Lecture 9 - Forearm

Question 1

What is the ulna?

Answer 1

• one of two bones that make up the forearm
• forms the elbow joint with the humerus & also articulates with the radius both proximally and distally
• located in the medial forearm when the arm is in the anatomical position

Question 2

What are the 5 landmarks of the ulna?

Answer 2

• olecranon process
• coronoid process
• ulnar Tuberosity
• radial notch
• shaft: head of ulna, ulnar styloid process

Question 3

What is the olecranon process of the ulna?

Answer 3

• Expanded posterior & superior portions of the proximal ulna
• Forms the bony tip of the elbow

Question 4

What is the coronoid process of the ulna?

Answer 4

• The smaller of two projections located on the proximal end of the ulna
• Stabilizes the elbow joint & prevent the hyper-flexion of the elbow
• serves as the attachment for ligaments and muscles that act on the elbow joint

Question 5

What is the ulnar Tuberosity of the ulna?

Answer 5

• Roughened area located on the anterior, proximal ulna inferior to the coronoid process

Question 6

What is the radial notch of the ulna?

Answer 6

• Small, smooth area on the lateral side of the proximal ulna
• Articulates with the head of the radius when the elbow is maximally flexed

Question 7

What is the shaft of the ulna?

Answer 7

• The narrow, elongated, central region of the ulna
• contains the Head of the Ulna: Small, rounded distal end of the ulna, Articulates with the ulnar notch of the distal radius forming the distal radioulnar joint
• contains the Ulnar Styloid Process: Short, bony projection located on the medial end of the distal ulna

Question 8

What is the olecranon bursa?

Answer 8

• A thin, fluid-filled sac that is located between the olecranon process & the skin
• Bursae contain a small amount of lubricating fluid that allows the soft tissues to move freely over the underlying bone

Question 9

What is the radius?

Answer 9

• one of the two bones that make up the forearm
• forms the radio-carpal joint at the wrist and the radio-ulnar joint at the elbow
• located in the lateral forearm when in the anatomical position

Question 10

What are the 4 landmarks of the radius?

Answer 10

• head
• neck
• radial Tuberosity
• shaft: ulnar notch, radial styloid process

Question 11

What is the head of the radius?

Answer 11

• Disc-shaped structure that forms the proximal end of the radius
• Articulates with the capitulum of the humerus as part of the elbow joint, & with the radial notch of the ulna as part of the proximal radioulnar joint

Question 12

What is the neck of the radius?

Answer 12

• Narrowed region immediately distal to the head of the radius

Question 13

What is the radial Tuberosity of the radius?

Answer 13

• Oval-shaped, roughened protuberance located on the medial side of the proximal radius

Question 14

What is the shaft of the radius?

Answer 14

• Narrow, elongated, central region of the radius
• contains Ulnar Notch: Shallow, smooth area located on the medial side of the distal radius, Articulates with the head of the ulna at the distal radioulnar joint
• contains Radial Styloid Process: Pointed projection located on the lateral end of the distal radius

Question 15

What is the annular ligament?

Answer 15

• Forms a ring that surrounds the radial head, attaching to the anterior & posterior margins of the radial notch of the ulna
• Stabilizes the radial head within the radial notch of the ulna as it rotates during supination & pronation of the forearm

Question 16

What is the ulnohumeral joint of the elbow?

Answer 16

• the joint between the trochlea on the medial aspect of the distal end of the humerus & the trochlear notch on the proximal ulna
• give the elbow its characteristic hinge like properties

Question 17

What is the radiohumeral joint of the elbow?

Answer 17

• the joint between the capitulum on the lateral aspect of the distal end of the humerus with the head of the radius
• give the elbow its characteristic hinge like properties

Question 18

How does elbow movement work?

Answer 18

• Full Flexion:
  - Coronoid process (ulna) -> Coronoid fossa (humerus)
  - Radial head (radius) -> Radial fossa (humerus)
• Full Extension:
  - Trochlear notch (ulna) -> Trochlea (humerus)
  - Olecranon process (ulna) -> Olecranon fossa (humerus)
  - Radial head (radius) -> Capitulum (humerus)

Question 19

What is the medial/ulnar collateral ligament?

Answer 19

• extends from the medial epicondyle of the humerus to the coronoid process of the ulna
• triangular in shape, and is composed of three parts: an anterior, a posterior and an inferior band

Question 20

What is the lateral/radial collateral ligament?

Answer 20

• low attachment to the lateral epicondyle of the humerus
• The distal fibres blend with the annular ligament that encloses the head of the radius

Question 21

What is the proximal/superior radioulnar joint?

Answer 21

• is a uniaxial synovial pivot joint that connects the proximal ends of the radius and ulna
• the head of radius is placed within the ring formed by the radial notch of ulna & the annular ligament
• allows movements of pronation-supination

Question 22

What is the intermediate radioulnar joint?

Answer 22

• where the interosseous membrane is seen
• it is a syndesmosis type of fibrous joint

Question 23

What is the distal/inferior radioulnar joint?

Answer 23

• is a uniaxial synovial pivot joint between the distal ends of the radius & ulna
• allows for pronation, by which the forearm and hand rotate around the long axis of the forearm