Trap Tox; Botox Injection Technique Into the Trapezius Muscles

What is Trap Tox or Trapezius Tox?

Trap Tox or Trapezius Tox is another cosmetic use for botulinum toxin. Injecting botulinum toxin into the trapezius muscle, at the upper border of the trapezius, can create a smooth shoulder line for their dress as a result of neurogenic atrophy. Muscle mass loss can create the effects of a slimmer and longer neck appearance. 


Botulinum toxin injections in the trapezius muscle are primarily indicated for the treatment of chronic muscle tension, spasms, and pain. This application is particularly beneficial for patients with myofascial pain syndrome and chronic tension-type headaches originating from the trapezius muscle. The efficacy of botulinum toxin in reducing pain and improving muscle function has been substantiated in several studies. 


The trapezius muscle, a large, triangular muscle extending over the back of the neck and shoulders, plays a crucial role in moving, rotating, and stabilizing the scapula and extending the neck. No major blood vessel along the superficial trapezius muscle.

The accessory nerve travels caudally along the inferior surface of the trapezius muscle, after piercing its anterior border.


Identifying anatomical landmarks is crucial for effective botulinum toxin injection. Based on research, the landmarks should be placed like this:

  • C is the spinous process of C7.
  • A is the Acromion.
  • Draw a line from A to C and then divide that line into four equal sized sections (a,b,c,d).

This photo shows the staining of the accessory nerve and an illustration of the density of the perforating accessory nerve branches.

Place four dots equi-distant in box b, and two dots in box c. The yellow circle represents diffusion of the toxin.

The injection technique involves using a fine needle to inject botulinum toxin into the trapezius muscle. The procedure should be performed under sterile conditions. The number of injection points can vary, but they are generally evenly distributed over the muscle. Accurate needle placement is crucial to maximize efficacy and minimize side effects.

This is an example of an Alternative Injection Landmark

This researcher recommended that the injector avoid injecting medial to the most lateral point of the external occipital protuberance line, which extends from the occipital bone down to the trapezius muscle. This prevents toxin spread to muscles affecting breathing or swallowing. 

Trap Tox or Trapezius Tox Dosage Guide

Dosage from research studies by Allergan: Ranges From 10 to 50 units with 1-5 injection sites.

Injection for Trapezius muscle for Botox Therapeutic for chronic migraine: 5U per site, 3 injection sites per side, total of 15U per side or 30U for both right and left sides.

Injection for Trapezius muscle for Botox Therapeutic for cervical dystonia: mean dose of 68U for both right and left sides. 

Starting dosage should begin with 5 units per injection site, with 3-6 sites per side (15-30 units per side) in sections B & C, and titrate up as needed.

Many studies used up to 50 units per side.

Side Effects

Common side effects include:

  • Localized pain, swelling, and bruising at the injection site.
  • Muscle soreness in muscles not injected, possibly due to compensation from trapezius muscle weakness.
  • More severe but rare side effects can include muscle weakness, dysphagia, or respiratory difficulties.

Physicians should educate patients about potential side effects and ensure appropriate post-procedure care.

For more information about Comprehensive Guide to Botulinum Toxin Injection Training, contact us at or call us at (212) 470-8059.

Statement of Responsibility

Cosmetic Medical Training recognizes that many of the techniques and recommendations are for procedures that are considered off-label use.  Our recommendations are based on many textbooks, published articles, seminars, and practical knowledge and experience.  The authors have attempted to maintain up to date knowledge and information in this training manual with the current standard of care.  However, due to the continuing flow of new research and information relating to the drugs being used in this course, we recommend that you check with the manufacturer for any changes in the package inserts, warnings, and precautions.  All information and tools presented within this site are intended for educational purposes. We do not guarantee that the information will be completely accurate and up to date; therefore the authors will not be held responsible for any errors, omissions, or inaccuracies published.  Application of the knowledge is ultimately the responsibility of the practitioner.

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