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🦴 CLAVICLE - "The Beauty Bone / Collar Bone"

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1. BASIC INTRODUCTION

• Latin name: Clavicula = "small key" (rotates like a key)
• Only horizontal long bone in the body
• Connects sternum (medially) to acromion of scapula (laterally)
• Subcutaneous = felt under skin throughout its length

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2. SHAPE - Easy to Remember

"Medial = Round, Lateral = Flat"

• Shaft = Lateral 1/3 + Medial 2/3
• Weakest point = junction between the two curves (most common fracture site)

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3. TWO ENDS

• Large, quadrilateral
• Articulates with manubrium sterni → forms Sternoclavicular joint
• Also touches 1st costal cartilage

• Flat
• Articulates with acromion → forms Acromioclavicular joint

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4. MUSCLE ATTACHMENTS - Mnemonic

"2 muscles on top, 3 on bottom" (superior vs inferior surface)

Superior Surface:

Inferior Surface:

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5. IMPORTANT LANDMARKS (Inferior Surface)

• Subclavian groove = for subclavius muscle
• Conoid tubercle = for conoid ligament (part of coracoclavicular)
• Trapezoid ridge = for trapezoid ligament
• Impression for costoclavicular ligament = at medial end

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6. PECULIARITIES - Top Viva Points! ⭐

Mnemonic: "SOLO-HMM"

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7. OSSIFICATION ⭐ (High Yield Viva)

• First bone in body to ossify (5th-6th week of intrauterine life)
• 2 primary centres in shaft → fuse by 45th day
• 1 secondary centre for medial (sternal) end → appears at 15-17 years, fuses at 21-22 years
• Ossifies in membrane (not cartilage) - exception among long bones

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8. CLINICAL ANATOMY ⭐⭐

• Most common fracture site: Junction of lateral 1/3 and medial 2/3 (weakest point)
• Cause: Fall on outstretched hand (indirect violence)
• Displacement after fracture:
  • Medial fragment → pulled up by SCM
  • Lateral fragment → pulled down by weight of limb (trapezius alone can't support it)
• Cleidocranial dysostosis: Congenital absence/hypoplasia of clavicle → shoulders can be brought together in front of chest
• Subclavian vessels + brachial plexus pass between inferior surface of clavicle and 1st rib → protected by subclavius muscle (acts as cushion)

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9. SIDE DETERMINATION (To Identify Right/Left)

1. Flat end → Lateral (acromial)
2. Concave surface of lateral end faces forward
3. Subclavian groove → inferior surface, lateral half
4. Conoid tubercle projects downward near acromial end

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QUICK VIVA FIRE ROUND ⚡

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Memory tip for shape: Think of clavicle like the letter "f" lying flat - the medial part is long and rounded, the lateral part is short and flat.

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🦴 RADIUS - "The Rotating Forearm Bone"

Memory trick: "R for Radius = Rotates = Right side of forearm (when palm faces forward)"

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1. BASIC INTRODUCTION

• Lateral bone of forearm
• Homologous with tibia of lower limb
• Upper end = small/rounded (head)
• Lower end = wide/broad (with styloid process)
• Has: 1 upper end + 1 shaft + 1 lower end

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2. SIDE DETERMINATION (How to identify Right/Left)

Remember: "Head up, Broad down, Styloid lateral"

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3. UPPER END (3 parts)

a) HEAD

• Disc-shaped, covered with hyaline cartilage
• Superior concave surface → articulates with capitulum of humerus (elbow joint)
• Circumference → fits into radial notch of ulna + annular ligament → forms Superior Radioulnar Joint

b) NECK

• Enclosed by narrow lower margin of annular ligament
• Head + Neck = FREE from capsular attachment (can rotate freely)

c) RADIAL TUBEROSITY

• Just below medial part of neck
• Rough posterior part = insertion of Biceps Brachii
• Smooth anterior part = covered by bursa

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4. SHAFT - 3 Borders + 3 Surfaces

Borders:

Surfaces:

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5. LOWER END - Most Important! ⭐

• Widest part of bone, has 5 surfaces
• Styloid process = lateral surface prolonged downward (Greek = pillar)

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6. MUSCLE ATTACHMENTS ⭐

Insertion INTO Radius (muscles that insert):

Origin FROM Radius (muscles that arise):

Mnemonic for insertions: "Be Super Pro Pro Bra" Biceps, Supinator, Pronator teres, Pronator quadratus, Brachioradialis

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7. SIX GROOVES UNDER EXTENSOR RETINACULUM ⭐⭐

Mnemonic: "2 Thumbs, 2 Carpi, 1 Digitorum, 1 Indicis" = 1 to 6

Groove 1-4 on Radius, Groove 5 at junction of Radius & Ulna, Groove 6 on Ulna Dorsal tubercle of Lister lies between groove 2 and 3

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8. OSSIFICATION ⭐ (Viva Favourite)

Key point: Lower end is the growing end (appears 1st year, fuses last at 20) Upper end fuses earlier (18 years)

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9. CLINICAL ANATOMY ⭐⭐ (Top Viva!)

A. Colles' Fracture

• Most common fracture = 2 cm above lower end
• Cause: Fall on outstretched hand (FOOSH)
• Distal fragment displaced backward + upward
• Deformity = "Dinner Fork deformity"
• Radial styloid comes to lie proximal to ulnar styloid (normally distal)

B. Smith's Fracture

• Reverse of Colles' = distal fragment displaced forward
• Cause: Fall on back of hand
• Called "Reversed Colles'"

C. Pulled Elbow (Subluxation of Radial Head)

• Sudden jerk on child's hand → head of radius pulled out of annular ligament
• Also called "Nursemaid's Elbow"
• Head felt in hollow behind lateral epicondyle

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10. QUICK VIVA FIRE ROUND ⚡

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BONUS - Radius vs Ulna at a Glance

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Final memory trick: Radius = "R"adius = "R"otates - it rotates around ulna to produce pronation/supination. Ulna is the fixed, stable bone; Radius is the mobile, rotating one!

🦴 RADIUS vs TIBIA - Homologous Bone Comparison

Why homologous? Both are the medial/larger weight-bearing bones of their respective limbs... wait - actually both Radius and Tibia are the bones that articulate with the more important joint distally and are lateral in anatomical position in their respective limbs.

Simple way to remember: Radius is to the upper limb what Tibia is to the lower limb.

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1. BASIC POSITION COMPARISON

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2. GENERAL STRUCTURE COMPARISON

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3. ENDS - DETAILED COMPARISON

UPPER END

LOWER END

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4. SHAFT COMPARISON

Key contrast: Radius - nutrient foramen opens UP. Tibia - nutrient foramen opens DOWN (away from knee, toward ankle). Mnemonic: "To the Elbow I Flee" - radius opens toward Elbow. Tibia opens away from knee (downward).

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5. MUSCLE ATTACHMENTS COMPARISON

Insertions INTO the bone:

Origins FROM the bone:

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6. JOINTS FORMED - COMPARISON

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7. OSSIFICATION COMPARISON ⭐⭐

KEY VIVA POINT:

• Radius growing end = LOWER (wrist end)
• Tibia growing end = UPPER (knee end)
• Mnemonic: "Radius grows Away from elbow, Tibia grows Toward knee" = both grow away from elbow, toward knee
• This is the rule: "Grow away from elbow, grow toward knee"

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8. CLINICAL COMPARISON ⭐⭐

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9. INTEROSSEOUS MEMBRANE COMPARISON

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10. QUICK VIVA FIRE ROUND ⚡

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SUMMARY TABLE - ONE GLANCE REVISION

Dorsal Tubercle of Lister - Acts as Pulley for:

✅ Extensor Pollicis Longus (EPL)

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How to Remember This:

"Lister's tubercle = THUMB's pulley" EPL = Extensor Pollicis (Pollicis = Thumb in Latin) Longus

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Why it acts as a pulley:

• The tendon of EPL winds around the medial side of Lister's tubercle
• Then changes direction - goes obliquely across the wrist toward the thumb
• The tubercle acts like a pulley/fulcrum - changes the direction of pull of EPL
• This allows EPL to retropulse (extend + adduct) the thumb - called "hitchhiker's movement"

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Location of Lister's Tubercle:

• On the posterior surface of lower end of radius
• Lies between 2nd groove (ECRL + ECRB) and 3rd groove (EPL)
• EPL passes in 3rd groove, medial to Lister's tubercle

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Clinical Importance ⭐

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Groove Number Summary (around Lister's):

Mnemonic: "Lister's = L = Longus Pollicis Extensor uses it"