L6 Intro to the Upper Extremities

Question 1

Answer 1

Ø Hand

§ Palmar/Dorsum side

§ Lines are the joints of the digits (3 joints per digit, 2 per thumb)

§ Thumb = Pollex (pollicis)

§ Digits = Other 4

§ Thenar/Hypothenar eminence

Question 2

Answer 2

Clavicle – Scapula – Humerus – Radius/Ulna/Body (RUB - Ulna being more proximal) – Carpal bones – Bones of hand/digits

Question 3

Parts of the clavicle? How do we know the orientation (sup/inf, left/right) of the clavicle?

Answer 3

• Clavicle
• ~ shaped bone
• Superior (smoother) and inferior (bumpier) surface
• Medial (flat, blunt)
• Sternal end – Attaches with sternum
• Lateral end
• Acromial end
• Convex (medial) to concave (lateral) anteriorly
• Groove for subclavius muscle on interior
• Conoid tubercle (more lateral)

Convex to concave, smoother surface superiorly

Question 4

What landmarks can we use in the scapula to determine vertebra level?

Answer 4

• LANDMARKS:
  
  • Spine (lateral end) – TIII
  • Inferior corner – SP of TVII (close to TVIII because thoracic SPs angle down)

Question 5

Name the different parts of the scapula

Answer 5

• Scapula
  
  • Triangular shaped
    
    • 3 borders (Superior, medial and lateral) and 3 angles (lateral, inferior and superior)
  • Processes
    
    • Coracoid process
• Anterior side (beak-like structure)
• Spine
• Posterior side (splits scapula into two)
• Acromion
• Extension of the coracoid process
• Extends vertically
• Fossae
• Glenoid fossa
• Lateral
• Socket of the ball/socket joint of shoulder

Question 6

Parts of the humerus?

Answer 6

• Head of the Humerus
  
  • Anatomical (proximal) and surgical (distal)
• Tubercles
  
  • Greater tubercle
    
    • Visible both post/ant
  • Lesser tubercle
    
    • Only visible anteriorly
• Deltoid tuberosity
  
  • Attaches with deltoid

Question 7

Parts of the sternoclavicular joint? Movements made possible due to joint?

Answer 7

• Sternum and medial end of clavicle
  
  • Synovial saddle (clavicle requires a lot of movement)
    
    • Saddle = palms together
    • Elevation/depression (shrugs)
    • Pro/retraction (crack/squeeze)
    • Slight rotation (rolls on sternal end when circumduction of arm)
• Costal cartilage associated to rib 1
• Ligaments
  
  • Costoclavicular ligament ( _ )
  • Interclavicular ligament ( v )
  • Sternoclavicular ligament ( - )
    
    • (_-v-_)
• Movements:
  
  • Elevation/depression (shrugs)
  • Protraction/Retraction (box)

Question 8

Describe the acromioclavicular joint

Answer 8

• Acromial end of clavicle and acromiom of humerus
  
  • Ligaments
    
    • Acromio-clavicular ligament
      
      • Stabilizes the lateral end of the clavicle
      • Acromiom and clavicle
    • Coraco-clavicular ligament
      
      • Coracoid process and clavicle
      • Wraps around coracoid
      • Trapezoid and conoid ligament
    • Coraco-acromial ligament
      
      • Coracoid and acromiom
      • Prevents the humerus from pushing through the coracoid process and acromiom
        
        • Common case: Clavicle sits above acromiom

Question 9

What are the different ligaments that make up the glenohumeral joint? Possible dislocations?

Answer 9

• Ligaments
  
  • Coracohumeral ligament
    
    • Divided in two by the biceps brachii tendon down the middle
    • Prevents dislocation superiorly
    • Ant/post
  • Glenohumeral ligaments
    
    • Superior – middle – inferior
    • Prevents dislocation anteriorly
    • Anterior only
  • Dislocations
    
    • Anterior – Head of the humerus rips past the joint and sits anterior to the glenoid fossa
      
      • More common (sports, weak structural support)
    • Posterior – Head of humerus pushed posteriorly (breaking a fall with outstretched arm)

Question 10

What additional structures does the glenohumeral joint have to improve movement? What are the movements that this joint is capable of?

Answer 10

• Glenoid fossa and head of humerus
• Ball and socket joint (3 axis)
• Shallow socket
  
  • Sacrifices structural support to increase movement of the humerus
  • Glenoid labrum – Ring of fibrocartilage that provides structural support between head of humerus and glenoid fossa
• Large synovial cavity
  
  • Needs to wrap around the whole joint
  • Large capsule
  • Redundant capsule
    
    • Extension, leg of capsule
    • Allows full abduction of shoulder (original capsule doesn’t have to stretch to accommodate to movement)
• Ball and socket:
  
  • Flexion/Extension
  • Abduction/Adduction
  • Medial/lateral rotation (fixed elbow)

Question 11

What is the scapulo-thoracic “joint”? Why “joint”? Importance in scapulohumeral rhythm?

Answer 11

• Scapulo-thoracic “joint”
  
  • Empty space between subscapular fossa and ribs
  • No ligaments therefore not a real joint
  • Scapulohumeral rhythm
    
    • 2:1 degree ratio of glenohumeral to scapulothoracic movement
    • First 30 degrees of abduction – Only glenohumeral, no scapula
    • Beyond 30 degrees of abduction – Both glenohumeral and scapula
      
      • Prevents the head of the humerus to detach itself from the glenoid fossa