Lecture 9 - Elbow & Forearm

Question 1

What is the elbow?

Answer 1

• it is a hinge joint that allows flexion/extension movements; the only movement that happens at the elbow
• made up of the humerus & ulna

Question 2

What is the forearm ?

Answer 2

• it is a pivot joint that allows supination/pronation movements; the only movement of the forearm
• the forearm is made up of the radius & ulna

Question 3

What is the coronoid process of the ulna?

Answer 3

• a short hook-like process that projects anteriorly & laterally from the superior margin of the scapula
• forms the trochlear notch with the olecranon process
• provides some stability & helps prevent posterior dislocation

Question 4

What is the olecranon process?

Answer 4

• expands the posterior & superior portions of the proximal ulna
• forms the bony tip of the elbow
• provides stability for elbow flexion/extension

Question 5

What is the ulnar tuberosity ?

Answer 5

• inferior to the coronoid process
• it is a muscle attachment for the biceps brachii

Question 6

What is the ulna?

Answer 6

• the medial bone of the forearm (pinky side) (inside)
• it is the stabilizing bone for the radius
• it is an elbow joint

Question 7

What is the olecranon bursae ?

Answer 7

• a synovial sac between the olecranon process & the skin to prevent friction

Question 8

What is the radius ?

Answer 8

• it is the lateral side of the forearm (thumb side) (outside)
• it is shorter than the ulna

Question 9

What is the head of the radius?

Answer 9

• a disc-shaped structure that forms the proximal end
• the small depression articulates with the capitulum of the humerus
• the smooth, outer part articulates with the radial notch of the ulna at the proximal Radioulnar joint

Question 10

What is the neck of the radius?

Answer 10

• a narrowed region below the expanded head
• an oval-shaped, bony protuberance that serves as a muscle attachment point for the biceps brachii

Question 11

What is the shaft of the radius?

Answer 11

• slightly curved & has a small ridge along its medial side
• it forms the interosseous border
• also forms the ulnar notch & articulates with the head of the ulna; which makes contact with the radius

Question 12

What is the radial styloid process?

Answer 12

• on the lateral end of the radius

Provides attachment for ligaments that support the lateral side of the wrist joint

Question 13

What is the ulnohumeral joint

Answer 13

• the joint where movement occurs between the ulna & humerus
• it is a synovial hinge joint that is uniaxial
• the trochlear is thicker medially
• it creates the carrying angle; an acute angle formed between the extended arm & forearm

Question 14

What is the radiohumeral joint?

Answer 14

• where movement occurs between the radius & humerus
• Radius must also move with the ulna during elbow Flexion/extension
• Ulna creates the hinge

Question 15

What is full flexion of elbow movement?

Answer 15

• Coronoid process of the ulna sits in the coronoid fossa of the humerus
• Radial head rests in radial fossa on the anterior surface of the humerus

Question 16

What is full extension of elbow movement?

Answer 16

• Trochlear notch of the ulna still slides on trochlea of the humerus
• Ulna migrates laterally & creates Carrying Angle
• Olecranon process of the ulna is locked in the olecranon fossa of the humerus
• Radial head articulates with the inferior portion of the capitulum on the humerus

Question 17

What is the medial/ulnar collateral ligament?

Answer 17

• Extends from the medial epicondyle to the top of the ulna
• runs through the inner side of the elbow to support certain motions (On the inside, pinky side)
• Restricts valgus stress; mcl damage (lateral to medial) (comes together)

Question 18

What is the lateral/radial collateral ligament?

Answer 18

• Extends from the lateral epicondyle to the annular ligament
• a thin, strong band of tissue that connects from the humerus to the radius (On the outside thumb side)
• Restricts varus stress; LCL damage (medial to lateral) (knees apart)

Question 19

What is the proximal/superior Radioulnar joint?

Answer 19

• located distal to the elbow, articulated between the head of the radius & the radial notch of the ulna
• it is a Synovial-pivot joint
• Radius & ulna are always side by side proximally
• They cross each other distally in pronation
• allows supination/pronation movements

Question 20

What is the intermediate Radioulnar joint?

Answer 20

• a Fibrous joint between the shafts of the radius and ulna: interosseus;
• Has membrane fibers that run inferiorly and medially
• Site of muscle attachment, increases stability between two bones

Question 21

What is the distal/inferior Radioulnar joint?

Answer 21

• located proximal to the wrist joint, articulates between the ulnar notch of the radius & the ulnar head
• binds the radius & ulna together & holds them together during movement; allows pronation/supination movements (Synovial-pivot joint)

Question 22

What is the pronation/supination mechanism?

Answer 22

• Proximal radius must be fixed in its “collar” (annular ligament)
• Ulna fixed at elbow joint (trochlea)
• Radius spins on the capitulum of the elbow proximally and crosses over ulna distally