Elbow

Elbow

GROSS ANATOMY

Joint Capsule Attachments

• Posterior

Proximally attaches to humerus proximal to olecranon fossa and capitellum; distally attaches to proximal ulna
• Anterior

Proximally attaches to humerus proximal to coronoid and radial fossae; distally attaches to coronoid process and annular ligament
• Anterior and posterior elbow fat pads are intracapsular but extrasynovial
• Capsule of elbow is weakest anteriorly; it is strengthened on both sides by ligaments
• Synovial recesses

Olecranon recesses

– Largest; superior, medial, and lateral around olecranon process

Anterior humeral recess

– Proximal to coronoid fossa

Annular recess

– Surrounds radial neck

Ulnar collateral ligament recess

– Deep to ligament

Radial collateral ligament recess

– Deep to ligament

Capsule of elbow is weakest anteriorly

– Capsule is strengthened on both sides by collateral ligaments

Ligaments

• Ulnar collateral ligament

Extends from distal aspect of medial epicondyle to coronoid and olecranon portions of ulna

Separated from overlying common flexor tendon by thin layer of fat

3 bands: Anterior, posterior, and transverse

– Anterior band: Most important; cord-like, 4-6 mm thick, taut in extension, extends from medial epicondyle to coronoid process (sublime tubercle); divided into superficial and deep layers

– Posterior band: Less important; fan-like and thinner, taut in flexion, extends from medial epicondyle to olecranon

– Transverse band: Functionally unimportant; forms base of triangle between anterior and posterior bands
• Radial collateral ligament

Triangular in shape

Apex on lateral epicondyle → blends distally with annular ligament

Lies deep to common extensor tendon

Provides origin for superficial head of supinator muscle
• An n ular ligament

Attached to anterior and posterior aspects of radial notch of ulna forming collar around radial head

– Anterior attachment becomes taut in supination

– Posterior attachment becomes taut in extreme pronation

– Provides origin for superficial head of supinator muscle

Tendons

• Triceps tendon

3 heads combine to insert onto olecranon process

Medial fibers insert exactly on medial margin of olecranon

Lateral fibers may fan out as lateral cubital retinaculum to connect with ulna and antebrachial fascia
• Biceps tendon

Flat tendon forms ~ 7 cm proximal to elbow joint

Twists 90° as it passes deep so that anterior surface faces laterally

– Expands close to attachment into radial tuberosity; attachment area is ~ 3 cm²

Short and long heads have separate adjoined attachments

Also attaches to bicipital aponeurosis

– Bicipital aponeurosis completely encircles ulnar forearm flexor muscles

– Merges with investing fascia of forearm

– May be important in stabilizing distal aspect of biceps tendon
• Common extensor tendon

Arises from lateral epicondyle

Superficial to radial collateral ligament

Composed of extensor-supinator group

– Extensor carpi radialis brevis, extensor carpi radialis longus, extensor digiti minimi, extensor digitorum communis
• Common flexor tendon

Arises from medial epicondyle

Superficial to ulnar collateral ligament

Composed of flexor-pronator group

– Flexor carpi radialis, flexor carpi ulnaris, flexor digitorum superficialis, pronator teres, palmaris longus

Bursae

• Subtendinous olecranon bursa

Between triceps tendon and olecranon
• Subcutaneous olecranon bursa

Between skin and olecranon process
• Bicipitoradial burs a

Between biceps tendon and radial tuberosity
• Radioulnar bursa

Between extensor digitorum and radiohumeral joint

ANATOMY IMAGING ISSUES

Imaging Recommendations

• High-frequency linear transducer
• Large amount of gel for superficial structures
• Examination is usually tailored to site of symptoms
• Lateral elbow is best seen with elbow fully or slightly flexed
• Medial elbow is best seen with elbow extended
• Distal biceps tendon is best seen with forearm in full supination
• Distal biceps tendon insertion is best seen from posterior part of elbow with forearm fully pronated and elbow flexed with transducer aligned transversely over radial tuberosity
• Effusion will displace fat pads away from bone

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Tags: Diagnostic Ultrasound Musculoskeletal

Apr 9, 2020 | Posted by admin in MUSCULOSKELETAL IMAGING | Comments Off

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