Basic Medical Sciences: Anatomy, Physiology, Biochemistry, Pathology, Pharmacology, Microbiology/Immunology
This domain covers the pre-clinical foundation the exam expects you to apply at the chair: head and neck anatomy, physiology, biochemistry, general pathology, pharmacology and microbiology/immunology. Questions rarely test isolated facts; they present a patient scenario and ask whether you can link mechanism to clinical decision.
Anatomy and physiology anchors
- The chorda tympani carries taste from the anterior two-thirds of the tongue and runs with the lingual nerve before joining CN VII, so lingual nerve injury alone also disturbs taste on that side.
- Loss of the corneal reflex indicates a V1 lesion; V3 carries the lingual and inferior alveolar nerves.
- Salivary secretion is driven mainly by parasympathetic M3 receptors; anticholinergics cause xerostomia.
Pathology, pharmacology, microbiology
Inflammation follows the classic vascular-then-cellular sequence; periodontitis is plaque-driven but host-mediated destruction. Aminoglycosides and tetracyclines act on the 30S subunit, macrolides on the 50S - the standard discriminator. Anaphylaxis to penicillin is type I (IgE) hypersensitivity; a maculopapular rash is type IV. Hepatitis B is the dominant occupational blood-borne risk in dentistry.
Worked example
A 55-year-old has right facial weakness, loss of taste on the right anterior tongue, and reduced lacrimation; facial sensation is intact. Motor weakness localises to CN VII; anterior tongue taste travels in the chorda tympani; lacrimal fibres run in the greater petrosal nerve; intact sensation excludes V. The lesion therefore lies proximal to the geniculate ganglion - a lower motor neuron VII lesion such as Bell's palsy, not a central lesion.
Traps that cost marks
Confusing the lingual nerve with the chorda tympani; assuming central facial palsy spares the forehead in every case; mixing 30S and 50S antibiotic targets; prescribing prophylactic antibiotics for routine extractions in healthy patients.