Humeral, Ulnar, Radial Landmarks, Elbow Joint and Muscles

LAB 6: HUMERAL, ULNAR, RADIAL LANDMARKS, ELBOW JOINT AND MUSCLES

True elbow joint- flexion and extension

HUMERAL LANDMARKS

  • Medial epicondyle

    • Prominent bony landmark on the medial side of the humerus, serves as an attachment point for forearm flexor muscles.

  • Medial epicondylar ridge

    • Ridge located along the medial epicondyle, provides further surface area for muscle attachment.

  • Head

    • The upper end of the humerus that articulates with the glenoid cavity of the scapula.

  • Olecranon fossa

    • A depression on the posterior aspect of the distal humerus that accommodates the olecranon process of the ulna during elbow extension.

  • Surgical neck

    • The area just below the head of the humerus which is a common fracture site.

  • Anatomical neck

    • The area just below the head of the humerus, is the site of the epiphyseal plate in growing bones.

  • Trochlea

    • A spool-shaped surface on the distal humerus that articulates with the ulna.

  • Greater Tubercle

    • A large, prominent projection on the lateral aspect of the humerus serving as an attachment point for shoulder muscles.

  • Lesser Tubercle

    • Smaller anterior projection on the proximal humerus, also a site of muscle attachment.

  • Intertubercular groove

    • A groove between the greater and lesser tubercles, where the tendon of the biceps brachii runs.

  • Deltoid tuberosity

    • A roughened area on the lateral side of the humerus for the attachment of the deltoid muscle.

  • Lateral epicondylar ridge

    • A ridge along the lateral aspect of the distal humerus.

  • Lateral epicondyle

    • Serves as an attachment point for forearm extensor muscles.

  • Capitulum

    • Round structure at the lateral edge of the distal humerus that articulates with the head of the radius.

ULNAR BONY LANDMARKS

  • Ulna

    • One of the two long bones in the forearm, located medial to the radius.

  • Trochlear Notch

    • A deep notch that articulates with the trochlea of the humerus.

  • Coronoid process

    • A projections that fits into the coronoid fossa of the humerus when the elbow is flexed.

  • Radial notch

    • A smooth area on the ulna that articulates with the head of the radius.

  • Ulnar tuberosity

    • A roughened area on the ulna below the coronoid process for muscle attachment.

  • Styloid process

    • A bony projection at the distal end of the ulna.

RADIAL BONY LANDMARKS

  • Radius

    • The shorter of the two forearm bones, located lateral to the ulna.

  • Radial tuberosity

    • A projection on the radius where the biceps brachii muscle attaches.

  • Styloid process

    • A prominent bony projection at the distal end of the radius, serves as an attachment point for ligaments of the wrist.

THE ELBOW JOINT

  • Type of Joint

    • The elbow is classified as a hinge joint, allowing for flexion and extension.

  • Movements at the Elbow

    • The main movements involve the interaction between the humerus and the ulna.

  • Trochlea/Trochlear Notch

    • The trochlea of the humerus fits into the trochlear notch of the ulna.

  • Contact Points

    • The head of the radius has minimal contact with the humerus during movement.

  • Olecranon fossa/Olecranon Process

    • The olecranon process of the ulna fits into the olecranon fossa of the humerus when the elbow is extended.

LIGAMENTS

  • Annular Ligament

    • A ligament that encircles the head of the radius, attaching to the radial notch of the ulna. ( pronation and supination )

  • Radial Collateral Ligament

    • A ligament that supports the lateral side of the elbow, involved during flexion movements.

  • Ulnar Collateral Ligament (UCL)

    • This ligament prevents the elbow from abducting; it is critical for joint stability.

MOVEMENTS

  • Flexion

    • Reducing the angle between the forearm and the upper arm.

  • Extension

    • Increasing the angle between the forearm and the upper arm.

  • Supination

    • Rotating the radius around the ulna so that the palm faces upwards.

  • Pronation

    • Rotating the radius around the ulna so that the palm faces downwards.

UCL RECONSTRUCTION: "TOMMY JOHN SURGERY"

  • This is a surgical procedure to reconstruct the ulnar collateral ligament in the elbow, commonly performed on athletes.

MUSCLES OF THE ELBOW

  • Anterior Muscles (B3P2)

    • Biceps Brachii

    • Origin: Long head from above the glenoid fossa, Short head from the coracoid process.

    • Insertion: Tuberosity of the radius.

    • Action: Elbow flexion and supination.

    • Brachioradialis

    • Origin: Lateral supracondylar ridge of humerus.

    • Insertion: Styloid process of the radius.

    • Action: Elbow flexion, pronation, and supination.

    • Brachialis

    • Origin: Distal, anterior shaft of humerus.

    • Insertion: Coronoid process of ulna.

    • Action: Elbow flexion.

    • Pronator Teres

    • Origin: Medial epicondyle of humerus and medial proximal ulna.

    • Insertion: Lateral surface of radius.

    • Action: Pronation.

    • Pronator Quadratus

    • Origin: Anterior distal ulna.

    • Insertion: Anterior distal radius.

    • Action: Pronation.

  • Posterior Muscles (SAT)

    • Supinator

    • Origin: Lateral epicondyle of humerus and posterior proximal ulna.

    • Insertion: Lateral proximal radius.

    • Action: Supination.

    • Anconeus

    • Origin: Posterior side of lateral epicondyle of humerus.

    • Insertion: Posterior olecranon process and proximal posterior ulna.

    • Action: Extension.

    • Triceps Brachii

    • Origin: Long head from infraglenoid tubercle (scapula), Lateral head from proximal posterior humerus, Medial head from distal posterior humerus.

    • Insertion: Olecranon process of ulna.

    • Action: Extension.