Definition Table
| Category | Explanation |
|---|---|
| What is it? | – One of the two long bones of the forearm – Located on the lateral (thumb) side |
| Most unique feature | – Rotates around the ulna to enable pronation and supination – Participates in both the elbow and wrist joints |
| Structurally characterized by | – Proximally articulates with the humerus at the elbow – Distally articulates with carpal bones at the wrist – Shaft gradually increases in size distally |
| Functionally characterized by | – Facilitates rotation of the forearm – Transmits forces from the hand to the elbow – Critical in wrist and forearm movements |
| Composed of | – Proximal end: Head, neck, radial tuberosity – Shaft: Curved bone body – Distal end: Styloid process, ulnar notch, articulation with carpal bones |
| Common diseases | – Radial head fractures – Colles’ fracture (distal radius fracture with dorsal displacement) – Smith’s fracture (distal radius fracture with volar displacement) – Galeazzi fracture (radius fracture with distal radioulnar dislocation) |
| Diagnosis – Clinical | – Pain, swelling, and deformity in elbow, forearm, or wrist – Loss of forearm rotation or wrist motion – Visible angulation in distal fractures |
| Diagnosis – Imaging | – X-ray: Essential first-line imaging – CT: For complex intra-articular fractures – MRI: For associated soft tissue injuries |
| Diagnosis – Labs | – Rarely needed unless infection or tumor suspected – CBC, ESR/CRP if necessary |
| Treatment (Rx) | – Conservative management (casting) for non-displaced fractures – Surgical fixation (plates, screws) for displaced or unstable fractures – Physical therapy for range of motion recovery |
2. Parts Table
| Part | Description |
|---|---|
| Head | – Disc-shaped proximal structure – Articulates with capitulum of humerus and radial notch of ulna – Allows rotation (pronation/supination) |
| Neck | – Narrow region below the head – Common site for fractures |
| Radial tuberosity | – Bony prominence below neck – Insertion site for biceps brachii tendon |
| Shaft | – Long, slightly curved body – Transfers forces along the forearm |
| Distal end | – Broad, flat region – Forms part of the wrist joint – Styloid process projects laterally – Ulnar notch articulates with ulna for distal radioulnar joint |
3. Historical Note
| Era | Highlights |
|---|---|
| Ancient Times | – Recognition of wrist injuries and fractures in Egyptian and Roman writings – Splinting techniques documented |
| Classical Era | – Galen described forearm rotations (pronation/supination) involving radius movement around the ulna |
| Modern Era | – Improved classification of distal radius fractures (e.g., Colles’, Smith’s) – Development of internal fixation techniques for complex fractures – MRI allowed better detection of subtle radial head injuries |
4. MCQs
🧠 Basic Science
Q1: Which part of the radius articulates directly with the capitulum of the humerus?
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A. Radial tuberosity
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B. Head
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C. Neck
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D. Shaft
Answer: B. Head
Explanation:
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Head (Correct): Articulates with capitulum allowing rotation at elbow.
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Radial tuberosity (Incorrect): Insertion point for biceps, not articulation.
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Neck (Incorrect): Narrow part below head, no direct articulation.
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Shaft (Incorrect): Forms the main body; no direct articulation with capitulum.
Q2: The biceps tendon inserts onto which part of the radius?
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A. Head
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B. Radial tuberosity
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C. Neck
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D. Distal end
Answer: B. Radial tuberosity
Explanation:
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Radial tuberosity (Correct): Insertion of biceps brachii, key for forearm flexion and supination.
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Head (Incorrect): Articulates with humerus, no insertion.
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Neck (Incorrect): No major muscular insertion.
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Distal end (Incorrect): Forms wrist joint; no biceps insertion.
🩺 Clinical
Q3: A Colles’ fracture involves:
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A. Proximal shaft of the radius<br>- B. Distal radius with dorsal displacement<br>- C. Radial head fracture<br>- D. Distal radius with volar displacement
Answer: B. Distal radius with dorsal displacement
Explanation:
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Distal radius with dorsal displacement (Correct): Typical in falls onto outstretched hand (FOOSH injury).
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Proximal shaft (Incorrect): Different injury type.
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Radial head fracture (Incorrect): Involves elbow, not distal radius.
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Distal radius with volar displacement (Incorrect): Describes Smith’s fracture.
Q4: Loss of forearm supination after trauma suggests injury to:
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A. Radius
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B. Ulna
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C. Clavicle
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D. Scapula
Answer: A. Radius
Explanation:
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Radius (Correct): Primary bone moving during pronation/supination.
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Ulna (Incorrect): Relatively stable during forearm rotation.
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Clavicle (Incorrect): Part of shoulder girdle, unrelated to forearm rotation.
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Scapula (Incorrect): Shoulder blade; no direct role in supination.
🖼️ Imaging
Q5: What imaging modality is first-line to assess suspected distal radius fractures?
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A. CT scan
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B. MRI
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C. Bone scan
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D. X-ray
Answer: D. X-ray
Explanation:
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X-ray (Correct): Primary tool to diagnose fractures initially.
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CT scan (Incorrect): Reserved for complex intra-articular fractures.
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MRI (Incorrect): Best for soft tissues, not primary for bone fractures.
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Bone scan (Incorrect): Used for occult fractures or metastases.
Q6: A Galeazzi fracture involves:
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A. Isolated radial head fracture<br>- B. Radial shaft fracture with distal radioulnar joint dislocation<br>- C. Ulna shaft fracture with radial head dislocation<br>- D. Isolated distal radius fracture
Answer: B. Radial shaft fracture with distal radioulnar joint dislocation
Explanation:
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Radial shaft fracture + DRUJ dislocation (Correct): Definition of Galeazzi fracture.
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Isolated radial head fracture (Incorrect): Different entity, no wrist involvement.
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Ulna shaft fracture + radial head dislocation (Incorrect): Describes Monteggia fracture.
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Isolated distal radius fracture (Incorrect): No dislocation of DRUJ.
5. Memory Image Idea 💡
| Concept | Components |
|---|---|
| The Rotating Rod | – Visualize the radius as a sleek rod that spins around a stable post (the ulna) – Head acts as a small wheel turning at the elbow – Shaft acts like a flexible lever to transmit forces – Distal end looks like a flat paddle articulating with the wrist – During pronation and supination, the rod spins gracefully – Title: “The Rotating Rod – TheCommonVein.com“ |