9.1
Oromandibular dystonia (difficult to open mouth)
![](https://i0.wp.com/entokey.com/wp-content/uploads/2021/08/f09-01-9780323697156.jpg?w=960)
- 1.
Called lockjaw.
- 2.
Clinical feature: reduced mouth opening caused by involuntary spasm of the mastication muscles.
- 3.
Botulinum toxin injection:
- a.
Primary target muscles: temporalis (1-1) and masseter (1-2).
- b.
Secondary target muscles: medial pterygoid (1-3) only because of technical difficulties.
- a.
∗In addition, if jaw is deviated to right (left) side, then right (left) lateral pterygoid (1-4) is indicated for injection.
9.2
Oromandibular dystonia (difficult to close mouth)
![](https://i0.wp.com/entokey.com/wp-content/uploads/2021/08/f09-02-9780323697156.jpg?w=960)
- 1.
Clinical feature: difficult to close mouth caused by involuntary spasm of the mouth opening muscles.
- 2.
Botulinum toxin injection:
- a.
Primary target muscle: lateral pterygoid muscle (1-4).
- a.
9.3
Bruxism (teeth grinding)
![](https://i0.wp.com/entokey.com/wp-content/uploads/2021/08/f09-03-9780323697156.jpg?w=960)
- 1.
Clinical feature: teeth grinding (similar to oromandibular dystonia, difficult to open mouth)
- 2.
Botulinum toxin injection:
- a.
Primary target muscles: temporalis (1-1), masseter (1-2), and lateral pterygoid (1-4).
- b.
Secondary target muscle: medial pterygoid (1-3) It is recommended as secondary target muscle only because of technical difficulties. If approach to this muscle is not difficult, it could be a primary target muscle.
- a.
9.4
Torticollis
![](https://freepngimg.com/download/social_media/63059-media-icons-telegram-twitter-blog-computer-social.png)
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