Brachial Plexus

What is Brachial Plexus?

The brachial plexus is a bundle of nerves that originate from the neck (cervical spine) and upper-middle back (thoracic spine) and travel down the arm to the hands.  An injury can be where a nerve within the bundle is either overstretched, compressed, or possibly even torn from the spinal cord.

Contact sports injuries to the brachial plexus are typically minor, but trauma during a motor vehicle accident or fall may lead to more severe damage. Regardless of how the injury occurs, a brachial plexus injury (BPI) is at best uncomfortable if not downright painful.

An injury to the brachial plexus is complex, so having some knowledge of the neck and upper back anatomy is important. Your neck is made up of 7 vertebrae (C1-C7), bones, and named by their location within the spine. C1 is at the base of the skull and C7 is the transitional vertebra from the neck to the upper back, also known as the thoracic spine.

C1 and C2 are shaped differently compared to most of the other vertebrae in our spine. C1, called the atlas, connects the spine to the skull and is responsible for approximately 50% of the head forward (flexion) and backward (extension) bending. C2, called the axis, has a hook that points upward to connect with C1. The axis vertebra is responsible for approximately 50% of head rotational movements.

C3-C6 progressively get bigger in size as they stack upon one another. This structure allows for head movement in multiple directions, yet these vertebrae also protect the spinal cord as it leaves the skull and goes down the spinal column.

C7 is uniquely shaped; it is a transitional vertebra that connects the cervical spine to the thoracic spine. C7 is larger, has more muscles connecting to it, and takes on most the weight of the head. The C7 is the most common level of injury in the neck.

The upper to middle back is considered the thoracic spine. The thoracic spine has 12 bones (T1-T12). T1 connects to the cervical spine at C7 and T12 connects to the lumbar (low back) spine at L1. The thoracic spine is from about shoulder level to approximately five inches below the shoulder blade. This part of the spine is the most stable, meaning it has very little movement. The risk of injury to this part of the spine is less common but can occur.

We have eight cervical roots (C1-C8) which are named by where they exit the spinal column.

From C5-T1 is where the brachial plexus bundle of nerves branches out from the spine. The brachial plexus can injure through wear and tear, impingement, disease, or by a traumatic event.

We each have two brachial plexus branches, one for each shoulder and arm. There are five root nerves (C5-T1) that provide us with the sensation of the skin and movement of the muscles of the neck and upper back, down the arms, and to our hands.

Here is where it gets complex. The brachial plexus, made of five anatomical sections-spinal nerves, trunks, divisions, cords, and branches. An injury can occur at any section within the brachial plexus.

 

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  • Nerves: The spinal nerves are C5-T1. They originate from the spinal cord and enter the vertebrae. At this entry point to the vertebrae, they separate to form two nerves. The first is anterior (front) and the second is the posterior (back). The anterior nerves go on to form the brachial plexus while the posterior nerves go on to serve the sensation of our and for muscle control within the torso (trunk) area.
  • Trunks: The anterior nerve roots, also known as the brachial plexus converge to form three separate “trunks.” C5 and C6 nerve root form the superior trunk (top); C7 forms the middle trunk; C8-T1 form the inferior trunk (bottom).
  • Divisions: As the trunks (C5-C6, C7, and C8-T1) move away from the spine and travel towards the arm, they each separate again into two nerve pathways, anterior (front) and posterior (back). Each nerve pathway passes through the side of your neck, called the posterior triangle, and moves towards the front of your neck, called the anterior triangle.
  • Cords: From the anterior and posterior triangles of the neck the brachial plexus bundle of nerves passes through to the chest wall and moves towards your arm. It is here where they separate again into “” The three cords are lateral, posterior, and medial.
  • Lateral Cord- anterior division of C5-C7 (superior and middle)
  • Posterior Cord-posterior division of C5-T1(superior, middle, and inferior)
  • Medial Cord-anterior division of C8-T1 (inferior)
  • Branches: The brachial plexus nerve root then travels down the arm. The nerves separate into 5 “branches” which intervenes with muscles to control movement and allows for sensation. The following is a high-level summary of the branches (not meant to be fully detailed):
  • Musculocutaneous nerve (C5-C7): Assists with motor functions of the biceps; provides a sensory function to the side of your upper arm and forearm.
  • Axillary Nerve (C5 and C6): Assists with motor functions of the deltoid muscles (upper part of the arm); provides a sensory function within the same area.
  • Median Nerve (C6-T1): Assists with motor function of the forearm flexor muscles (the muscles that help you bend your wrist towards your body while the palm is up); provides a sensory function to the palm, thumb, index finger, and the middle finger.
  • Radial Nerve (C5-T1): Assists with motor functions of the triceps (muscle in the back of the upper arm) and wrist extension (muscles that help you bend your wrist towards your body while your palm is down); provides a sensory function to the back of your hand.
  • Ulnar Nerve (C8-T1): Assists with motor functions of the palm side of your pinky as well as your pinky and ring finger; provides a sensory function to the middle of the palm towards the pinky.

The complex design of the brachial plexus can be confusing to anyone; however, any physician, surgeon, the physical or occupational therapist is well versed in this anatomy. Despite the complexity of the structure, your health care provider can quickly diagnose where the injury is purely by assessing your symptoms, muscle strength and sensory reactions within and around your neck and upper arm.

What causes brachial plexus injuries?

The most common causes of a BPIs are:

  • Contact sports-collisions, over stretching the arm and neck through forced movements
  • Difficult births– when baby’s shoulder gets wedged within birth canal
  • Inflammation-trauma to the area of the neck or shoulder causing inflammation and pressure on the nerve bundle
  • Radiation-may cause damage to the tissue in and around the brachial plexus
  • Trauma-motorcycle or auto accidents, falls, bullet wounds, knife wounds
  • Tumors-cancerous or noncancerous tumors growing around the nerve bundle
  • Work related-blunt force from falling object, slip and fall, or other accidents

Symptoms of Brachial Plexus

Symptoms of BPI will vary depending on which part of the nerve bundle is damaged, as well as how severe the injury is. Below is a common list of symptoms:

  • Burning sensation
  • Loss of sensation
  • Muscle atrophy (loss of muscle mass)
  • Numbness or tingling
  • Pain
  • Permanent disability (paralysis), loss of all function and sensation
  • Stiff joints
  • Weakness

How is a brachial plexus injury diagnosed?

A good starting point is a physical examination by your physician. He or she will review your medical history, examine your range of motion and muscle strength of your upper body, and check for deformities like muscle wasting of the arms and hands.

Sometimes your physician may run a battery of tests to rule in, or rule out, other medical conditions causing your symptoms. A few of those tests may include:

  • Blood draw, check for infection and inflammation levels
  • EMG (electromyogram)-check nerve signals that impact muscle function
  • MRI (magnetic resonance image)-take a picture view of your bones, tissue, and nerves

Once diagnosed with BPI, your physician will then categorize the injury based on how it occurred. The categories are:

  • Avulsion-total separation of the nerve from the spinal cord, no recovery
  • Rupture-an overstretched nerve causing partial separation of the nerve, not at the spinal cord
  • Neurapraxia-mild irritation to the nerve, fully intact just over stretched or slightly compressed, excellent recovery
  • Axonotmesis-the nerve endings, or axons, are damaged; moderate recovery
  • Neuroma-a tumor that grows from nerve endings which won’t regenerate; prognosis variable

Treatment of Brachial Plexus

Treatment will vary depending on the type and severity of BPI. In milder cases, like in sports when you get a “zinger” it may just go away with a little bit of time. In other cases, when there is moderate to severe damage, treatment is necessary.

Anytime a nerve injuries occur, it can be uncomfortable and painful. With moderate to severe damage to a nerve, medications may be prescribed by your doctor. Managing pain and neurological symptoms are important during the healing process.

Often, physical or occupational therapy is prescribed. Your therapist will work with you on managing your symptoms as well as to maximize your recovery based on the injury. In some cases, achievement of full recovery occurs while the prognosis is less than full functional return in other cases. Both your physician and therapist will educate you on realistic expectations for recovery as well as the timeline for healing.

Nerves take a while to regenerate and heal so that you may experience symptoms for some time. The goal is to manage those symptoms while progressing your function abilities. Therapies may include sensory integration (kind of like waking up your nerves), muscle strengthening, the range of motion, posture retraining, and in some cases where you lost sensation, safety training.

In addition to physical or occupational therapy, your physician may prescribe vocational rehabilitation for returning to work. Whether you are returning to your same job, or a different job, after a BPI, your physician wants to ensure you can complete work related activities safely. The physician may have you use a work conditioning program as well as vocational counseling.

In rare cases where conservative treatment through rehabilitation is not an option, or does not work; you may need surgery for BPI. There are no guarantees a full recovery will happen with surgery, but the surgeon’s goal will be to reduce symptoms and improve function.

There surgical techniques your surgeon may choose from depending on the type of BPI:

  1. Nerve repair-reattaches a torn nerve; common with gunshot and knife wounds
  2. Nerve graft-attaches a healthy nerve (taken from another part of the body) to a lacerated nerve so that the injured nerve can regenerate; cannot perform if there is an avulsion (torn from spinal cord)
  3. Nerve transfer-a donor nerve is connected to the damaged nerve (no functioning nerve stump for a graft) to provide a signal to a paralyzed muscle
  4. Tendon and muscle transfer-long after the initial injury occurred and when there is no ability to repair, graft, or transfer a nerve, a physician may choose this procedure; they transplant a muscle, tendon, artery, vein, and nerve to the damaged tissue

With any BPI surgery, physical or occupational therapy is needed afterward. There is typically a long recovery phase, so education, training, and supervision of safely restoring movement and function are needed. Managing symptoms and progression functional strength is the goal.

Next Steps

If the diagnosis is BPI, physical or occupational therapy is highly recommended. As a consumer of health care, you have a choice in where you receive your PT or OT services. To find highly qualified PT or OT in your area, please click on Find A Clinic. This link will help you find a PT or OT that has top national rankings for BPI.

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