**Core Concept:**
The question is testing our understanding of the terms used to describe excessive involuntary muscle contractions in medical terminology. Muscles involved in deglutition (swallowing) and respiration are under involuntary control and any excessive spasm could cause clinical problems.

**Why the Correct Answer is Right:**
Extensive spasm of the muscles involved in deglutition is referred to as "Dysphagia." Dysphagia is the clinical term for difficulty in swallowing, usually due to abnormality in the muscles or nerves controlling the process. Involuntary contractions of these muscles could lead to food or liquid aspiration into the lungs, causing aspiration pneumonia.

**Why Each Wrong Option is Incorrect:**
A. "Panicus" is not a medical term, and also, excessive spasm in the muscles of respiration is not specific enough, as it could refer to any respiratory muscle spasm, which is not what the question intends to highlight.
B. "Hypertonia" is a general term for increased muscle tone, but it does not specifically describe the clinical problem mentioned in the question.
C. "Spasticity" is a term often used to describe involuntary muscle contractions in neurological disorders, but it is not specific to swallowing or respiration muscles.
D. "Aspiration" is a clinical term for the passage of food or liquid into the respiratory tract, but it is not a term for excessive muscle contractions.

**Clinical Pearl / High-Yield Fact:**
Dysphagia and its various forms (e.g., oropharyngeal dysphagia, esophageal dysphagia, or laryngeal dysphagia) are important clinical entities to recognize as they may require specific diagnostic tests, such as barium swallow or flexible laryngoscopy, or treatment options including medication or surgical intervention, depending on the underlying cause.