Part of our ongoing `Deconstruction to Reconstruction` education series, this cadaveric demonstration with Prof Markus Scheibel describes aspects of anterior shoulder anatomy.
Welcome here from the York Shoulder Course from Deconstruction to Reconstruction. So in this specimen, we will show the inter-anatomy of the left shoulder. And we already have dissected tendons and also dissected nerves and vessels via the deltopectoral approach extending from the coracoid process down to the mid level of the forearm.
So we will remove these clamps now and show you the anatomy. If you dissect through the skin, obviously, you're entering the subcutaneous space and this is already open here. And the first thing what we dissected initially was the interval between the deltoid muscle and the pec major. And the first structure that we are aware of is the cephalic vein that we can see here which lies very close to the interior part of the deltoid muscle and extends inferiorly all the way to the hand.
So after dissecting the deltopectoral interval, we're using a sharp Hohmann retractor in order to expose the coracoid and this Langenbeck retractor is underneath the deltoid. We already have opened up the sulcus into tubercular groove where we see the biceps tendon, as you can see here. Here it enters inside the joint and it extends inferiorly underneath the pec major tendon, further into the biceps muscle which is down here, as you can see.
So what we did, initially, we took off the pec major tendon. We're using two sutures to hold the tendon in place, as you can see. And when we are lifting up the pec major, you can see that parts of the tendon or, basically, parts of the muscle that are coming from the abdominal wall, they insert proximally at the proximal humorous, and parts that are coming from the clavicle and from the sternum, they insert, as you can see here, distally at the proximal humerus. So there is a kind of a crisscross of the insertion of the pect major.
So the pec major is now reflected and underneath the pec major, we see the conjoined tendons extending from the coracoid down here. It's the short head of the biceps and also the coracobrachial muscle and underneath the short head, the lateral, we will find the insertion of the triceps. This is the triceps. It's already detached from the insertion part and we have used two sutures to retract, also, the triceps tendon.
So basically, everything is prepared now to expose and to show you the nerves and the vessels. So the first nerve we would like to identify is the musculocutaneous nerve which we know anyway, it's the anterior flexors of the upper arm, the biceps muscle and short head of the biceps and also, the coracobrachial muscle. So we reflect a little bit the short head of the biceps and the coracobrachial muscle.
And here, you'll see already the musculocutaneous nerve. Here, we see the musculocutaneous nerve entering the biceps, actually, quite distally, in this case. So it's approximately, I would estimate, 10 to 12 centimeters from the tip of the coracoid, so quite distally. There's a range between around three centimeters and, I think, 15 to 16 centimeters distally. It's quite a strong nerve, as you can see here. OK.
So if we reflect the pec major a little bit more, we're coming to the plexus and we already have dissected the plexus. Underneath the musculocutaneous nerve, here we will find the radial enough already and the radial nerve comes from the posterior cord here and the posterior cord distributes into the radial nerve and into the axillary nerve. And here, you'll see the axillary nerve underneath the subscapularis muscle, going around the subscap, and then here through the quadrilateral space to the posterior aspect of the proximal humerus.
So obviously, we have the artery and the remaining nerves of the plexus here. Here is the median nerve, underneath. Here is the brachial artery and the brachial vein. And if we go now lateral again, what we'll see here-- let's just hone in over there-- again, we see the axillary underneath the subscapularis. Here is the subscapularis. Here, we have the tendon, the tendonous part and the muscular part. If I rotate the arm externally, like this, you also see the three sisters. These are the anterior circumflex artery and the two veins, the two accompanying veins that are going here to the lesser tuberocity.
So our main structure is here, the axillary nerve that we identified that, anyway, it's obviously the deltoid muscle and parts of the skin on the lateral side. So now, I am releasing the subscap here from the duodenotomy from the lesser tuberocity. And I'm releasing it on block with the underlying capsule.
So now you see the humeral head. We also can see the capsule here that is coming over and inserting at the anatomical neck of the proximal humerus. I will now-- can you pull a bit too far? Thank you. I will now also release the capsule here from the anatomical neck, being very close to the humeral head. Now, we insert another Hohmann. And what we now can do, we can rotate the humerus around and we completely have opened the joint and we can see, even here, in the axillary pouch. OK?
So finally, what we will show, the anterior ligaments. I will remove a little bit more of the muscular part of the subscap. OK? So while reflecting the subscap, looking from the inside, here against the tendonous part, here is the muscular part, and here we have the labrum. That's the superior aspect of the labrum extending all the way around the glenoids.
And from the labrum, we have the superior glenohumeral ligament, which is this one. We have the medial glenohumeral ligament, which is this one, and it moves basically lateral into the subscap. And very far inferior, we will find the inferior glenohumeral ligament, which is here. So this is the anterior capsule of the shoulder with quite a strong medial ligament in this particular specimen.
Recorded at the Smith & Nephew Surgical Skills Centre, UK.