What is Trismus?

Appeared in: Bihar CHO - 2021

Explanation

Trismus is defined as the limited ability or complete inability to open the mouth.
This condition is commonly referred to as 'lockjaw' and is a hallmark symptom of tetanus.
It is caused by a sustained, tonic spasm of the muscles of mastication (chewing muscles), primarily the masseter, temporalis, and pterygoid muscles.

Option A: This is too general. Trismus specifically involves the muscles of mastication (chewing), which are controlled by the trigeminal nerve (CN V), not all facial muscles, which are primarily for expression and controlled by the facial nerve (CN VII).
Option C: This describes dysphagia. While severe trismus can interfere with the oral phase of swallowing, the core definition of trismus is restricted mouth opening, not the inability to swallow itself.
Option D: This is a nonsensical and medically irrelevant option. Trismus is a state of muscle hypertonicity (spasm), which is the opposite of paralysis.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Definition of Trismus (Lockjaw) as background academic context rather than a clinical decision trigger.
For a nurse, recognizing trismus is a critical assessment finding as it can signal a life-threatening condition like tetanus or a deep head and neck infection, both requiring immediate medical intervention.
Trismus poses a significant risk for airway compromise. The inability to open the mouth makes intubation extremely difficult, requiring specialized airway management techniques.
What if? If a patient develops trismus after a dental procedure, the most likely cause is not tetanus but rather inflammation, muscle strain, or a hematoma from the local anesthetic injection. The nursing priority would be pain management and notifying the dentist.

How to Approach the Question

The question asks for the definition of a specific medical term, 'Trismus'. This is a factual recall question.
Recall or associate the common name for trismus, which is 'lockjaw'.
Analyze the options based on the term 'lockjaw'. The inability to open the mouth is a direct description of a locked jaw.
Differentiate this from other options. 'Spasm of facial muscles' is too broad. 'Inability to swallow' is dysphagia. 'Paralysis-free muscles' is not a valid medical description.
Select the option that most accurately and specifically defines the term.

Concept Tested & Keywords

Q4RO89lCAUP3PMBAu0ZfUH

E6 Medicine Davidson Principles Practice 24e p. 1146-1148

E6 Medicine Harrison 22e Part 2 p. 1458-1460

E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 1826-1828

Practise the full Bihar CHO - 2021

Attempt every question from this paper in a timed mock, then review the full solution for each one.