Surface Anatomy

Arm And Elbow Anatomy Study Notes

Bones - Osteology

  • Humerus
      - Anterior Medial and Lateral Supracondylar Ridge
      - Medial and Lateral Epicondyle
      - Condyles
        - Medial - trochlea
        - Lateral - capitulum
      - Fossa
        - Radial fossa
        - Coronoid fossa
        - Olecranon Fossa (Posterior)
      - Groove for Ulnar Nerve

Radius and Ulna Overview

  • Radius
      - Head
      - Neck
      - Radial Tuberosity
      - Styloid Process
      - Radial Notch

  • Ulna
      - Trochlear Notch
      - Olecranon
      - Coronoid Process
      - Ulnar Tuberosity
      - Styloid Process

Carrying Angle of the Elbow

  • Definition: When the arms are at the side with palms facing forward, the forearm and hands normally form an angle of 5 to 15 degrees away from the body.

  • Function: This angle helps the forearms clear the hips during movements such as walking.

Joints and Ligaments

  • Motions at the Elbow Joint
      - Humeral-Ulnar & Humeral-Radial Motions
        - Flexion: Range of motion typically 75°-90°.
        - Extension: Neutral position at 0°.
      - Radioulnar Motions
        - Supination: 180° motion.
        - Pronation: 180° motion.

The Elbow - A Tale of Three Joints

  • Humeroulnar Joint: A hinge joint formed by the distal end of the humerus and the olecranon of the ulna.
      - Allows flexion and extension of the elbow.

  • Humeroradial Joint: Formed by the head of the radius articulating with the humerus.
      - Also permits flexion and extension of the elbow.

  • Proximal Radioulnar Joint: A pivot joint formed by the radius and ulna.
      - Allows for pronation and supination of the forearm.

Ulnar Collateral Ligament (UCL)

  • Components: Consists of three bundles
      - Anterior Bundle: Strongest and most frequently injured; surgical focus.
      - Posterior Bundle: Weakest of the three.
      - Transverse Bundle: Deepens the socket for the trochlea and helps prevent valgus stress.

Clinical Application - UCL Tears

  • Tommy John Surgery: Reconstructs torn ligament with a tendon (palmaris longus or semitendinosus).
      - Created by Dr. Frank Jobe in 1974.
      - Time frame to return to throwing: 12-13 months; full recovery takes 2 years.
      - Success rate: Approximately 80-90% based on study data.

  • Options for UCL Tear:
      - Repair with Internal Brace: Developed by Dr. Jeff Dugas in 2013.
      - Time frame to return to throwing: 8 months for pitchers.
      - Success rate: Approximately 92%, though long-term data is limited.

Examples of UCL Injuries

  • Bryce Harper: Underwent full Tommy John surgery with ulnar nerve transposition. Expected to return to designated hitter (DH) role in 7 months and back to right field in 10 months.

  • Brock Purdy: Received UCL repair with internal brace. Return to play (RTP) estimated at 6-8 months.

Lateral Elbow Ligament - Radial Collateral Ligament (RCL)

  • Role: Provides protection against varus stress.

Radial-Ulnar Joint Ligaments

  • Proximal Radioulnar Joint: Supported by the annular ligament with reinforcement by the interosseous membrane.

  • Key Components:
      - Annular Ligament
      - Distal Humerus
      - Capitulum

Bursa

  • Function: Reduces friction between skin and bone, tendon & bone, and ligament & bone.

  • Olecranon Bursa: Specifically associated with the elbow.
      - Olecranon Bursitis: Inflammation of this bursa can occur.

Clinical Application - Bursa Infections

  • Common Affected Areas: Superficial bursae like olecranon and prepatellar bursae.

  • Cause: Microorganisms can enter through skin trauma (cuts, scrapes, punctures, bug bites).
      - Typical bacteria involved include Staphylococcus aureus and Streptococcus species.
      - If untreated, may progress to septic bursitis.

Muscles of the Elbow Region

Biceps Brachii

  • Action:
      - Flexion of the elbow (humeroulnar joint).
      - Supination of the forearm (radioulnar joints).
      - Flexion of the shoulder (glenohumeral joint).

  • Origin:
      - Short head: Coracoid process of scapula.
      - Long head: Supraglenoid tubercle of scapula.

  • Insertion: Tuberosity of the radius and aponeurosis of the biceps brachii.

  • Nerve Supply: Musculocutaneous nerve (C5, C6).

Brachialis

  • Action: Flexion of the elbow (humeroulnar joint).

  • Origin: Distal half of anterior surface of humerus.

  • Insertion: Tuberosity and coronoid process of ulna.

  • Nerve Supply: Musculocutaneous nerve and a small branch from radial nerve (C5, C6).

Brachioradialis

  • Action: Flex the elbow (humeroulnar joint); assist in pronation and supination when resisted (humeroradial joints).

  • Origin: Proximal two-thirds of the lateral supracondylar ridge of the humerus.

  • Insertion: Styloid process of radius.

  • Nerve Supply: Radial nerve (C5, C6).

Triceps Brachii

  • Action: All heads extend the elbow (humeroulnar joint); long head also extends and adducts the shoulder (glenohumeral joint).

  • Origins:
      - Long head: Infraglenoid tubercle of the scapula.
      - Lateral head: Posterior surface of proximal half of the humerus.
      - Medial head: Posterior surface of distal half of the humerus.

  • Insertion: Olecranon process of the ulna.

  • Nerve Supply: Radial nerve (C6, C7, C8, T1).

Anconeus

  • Action: Extend the elbow (humeroulnar joint).

  • Origin: Lateral epicondyle of the humerus.

  • Insertion: Olecranon process and posterior proximal surface of ulna.

  • Nerve Supply: Radial nerve (C7, C8).

Major Arteries and Nerves of the Elbow

Blood Supply

  • Brachial Artery: Begins at the lower border of the teres major; divides in the cubital fossa into the radial and ulnar arteries.
      - Radial Artery: Supplies anterolateral aspect of the forearm.
      - Ulnar Artery: Supplies anteromedial aspect of the forearm; gives rise to anterior and posterior interosseous arteries.

Nerves Around the Elbow

  • Radial Nerve

  • Median Nerve

  • Ulnar Nerve

Cubital Fossa

  • Definition: Comparable to the popliteal fossa found in the knee.

  • Borders:
      - Between musculature of forearm and upper arm; typically defined by the anatomical landmarks.

Contents of the Cubital Fossa

  1. Median nerve (medial side)

  2. Brachial artery, divides into radial and ulnar arteries at the apex of fossa.

  3. Biceps brachii tendon

  4. Deep branch of the radial nerve (lateral side).

End of Notes