anterior intercostal artery in each space.  Quiz What is the origin of the 2nd posterior intercostal artery? A) From the internal thoracic artery B) From the musculophrenic artery C) From the superior epigastric artery D) From the superior intercostal artery E) From the descending thoracic aorta Answer: D  Intercostal Veins In each space there is one posterior and 2 anterior 1st, intercostal veins. 2nd Anterior intercostal veins 3rd Number: 2 in each of the upper 9 spaces. 4th Course: pass with the corresponding arteries. Termination: 5th The 1st, 2nd and 3rd: end in the internal thoracic vein. 6th The 4th, 5th and 6th: end in the vena comitantes of the 7h internal thoracic artery. 8th The 7th, 8th and 9th: end in the vena comitantes of the 9th musculophrenic artery.  Intercostal Veins Posterior intercostal veins Number: 1 in each of the 11 spaces Course: pass with the corresponding arteries.  Termination Right side Left side 1st (Supreme): Rt brachiocephalic vein 1st (Supreme): Lt brachiocephalic vein 2-3: unite to form Rt superior 2-3: unite to form Lt superior intercostal vein which end into azygos intercostal vein which end into Lt vein. brachiocephalic vein. 4-11: azygos vein. 4-8: superior hemiazygos vein. 9-11: inferior hemiazygos vein. Azygos vein terminates into superior Hemiazygos veins terminate into the vena cava (at the level of sternal azygos vein opposite T8. plane). Arch of azygos superior  Quiz What is the termination of the 4th left posterior intercostal vein? A) Into the azygos vein B) Into the left brachiocephalic vein C) Into the hemiazygos vein D) Into the accessory hemiazygos vein E) Into the left superior intercostal vein Answer: D  Internal Thoracic Artery Origin: from the 1st part of subclavian artery. Course: descends behind the clavicle and the medial ends of the upper 6th costal cartilages 1.5 cm lateral to the sternal margin. Termination: in the 6th intercostal space by dividing into superior epigastric and musculophrenic arteries.  Internal Thoracic Artery Branches: 1) Anterior intercostal arteries: 2 in each of the upper 6 spaces. 2) Pericardio-phrenic artery: Passes with the phrenic nerve. Supplies the pleura, pericardium and diaphragm. 3) Perforating arteries: Pass with the anterior cutaneous nerves. The 2nd, 3rd and 4th supply the mammary gland. 4) Musculophrenic artery: ✓ Course: passes along the costal margin. ✓ Branches: a)2 anterior intercostal arteries in the 7th, 8th and 9th spaces. b)Branches to the pleura, pericardium, diaphragm. 5) Superior epigastric: ✓ Course: passes through the diaphragm to reach the rectus sheath.