 This is a 3D prism representing the anatomical space known as the axilla. Axilla is the 17th century Latin term for armpit. First the bones that surround the space are the clavicle, scapula, humerus and ribs. Most of the surfaces that define this space are muscles. Anteriorly that is pectoralis major, inserting on the lateral lip of the inter tubercular sulcus and providing the axilla's anterior surface. Moving inside the rib cage now, we are looking toward the medial surface of the axilla. Providing the medial surface of the axilla is the ribs, the intercostal muscles and part of serratus anterior. Let's move back to observe the angle of that medial surface and moving to the posterior aspect now, we will remove the scapula to better display three muscles forming the posterior surface of the axilla. These are subscapularis, teres major and latissimus dorsi. Moving back now that is subscap, teres major and lat dorsi. The scapula then completes the picture. The anatomical landmark that is cited as the lateral surface is the inter tubercular sulcus of the humerus. The lips of this groove provide attachment for teres major, medially and pec major, laterally. The space between these is the lateral surface of the axilla, the inter tubercular sulcus. To the inferior surface now which is mostly skin, the area not covered by skin allows passage of the axilla's contents into the rest of the arm. The superior boundary is also known as the inlet of the axilla. This schematic model represents a simplified version of what will now draw out the true borders of the superior boundary. The anatomical borders are the clavicle, the coracoid process and superior border of the scapula and the lateral border of the first rib connected up by ceratocenteria. In our model we have a simplified version instead. The bottom line is this superior boundary is open and allows in the contents of the axilla. These contents are the axillary artery, axillary vein, the brachial plexus or a schematic portion of it, axillary lymph nodes, the muscular contents are the short head of biceps brachii and coraco brachialis. Removing the former we see here the course of coraco brachialis from humerus to coracoid process. Now that we've discussed the boundaries and contents of the axilla let's take a short tour through it. We'll begin at the subclavian artery which becomes known as the axillary artery once it is passed by the first rib. You may remember the first rib is also part of the superior boundary so having passed that we are now in the axilla. We see schematic versions of the contents around us as well as coraco brachialis and the short head of biceps brachii. If we look inferiorly we see the opening that allows vessels further passage through the arm and that's it for now. Hit subscribe if you liked this video thanks for watching and we will see you next time.