Anatomy of the Elbow and Forearm

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Questions and Answers

What is the action of the Brachialis muscle?

Pronation of the radioulnar joint

Extension of the elbow joint

Elbow joint flexion (correct)

Supination of the radioulnar joint

Which muscle has an origin at the medial epicondyle of the humerus?

Teres Pronator (correct)

Anconeus

Pronator Quadratus

Supinator

How many bones are in the elbow?

3 (correct)

What is the action of the Triceps Brachii muscle?

Elbow joint extension Signup and view all the answers

What is the main function of the humeroulnar joint?

Provides most of the structural stability to the elbow Signup and view all the answers

Which muscle has an insertion at the radial tuberosity?

Biceps Brachii Signup and view all the answers

Which joint is formed by the ball-shaped capitulum of the humerus and the bowl-shaped fovea of the radius?

Humeroradial joint Signup and view all the answers

What is the action of the Pronator Quadratus muscle?

Pronation of the radioulnar joint Signup and view all the answers

What occurs at both the proximal and distal radioulnar joints?

Forearm pronation and supination Signup and view all the answers

Which muscle has an origin at the lateral epicondyle of the humerus?

Anconeus Signup and view all the answers

Which structure encases three articulations of the elbow?

Articular capsule Signup and view all the answers

What is the action of the Supinator muscle?

Supination of the radioulnar joint Signup and view all the answers

What is the function of the medial collateral ligament?

Resists cubital valgus forces Signup and view all the answers

Which muscle has three attachment points?

Triceps Brachii Signup and view all the answers

Which muscle originates from the lateral epicondyle of the humerus and inserts into the styloid process of the radius?

Brachioradialis Signup and view all the answers

What is the function of the supinator muscle?

Supinates the forearm Signup and view all the answers

How many joints are in the elbow and forearm?

4 Signup and view all the answers

What is the main function of the annular ligament?

Maintains contact between the radius and ulna Signup and view all the answers

Study Notes

Functional Anatomy of the Elbow and Forearm

The elbow consists of 3 bones (humerus, radius, and ulna) and 2 joints (humeroulnar and humeroradial) that enable elbow flexion and extension.
The forearm consists of 2 bones (radius and ulna) and 2 joints (proximal radioulnar joint and distal radioulnar joint) that enable forearm pronation and supination.

Joints of the Elbow and Forearm

Humeroulnar joint provides most of the structural stability to the elbow through the trochlear notch of the ulna interlocking with the trochlea of the humerus.
Humeroradial joint is formed by the capitulum of the humerus and the fovea of the radius, permitting continuous contact during pronation and supination.
Proximal radioulnar joint is an articulation of the head of the radius and the radial notch of the ulna.
Distal radioulnar joint is a rotation of the distal end of the radius around the distal end of the ulna.
Supination and pronation occur at both joints and in the forearm.

Bony Landmarks of the Elbow and Forearm

Distal humerus (anterior) features: trochlea, capitulum, medial epicondyle, lateral epicondyle, ulna nerve sulcus, and radial fossa.
Distal humerus (posterior) features: trochlea, medial epicondyle, lateral epicondyle, lateral supracondylar ridge, and olecranon fossa.
Proximal ulna (lateral) features: olecranon process, trochlear notch, coronoid process, and ulnar tuberosity.
Proximal ulna (anterior) features: olecranon process, trochlear notch, coronoid process, and radial notch.
Radius features: head, radial tuberosity, and neck.
Ulna features: head and styloid process.

Supporting Structures of the Elbow

Articular capsule: a thin connective tissue encasing 3 articulations.
Medial (ulna) collateral ligament: crosses the elbow medially from the medial epicondyle to the coronoid and olecranon processes, providing stability in resisting cubital valgus forces.
Lateral (radial) collateral ligament: crosses the elbow laterally from the lateral epicondyle to the annular ligament, providing stability in resisting cubital varus forces.
Annular ligament: a band of fibers that circles the radius, maintaining contact between the radius and humerus.

Muscles of the Elbow and Forearm

Biceps brachii: originates from two proximal insertions, inserts into the radial tuberosity, and acts to flex the elbow joint and supinate the forearm.
Brachialis: originates from the lower half of the humerus, inserts into the coronoid process of the ulna, and acts to flex the elbow joint.
Brachioradialis: originates from the lateral epicondyle of the humerus, inserts into the styloid process of the radius, and acts to flex the elbow joint.
Triceps brachii: originates from three attachment points, inserts into the olecranon process of the ulna, and acts to extend the elbow joint.
Anconeus: originates from the lateral epicondyle of the humerus, inserts into the lateral portion of the olecranon and upper ulna, and acts to extend the elbow joint.
Supinator: originates from the lateral epicondyle of the humerus, ulna, and annular and radial collateral ligaments, inserts into the upper third of the radius, and acts to supinate the forearm.
Pronator teres: originates from the humeral head and coronoid process of the ulna, inserts into the midpoint of the lateral surface of the radius, and acts to pronate the radioulnar joint and flex the elbow joint.
Pronator quadratus: originates from the palmar surface of the ulna, inserts into the palmar surface of the radius, and acts to pronate the radioulnar joint.