 Good day everybody. This is Dr. Sanjay Sanyal, Professor Department chair. I'm going to demonstrate a few salient clinical features about the humerus and its articulations. So I'm holding up the right humerus in front of you. So let's take a quick look at the parts of the humerus. This is the particular surface which forms the shoulder joint. So this is the head of the humerus and then like this is covered by halide cartilage. Only one-third of this surface is in contact with the glenoid fossa. I shall tell you about the joint a little later. Just behind that we can see one blue line. That is a small shallow groove and that is called an atypical neck of the humerus. And under that we can see two projections. One projection is this one, the other one is this one. This is the greater tubercle and this gives attachment to the rotator cuff muscles, supraspinitus, infraspinitus, teres minor. And then we have the lesser tubercle which gives attachment to the other rotator cuff muscle, namely the subscapularis. And in between we can see a shallow groove here. This is called the inter tubercular sulcus. In life this is bridged over by a ligament called the transverse humeral ligament. And therefore it is converted into a tunnel and through that tunnel passes the long end of the bicep tendon in its sine of your sheath. And attached to the floor of the inter tubercular sulcus is the latissimus dorsi. Attached to the lateral lip is the pectoralis major. And attached to the medial lip of the inter tubercular sulcus is the teres major. Under the greater tubercle and the lesser tubercle we have this portion where my finger is tracing that is called the surgical neck of humerus. And right adjacent to the surgical neck of humerus where my finger is located this is the location of the quadrangular space. Therefore we can see that the quadrangular space is located just under the head. And laterally it is bounded by the surgical neck of humerus. There are other structures which are bounding the quadrangular space. Through the quadrangular space passes the axillary nerve along with the posterior circumflex humoral artery. So therefore in surgical neck of humerus fracture or inferior dislocation of the shoulder joint it can impinge in the quadrangular space and can injure the axillary nerve with paralysis of the deltoid. The deltoid muscle is located here. The deltoid muscle gets inserted on a tuberosity on the lateral surface. This is the place and that's called the deltoid tuberosity. This is the next ray showing two views of the shoulder joint to show surgical neck of humerus fracture. This is the shaft of the humerus and if you look at the back of the shaft of the humerus you can see there's an oblique shallow line which runs like this. The way my finger is tracing from medial to lateral, oblique lead down. This is called the radial groove with a spiral groove. And we cannot see it very clearly here but its location is here. And through this radial groove the spiral groove runs the radial nerve and the profundal artery. Before that it is visible through the triangular interval. So therefore when we have a fracture of the shaft of the humerus we are allowed to injure the radial nerve. This is the next ray of the left arm to show fracture of the bit shaft of the humerus with the associated injury possibility. This shallow groove the radial groove demarcates the attachment of the two heads of the triceps. Namely above the radial groove a lateral to it is the lateral head of the triceps and below the radial groove and medial to that is the medial of the triceps. So therefore the radial groove is between the attachments of these two muscles. When the radial nerve is traveling through the radial groove it gives branch to the lateral head. The branch to the long head of the triceps and the medial of the triceps is given up before it enters the radial groove. So therefore if the radial nerve is injured in the radial groove the lateral head is paralyzed. The lateral head of the triceps is the powerful extensor against resistance. But the rest of the functions are performed by the medial head of the triceps which is the workhorse extensor. So that is not paralyzed in fracture of the shaft of the humerus. To continue down we see these two ridges one on the medial side and one on the lateral side. These are known as the supracondyler ridge medial and lateral. They give it as fit to a facial septum. The medial intramuscular septum and the lateral intramuscular septum which gets attached to the brachial fascia. And these two septa are the ones which divide the brachium into an anterior flexor compartment and a posterior extensor compartment. Pairing the medial intramuscular septum we have the ulnar nerve which pierces from the front and it goes behind. It runs behind the medial epicondyle of the humerus. Along with that is the superior ulnar collateral artery which also runs behind. Then brings me to this lower part of the humerus. We can see the lower part of the humerus is the one which articulates with the radius and the ulnar to form the humeral nerve joint and the radio-humeral joint. So let's take a look at the parts. This is called the capitulum. Capitulum means like a head. This articulates with the head of the radius to form the radio-humeral joint. And this portion is called the trochlea. This is the one which articulates with the trochlear notch of the ulnar. And that is the one which forms the humeral ulnar joint. In front we can see a depression not one but two. Lateral depression is called the radial fossa. Because when the arm is fully flexed the head of the radius impinges here. And the medial depression is referred to as the coronoid fossa. The arm is fully flexed. The coronoid process of the ulnar fits here. Now I am going to turn this. We can see yet another depression. And we can see only the trochlea here. We don't see the capitulum here. This depression is referred to as the olecranon fossa. When the arm is fully extended the olecranon impinges here. This whole region is called the supracondyle. If you have a supracondylar fracture of the humerus, which is quite common in children when they fall on the outstretched hand. Or if they have anti-idusification of the elbow, which is also quite common in children. Then the upper fragment, the dislocated portion, can impinge on the cubital fossa. And it can injure the median nerve and or the brachial artery. So therefore whenever we see a child swelling in the cubital fossa, we should immediately feel for the radial pulsation. And if the hand is cold and the radial pulse is absent, then we should immediately take for surgical intervention to reduce the fracture, to reduce decompress the brachial artery. This is an extract of the elbow with a child to show anti-idusification of the elbow. Note the epiphysis of the olecranon process also. It is the fracture of the medial epicondyle. Then the ulnar nerve is at risk. Because I told you just now the ulnar nerve passes behind the medial epicondyle. The radial nerve which I mentioned runs in the radial groove. After it runs, it comes to the front of the lateral epicondyle. So this is the lateral epicondyle. And here it is located under the brachial radialis. So this is the region of the cubital fossa. And the contents of the cubital fossa are from median to lateral. We have the median nerve, the brachial artery, the biceps tendon and the radial nerve. MBBR. Now let's take a quick look at the joints. I've held up the scapula here in front of me. And we can see this is the shoulder joint. And we can see that only approximately one-third of this articulates with the glenoid fossa. So we have the fibrous capsule of the shoulder joint. And of course we also have a series of ligaments called the glenohumeral ligament which extends from the glenoid margin to the humerus. Superior, middle and inferior gleno-humeral ligaments. If you take a look at the scapula here, this tubercle above the glenoid fossa is the supraglenoid tubercle. And this tubercle below the glenoid fossa is called the intraglenoid tubercle. The supraglenoid tubercle gives attachment to the long end of the biceps. It runs through the shoulder joint and then it runs in the inter tubercular sulcus in the tunnel made by the transverse superior ligament. This is the clinical picture of a patient that I happen to see who had ruptured of the tendon of the long head of the biceps on the right side. From the intraglenoid tubercle we have a long head of the triceps. Now I will show you how the lower end of the humerus forms the elbow joint. So this is articulated specimen that this is the ulna here. This is the trochlia nut of the ulna, which fits into the trochlia and this is the head of radius which fits into the capitula. So therefore when the arm is fully flexed, head of the radius fits into the radial fossa and the coronite process which is the anterior fits into the coronite fossa. When the arm is fully extended, olecranon process fits into the olecranon fossa. This is a lateral X-ray of the elbow to show how the trochlia of the humerus fits into the trochlia nut of the ulna. And this is an antrepressory X-ray to show how in a fully extended elbow the oligrenal process fits into the oligrenal fossa. If a child is pulled by the hand, sometimes the head of the radius can subluxate either subclinically or clinically or it can even dislocate and it can come out from the annular ligament in this region. In such a situation it can injure the radial nerve which is located right in front of the lateral epicondyle. So these are some of the points which I wanted to mention to you about the humerus and its articulations. Thank you very much for watching. If you have any questions or comments please put them in the comment section below. Have a nice day.