Elbow and Forearm - Chapter 4, Biomechanics

What three bones make up the elbow and forearm?

Humerus, ulna, radius

Which bone forms the upper arm?

The humerus

Which two bones make up the forearm?

Radius and ulna

In anatomical position, where is the ulna located?

On the medial (pinky finger) side of the forearm

In anatomical position, where is the radius located?

On the lateral (thumb) side of the forearm

What are the two bony prominences at the distal end of the humerus?

Medial epicondyle and lateral epicondyle

What is the function of the medial and lateral epicondyles?

They provide attachment sites for muscle and ligaments

What is located on the anterior side of the humerus above the trochlea?

Coronoid fossa

What structure fits into the coronoid fossa during elbow flexion?

Coronoid process of ulna

What is located lateral to the coronoid fossa

Radial fossa

What structure fits into the radial fossa during elbow flexion?

Head of the radius

What is located on the posterior side of the humerus?

Olecranon fossa

What structure fits into the olecranon fossa during elbow extension?

Olecranon process of ulna

Which forearm bone is the primary bone that articulates with the wrist?

Radius

What is the proximal end of the radius called?

Radial head

What is the radial tuberosity?

Roughened area where biceps brachii tendon inserts

What is the large projection at the proximal end of the ulna called?

Olecranon process

What is the projection on the anterior side of the ulna called?

Coronoid process

What is the distal projection of the ulna called?

Ulnar styloid process

How many joints are formed by the humerus, radius, and ulna?

Four

What are the four joints of the elbow and forearm?

Radiohumeral, ulnohumeral, proximal radioulnar, distal radioulnar

Which bones form the radiohumeral joint?

Capitulum of humerus and head of radius

Which bones form the ulnohumeral joint?

Trochlea of humerus and trochlear notch of ulna

Which joints allow pronation and supination?

Proximal and distal radioulnar joints

What is that function of the joint capsule?

Surrounds all 3 elbow joints and helps stabilize elbow

What does the annular ligament do?

Surrounds head of radius and holds it against ulna while allowing rotation

What does the ulnar collateral ligament connect?

Humerus and ulna on medial side of elbow

What does the radial collateral ligament connect?

Humerus and radius on lateral side of elbow

Which ligament is most important for holding the proximal radius in place?

Annular ligament

What are the four movements of the elbow and forearm?

Flexion, extension, pronation, supination

What is elbow flexion?

Decreasing angle between arm and forearm

What is elbow extension?

Increasing angle between arm and forearm

What is pronation?

Rotation of forearm so palm faces downward, with radius crossing over ulna

What is supination?

Rotation of forearm so palm faces upward, with radius and ulna remaining parallel

Which muscles produce elbow flexion?

Brachialis, brachioradialis, biceps brachii

Which muscle is the primary elbow flexor?

Brachialis

Which muscles produce elbow extension?

Triceps brachii, anconeus

Which muscle is the primary elbow extensor?

Triceps brachii

Which muscles pronate the forearm?

Pronator teres, pronator quadratus

What is the action of the pronator teres?

Pronation of the forearm

What is the action of the pronator quadratus?

Pronation of the forearm

Which muscles supinate the forearm?

Supinator, biceps brachii

Why is the biceps brachii able to supinate the forearm?

Tendon inserts on radial tuberosity, allowing rotation of radius laterally during contraction

What is the primary action of the supinator muscle?

Supination of forearm

Which ligament holds the head of the radius against the ulna?

Annular ligament

Which ligament is found on the medial side of the elbow?

Ulnar collateral ligament

Which ligament is found on the lateral side of the elbow?

Radial collateral ligament

During pronation, what happens to the radius?

It crosses over the ulna

During supination, how are the radius and ulna positioned?

They are parallel

Which muscles belong to each movement group?

Flexion: brachialis, brachioradialis, biceps brachii; Extension: triceps brachii, anconeus; Pronation: pronator teres, pronator quadratus; Supination: supinator, biceps brachii