Intercostal Muscles

University:
The University Of Western Ontario
Course:
ANAT 2200B | Systemic Anatomy of the Human Body
Academic year:

2022
Views:

82

Pages:

6
Author:

Kyuwon J.

Intercostal Muscles ● Intercostal muscles fill in the intercostal spaces ● Maintain rigidity of thoracic wall ○ Assist on respiration ● 3 muscular layers ○ External Intercostal Muscles ■ Extent ● From tubercle of rib to costochondral junctions ● External intercostal membranes ■ Fiber direction ● Downwards ● Forwards “Hand in pockets” orientations ■ Functions ● Elevation of ribs ● Activation in inspiration ■ Innervations ● Intercostal Nerve ○ T1-T11 ○ Internal Intercostal Muscles ■ Extent ● Sternum to angle of rib ● Is replaced posteriorly ○ Through internal intercostal membranes ■ Fiber directions ● Downwards ● Backwards ● Perpendicular to external intercostal ■ Functional parts ● Interosseous parts ○ Depressed ribs ○ Forced for expirations ● Interchondral parts ○ Elevation of ribs ■ Innervation ● Intercostal nerves ○ Innermost Intercostal Muscles ■ Discontinuous muscle layer ■ Separation from internal intercostals through neurovascular plane ■ Innermost intercostals ■ Subcostales ● Posterior ■ Transversus thoracis ● Anterior ■ Used to act with internal intercostals ■ Assist on forced expirations ● High Yield Neurovascular Bundle ○ Runs on costal grooves of upper limbs ■ Internal intercostal ■ Innermost intercostal ○ Arrangements ■ Superior ⇒ Inferior ■ Vein ■ Artery ■ Nerves ■ VAN drives between ribs ● Intercostal Nerves ○ From T1-T11 ○ Paravertebral regions ○ Coastal grooves ○ Lateral cutaneous branches ■ Midaxillary line ○ Anterior cutaneous branches ■ Parasternal ○ Motor ⇒ intercostal muscles ○ Sensory ⇒ skin of thorax and upper abdomen ○ Autonomic ⇒ sweat glands and vessels Intercostal Space ● Wall ● Draining fluids ● Significant for chest tube insertions ● Muscle ○ Superficial to deep ■ External Intercostal ● Runs “Hand in Pockets” ● Down and Medial ● Inspirational ■ Internal costals ● Perpendicular ● External ● Down and lateral ● Used for Expirations ■ Innermost Intercostals ● Same directional compared to Internal ● Separated by neurovasculature bundle ○ VAN bundle ■ Neurovascular bundle through Costal Groove ■ Between Internal and Innermost muscle layer ● Order ○ Superficial ⇒ inferior ● Veins ○ Protected by rib superior ○ Most protected part ● Artery ● Nerve ○ Most exposed ○ Inferior ● Potential Question Q) Where would you insert a needle on Thoracetesis A) Superior to rib. This is to avoid hitting any vital nerves which could be hanging down from the rib superior from the insertion point. Division of mediastinum ● Torax ○ Divided into specific compartments ○ Transverse Toracic Plane ■ T4-T5 ● Phrenic ● Vagus ● Thoracic Duct ● Left Recurrent Laryngela ● ● ● ● ● ● Brachiocephalic veins Aortic Arch Thymus Trachea Lymph nodes Esophagus ○ Anterior Mediastinum ■ Under T4 and T5 ■ In front of pericardium ● Thymus - for children ● Fat ● Lymph nodes ○ Medial Mediastium ■ Pericardial Sac ● Heart ● Pericardium ● Root of great vessels ○ Posterior Mediastinum ■ Posterior to pericardium ■ Anterior to Vertebrae ● T5-T12 ■ Descending Aorta ■ Azygos and Hemiazygos veins ■ Thoracic Ducts ■ Esophagus ■ Sympthetic Trunks