Brain Structure, Function, Stroke, and Head Injury

Vocabulary flashcards covering brain structure, neurophysiology, stroke pathophysiology, and head injury mechanisms based on the lecture transcript.

Gyri

The ridges located on the surface of the cerebrum.

Sulci

The shallow grooves located on the surface of the cerebrum.

Grey Matter

The outer layer of the cerebral hemispheres, approximately $3\,mm$ thick, which contains neuronal cell bodies.

White Matter

Brain tissue located deep to grey matter consisting mainly of myelinated fibres responsible for communication within the central nervous system.

Primary Motor Cortex

Cortical area located in the precentral gyrus of the frontal lobe that controls voluntary skeletal muscle movement on the contralateral side of the body.

Primary Somatosensory Cortex

Cortical area located in the postcentral gyrus of the parietal lobe that receives sensory information regarding touch, pressure, vibration, pain, temperature, and proprioception.

Visual Cortex

Cortical area located in the posterior occipital lobe that receives visual information directly from the retina.

Auditory Cortex

Cortical area located in the temporal lobe that receives auditory information directly from the inner ear.

Olfactory Cortex

Cortical area located in the temporal lobe responsible for conscious awareness of odours.

Visceral Cortex

Cortical area located in the insula that perceives visceral sensations, such as an upset stomach or a full bladder.

Gustatory Cortex

Cortical area located in the insula responsible for taste perception.

Vestibular Cortex

Cortical area located in the insula responsible for the awareness of balance.

Commissures

Nerve fibre tracts, such as the corpus callosum, that connect the two cerebral hemispheres.

Association Fibres

Nerve fibres that connect different areas within the same cerebral hemisphere.

Projection Fibres

Nerve fibres that connect the cerebral cortex with other regions of the central nervous system.

Basal Ganglia

Concentrations of grey matter located deep within cerebral white matter that coordinate unconscious components of movement, including posture and balance.

Thalamus

Diencephalic structure surrounding the third ventricle that receives most sensory impulses and relays them to specific areas of the cerebral cortex.

Hypothalamus

Small diencephalic structure providing the highest level of endocrine control, producing pituitary-regulating hormones, and controlling heart rate, blood pressure, respiration, body temperature, and blood osmotic pressure.

Brainstem

Structure consisting of the midbrain, pons, and medulla oblongata that connects the brain to the spinal cord and houses vital autonomic control centres.

Cerebellum

The second largest part of the brain, located behind the brainstem and below the occipital lobes, responsible for subconscious coordination of skeletal muscle activity to make movement smooth.

Cerebrospinal Fluid (CSF)

Clear, colourless fluid derived from plasma with a total volume of approximately $150\,mL$, replaced every $8\,\text{hours}$, that cushions the central nervous system, supplies nutrients, and removes waste.

Intracranial Pressure (ICP)

The pressure exerted inside the rigid skull by brain tissue ($80\%$), blood ($12\%$), and CSF ($8\%$), with normal values ranging between $5-13\,mmHg$.

Circle of Willis

A vascular ring formed by branches of the internal carotid and basilar arteries at the base of the pituitary that provides collateral blood supply.

Blood-Brain Barrier (BBB)

A selective barrier formed by tight capillary junctions and astrocytes that controls interstitial fluid composition to provide a stable environment.

Autoregulation

The intrinsic response of cerebral arterioles to dilate when systemic blood pressure decreases or local $CO_2$ increases, and constrict when systemic blood pressure increases, maintaining constant cerebral blood flow.

Stroke

Sudden neurological impairment resulting from a disruption of cerebral blood supply due to ischaemia (approximately $85\%$) or haemorrhage (approximately $15\%$).

Transient Ischaemic Attack (TIA)

A temporary occlusion of cerebral blood flow causing neurological symptoms that completely resolve within $24\,\text{hours}$ without permanent tissue death.

Ischaemic Penumbra

A region of mild-to-moderate ischaemia surrounding the severely ischaemic core zone after a stroke, containing viable tissue that is the primary target for acute pharmacological treatment.

Cytotoxic Oedema

Early intracellular swelling of neurons, glial cells, and endothelial cells occurring within minutes to hours after ischaemia, caused by ATP depletion and failure of ion transport leading to $Na^+$ and water influx.

Vasogenic Oedema

Extracellular swelling developing over hours to days following a stroke, caused by increased small-vessel permeability due to a local inflammatory response.

Stroke in Evolution

Progressive arterial occlusion and expanding ischaemia that develops gradually over minutes, hours, or days.

Berry Aneurysm

An arterial wall defect present from birth that develops over years around the Circle of Willis and can rupture to cause a subarachnoid haemorrhage.

Reticular Formation

A diffuse neurological pathway involved in arousal, responsiveness, alertness, sleep, and postural muscle tone.

Closed Head Injury

A brain injury usually caused by blunt trauma where the skull remains intact.

Open Head Injury

A brain injury usually caused by penetrating trauma where the skull is penetrated and the dura mater is breached.

Coup Injury

A focal brain contusion occurring directly beneath the site of impact.

Contrecoup Injury

A focal brain contusion occurring on the side of the brain opposite to the impact site.

Glasgow Coma Scale (GCS)

A standardized scoring system used to assess the severity of brain injury using standard stimuli, ranging from a score of $3$ (worst) to $15$ (best).

Mean Arterial Pressure (MAP)

A clinical measurement calculated as $\text{MAP} = \text{DBP} + \frac{1}{3}(\text{SBP} - \text{DBP})$.