Olecranon

The olecranon is the large, prominent proximal projection of the ulna that forms the palpable point of the elbow. Because it lies immediately beneath the skin on the posterior aspect of the elbow, it is one of the easiest bony landmarks of the upper limb to identify.

The olecranon forms the superior portion of the proximal ulna and contributes to the trochlear notch, which articulates with the trochlea of the humerus. It also provides the major insertion site for the triceps brachii, allowing powerful extension of the forearm at the elbow.

In surface anatomy, the olecranon is particularly useful because its relationship to the medial and lateral epicondyles changes predictably with elbow flexion and extension. These three landmarks can therefore be used to assess elbow alignment and identify possible fractures or dislocations.

Location

The olecranon is located at the proximal end of the ulna on the posterior aspect of the elbow.

Its posterior surface is subcutaneous and creates the visible and palpable prominence commonly called the point of the elbow.

Surface Appearance

The olecranon is most obvious when the elbow is flexed.

Its prominence can usually be seen and palpated directly through the skin without needing to displace substantial muscle or adipose tissue.

Palpation

The olecranon can be palpated by placing the fingers over the posterior elbow and identifying the central bony prominence.

Flexing and extending the elbow demonstrates that the olecranon moves with the ulna relative to the distal humerus.

Palpation Technique

1. Position the elbow in approximately 90 degrees of flexion.
2. Identify the prominent bony point on the posterior elbow.
3. Palpate its superior, medial, and lateral margins.
4. Locate the medial and lateral epicondyles of the humerus on either side.
5. Extend and flex the elbow to observe how the relationship among the three landmarks changes.

Proximal Ulna

The olecranon is continuous with the proximal ulna and forms the posterior and superior portion of the bone around the elbow joint.

Anterior to it is the large trochlear notch, while the coronoid process forms the inferior anterior part of this notch.

Trochlear Notch

The trochlear notch is a large C-shaped articular depression between the olecranon and coronoid process.

It articulates with the trochlea of the humerus and forms the principal articulation of the humeroulnar joint.

Relationship to the Coronoid Process

The coronoid process projects anteriorly from the proximal ulna below the trochlear notch.

Together, the olecranon and coronoid process embrace the trochlea of the humerus and contribute to the stability of the elbow joint.

Relationship to the Humerus

The olecranon articulates indirectly with the distal humerus through the trochlear notch of the ulna.

During elbow movement, the proximal ulna rotates around the trochlea as the elbow flexes and extends.

Olecranon Fossa

The olecranon fossa is a deep depression on the posterior surface of the distal humerus.

During full elbow extension, the olecranon projects into this fossa.

Elbow Extension

As the elbow extends, the olecranon moves into the olecranon fossa of the humerus.

This relationship contributes to the bony limit of extension at the humeroulnar joint.

Elbow Flexion

During flexion, the olecranon moves out of the olecranon fossa and becomes more prominent posteriorly.

This makes the landmark particularly easy to identify when the elbow is bent.

Triceps Brachii Insertion

The tendon of the triceps brachii inserts primarily onto the superior and posterior aspects of the olecranon.

Contraction of the triceps pulls on the olecranon to extend the forearm at the elbow.

Triceps Tendon

The triceps tendon can be palpated immediately proximal to the olecranon.

It becomes more prominent when the patient contracts the triceps against resistance.

Anconeus Relationship

The anconeus is a small triangular muscle on the posterolateral aspect of the elbow.

It inserts partly onto the lateral surface of the olecranon and proximal posterior ulna and assists elbow extension and stabilization.

Olecranon Bursa

A superficial olecranon bursa lies between the skin and the posterior surface of the olecranon.

This bursa allows the skin to move smoothly over the bony prominence during elbow movement.

Subcutaneous Position

The posterior surface of the olecranon has very little soft tissue covering.

This makes it easy to palpate but also exposes it to direct pressure and trauma.

Relationship to the Medial Epicondyle

The medial epicondyle lies medial to the olecranon and is readily palpable.

The ulnar nerve passes posterior to the medial epicondyle in a groove between the epicondyle and olecranon region.

Relationship to the Lateral Epicondyle

The lateral epicondyle lies lateral and slightly superior to the olecranon region.

Together with the medial epicondyle and olecranon, it provides a useful set of palpable landmarks for assessing elbow alignment.

Three-Point Relationship

With the elbow flexed to approximately 90 degrees, the olecranon and the medial and lateral epicondyles form a roughly triangular arrangement.

With the elbow extended, these three palpable landmarks lie approximately along a transverse line.

Elbow Landmark Alignment

Elbow Position	Relationship
Extension	Olecranon and humeral epicondyles lie approximately in a straight transverse line
90° flexion	Olecranon and epicondyles form a triangular configuration

Clinical Use of the Three-Point Relationship

The normal relationship among the olecranon and epicondyles can help assess whether the anatomical alignment of the elbow has been disrupted.

Changes may occur with certain fractures or dislocations, although diagnosis requires the complete clinical and imaging assessment.

Ulnar Nerve Relationship

The ulnar nerve passes posterior to the medial epicondyle, medial to the olecranon.

Its superficial position in this region makes it vulnerable to compression or direct impact.

Cubital Tunnel

The ulnar nerve passes through the cubital tunnel around the posteromedial elbow.

The medial epicondyle and olecranon region provide useful surface orientation to this neural pathway.

Relationship to the Radial Head

The radial head lies on the lateral side of the elbow, distal to the lateral epicondyle.

Unlike the olecranon, which is part of the ulna and forms the posterior elbow point, the radial head can be palpated during forearm pronation and supination.

Relationship to the Elbow Joint

The elbow is a compound synovial joint involving the humeroulnar, humeroradial, and proximal radioulnar articulations.

The olecranon is directly related to the humeroulnar component and is therefore central to the mechanics of flexion and extension.

Posterior Elbow Surface Landmarks

Landmark	Surface Relationship
Olecranon	Central posterior elbow prominence
Triceps tendon	Immediately proximal to olecranon
Medial epicondyle	Medial to olecranon
Lateral epicondyle	Lateral to olecranon
Ulnar nerve	Passes posteromedial to medial epicondyle near olecranon

Clinical Significance

Olecranon Bursitis

Olecranon bursitis is inflammation or distension of the superficial bursa overlying the olecranon.

It can produce a visible and palpable swelling over the posterior elbow.

Repeated Pressure

Repeated pressure on the point of the elbow can irritate the olecranon bursa.

This relationship explains why prolonged leaning on the elbows can contribute to superficial bursal inflammation.

Olecranon Fracture

The olecranon can fracture after direct trauma to the posterior elbow or from forces transmitted through the upper limb.

Because the triceps inserts onto the olecranon, displaced fractures can interfere with active elbow extension.

Triceps Tendon Injury

Injury to the distal triceps tendon can occur near its insertion on the olecranon.

Weakness or loss of active extension may occur with substantial disruption of the extensor mechanism.

Elbow Dislocation

The relationship between the olecranon and the humeral epicondyles is useful when evaluating suspected elbow dislocation.

Disruption of the normal landmark configuration may indicate altered joint alignment.

Ulnar Nerve Irritation

Because the ulnar nerve passes superficially near the medial epicondyle and olecranon, direct impact in this region can produce tingling or an electric sensation along the nerve distribution.

Pressure Injury

The subcutaneous position of the olecranon makes the posterior elbow susceptible to pressure-related skin and soft tissue injury in individuals with limited mobility.

Olecranon Fracture and the Extensor Mechanism

The triceps tendon transmits force directly to the olecranon.

A fracture that disrupts continuity between the triceps insertion and the ulna can impair the mechanical pathway responsible for elbow extension.

Imaging Orientation

The olecranon is readily visible on radiographs of the elbow and provides an important reference for evaluating the proximal ulna, trochlear articulation, and posterior soft tissues.

Cross-sectional imaging can further demonstrate the relationship between bone, tendon, bursa, and surrounding structures.

Anatomical Variation

The size and prominence of the olecranon vary among individuals.

Body habitus and soft tissue thickness can alter its visible appearance, but the bony prominence is usually readily palpable.

Olecranon Compared with Nearby Landmarks

Landmark	Bone	Main Surface Feature
Olecranon	Ulna	Point of elbow
Medial epicondyle	Humerus	Medial elbow prominence
Lateral epicondyle	Humerus	Lateral elbow prominence
Radial head	Radius	Palpable laterally during pronation and supination

Key Surface Anatomy Features

Feature	Key Point
Bone	Ulna
Location	Posterior proximal ulna
Surface landmark	Point of elbow
Major muscle attachment	Triceps brachii
Articular relationship	Forms part of trochlear notch
Humeral relationship	Enters olecranon fossa during extension
Superficial structure	Olecranon bursa
Nearby nerve	Ulnar nerve medially
Alignment landmarks	Medial and lateral epicondyles
Clinical importance	Bursitis, fracture, triceps injury and elbow alignment

Anatomical Importance

The olecranon is a major landmark of upper limb surface anatomy because it forms the easily palpable point of the elbow. Its subcutaneous position allows direct assessment of the proximal ulna and provides a central reference for locating the humeral epicondyles, triceps tendon, and nearby ulnar nerve.

Functionally, the olecranon forms part of the trochlear notch and receives the insertion of the triceps brachii. During elbow extension it enters the olecranon fossa of the humerus, while during flexion it becomes increasingly prominent posteriorly.

Its changing relationship with the medial and lateral epicondyles provides a useful method of assessing elbow alignment. The landmark is also clinically important in olecranon bursitis, fractures, triceps tendon injuries, ulnar nerve assessment, and posterior elbow trauma.