Topic 4: Bones, Joints and Muscles of the Elbow and Forearm

Question 1

elbow joint

Answer 1

• synovial, uniaxial, hinge joint
• flexion and extension of the forearm
• articular surfaces: trochlear notch of the ulna and trochlea of humerus, head of radius and capitulum o f the humerus

Question 2

proximal (superior) radioulnar joint

Answer 2

synovial, uniaxial, pivot
articular surfaces: head of radius, radial notch of ulna

Question 3

distal (inferior) radioulnar joint

Answer 3

classification: synovial, uniaxial pivot
articular surfaces: head of ulna, ulnar notch of radius
has an articular disc from ulnar notch of radius to styloid process of ulna

Question 4

ulnar (medial) collateral ligament

Answer 4

• from medial epicondyle of humerus to coronoid process and olecranon of ulna
• made of three bands
• function: prevents abduction of the forearm

Question 5

radial (lateral) collateral

Answer 5

• from lateral epicondyle of humerus to annular ligament (blends distally)
• fan shaped
• function: prevents adduction of the forearm

Question 6

annular ligament

Answer 6

• ring shaped
• attaches to the anterior and posterior margins of the radial notch of the ulna
• encircles the head of the radius to hold it in place
• allows for pronation and supination of the forearm

Question 7

interosseous membrane

Answer 7

• fibrous tissue with an oblique orientation from the radius to the ulna
• maintains the interosseous space between the radius and ulna through forearm rotation and actively transfers forces from the radius to the ulna

Question 8

biceps brachii

Answer 8

Origin:
- long head: supraglenoid tubercle of scapula (lateral)
- Short head: coracoid process of scapula (medial)
Insertion: radial tuberosity (and forearm fascia via bicipital aponeurosis)
Actions: flexion of the shoulder joint

Question 9

brachialis

Answer 9

Origin: distal 1/2 of anterior shaft of humerus
Insertion: ulnar tuberosity and coronoid process of ulna
Actions: flexion of the elbow joint
Sits deep to biceps brachii
Anterior compartment of arm

Question 10

brachioradialis

Answer 10

Posterior (superficial)
Origin: lateral supracondylar ridge of humerus
Insertion: distal radius, just proximal to styloid process
Action: flexion of forearm (at elbow joint) in mid-prone position

Question 11

triceps brachii

Answer 11

Origin:
- Long head: infraglenoid tubercle of scapula
- Lateral head: posterior shaft of humerus (superior to radial groove)
- Medial head: posterior shaft of humerus (inferior to radial groove)
○ Insertion: olecranon of ulna
Actions: extension of shoulder joint (long head only)

Question 12

anconeus

Answer 12

Posterior compartment of arm
Origin: lateral epicondyle of humerus
Insertion: proximal part of posterior ulna, lateral surface of olecranon of ulna
Actions: extension of elbow joint

Question 13

pronator teres

Answer 13

Anterior (deep)
Origin: medial epicondyle of humerus, coronoid process of ulna
Insertion: middle of convexity on lateral shaft of radius
Actions: pronator of the forearm and flexion of elbow joint

Question 14

pronator quadratus

Answer 14

Anterior (deep)
Origin: distal 1/4 of anterior ulna
Insertion: distal 1/4 of anterior radius
Actions: pronation