OTR 704 2.4 Elbow, Forearm, & Wrist

What structure is shown?

Humerus

What structure is shown?

Head of humerus

What structure is shown?

Greater tubercle

What structure is shown?

Lesser tubercle

What structure is shown?

Intertubercular groove

What structure is shown?

Deltoid tuberosity

What structure is shown?

Medial epicondyle

What structure is shown?

Lateral epicondyle

What structure is shown?

Olecranon fossa

What structure is shown?

Capitellum

What structure is shown?

Trochlea

What structure is shown?

Coronoid fossa

What structure is shown?

Ulna

What structure is shown?

Trochlear notch

What structure is shown?

Olecranon process

What structure is shown?

Coronoid process

What structure is shown?

Ulnar styloid process

What structure is shown?

Ulnar tuberosity

What structure is shown?

Radial notch

What structure is shown?

Radius

What structure is shown?

Head of the radius

What structure is shown?

Radial tuberosity

What structure is shown?

Radial styloid process

What structure is shown?

Carpals

What structure is shown?

Scaphoid

What structure is shown?

Lunate

What structure is shown?

Triquetrum

What structure is shown?

Pisiform

What structure is shown?

Trapezium

What structure is shown?

Trapezoid

What structure is shown?

Capitate

What structure is shown?

Hamate

What structure is shown?

Anatomical snuffbox

What structure is shown?

Carpal tunnel

What structure is shown?

Interosseus membrane

What structure is shown?

Triangular fibrocartilage complex (TFCC)

What structure is shown?

Extensor retinaculum

Ulna function

Primary articulation and stable base for:

1. Elbow flexion

2. Forearm pronation/supination

Interosseous membrane

Connects the radius and ulna; functionally:

• Transmits force to the ulna

• Protects humeroradial joint from excessive compression

• Forms a fibrous “joint” that allows for functional forearm movements

Carrying angle

Natural valgus (lateral) deviation of the forearm relative to the humerus

• More obvious in extension

• Angulation of the articulating surfaces

• Functional purpose: allows objects to be carried away from the body

Humeroulnar joint

Primary hinge joint of the elbow (trochlea → trochlear notch)

• Uniaxial; allows for flexion & extension

• Articulating surface & joint capsule allow for mobility

• Ligamentous structures stabilize the joint (virtually no translation)

Humeroradial joint

Modified hinge joint (radial head moves about capitellum)

• Technically biaxial; allows for flexion, extension, & rotation

• Supports motion of the elbow

• Less bony surface contact & congruency compared to humeroulnar joint

Proximal radioulnar joint

Pivot joint

• Uniaxial; allows for pronation & supination

• Supported by annular ligament

What three supporting ligaments stabilize the elbow?

• Annular ligament

• Ulnar collateral ligament (UCL)

• Radial collateral ligament (RCL)

Annular ligament

Holds the radial head in place; prevents inferior displacement of the radius

Ulnar collateral ligament (UCL)

Prevents excessive valgus (lateral deviation) of the elbow

• Repaired in Tommy John surgery

Radial collateral ligament (RCL)

Prevents excessive varus (medial deviation) of the elbow

Bursae of the elbow

Sacs containing synovial fluid that help minimize friction in areas subject to stress; absorbs excessive forces that are applied to the elbow joint (e.g., higher-impact daily forces, trauma)

• Seven bursa surround the elbow

• Olecranon bursa is the largest

• Olecranon bursitis is common from blunt force (“hitting”) the elbow

What muscles are the main flexors of the elbow?

The three B’s/three elbow benders

• Biceps brachii

• Brachialis

• Brachioradialis

What muscles are the main extensors of the elbow?

• Triceps brachii

• Anconeus

What functional activity is extension of the elbow essential for?

Transfers (e.g., pushing up out of a chair)

(Scapular) depression transfers

Locked elbow joint allows scapular movements to compensate for a loss of active elbow extension to perform transfers

What are the primary rotators of the forearm?

• Biceps brachii

• Supinator

• Pronator teres

• Pronator quadratus

Biceps brachii action

Elbow flexion; forearm supination; shoulder flexion

Biceps brachii origin

Short head: coracoid process of scapula

Long head: supraglenoid tubercle of scapula

Biceps brachii insertion

Radial tuberosity & bicipital aponeurosis

Biceps brachii innervation

Musculocutaneous

Brachialis action

Elbow flexion

Brachialis origin

Distal ½ of anterior surface of humerus

Brachialis insertion

Ulnar tuberosity & coronoid process of ulna

Brachialis innervation

Musculocutaneous, small branch from radial

Brachioradialis action

Elbow flexion; assists forearm supination & pronation (when movements are resisted)

Brachioradialis origin

Proximal 2/3 of lateral supracondylar ridge of humerus

Brachioradialis insertion

Radial styloid

Brachioradialis innervation

Radial

Triceps brachii action

All heads: elbow extension

Long head: shoulder extension & adduction

Triceps brachii origin

Long head: infraglenoid tubercle of scapula

Lateral head: posterior surface of proximal ½ of humerus

Medial head: posterior surface of distal ½ of humerus

Triceps brachii insertion

Olecranon process of ulna

Triceps brachii innervation

Radial

Anconeus action

Elbow extension

Anconeus origin

Lateral epicondyle of humerus

Anconeus insertion

Olecranon process and posterior, proximal surface of ulna

Anconeus innervation

Radial

Supinator action

Forearm supination

Supinator origin

Lateral epicondyle of humerus, radial collateral ligament, annular ligament, and supinator crest of ulna

Supinator insertion

Anterior, lateral surface of proximal 1/3 of radial shaft

Supinator innervation

Radial

Pronator teres action

Forearm pronation; assists elbow flexion

Pronator teres origin

Common flexor tendon from medial epicondyle of humerus and coronoid process of ulna

Pronator teres insertion

Middle of lateral shaft of radius

Pronator teres innervation

Median

Pronator quadratus action

Forearm pronation

Pronator quadratus origin

Medial, anterior surface of distal ulna

Pronator quadratus insertion

Lateral, anterior surface of distal radius

Pronator quadratus innervation

Median

Cubital tunnel syndrome

Compression of ulnar nerve at the (medial) elbow as it passed through the cubital tunnel

• Often results from overworking the wrist flexors and/or elbow extensors

Lateral epicondylitis

“Tennis elbow”; inflammatory condition related to overuse of the wrist extensors

Medial epicondylitis

“Golfer’s elbow”; inflammatory condition related to overuse of the wrist flexors

Distal radioulnar joint

Pivot joint

• Uniaxial; contributes to pronation & supination

• Supporting ligaments: palmar radioulnar ligament & dorsal radioulnar ligament

Radiocarpal joint

The “wrist”; an ellipsoid joint

• Primary articulation between distal forearm and proximal carpals

• Biaxial; allows for flexion/extension & radial/ulnar deviation

Intercarpal (midcarpal) joints

Gliding joints

• Aggregated axis for wrist motion located near proximal capitate

• All global wrist motions involve radiocarpal and midcarpal joints

Triangular Fibrocartilage Complex (TFCC)

Ligaments that cushion between the distal ulna & carpals

• Shock absorber during weight-bearing

• Stability on ulnar aspect of wrist

Where do the extrinsic wrist flexors orginate?

The medial epicondyle (minus pollicis longus)

What are the extrinsic wrist flexors?

• Flexor carpi radialis

• Flexor carpi ulnaris

• Palmaris longus

• Flexor digitorum superficialis & profundus

• Flexor pollicis longus

Where do the extrinsic wrist extensors originate?

The lateral epicondyle

What are the extrinsic wrist extensors?

• Extensor carpi radialis longus & brevis

• Extensor carpi ulnaris

• Extensor digitorum

• Extensor indicis

• Extensor digiti minimi

• Abductor pollicis longus

• Extensor pollicus longus & brevis

Flexor carpi radialis action

Wrist flexion & radial deviation; assists in elbow flexion

Flexor carpi radialis origin

Common flexor tendon from medial epicondyle of humerus

Flexor carpi radialis insertion

Bases of 2^nd & 3^rd metacarpals

Flexor carpi radialis innervation

Median