Smallest Bone In The Human Body- All You Need To Know

Smallest Bone In The Human Body- All You Need To Know

Smallest Bone In The Human Body

The smallest bone in the human body is called a ‘styloid process’ and sits at the base of your thumb.

When you move each of your fingers, a sheath of tissue is called a tenosynovium.

Causes small ligaments to glide over it making movement easy.

This small bump is often fractured through physical activity such as climbing or rugby which can cause considerable pain and discomfort.

It can be treated by simply resting the hand for several weeks and then gently getting back into normal activities.

Surgery is rarely required unless there is an open fracture that needs stitching up.

The styloid process may also be referred to as: styloid process phalangeal joint or styloid process of the radius or ulna.

The styloid processes are bony anatomical variants that project from the base of the distal end of the ulna.

And the base of the proximal end of the fifth metacarpal bone in about 10% of Caucasians.

It is present in approximately 20% to 25% of Asians, 50% to 60% of American blacks, 80-90% of East Indians.

85%-95% percent of Polynesians, 97%-100% percent of Melanesians.

77%-97% percent West Africans, 100% Pygmies and 30%-50 % Egytian Nubians.

They are usually bilateral but are not normally palpable.

Because the styloid processes are small and have no clinical importance.

Smallest Bone In The Human Body

Although they can be used as a way of differentiating the ulna from the radius.

When both bones are affected or badly fractured. X-ray analysis is necessary to establish their presence.

Clinical Significance: The function of the styloid process is uncertain.

However it may be involved in distal radioulnar joint stability – see olecranon bursitis for details about possible causes.

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There has been some work done that suggests that since the styloid processes vary in shape.

Density, texture and size, these factors contribute to biomechanical variations.

Seen in cross-sectional geometry measurements of the ulna.

This is because of similarities in appearance that they shar with the olecranon process.

Which has a similar function to the styloid process.

The size of the styloid process can vary greatly among individuals, even within an individual throughout their lifetime.

It averages around 4mm for men and 3mm for women, but may increase up to 12mm in some people.

They are more common on one side than another—80 percent are found on the right side of the body.

If they are present, there is an increased risk of injury to the distal radioulnar joint.

During certain wrist movements or trauma to that area.

Since fractures of the styloid process have no clinical importance they are classified as a normal finding.

Smallest Bone In The Human Body

They are important to recognize however, because their location can be mistaken for fractures of the distal radius or ulna.

Which could lead to unnecessary medical or surgical intervention.

Styloid process fracture is an uncommon condition that affects skeletally mature individuals.

And presents with localized pain in the anatomic region of the styloid process.

Followed by stiffness and swelling over the back of the wrist.Smallest Bone In The Human Body

The etiology of this fracture is disputed; however it is believed that avulsion injuries secondary to forceful supination.

Combined with radial deviation during pronation often lead to these fractures.

When there is suspicion for this injury, radiographs should be obtained promptly given the rapid union time for these injuries (4 weeks).

Imaging studies are useful for further characterization of the fracture morphology.

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And to exclude a radiological alternative diagnosis.

There are two types of fractures associated with the styloid process.

  • dorsal avulsion fractures.
  • volar displaced fractures.

The former occurs from an avulsion at the origin of the extensor carpi radialis brevis.

While the latter occurs from direct trauma to this area.

In both cases, conservative management is recommended as surgical intervention is not required due to high rate of union.

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In general, it takes 10 weeks to return to normal activities following these injuries.

Fractures through the styloid processes have been reported in literature since 1848.

Most commonly they occur by a crush injury or a fall on an outstretched hand.

They may also occur in rapid deceleration injuries.

They are most commonly found on the radial styloid process, but may also affect the ulnar styloid process.

Fractures of the radix (base) or body of the radius are rare and make up only 0.4% of all fractures.

The styloid processes are part of the lateral border of this bone which allows for fracture through them.

These fractures make up 30% to 50% of all forearm fractures in adults.

There is no gender predilection for these injuries; however, they do tend to be more common in adults than in children due to increased calcification.

Smallest Bone In The Human Body

They usually involve complete avulsions rather than isolated spicules.

This type fracture can easily mimic an open fracture because of the degree of trauma associated with this injury.

Fractures through the styloid process are unusual but should be considered in patients.

Who present with elbow pain following a direct blow to the back of their hand or wrist.

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Especially if there is radial shortening, tenderness over the ulnar side of forearm or swelling at that site.

The possibility for misdiagnosis can lead to unnecessary surgery and even patient death.

Although these processes may fracture spontaneously due to degenerative changes.

They may also occur as a result of excessive force transmitted through an outstretched hand during high-energy trauma.

Such as traffic collisions or falls from heights.

Injuries that have been described include motor vehicle accidents (VAs).

Blunt trauma from fist fights, falls from heights, and high-speed collisions .

The diagnosis of fractures through the styloid process is challenging.

Diaphyseal fractures are uncommon types of fracture in general.

Furthermore, these injuries are often occult or associated with pseudoarthrosis or nonunion due to the lack of clinical significance.

They may be easily missed on trauma radiographs if they are isolated spicules.

Subtle findings such as minimal angulation, displacement or sclerosis can help to identify these fractures.

Careful evaluation should be made about any reduced range of motion following a traumatic injury that could have involved the styloid processes.

In conclusion, if you have injured your ulna, do not panic.

These are very small pieces of bone that are common in both children.

And adults small bones that can be forgotten when people fracture their arm or wrist.

Even if it does require surgery, don’t fret- you will recover just fine.

Fractures through the styloid process may mimic open fractures as they can bleed profusely

A study on the causes of death after a styloid fracture showed that

 “the majority of patients died from exsanguination due to the arterial injury”

Therefore, time is essential for diagnosis and treatment. Prompt recognition and management can improve patient outcomes.


Praise Adughele

I am a practising physician and medical expert also a blogger and content creator

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