Os styloideum

Dr Yuranga Weerakkody ◉ and Dr David Tunchon et al.

The os styloideum is an accessory ossicle of the wrist, situated between the 2^ndand 3^rd metacarpal bases.

Radiographic appearance

Given its position next to the 2^nd and 3^rd metacarpal bases, it may be mistaken for a fracture, though this should not occur if an adequate lateral radiograph is assessed ².

Related pathology

It may be implicated in degenerative conditions such as osteoarthritis with localized pain occurring at this region ².

Differential diagnosis

carpal boss

References

Anatomy: Upper limb

skeleton of the upper limb
- clavicle
  - conoid tubercle
  - supraclavicular foramen
- scapula
- humerus
  - supracondylar spur
  - olecranon foramen
- radius
- ulna
- carpal bones (mnemonic)
  - scaphoid
    - bipartite scaphoid
  - lunate
    - lunate morphology
  - triquetrum
  - pisiform
  - trapezium
  - trapezoid
  - capitate
  - hamate
  - variants
    - carpal coalition
      - lunotriquetral coalition
      - capito-hamate coalition
- metacarpals
- phalanges
  - terminal tuft
- accessory ossicles of the upper limb
  - accessory ossicles of the shoulder
    - os acromiale
  - accessory ossicles of the elbow
    - os supratrochleare dorsale
    - patella cubiti
  - accessory ossicles of the wrist (mnemonic)
    - os centrale carpi
    - os epilunate
    - os styloideum
    - os hamuli proprium
    - lunula
    - os triangulare
    - trapezium secondarium
    - os paratrapezium
    - os radiostyloideum (persistent radial styloid)
joints of the upper limb
- pectoral girdle
  - shoulder joint
    - articulations
    - associated structures
    - movements
      - scapulothoracic joint
        
        scapular retraction (adduction)
        
        scapular protraction (abduction)
        
        scapular elevation
        
        scapular depression
        
        scapular lateral rotation
        
        scapular medial rotation
      - glenohumeral joint
        
        arm flexion
        
        arm extension
        
        arm abduction
        
        arm adduction
        
        arm internal rotation (medial rotation)
        
        arm external rotation (lateral rotation)
        
        circumduction
    - blood supply - scapular anastomosis
    - ossification centers
- elbow joint
  - proximal radioulnar joint
  - ligaments
    - medial (ulna) collateral ligament complex
    - lateral (radial) collateral ligament complex
      - lateral ulnar collateral ligament
  - associated structures
  - movements
  - alignment
  - blood supply - elbow anastomosis
  - development
    - elbow ossification (mnemonic)
    - elbow ossification centers
- wrist joint
  - articulations
  - ligaments
    - intrinsic ligaments
    - extrinsic ligaments
  - associated structures
    - extensor retinaculum
    - flexor retinaculum
    - joint capsule
  - movements
  - alignment
  - ossification centers
- hand joints
  - articulations
    - carpometacarpal joint
      - triscaphe joint
    - metacarpophalangeal joints
      - palmar ligament (plate)
      - collateral ligament
    - interphalangeal joints
      - palmar ligament (plate)
      - collateral ligament
  - movements
  - ossification centers
spaces of the upper limb
muscles of the upper limb
blood supply to the upper limb
- arteries
- veins
innervation of the upper limb
- intercostobrachial nerve
- brachial plexus (mnemonic)
  - branches from the roots
  - branches from the trunks
    - suprascapular nerve
  - branches from the cords
    - lateral cord
      - lateral pectoral nerve
    - posterior cord
    - medial cord
  - terminal branches
    - ulnar nerve
    - radial nerve
      - posterior interosseous nerve (deep radial nerve)
      - superficial radial nerve
    - musculocutaneous nerve
    - axillary nerve
    - median nerve
      - anterior interosseous nerve
      - bifid median nerve
lymphatic drainage of the upper limb
- axillary lymph nodes

Article information

rID: 54802

System: Musculoskeletal

Section: Anatomy

Tag: cases, refs

Synonyms or Alternate Spellings:

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Cases and figures

Figure 1: expected locationFigure 1: expected location

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Case 1: os styloideumCase 1: os styloideum