Elbow and Forearm

Question 1

What joints create the elbow joint? What type of joint do they create? What movements do they have?

Answer 1

• humeroulnar and humeroradial joint
• hinge joint
• a single axis of rotation for flexion and extension

Question 2

What type of joint is the humeroulnar joint? Explain the anatomy of the humeroulnar joint and it’s importance to the type of movement the joint has and our carrying angle.

Answer 2

• synovial, hinge joint
• the shape of the trochlea of humerus prevents side to side movement
• the medial side of the trochlea is more distal, which sets the ulna at an angle (creating the carrying angle)

Question 3

What type of joint is the humeroradial joint? What 2 degrees of freedom does this joint have?

Answer 3

• synovial condyloid joint
• flexion/extension
• supination/pronation of the radioulnar joint results in movement at this joint

Question 4

Where does the elbow joint capsule attach? Where is the capsule loose and tight? What does this imply with respect to motion?

Answer 4

• attaches to the humerus, ulna, and annular ligament on the radius
• loose anteriorly and posteriorly
• tight medially and laterally
• only 1 degree of freedom: flexion/extension, so can’t have any movement in frontal plane

Question 5

What are the 3 ligaments of the elbow?

Answer 5

-ulnar collateral ligament
-radial collateral ligament
-annular ligament
all function to restrain distraction (especially babysitter’s elbow)

Question 6

What type of ligament is the ulnar collateral ligament? Where does the ulnar collateral ligament of the elbow run? What does each band resist? Which is the strongest band?

Answer 6

• capsular
• anterior: from the coronoid process of ulna to medial epicondyle of humerus; resists elbow abduction/valgus stress from 0-90 flexion
• posterior: from olecranon of ulna to medial epicondyle of humerus; resists abduction/valgus stress after 90 flexion
• oblique band: from olecranon to coronoid; no purpose
• strongest is anterior band

Question 7

What type of ligament is the radial collateral ligament? Where does the radial collateral ligament of the elbow run? What does it resist? What muscle does it blend with?

Answer 7

• capsular
• from lateral epicondyle of humerus to proximal lateral ulna
• from lateral epicondyle of humer to annular ligament
• resists elbow adduction/varus stress
• blends w/ supinator muscle

Question 8

What are the 3 radioulnar joints?

Answer 8

proximal, middle, distal radioulnar joints

Question 9

What type of joint is the proximal radioulnar joint? What 2 ligaments support it, where do they run, and what do they resist?

Answer 9

-synovial, pivot joint
-annular ligament: from anterior to posterior radial notch, encircling 80% circumference of radial head
blends w/ LCL, supinator, elbow joint capsule
-oblique cord: from ulna tuberosity to inferior radial tuberosity
resists supination

Question 10

What type of joint is the middle radioulnar joint? Where does the interosseus membrane run? What does it resist and why?

Answer 10

• fibrous joint
• medial radius to lateral ulna
• resists superior displacement of the radius since the fibers are oriented up towards the radius
• b/c radius needs more protection: not as stable as the ulna on the humerus and 80% force of a FOOSH transmitted to radius

Question 11

What type of joint is the distal radioulnar joint? Where does the joint capsule attach? What is contained within the triangular fibrocartilage complex?

Answer 11

• synovial pivot joint
• head of ulna, ulnar notch, and triangular fibrocartilage
• complex: triangular fibrocartilage, dorsal radioulnar lig’t, and palmar radioulnar lig’t

Question 12

Where does the palmar/dorsal radioulnar ligaments runs? And what do they resist?

Answer 12

palmar: from palmar base of styloid process of ulna to palmar-medial distal radius; taut in supination
dorsal: from dorsal base of styloid process of ulna to dorsal-medial distal radius; taut in pronation