Weakness or paralysis of the serratus anterior muscle is considered a neuromuscular condition that can significantly affect shoulder movement and stability, which in turn impacts a person’s ability to perform simple daily activities such as lifting the arm, carrying objects, or even pushing against surfaces. The importance of this muscle lies in its essential role in stabilizing the scapula against the rib cage; therefore, any dysfunction in its activity may lead to disruption in normal shoulder biomechanics and the appearance of troubling symptoms such as pain, muscle weakness, and abnormal prominence of the scapula.

The causes of this condition vary, ranging from direct injury to the nerve supplying the muscle, repetitive strain, complications of certain surgical procedures, or sports-related injuries. Symptoms also differ in severity, from mild weakness to complete paralysis that can severely affect shoulder function.In this article from Dili Medical, we will cover everything related to serratus anterior muscle weakness or paralysis, including its causes, symptoms, complications, as well as the latest diagnostic and treatment approaches, in order to provide a complete understanding of this condition and how to manage it properly.

What is Serratus Anterior Muscle Weakness or Paralysis?

Weakness or paralysis of the serratus anterior muscle is a condition that occurs due to a dysfunction in the muscle itself or in the nerve responsible for its supply, known as the long thoracic nerve. This leads to a condition commonly called “winged scapula”, where the shoulder blade protrudes abnormally away from the rib cage due to loss of its stabilizing function.

Common Symptoms Include:

• Shoulder pain
• Difficulty lifting the arm above head level
• Visible protrusion of the scapula, especially during movement or pushing activities

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Is scapular winging a serious sign?

Scapular winging is not always a serious condition, but it can indicate weakness of the serratus anterior muscle or injury to the long thoracic nerve. Early medical evaluation is recommended to identify the underlying cause and prevent possible complications.

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Does serratus anterior weakness cause pain?

Yes, some patients experience varying degrees of pain, usually in:

• The shoulder
• Upper back
• Neck region in some cases

The pain typically worsens with movement, especially when lifting the arm or performing physical effort.

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Can it cause numbness?

In some cases, numbness or a burning sensation may occur if nearby nerves are affected or compressed, leading to additional neurological symptoms alongside muscle weakness.

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Can children be affected?

Although serratus anterior muscle weakness or paralysis is more common in adults, it can also occur in children, but less frequently. In children, it is usually associated with trauma, accidents, or, in rare cases, neurological disorders affecting the nerve supply to the muscle.

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Does it affect daily life?

Yes, it can significantly affect daily activities that depend on shoulder and arm movement, such as lifting objects, dressing, or performing manual tasks.

However, early diagnosis and appropriate treatment—especially physical therapy and rehabilitation—can greatly improve the condition and help restore shoulder function over time.

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Types of Serratus Anterior Muscle Weakness or Paralysis

This condition can be classified into several types depending on severity, cause, and the extent of long thoracic nerve involvement.

1. Partial weakness

This is the mildest form, where the muscle still functions but with reduced efficiency.

Symptoms:

• Mild shoulder weakness
• Fatigue during movement
• Mild to moderate pain
• Slight scapular winging

Common causes:

• Muscle overuse
• Improper or intense exercise
• Mild nerve compression

Usually improves with rest and physical therapy.

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2. Complete paralysis

In this type, the muscle loses most or all of its function due to significant nerve damage.

Symptoms:

• Severe scapular winging
• Marked difficulty in lifting the arm
• Severe shoulder weakness
• Loss of scapular stability

Causes:

• Severe nerve injury or rupture
• Major trauma to the shoulder or chest
• Surgical complications

May require long-term rehabilitation and sometimes surgery.

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3. Temporary paralysis

This occurs when the nerve is temporarily affected due to inflammation or mild compression.

Features:

• Sudden onset of symptoms
• Gradual recovery over weeks or months
• Often reversible

Causes:

• Viral infections
• Nerve inflammation
• Severe muscle strain

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4. Chronic paralysis

Occurs when the condition persists for a long time without treatment or when there is permanent nerve damage.

Symptoms:

• Persistent weakness
• Muscle atrophy
• Noticeable scapular deformity
• Limited arm movement

May require long-term rehabilitation or surgical intervention.

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5. Nerve injury-related paralysis

This type is directly caused by damage to the long thoracic nerve.

Causes:

• Trauma and accidents
• Chest or axillary surgery
• Sports injuries
• Sudden stretching of the neck or arm

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6. Functional weakness (without nerve damage)

In some cases, there is no actual nerve injury, but muscle weakness occurs due to functional factors.

Causes:

• Lack of shoulder use
• Poor posture for long periods
• General muscle weakness

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Causes of Serratus Anterior Muscle Weakness or Paralysis

1. Long thoracic nerve injury

This is the most common cause, as this nerve directly controls the serratus anterior muscle.

Common reasons include:

• Repetitive heavy lifting
• Improper or intense exercise
• Direct trauma to the shoulder or neck
• Repetitive overhead arm movements
• Surgeries in the chest or armpit area

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2. Sports injuries

Certain sports may place continuous strain on the nerve or muscle, such as:

• Swimming
• Boxing
• Weightlifting
• Tennis

Repeated strain can gradually lead to muscle weakness.

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3. Accidents and trauma

Examples include:

• Car accidents
• Falling on the shoulder
• Sudden pulling of the neck or arm

These may cause direct nerve injury or compression.

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4. Viral or neurological inflammation

In some cases, nerve inflammation may occur following a viral infection, leading to:

• Temporary muscle weakness
• In severe cases, persistent dysfunction 

Fifth: Neck and nerve problems

Certain cervical spine disorders or compression of the nerves emerging from the neck may affect the long thoracic nerve, which in turn negatively impacts the function of the serratus anterior muscle.

Sixth: Surgical procedures

Some surgical operations may unintentionally lead to nerve injury, such as:

• Breast surgery
• Lung surgery
• Axillary lymph node surgery

Seventh: Neuromuscular and muscle diseases

These are less common causes, but they may still lead to muscle weakness, such as:

• Muscular dystrophy
• Peripheral neuropathies
• Neuromuscular disorders

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Symptoms of Serratus Anterior Muscle Weakness or Paralysis

First: Scapular winging

This is one of the most prominent signs, where the shoulder blade protrudes outward in a wing-like shape. It becomes more noticeable in the following situations:

• When pushing against a wall
• While lifting the arm
• When carrying objects

This condition is medically known as scapular winging.

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Second: Weakness in arm elevation

The patient may have difficulty performing movements that require raising the arm, such as:

• Lifting the arm above head level
• Combing hair
• Putting on clothes
• Carrying or lifting objects

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Third: Shoulder or upper back pain

Pain may appear in different areas, such as:

• Shoulder
• Upper back
• Neck in some cases

The pain is usually:

• Continuous or intermittent
• Worsens with movement
• May sometimes radiate to the arm

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Fourth: General shoulder weakness

The patient may feel that the shoulder is:

• Unstable
• Weaker than normal
• Easily fatigued during use or exertion

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Fifth: Difficulty with pushing or pulling

Since the serratus anterior muscle plays an important role in pushing movements, the patient may have difficulty with:

• Pushing doors
• Moving furniture
• Performing push-up exercises

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Sixth: Clicking or friction sensation

Some patients may notice:

• Clicking sounds
• A feeling of friction inside the shoulder

This occurs due to instability of the scapula during movement.

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Seventh: Change in shoulder shape

There may be visible changes in shoulder appearance, such as:

• Drooping of the affected shoulder compared to the other side
• Noticeable asymmetry between both shoulders
• Abnormal prominence of shoulder bones

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Eighth: Early fatigue in the arm

Even simple activities may cause:

• Rapid fatigue
• Reduced ability to continue movement
• A feeling of heaviness in the arm

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How is Serratus Anterior Muscle Weakness or Paralysis Diagnosed?

First: Clinical examination

Diagnosis usually begins with a physical examination, where the doctor observes shoulder shape and scapular movement during activity.

Key signs include:

• Scapular winging
• Weak arm elevation
• Shoulder instability during movement
• Visible asymmetry between both shoulders

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Second: Wall push test

This is one of the most important diagnostic tests.

Procedure:

The patient is asked to push against a wall using both hands while the doctor observes scapular movement.

Interpretation:

If marked scapular winging appears during the push, it may indicate serratus anterior weakness or long thoracic nerve injury.

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Third: Assessment of shoulder movement and strength

The doctor evaluates:

• Range of motion of the arm
• Strength of shoulder muscles
• Presence of pain during movement
• Ability to raise the arm above head level

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Fourth: Electromyography (EMG) and nerve studies

These are essential tests to confirm the diagnosis and determine severity.

They include:

• Electromyography (EMG)
• Nerve conduction studies

Importance:

• Identifying long thoracic nerve injury
• Determining the degree of nerve damage
• Differentiating between temporary weakness and complete paralysis

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Fifth: Imaging studies

X-rays

Used to rule out:

• Bone fractures
• Bone abnormalities
• Shoulder joint deformities

Magnetic Resonance Imaging (MRI)

May be used to examine:

• Neck
• Shoulder

It helps detect:

• Nerve compression
• Muscle injuries
• Cervical spine problems 

Sixth: Medical tests (laboratory investigations)

The doctor may request certain laboratory tests in suspected cases, such as:

• Nerve inflammation
• Muscle diseases
• Autoimmune disorders

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Seventh: Identifying the underlying cause

An important part of diagnosis is determining the root cause. The doctor may ask about:

• Previous shoulder or neck injuries
• Participation in intense or contact sports
• Recent surgeries
• Presence of neck pain
• Previous infections or inflammations

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When is urgent medical evaluation needed?

Immediate medical consultation is necessary in the following cases:

• Sudden and noticeable weakness in the arm
• Severe difficulty moving the shoulder
• Increasing scapular winging over time
• Severe or persistent pain
• Symptoms appearing after an accident or surgery

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Complications of Serratus Anterior Muscle Weakness or Paralysis

First: Permanent scapular winging

One of the most common complications, where the scapula remains visibly protruded even at rest.

It may lead to:

• Difficulty moving the shoulder
• Shoulder asymmetry
• Persistent discomfort or irritation

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Second: Chronic shoulder weakness

Delayed treatment or neglect may lead to long-term weakness, causing:

• Reduced arm strength
• Difficulty carrying objects
• Limited ability to perform daily activities

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Third: Limited arm movement

With progression, movement of the arm may become restricted, such as:

• Difficulty lifting the arm overhead
• Reduced shoulder flexibility
• Difficulty performing sports or manual tasks

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Fourth: Chronic pain

Pain may become persistent due to shoulder instability, including:

• Shoulder pain
• Upper back or neck pain
• Increased pain with movement or exertion

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Fifth: Shoulder instability

Muscle weakness disrupts normal shoulder balance, leading to:

• A feeling of instability
• Difficulty performing precise movements
• Early fatigue during activity

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Sixth: Muscle atrophy

In chronic cases, the following may occur:

• Reduction in muscle size
• Progressive muscle weakness
• Loss of muscle mass

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Seventh: Impact on surrounding muscles

When the serratus anterior is weak, other muscles compensate, which may lead to:

• Persistent muscle tightness
• Overuse of neck and shoulder muscles
• Secondary muscle inflammation

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Eighth: Reduced physical and functional performance

Physically active individuals may experience:

• Decreased performance
• Poor endurance
• Difficulty with repetitive arm movements

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Ninth: Shoulder stiffness

Reduced movement and chronic pain may result in:

• Shoulder stiffness
• Reduced range of motion
• Difficulty moving the arm normally

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Drug Treatment for Serratus Anterior Muscle Weakness or Paralysis

Can medications cure paralysis?

Medications do not directly cure paralysis, but they help by:

• Relieving pain
• Reducing inflammation
• Supporting nerve function
• Improving tolerance to physical therapy

In cases of severe nerve damage, physical therapy or other interventions are usually required.

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First: Pain relievers

Used to reduce shoulder and upper back pain.

Examples:

• Paracetamol
• Ibuprofen
• Diclofenac

Benefits:

• Pain relief during movement
• Easier participation in rehabilitation exercises

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Second: Anti-inflammatory drugs

Used when inflammation affects nerves or surrounding tissues.

Examples:

• Naproxen
• Celecoxib

Effects:

• Reducing swelling
• Relieving nerve pressure
• Improving shoulder mobility

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Third: Neuropathic pain medications

Used when pain includes burning, tingling, or nerve-related discomfort.

Examples:

• Pregabalin
• Gabapentin

Benefits:

• Reducing nerve pain
• Improving sleep quality
• Decreasing burning and tingling sensations

Possible side effects:

• Drowsiness
• Dizziness
• Reduced concentration

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Fourth: Nerve-supporting vitamins

Used to support nerve health and recovery.

Include:

• Vitamin B1
• Vitamin B6
• Vitamin B12

Benefits:

• Supporting nerve regeneration
• Improving nerve signal transmission
• Reducing numbness and weakness

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Fifth: Muscle relaxants

Used when there is muscle spasm in the neck or shoulder.

Examples:

• Baclofen
• Cyclobenzaprine

Benefits:

• Reducing muscle spasms
• Improving shoulder comfort during movement

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Sixth: Corticosteroids

Used in some severe inflammatory cases under medical supervision.

Example:

• Prednisone

Benefits:

• Reducing nerve inflammation
• Decreasing pain and swelling

⚠️ Long-term use should be avoided due to potential side effects.

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Is medication alone enough?

Usually not. The most important part of treatment includes:

• Physical therapy
• Shoulder strengthening exercises
• Improving scapular movement
• Treating the underlying nerve cause

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When are additional treatments needed?

Other options may be considered if:

• Weakness persists for a long time
• Nerve recovery does not occur
• Muscle atrophy develops
• The nerve injury is severe

In rare cases, surgery may be required.

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General treatment advice

• Avoid heavy lifting
• Do not overuse the affected shoulder
• Stick to physical therapy
• Maintain proper posture during sitting and sleeping
• Consult a doctor if pain or weakness worsens

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Surgical Treatment of Serratus Anterior Muscle Weakness or Paralysis

First: Long thoracic nerve repair surgery

Used when the condition is caused by compression or direct nerve injury.

Procedure:

• Surgically accessing the affected nerve
• Releasing nerve compression or adhesions
• Repairing or reconnecting the damaged nerve

Goal:

• Restore nerve signals to the muscle
• Improve shoulder stability and movement

Best timing:

Better results are usually achieved when performed within the first months after injury.

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Second: Nerve grafting or nerve transfer

Used when the nerve is severely damaged and cannot be directly repaired.

Procedure:

• Taking a healthy nerve segment from another body area
• Connecting it to the damaged nerve
• Promoting nerve fiber regeneration

Advantages:

• May restore muscle function gradually

Disadvantages:

• Long recovery period
• Results appear slowly over months

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Third: Muscle or tendon transfer

One of the most common options in chronic cases.

Example:

Transfer of part of the pectoralis major muscle to compensate for serratus anterior function.

Procedure:

• Detaching a muscle/tendon segment
• Reattaching it to the scapula
• Improving shoulder stability

Goals:

• Reduce scapular winging
• Improve arm elevation
• Enhance shoulder stability

Results:

Often leads to significant improvement in daily function and movement quality.

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Fourth: Scapular fixation

Used in severe or non-rehabilitative cases.

Procedure:

• Fixing the scapula to the chest wall using surgical methods or supportive tissues

Goals:

• Reduce abnormal movement
• Relieve pain

Disadvantage:

• May significantly limit shoulder mobility

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Fifth: Shoulder or scapulothoracic fusion

A rare option used only in very severe cases.

Goal:

• Permanent stabilization of the shoulder
• Reduction of chronic pain

Disadvantage:

• Major loss of shoulder mobility

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Sixth: Arthroscopic surgery

In some cases, minimally invasive (arthroscopic) techniques may be used, especially for nerve decompression.

Advantages:

• Smaller incisions
• Less postoperative pain
• Faster recovery