Thorax Wall Anatomy PDF

Thoracic Wall Thorax is the part of the trunk – narrow opening superiorly – large opening inferiorly Thoracic skeleton forms the osteocartilaginous thoracic cage thoracic part of the vertebral column the sternum and costal cartilages Superior thoracic apertura (Thoracic inlet) is bounded by: 1. thor...

Thoracic Wall Thorax is the part of the trunk – narrow opening superiorly – large opening inferiorly Thoracic skeleton forms the osteocartilaginous thoracic cage thoracic part of the vertebral column the sternum and costal cartilages Superior thoracic apertura (Thoracic inlet) is bounded by: 1. thoracic vertebra posteriorly pair of 1. ribs and their costal cartilage Superior border of the manubrium anteriorly – Jugular notch (suprasternal notch) Inferior thoracic apertura (Thoracic outlet) oblique is closed by the: is bounded by : 12. Th vertebra 11. & 12. pairs of ribs Costal cartilages of ribs 7 through 10 Xiphosternal joint (subcostal angle) Intercostal space seperate the ribs 11 intercostal space Contains three muscles (intercostal) of respiration Internal surface of thoracic wall is lined with the endothoracic fascia, which is lined with the parietal pleura internally Intercostal muscles occupy intercostal space Superficial layer: external intercostal Intermediate layer: internal intercostal deepest layer: Transversus thoracis innermost intercostal Subcostal m. External Intercostal M 11 pairs occupy Intercostal Space from the tubercles posteriorly to the costochondral junction anteriorly. Anteriorly, replaced by the external intercostal membrane N: T1-T11 Rib Head Neck Tubercle Shaft Angle Tubercle has facet for transverse process of corresponding thoracal vertebra Internal surface of Body →costal groove Internal intercostal muscles deep to the EIM run inferoposteriorly from the inferior border of the rib above to the superior borders of the rib below Medial to the angles IIM are replaced by the internal intercostal membrane Innermost Intercostal muscle Between the angle & costacondral junction Inferior border of ribs Superior borders of ribs below N: T1-11 Transversus thoracis m (Sternocostal M) O: posterior surface of stenum I: internal surface of the costal cartilages 2-6 Depress the ribs Subcostal Muscle variable in size & shape extend from the internal surface of the angle of one rib to the internal surface of the second or third rib inferior to it Elevate ribs Costavertebral & Sternocostal joints Nerves of the Thoracic Wall 12 pairs of thoracic spinal nerves intervertebral foramen - ventral &dorsal rami Ventral rami of T1T11 nerves intercostal n Ventral rami of T12 nerve subcostal n Typical intercostal n (3rd-6th) Enters the intercostal space between the parietal pleura and internal intercostal membrane Runs forward inferior to the vessels in the costal groove between the internal intercostal & innermost intercostal muscles The branches of the typical intercostal nerves communicating branch: each intercostal nerve to the sympathetic trunk collateral branches: arise near the angle of the ribs innervate the intercostal m lateral cutaneous branch: ant cutaneous branch: muscular branch: intercostal, subcostal, transversus thoracis, levator costarum, serratus posterior m Atypical Intercostal N 1th & 2nd intercostal nerves course on the internal surface of the 1st & 2nd ribs 7th-11th IN after giving rise to lat cut branch,cross the costal margin and supply the abdominal skin and muscles. They become thoraco-abdominal nerves of the anterior abdominal wall 1st Intercostal nerve has no ant cutaneous branch often no lat cutaneous branch Ventral ramus of first thoracic spinal nerve: superior & inferior parts Brachial plexus 2nd Intercostal N is larger branch of ventral ramus of 2nd thoracic spinal n smaller branch of T2 n joins with the brachial plexus intercostabrachial Lateral cut branch of IN nerve innervates axilla & communicates with medial cutaneous nerve of arm Arteries of the Thoracic Wall – Thoracic aorta-posterior intercostal and subcostal arteries – Subclavian artery-internal thoracic and supreme intercostal arteries – Axillary artery-superior and lateral thoracic arteries Posterior Intercostal arteries One in each of the 11 spaces 1st & 2nd arise from superior Intercostal artery of costocervical trunk of 2nd part of subclavian artery The lower 9 arteries & subcostal artery arise from descending thoracic aorta. Posterior Intercostal A Subclavian a. superior (suprema) intercostal a costocervical trunk 1st & 2nd posterior intercostal a 3rd to 11th PIA & Subcostal A Branches from thoracic aorta Anterior Intercostal arteries The upper 6 from internal thoracic artery The lower 3 from musculophrenic artery Anterior Intercostal Arteries upper nine intercostal spaces Internal thoracic artery 1st-6th AIA Musculophrenic artery 7th- 9th anterior intercostal a Internal Thoracic Artery superior epigastric a musculophrenic a Posterior intercostal vein On both sides: 1st Post intercostal Vbrachiocephalic v On the right side: 2nd3rd(4th) PİV unite to form the right superior intercostal vein draining to the azygos v. Others drain azygos v. directly Posterior intercostal vein On the left side: 2nd3rd(4th) PİV unite to form the left superior intercostal vein draining to the left brachiocephalic vein. On the left side: 5-8 PİV drain into the accessory hemiazygos vein 9-11 PİV drain into hemiazygos vein Anterior intercostal veins 9 pair of AIV 1st-6th AIV internal thoracic v 7th-9th AIV musculophrenic v Thoracocentesis