Bones of the upper limb

Definitions & Key takeaways

The upper limb starts from the pectoral girdle to hand. The pectoral girdle is made up of the clavicle and scapula. Next is the arm, which contains the humerus, the forearm containing the radius and the ulna; the wrist made up of the carpals; the hand made up of the metacarpals; and finally, digits contain phalanges. Each bone has a unique shape that helps it perform its specific function.

Chapters:

Watch video only

Introduction0:00–0:53

The upper limb is connected to the axial skeleton, which is the cranium, vertebral column, and associated thoracic cage, by the bony pectoral girdle at the sternoclavicular joint, which is the connection between the clavicle and the sternum.
Each upper limb is made up of 32 bones and has a number of different regions. First, there's the pectoral girdle, which consists of two bones, the scapula, also called the shoulder blade, and the clavicle, also known as the collarbone.
Then there's the arm which only has one bone called the humerus. Then we have the forearm which has two bones called the radius and the ulna.
Next there's the wrist which has 8 carpal bones. And finally, the hand, which has 5 metacarpal bones, and the fingers, we have 14 phalanges in total.

Scapula0:53–4:21

All right, now let's have a look at the shoulder girdle first. The shoulder girdle consists of the scapula and clavicle.
It articulates anteriorly with the manubrium of the sternum. Starting with the scapula, it's a flat triangular bone located on the posterior aspect of the shoulder extending over the 2nd to the 7th ribs.
The scapula helps to connect the rest of the upper limb to the trunk while stabilizing and assisting the shoulder during movement while serving as an attachment point for numerous muscles and ligaments.
Now, like any respectable triangle, the scapula has three borders. The shortest and the thinnest of them is the superior border.
Then there's the medial border which runs parallel to the vertebral column. And finally there's the lateral border, which is the thickest one.
The lateral border is also known as the axillary border because it points towards the axilla or armpit region. The point where the medial and lateral borders meet is the inferior angle.
We also have the superior angle, which is the junction of the superior and medial borders. At the lateral part of the superior border there is a small indentation called the scapular notch through which the suprascapular nerve passes.
Immediately lateral to the notch, the scapula has a bony projection called the coracoid process, which is this bony hook that first projects anteriorly and then curves toward the lateral side similar to a bent finger.
The coracoid process serves as an attachment point for four structures, including the corico acromial ligament, the pectoralis minor muscle.
The Corico brachialis muscle and the short head of the biceps brachii. All right, now the anterior surface of the scapula has a wide depression called the subscapular fossa, which is where the subscapularis muscle attaches.
If we flip the scapula over, we can see its posterior surface. Below the superior border, there's a prominent ridge of bone called the spine of the scapula, which becomes broader as it extends laterally and superiorly to give rise to the acromion process, or simply the acromion.
The surface below the spine of the scapula is called the infraspinous fossa, where infra means below, and spinus refers to the spine of the scapula.
This is where a muscle called the infraspinatus attaches. The space above the spine is called the supraspinous fossa, and as you might have guessed it, well, it has an attachment point for the supraspinatus muscle.
No surprises here. The spine of the scapula also has an attachment point for the deltoid muscle on the deltoid tubercle of the spine in addition to attachments for the trapezius muscle.
Inferior to the coracoid process on the superior lateral surface of the scapula, there's the glenoid cavity, which is a shallow cup-like fossa facing the lateral side.
The glenoid cavity fits the head of the humerus to form the glenohumeral or shoulder joint. And the Corico acromial ligament stabilizes this joint.
Just above the glenoid cavity there's a small bony bump called the supraglenoid tubercle, which serves as an attachment point for the long head of the biceps brachii muscle.
Again, immediately below the glenoid cavity, there's another bony bump called the infraglenoid tubercle, which serves as an attachment point for the long head of the triceps brachii muscle.
All right, now the tip of the acromion articulates with the lateral end of an S-shaped bone called the clavicle, forming the acromioclavicular joint, which helps with stability and motion of the shoulder joint.

Clavicle4:21–5:57

The medial end of the clavicle is enlarged and triangular shaped and articulates with the manubrium, which is the upper part of the sternum, to form the sternoclavicular joint.
The medial 2/3 of the clavicle are convex anteriorly, and the lateral third is flattened and concave anteriorly. On the inferior surface of the clavicle immediately medial to its lateral end, there is a small oblique ridge of bone called the trapezoid line where the trapezoid ligament attaches.
Medal to the trapezoid line, there is the conoid tubercle, which is where the conoid ligament attaches. Both the trapezoid and the conoid ligaments help stabilize the pectoral girdle.
Finally, the inferior side of the clavicle has a shallow groove called the subclavian groove, where the subclavius muscle attaches.
When determining the orientation of the clavicle, it's good to remember that the lateral portion is flat and the inferior surface is rough compared to the smooth superior surface.
Finally, the clavicle's most important job is to suspend the scapula away from the trunk, allowing the upper limb maximum freedom of motion.
The clavicle is also one of the bony boundaries of the cervical axillary canal, which is a passageway that extends between the upper limb and the neck, so the clavicle also protects the neurovascular bundle supplying the upper limb.
Alright, now that's a lot of info. Feel free to take a second to pause the video and see if you can label these missing parts of the scapula from A to F.

Quiz5:57–6:13

Humerus6:13–10:02

All right, so now let's look at that single bone in the arm, the humerus. The humerus is the largest bone of the upper limb.
Proximally, the humeral head articulates with the glenoid cavity to form the glenohumeral joint, while the distal end of the humerus articulates with the radius and the ulna distally to form the elbow joint.
Lateral to the humeral head there is a bony protuberance called the greater tubercle, and anterior to it is the lesser tubercle, which is more on the anterior humerus.
The greater tubercles and attachment point for the supraspinatus. Infraspinatus And terry minor muscles, while the lesser tubercle is an attachment point for the subscapularis muscle.
Between these two tubercles there is a narrow groove called the intertubercular sulcus or the bicipital groove because the tendon of the biceps brachii muscle passes through it.
Just below the humeral head there is the anatomical neck of the humerus. This is formed by a groove separating the humeral head from the greater and lesser tubercles and is where the glenohumeral joint capsule attaches.
Disal to the tubercles, there is the surgical neck of the humerus, which is where the broad proximal part of the humerus meets the narrow humeral shaft.
This makes the surgical neck relatively weaker and thus a common site for humeral fractures. On the posterior surface of the shaft there's a shallow but broad bone depression called the radial groove, which is where the radial nerve passes through.
On the lateral side of the shaft, there's a rough small bump called the deltoid tuberosity, which is where the deltoid muscle attaches.
Toward its distal end, the humerus flattens a bit, giving rise to two bony projections known as the medial and lateral epicondyles.
Above the lateral epicondyle there is the lateral supracondylar ridge, which is the roughened ridge of bone where the extensor carpi radialis longus, the brachioradialis muscle, and the triceps brachii muscles attach.
Above the medial epicondyle there's the medial supracondylar ridge which serves to attach the medial head of the triceps, the brachialis, and the pronator teres.
Finally, the tip of the distal humerus, referred to as the condyle of the humerus, has two articular surfaces which makes sense as it articulates with the two bones of the forearm, the radius and the ulna.
Immedially, there's the trochlia, which literally translates to pulley, which is lucky because it really looks like one.
The trochleaa articulates with the trochlear notch of the ulna. And latterly there's the capitulum, which articulates with the head of the radius, and it literally means tiny head because it looks a bit like a tiny bald head.
It can be tough to remember which fossa articulates with which bone, so you can try and remember the phrase crazy tulips.
The CRA in crazy represents the capitulum articulating with the radius, and the TUL in tulips represents the trochleaa articulating with the ulna.
On the anterior surface of the humerus proximal to the trochleaa, there's a small depression called the coronoid fossa. Lateral to the coronoid fossa, there's the radial fossa, which sits just proximally to the capitulum.
During flexion of the elbow, the coronoid fossa receives the coronoid process of the ulna, while the radial fossa is a cozy place for the radial head.
If we flip the bone and look on the posterior side just at the same level, there's a much larger depression called the lecranon fossa, which accommodates the leronon process of the ulna when the forearm is fully extended.
Next up there's the forearm, which is made of two parallel bones, the ulna medially and the radius laterally. You can remember their position when you text your friends, um, really.

Ulna10:02–12:14

The ulna is the main stabilizing bone of the forearm. At its proximal end, the ulna articulates with the trochleaa of the humerus and the head of the radius laterally.
To articulate with the humerus, the ulna has two prominent projections the olecranon, which forms the point of the elbow and sits in the olecranon fossa when the elbow is extended.
And the coronoid process, which projects anteriorly and sits in the coronoid fossa when the elbow is flexed. These two processes form the trochlear notch which grips the trochlear like a wrench.
Slightly distal to the coronoid process, there's the ulnar tuberosity, a bony bump where the brachialis muscle inserts. On the lateral side of the coronoid process, there is a smooth concavity called the radial notch of the ulna which articulates with the disc-shaped head of the radius forming the proximal radial ulnar joint.
The radial head is tied to the radial notch of the ulna by a ring-shaped ligament called the annular ligament. On the lateral side of the ulna inferior to the radial notch on the lateral ulna is a supinator crest, which is the attachment of the deep part of the supinator muscle needed for forearm supination.
Looking at the shaft of the ulna, its lateral side forms a long ridge of bone called the interosseous border of the ulna, where the interosseous membrane attaches.
The interosseous membrane, intermeaning between and osseous meaning bone, is a dense connective tissue that connects the ulna and radial shafts so that the forearm bones move as one.
Distally, the shaft of the ulna ends with a round area called the head of the ulna which stops short and does not participate in the radiocarpal joint of the wrist.
Toward the posterior side of the head of the ulna, there is a small bony projection called the styloid process of the ulna, which is where the ulnar collateral ligament of the wrist attaches.
Now let's have a look at the radius, which runs parallel and lateral to the ulna. On the proximal part of the radial head, there is a concave depression for when it articulates with the capitulum of the humerus during flexion and extension.

Radius12:14–14:03

The radial head itself is also disk shaped in nature, which is important during pronation and supination, or turning your forearm from keyboard typing position to anatomical position.
The medial side of the radial head articulates with the radial notch of the ulna, forming the proximal radial ulnar joint.
Immediately below the radial head, there's the narrow radial neck and distal to it on the medial side, there's an oval shaped bony protuberance called the radial tuberosity.
The radial tuberosity has two parts the posterior one, which is rough, and the anterior part, which is smooth. The posterior part is where the tendon of the biceps brachii muscle inserts.
Disal to the radial tuberosity, there's the radial shaft which becomes broader distally and bends slightly toward the medial side.
On its medial side there's the ulnar notch where part of the ulnar head fits to form the distal radial ulnar joint. On its posterior side, the distal radius has a bony prominence called Lister's tubercle or dorsal tubercle of the radius, which can be palpated on the dorsum of the wrist.
At the tip of the distal radius, there is a smooth, slightly concave surface that articulates with carpal bones, specifically the scaphoid and the lunate to form part of the radiocarpal joint, commonly called the wrist.
On the lateral side of the distal radius, there's a pointed bony projection called the styloid process of the radius, which projects more distally than the ulnar styloid process.
Now feel free to take a quick break and pause the video to test your radius of knowledge on the forearm bones. Can you label these missing parts A, B, C, D, and E on the following image?

Quiz14:03–14:17

Carpal bones14:17–17:01

All right then, next up there's the wrist, which is the base of the hand. The wrist is made up of 8 small carpal bones which are arranged in two rows of 4 bones each alonging flexibility of the wrist.
Looking at it from an anterior view, from lateral to the medial, the proximal row has the scaphoid bone, which means boat shaped, the moon-shaped lunate bone, the three-corned pyramid-shaped triquetrum, and finally the pisiform, which looks like a pea.
On the distal row, but going from medial to lateral instead, there is the hooked hamate bone, the capitate, which looks like a small head, the wedge-shaped trapezoid bone, and the table-looking trapezium.
The hamate bone has a prominence termed the hook of the hamate, where the ulnar nerve enters the hand by passing medial to the hook of the hamate through a groove between it and the pisiform bone.
The scaphoid and the lunate are the only carpals that articulate directly with the distal radius, forming the radioscapholunate joint or the radiocarpal joint to make things simple.
At the tip of the distal ulna, there's a fibrocartilaginous pad that spans the styloid process of the ulna and part of the distal end of the radius on the medial side.
This pad separates the ulna from the closest carpals, which are the luna and the triquetrum. So since it might be hard to cram all of these 8 carpels, let's use a cool mnemonic to remember their order.
So long to pinky. Here comes the thumb.
This pneumonic helps you remember the bones in a U shape starting from the lateral to medial in the proximal row and then going from medial to lateral in the distal row.
This also helps us remember that the pisiform is by the pinky and the trapezium is by the thumb. Another nice memory trick to remember that the trapezium is by the thumb is that they both have the letter M.
To determine if you're looking at the carpal bones from an anterior or posterior view, remember that the pisiform bone lies anterior to the triquetrum bone, so it's hidden in a posterior view.
Then to identify the bones, start by looking at the lateral side, the side with the thumb on it, and locate the scaphoid bone on the proximal row of bones.
Remember, the scaphoid bone is large and articulates with a distal radius. From there, identify the rest using the pneumonic we just learned.
Pause the video and try identifying the bones on this X-ray of the hand. All right, the distal carpal bones articulate with the five bones of the hand called the metacarpals, forming the carpal-metacarpal joints.

Metacarpal bones17:01–17:47

Metacarpals are numbered from 1 to 5, starting on the lateral side, which is the thumb side. The first metacarpal bone is separated from the rest, which facilitates free movement of the thumb independent of the palm.
Distally, metacarpals articulate with the proximal phalanges, which are also named from 1 to 5 starting from the thumb. The contact between the metacarpals and the first row of phalanges makes the metacarpal phalangeal joints, which are perceived as knuckles at the dorsum of the clenched hand.
Distal to the proximal phalanges are the middle and distal phalanges. However, the thumb only has two phalanges, a proximal and a distal.

Phalanges17:47–17:59

The phalanges are connected together by interphalangeal joints. All right, so let's take one more pause here before the recap and try to identify the bones labeled from A to J on the following image.

Quiz17:59–18:12

Review18:12–20:46

All right, as a quick recap. The upper limb starts with the pectoral girdle, which has two bones, the scapula and the clavicle.
The scapula is a triangular flat bone with the superior, the medial, and the lateral borders. On its posterior surface there is the spine of the scapula which becomes the acromion process laterally which articulates with the lateral end of the clavicle, the infraspinous and the supraspinous fossa.
On the anterior surface of the scapula, there is the subscapular fossa, and on the superior border there are the suprascapular notch, the coracoid process, and the lateral facing glenoid cavity.
Medal to the lateral end of the clavicle on the inferior side is the trapezoid line and the conoid tubercle in the subclavian groove.
Finally, there's its medial end which articulates with the manubrium of the sternum. The humerus articulates with the glenoid cavity proximally and is composed of the humeral head.
The anatomical neck, the greater and lesser tubercles, surgical neck, and the inner tubercular groove. The humeral shaft starts below the surgical neck, and it has a deltoid tuberosity, the radial groove, the medial and the lateral supracondylar ridges, and the epicondyles.
Distally, the humerus has the capitulum. Petrolia The coronoid and the radial fossa on the interior side.
And the olecranon fossa on the posterior side. The forearm has two bones, the ulna and the radius.
Proximally, the ulna has the olecranon and coronoid process, trochlear and radial notches, and tuberosity of the ulna. On its shaft, it has the interosseous border.
And the head of the ulna and the styloid process on the distal part. The proximal radius consists of the head, the neck, and the radial tuberosity.
The shaft has the inner osseous border, and distally we have the ulnar notch in the dorsal tubercle. The wrist has 8 carpals which are the scaphoid, the lunate, the triquetrum, the pisiform on the proximal row.
And then the hamate, capitate, trapezoid, and trapezium on the distal row. The hand has 5 metacarpals which are distally followed by a total of 14 phalanges of the fingers.