Lecture Notes on Anatomy, Physiology, Pathology, and Pharmacology

Anatomy & Histology

Meninges and Blood Supply

• Cerebrospinal fluid sample collection: Insert needle at L3/L4 interspinous level, in subarachnoid space.
• Acute MCA occlusion: Likely causes speech disorders.
• Oculomotor nerve palsy: Often due to compression from superior cerebellar artery aneurysm.

Brainstem

• Raphe nucleus is mediated by serotonin.
• Parkinson's disease shows loss of dopaminergic neurons in the substantia nigra.
• The corticospinal tract passes through the cerebral peduncle.

Cranial Nerves

• Glossopharyngeal nerve affects taste and tactile sensation in the posterior 1/3 of the tongue.
• Pterygopalatine ganglion invasion leads to increased tear secretion due to parasympathetic response.

Thalamus and Cerebral Cortex

• Hypothalamus is primarily responsible for homeostasis.
• Anterior nucleus of thalamus connects to mammillary bodies.
• Broca’s area damage affects speech production; located in the left inferior frontal gyrus.

Structure and Function of Head and Neck

• Scalene muscles are accessory muscles of inspiration.
• Accessory nerve crosses the same skull base opening as specific vessels.

Physiology

Somaesthetic Pathway and Somatic Sensation

• Meissner and Merkel receptors differ in their rate of adaptation.
• Loss of proprioception linked to medial lemniscus lesions.

Pain Pathway and Mechanisms of Pain

• Periaqueductal gray integrates pain signals in the brainstem.
• Referred pain phenomenon due to nociceptors connecting to the same second-order neurons.

Motor System

• Lacunar infarcts in basal ganglia lead to sudden hemiplegia.
• Right lower limb weakness due to left anterior cerebral artery occlusion.

Cerebellum

• Tandem walking test identifies cerebellar dysfunction.

Control of Movement

• Vestibulospinal tract controls axial muscles and posture.

Pathology

Pathology of CNS Infection

• Cryptococcus can cause meningitis in healthy individuals.
• Tuberculous meningitis causes fibrosis in subarachnoid space, leading to hydrocephalus.

Pathology of Raised Intracranial Pressure

• Hemorrhage from pontine arteries due to lipohyalinosis in hypertension.
• Epidural hematomas can compress cerebral arteries causing visual problems.

Microbiology

Infection of the CNS I: Bacterial and Fungal Infections

• Meningococcal meningitis characterized by high white cell count, mostly neutrophils.
• Cryptococcus neoformans in CSF indicates fungal infection.

Pharmacology

Infections of the CNS III: Principles of Antiviral Therapy

• Antiviral for influenza: Neuraminidase inhibitor.
• Acyclovir: Inhibits viral genome replication.

Sedatives and Hypnotics

• Diazepam increases frequency of Cl- channel opening linked to GABAA receptors.

Antidepressants

• SSRIs limit serotonin reabsorption into presynaptic cells.
• Noradrenaline reuptake inhibitors block transporters on presynaptic terminals.

Antipsychotics

• Blocking dopamine D2 receptors in the mesocortical region offers antipsychotic effects but may cause side effects like gynecomastia.