Humerus Anatomy and Pathology

Vocabulary-style flashcards covering the anatomical landmarks of the humerus, the five stages of fracture healing, and specific types of humeral fractures and their complications.

Humerus

A long bone located in the upper arm, also known as the brachium.

Humeral Head

The rounded proximal portion of the humerus that faces medially, posteriorly, and superiorly to articulate with the glenoid cavity of the scapula.

Trochlea

A distal feature of the humerus that articulates with the trochlear notch of the ulna.

Capitulum

A distal feature of the humerus that articulates with the radial head.

Lesser tubercle

An anteriorly facing projection on the proximal humerus.

Greater tubercle

A postero-lateral projection on the proximal humerus.

Intertubercular groove

A groove on the proximal humerus that contains the long head of the biceps.

Anatomical neck

An oblique angle located distal to the head and the site of the epiphyseal plate.

Surgical neck

A region distal to the tubercles leading to the shaft; it is a common fracture site.

Deltoid tuberosity

A feature located on the lateral aspect of the humeral shaft.

Radial/spiral groove

A groove on the lateral aspect of the shaft located between the heads of the triceps.

Olecranon fossa

A posterior distal depression that accommodates the olecranon process.

Coronoid fossa

An anterior distal depression that accommodates the coronoid process.

Radial fossa

An anterior distal depression that accommodates the radial head.

Rotator cuff muscles

The group of muscles that attach to the tubercles of the humerus.

Haematoma formation

The first stage of fracture healing where a blood clot forms $6-8\,\text{hours}$ after fracture, creating a fibrin network for angiogenesis and cell invasion.

Cellular proliferation

The second stage of fracture healing characterized by an inflammatory response and the influx of phagocytic cells to remove debris.

Callus formation

The third stage of healing where mesenchymal stem cells differentiate to produce a fibrocartilaginous callus (procallus), lasting about $3\,\text{weeks}$.

Ossification

The fourth stage of healing where osteoblasts replace cartilage with woven/primary bone; this lasts up to approximately $6\,\text{weeks}$.

Remodelling

The final stage of healing involving continuous cycles of resorption by osteoclasts and formation of lamellar bone by osteoblasts.

Supracondylar fracture

A common fracture in children (often $6-7\,\text{years}$ old) caused by FOOSH, typically involving the thin bone between the coronoid and olecranon fossae.

Gartland classification

A categorization for supracondylar fractures: Type I (undisplaced), Type II (displaced with intact posterior cortex), and Type III (complete displacement).

Cubitus varus

A misalignment or malunion complication that can occur following a supracondylar fracture.

Atrophic nonunion

A potential outcome for long spiral shaft fractures if they are left with good alignment but a significant gap between fragments.

AVN (Avascular Necrosis)

The death of bone tissue due to lack of blood supply, which has a much higher incidence in anatomical neck fractures than surgical neck fractures.

Hill-Sachs lesion

A fracture in the posterolateral head of the humerus caused by impaction against the glenoid rim.