Features of the Humerus

So this is a tutorial on the humerus. The humerus is this bone here, which runs from the shoulder down to the elbow. It articulates with the scapula here. This is the shoulder joint, the glenohumeral joint.

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There are several parts of the humerus that are important to know. The bit that articulates with the scapula is known as the head. It’s this bit here. I’ll just isolate the humerus, so you can look at that. You can see the humeral head here, which articulates with the glenoid cavity in the scapula. We’re just rotating it around posteriorly. The head is this small bit here.

Just next to the head, you’ve got a tubercle here known as the lesser tubercle. This is a slight bump which protrudes outwards. And then you’ve got the greater tubercle here.

Just to put it back in, orientate you again. The medial surface of the humerus articulates with the glenoid cavity. Then we’ve got the lesser tubercle and the greater tubercle.

In between the greater and lesser tubercles, we’ve got this groove, which is called the intertubercular sulcus or the bicipital groove.

Separating the humeral head from the tubercles is the anatomical neck. This is the anatomical neck of the humerus. Imagine this line I’m drawing here. It runs around like this. That’s known as the anatomical neck. The surgical neck is a bit lower down just inferior to the tubercles.   the surgical neck runs around just below the tubercles.

The surgical neck is called the surgical neck because most often, fractures occur at this site. Very rarely do fractures occur at the anatomical neck, so surgeons are often operating and it got that name because of the frequency of fractures.

The head faces medially. You’ve got the lesser tubercle and then the greater tubercle with the bicipital groove or the intertubercular sulcus running between the two tubercles and you’ve got the surgical neck and the anatomical neck.

The bicipital groove, the intertubercular groove is important because you’ve got the tendon of the long head of the biceps, which runs up through here. If I just show you on the other side, we can see how the tendon runs up. This is the tendon of the long head of the biceps running up through the intertubercular groove. And then it inserts onto the supraglenoid tubercle on the scapula.

The bicipital groove also is the site of attachment for three muscles. You’ve got the pectoralis major, which inserts on the lateral lip of the bicipital groove. The flow of the bicipital groove is the site of attachment for the latissimus dorsi. The medial lip is where the teres major muscle attaches.

A way of remembering that is the mnemonic ‘the lady between two majors’. Lady, l, latissimus dorsi lies between the two majors, so pectoralis major and the teres major.   The latissimus runs dorsi runs in the floor of the intertubercular sulcus between the pectoralis major and the teres major.   the pectoralis major is this big muscle here. The latissimus dorsi is the big muscle of the back. The teres major attaches to the lateral border of the scapula.

That’s a little bit about the intertubercular sulcus.   just a little bit inferior and lateral to the intertubercular sulcus, you’ve got a tuberosity on the side of the humerus, which isn’t really shown very well here, but there’s a tuberosity here where the deltoid muscle attaches. It’s known as the deltoid tuberosity.

You can see here where the deltoid muscle inserts laterally on the humerus just a little bit lateral and inferior to the intertubercular sulcus on the side here. That’s known as the deltoid tuberosity where that inserts.

The length of this bone is known as the shaft, which is not too complicated. And then distally, there are a few things that you need to know.

You’ve got these epicondyles here. You’ve got a medial epicondyle and a lateral epicondyle. A medial epicondyle is important because the posterior surface of the medial epicondyle is where the ulnar nerve runs.   the ulnar nerve winds around the medial epicondyle. You can actually palpate it here.   The medial epicondyle is quite an obvious bone in yourself. You can feel it quite easily.

And also at the distal end, you’ve got the articulation with the radius bone and the ulnar bone. It’s not actually shown very clearly on here, but you’ve got a condyle, which consists of a capitulum and the trochlea, which I’ll show you in another diagram.

I just switched over to one of these diagrams. We’re looking at the same view – anteriorly at the left humerus. You’ve got the head up here medially and you’ve got the medial epicondyle down here and the lateral epicondyle.

This is the condyle I was talking about, which is the articular part of the humerus.   The capitulum, which lies laterally, articulates with the radial head and the trochlea, which sits medially, articulates with the ulna.   this is the articular part of the humerus bone.

Also worth pointing out, just superior to the epicondyles, you’ve got these ridges. You’ve got a lateral and a medial supracondylar ridge or epicondylar ridge.   here, you’ve got the medial supracondylar ridge and here, you’ve got the lateral supracondylar ridge.

And then there’s three fossa that you need to know about in the distal humerus.   you’ve got a coronoid fossa, which lies superior to the trochlea. It’s a little hollowing just above the trochlea. You’ve got this radial fossa, which lies superior to the capitulum.

I’ve just flicked back to the 3D model. There’s another fossa at the back known as the olecranon fossa. This part of the ulnar bone is known as the olecranon. The fossa, you can just see it, this little indentation on the distal part of the posterior humerus. This is the olecranon fossa.

You’ve got three fossae. You’ve got the radial fossa, which lies just above the capitulum. You’ve got the coronoid fossa, which lies just above the trochlea. And you’ve got the olecranon fossa, which lies at the back of the humerus.

Fractures that you get above the condyle are called supracondylar fractures. They’re quite common in children.   when a child falls on their outstretched hand, it’s quite common to get a fracture, a supracondylar fracture (a fracture around this level here above the condyle). What most commonly happens is that the distal fragment displaces backwards. It will fracture here and this portion, the distal fragment will slip backwards and the proximal humerus, this proximal fragment will slip forward. This is important to know because the brachial artery runs anterior to this bone.

You can see I’ve just put in the brachial artery here. You can see its course in front of the humerus. You can see that if the fracture occurs here and the proximal fragment slips forward, it’s in danger of injuring the brachial artery.   it’s always important obviously to check vascular status of a patient who’s had a supracondylar fracture. Check the radial pulse.

That’s the humerus. I hope you’ve learned something from that.