Ulna + Radius, Surface, Clinical

Which bones make up the forearm?

The ulna and radius

Which forearm bone is medial and which is lateral in anatomical position?

• Ulna → medial

• Radius → lateral

What does the ulna and radius articulate with proximally?

The humerus, forming the elbow joint.

What do the radius and ulna articulate with distally?

The carpal bones at the wrist.

What are the major proximal features of the ulna?

• Trochlear notch

• Olecranon process

• Coronoid process

• Radial notch

• Ulnar tuberosity.

What is the trochlear notch of the ulna?

A large notch that articulates with the trochlea of the humerus.

What is the olecranon process?

The large proximal projection of the ulna that fits into the olecranon fossa of the humerus during elbow extension

What is the coronoid process of the ulna?

A proximal projection that fits into the coronoid fossa of the humerus during elbow flexion.

What is the radial notch of the ulna?

A notch on the lateral side of the ulna that articulates with the head of the radius

What is the interosseous ridge of the ulna?

A ridge that descends along the lateral shaft of the ulna.

What are the distal features of the ulna?

• Head of ulna

• Styloid process

What does the head of the ulna articulate with?

It articulates with the ulnar notch of the distal radius.

What is the styloid process of the ulna?

A pointed bony projection at the distal end of the ulna

What are the major proximal features of the radius?

• Head

• Neck

• Radial tuberosity

What is the radial head?

The proximal end of the radius that participates in articulation at the elbow and with the radial notch of the ulna.

What is the radial tuberosity?

A bony prominence on the proximal radius.

What is the interosseous ridge of the radius?

A ridge along the shaft of the radius that provides attachment for the interosseous membrane.

What is special about the distal styloid process of the radius?

It is larger than the styloid process of the ulna.

What happens to the radius during pronation and supination?

The radius moves/rotates around the ulna during pronation and supination.

🧠 This is a really important concept: the ulna stays relatively fixed while the radius crosses/rotates around it.

What features are found on the posterior surface of the distal radius?

Tubercles and grooves

What is the interosseous membrane?

A sheet of fibrous connective tissue between the interosseous ridges of the radius and ulna.

What is another name for the interosseous membrane?

The interosseous ligament.

What type of fibrous joint is the interosseous membrane?

A syndesmosis

Where is the interosseous membrane located?

Between the interosseous ridges of the radius and ulna

What are the functions of the interosseous membrane?

1. Prevents separation of the radius and ulna

2. Provides a site of muscle attachment/insertion

3. Transmits forces from the radius to the ulna.

Does the interosseous membrane prevent pronation and supination?

No.

It holds the radius and ulna together while still allowing pronation and supination

What surface landmarks of the pectoral girdle are identified in the lecture?

• Jugular notch

• Sternoclavicular joint

• Clavicle

• Acromioclavicular joint

• Midclavicular line

• Acromion.

Where is the jugular notch?

At the superior border of the manubrium of the sternum, between the clavicles.

What is the midclavicular line?

A vertical reference line passing approximately through the midpoint of the clavicle

Where can you palpate the acromion?

At the prominent bony point at the top/lateral aspect of the shoulder.

What is the sulcus sign?

A visible depression associated with a dislocated glenohumeral joint, caused by displacement of the acromion/shoulder contour.

What does the surface anatomy image on page 46 show?

Surface landmarks around the elbow and upper arm, including:

• Humerus

• Cubital fossa/brachialis region

• Triceps

• Biceps brachii

• Lateral epicondyle

• Olecranon process

What bony landmarks can be palpated around the posterior elbow?

The lateral epicondyle and olecranon process.

Which styloid processes can be identified at the wrist?

The styloid process of the radius and the styloid process of the ulna. The radius’s styloid process is larger.

Compare the radius and ulna in anatomical position.

	Radius	Ulna
Position	Lateral	Medial
Proximal	Head, neck, radial tuberosity	Trochlear notch, olecranon, coronoid
Distal	Larger styloid process	Head + styloid process
Movement	Rotates around ulna during pronation/supination	Relatively more stationary

Which structures of the ulna fit into the fossae of the humerus?

• Olecranon process → olecranon fossa during elbow extension

• Coronoid process → coronoid fossa during elbow flexion.

Which structures articulate at the proximal radius?

The head of the radius participates in the elbow joint and articulates with the radial notch of the ulna.

What are the key nerve associations around the humerus?

• Surgical neck → axillary nerve

• Radial groove → radial nerve

• Posterior to medial epicondyle → ulnar nerve.