Bones and Joints of the Upper Extremity: Elbow to Hand Flashcards
Bones of the Forearm
- Radius (extends further distally than ulna)
- Ulna (longer than radius)
Interosseous Membrane
- Syndesmosis: fibrous joint
- Collagenous sheet slanted distomedially
- Connects interosseous borders of radius and ulna
Elbow Joint
- Involves humerus, radius, ulna
- 3 separate articulations, share a synovial cavity
- Humeroradial
- Humero-ulnar
- Proximal radioulnar
Humeroradial Joint of Elbow
- Radial head
- Capitulum
Humero-Ulnar Joint of Elbow
- Trochlear notch
- Trochlea
Proximal Radioulnar Joint of Elbow
- Radial head
- Radial notch of the ulna
Ligaments of Elbow Joint
- Radial collateral
- Ulnar collateral
Radial Collateral Ligament
- Lateral epicondyle to annular ligament
Ulnar Collateral Ligament
- Medial epicondyle to coronoid process/olecranon
Movements of Elbow
- Flexion
- Extension
Proximal Radio-Ulnar Joint
- Pivot, synovial joint
- Between head of radius and radial notch of ulna
- Shares joint capsule with the elbow joint
Ligaments of Radio-Ulnar Joint
- Annular ligament of the radius
- Encircles head of radius
Movements of Proximal Radio-Ulnar Joint
- Head of radius rotates, distal radius moves around ulna
- Supination: palm turned anteriorly (superiorly)
- Pronation: palm turned posteriorly (inferiorly)
Distal Radio-Ulnar Joint
- Pivot, synovial joint
- Between head of ulna and ulnar notch of radius
- Supported by triangular fibrocartilage
Pulled Elbow (Nursemaid’s Elbow)
- Subluxation of radial head
- Caused by sudden longitudinal traction to extended elbow
- Most common in ages 1-4
- Dislocation more commonly seen with ulnar fracture
Medial Epicondyle Fracture Symptoms
- Paresthesia ulnar nerve distribution
- Weakness and atrophy of ulnar innervated muscles
- “Ulnar claw” deformity
- Wartenberg sign (inability to adduct 5th digit)
- Arm function is not altered
Colles Fracture
- Transverse fracture of distal radius with dorsal angulation, “dinner fork deformity”
- Impaction is common (causes shortening of the radius)
- Caused by a fall on an out stretched hand (FOOSH injury)
- Osteoporosis is a risk factor
Wrist Joint (Radiocarpal Joint)
- Synovial, condyloid (ellipsoid)
- Between the radius/triangular fibrocartilage and the proximal row of carpals (except for pisiform)
- Ulna does not participate
Ligaments of Wrist (Radiocarpal) Joint
- Radiocarpal and collateral ligaments
Wrist Joint (Radiocarpal) Movements
- Flexion/extension
- Abduction/adduction
- Circumduction
Intercarpal Joints
- Synovial plane joints
- Between carpal bones
- Midcarpal joint: between proximal and distal rows
Carpometacarpal Joint (CMC)
- Synovial plane, except for thumb and trapezium (saddle joint)
- Little motion, 4th and 5th have more, 1st allows flex/ext, abd/add, circumduction
Metacarpophalangeal (Knuckles)
- Synovial, condyloid
- Flexion/extension
- Abduction/adduction
Interphalangeal (IP) Joint
- Synovial, hinge joint
Scaphoid Fracture
- Most common carpal fracture (70-80%)
- Any age, more common in young adults/adolescents (elderly usually sustain a Colles fracture)
- Falling on an outstretched hand (FOOSH)/wrist extended
- High incidence of avascular necrosis
Avascular Necrosis (Osteonecrosis)
- Ischaemic death of bone
- Leads to early development of degenerative arthritis and instability
- Common in scaphoid fracture
Signs/Symptoms of Scaphoid Fracture
- Pain/swelling
- Pain with gripping and thumb movement
- Tenderness in anatomical snuff box
Carpal Dislocation
- Not common
- Perilunate most common
- Lunate most common single carpal dislocation
- FOOSH injuries
Lunate Single Carpal Dislocation
- Lunate dislocated volarly
Perilunate Dislocation
- Dislocation of the carpal bones relative to the lunate
- 60% are associated with scaphoid fracture
