THE_BRAIN_AND_THE_CRANIAL_NERVES

Central Nervous System

Central Nervous System

The part of the nervous system consisting of the brain and spinal cord.

Peripheral Nervous System

The part of the nervous system outside the central nervous system, including the cranial and spinal nerves.

Cerebrum

The largest part of the brain responsible for conscious thoughts and intellectual functions.

Cerebellum

The part of the brain that coordinates repetitive body movements.

Diencephalon

The region of the brain located under the cerebrum and cerebellum, linking the cerebrum to the brain stem.

Brainstem

The region of the brain that processes information between the spinal cord and higher brain centers.

Neural Cortex

The outer layer of gray matter on the surface of the cerebrum responsible for higher brain functions.

Ventricles

Cavities in the brain filled with cerebrospinal fluid.

Meninges

The three layers of protective membranes surrounding the brain and spinal cord.

Cranial Nerves

Nerves that emerge directly from the brain, responsible for functions like sensory input and motor output.

Dural Folds

Folds formed by the inner layer of the dura mater that extend into the cranial cavity, stabilizing and supporting the brain, and containing dural sinuses.

Falx Cerebri

Dural fold lying between the cerebral hemispheres, housing the superior sagittal sinus and the inferior sagittal sinus.

Tentorium cerebelli

Dural fold separating the cerebrum and cerebellum, containing the transverse sinus.

Falx Cerebelli

Dural fold dividing the cerebellar hemispheres below the tentorium cerebelli.

Cerebrospinal Fluid (CSF)

Fluid surrounding the CNS, cushioning neural structures, supporting the brain, and aiding in nutrient transport and waste removal.

Arachnoid Villi

Extensions of the arachnoid membrane that absorb CSF into the venous circulation.

Hydrocephalus

Accumulation of CSF in the brain, leading to an enlarged head, often requiring a shunt to drain excess fluid.

Blood-Brain Barrier (BBB)

Barrier isolating CNS neural tissue from general circulation, formed by tight junctions between endothelial cells of CNS capillaries.

Medulla Oblongata

Part of the brainstem that allows communication between the brain and spinal cord, coordinates autonomic reflexes, controls visceral functions, and contains autonomic nuclei, sensory and motor nuclei of cranial nerves, and transmission stations for sensory and motor pathways.

Autonomic Nuclei

Found in the reticular formation of the medulla oblongata, these nuclei regulate autonomic functions of the peripheral system such as cardiovascular centers (heart rate, blood flow, and pressure) and respiratory centers (respiratory rate and rhythm).

Sensory and Motor Nuclei

Associated with cranial nerves VIII, IX, X, XI, and XII, these nuclei are present in the medulla oblongata and play a role in sensory and motor functions.

Pons

Links the cerebellum with other areas of the brain and spinal cord, contains sensory and motor nuclei for cranial nerves V, VI, VII, and VIII, and houses nuclei involved in respiration and information processing to and from the cerebellum.

Midbrain

Composed of the tectum, tegmentum, and cerebral peduncles, with the tectum containing sensory nuclei like the corpora quadrigemina, and the tegmentum including the red nucleus and substantia nigra.

Cerebellum

A part of the brain responsible for coordination, balance, and motor control.

Diencephalon

The region of the brain that integrates sensory information and motor commands, consisting of the epithalamus, thalamus, and hypothalamus.

Epithalamus

The roof of the diencephalon, housing the pineal gland which secretes melatonin.

Thalamus

Acts as a sensory relay center for most sensory information, excluding olfactory, and contains various nuclei with specific functions.

Hypothalamus

Regulates various bodily functions such as body temperature, emotions, circadian rhythms, and controls the endocrine system.

Limbic System

A functional brain system involved in emotions, memory, and linking conscious functions with autonomic functions, consisting of various brain structures like the amygdala and hippocampus.

Cerebral Cortex

The outermost layer of the cerebrum formed by grey matter.

Gyri

Folds on the cerebral cortex that increase surface area.

Sulci

Shallow grooves on the cerebral cortex.

Fissures

Deep grooves on the cerebral cortex.

Lobes

Divisions of the cerebral hemispheres such as frontal, temporal, parietal, and occipital lobes.

Insula

An island of cortex located by separating the temporal and parietal lobes.

Central Sulcus

A shallow groove separating the frontal and parietal lobes.

White Matter

Consists of fibers formed by myelinated axons in the cerebrum.

Commissural Fibers

Connect the two cerebral hemispheres.

Projection Fibers

Connect the cerebrum with lower areas for sensory information.

Basal Nuclei

Masses of grey matter in the cerebrum that control muscle tone and movements.

Primary Motor Cortex

Located on the precentral gyrus of the frontal lobe, directing voluntary movements.

Primary Sensory Cortex

Found in the postcentral gyrus of the parietal lobe, receiving somatic sensory information.

Cerebral Cortex

The outer layer of the brain responsible for higher brain functions such as thought and action.

Frontal Lobe

The part of the brain responsible for voluntary control of skeletal muscles.

Parietal Lobe

The part of the brain responsible for conscious perception of touch, pressure, pain, and other sensations.

Occipital Lobe

The part of the brain responsible for conscious perception of visual stimuli.

Temporal Lobe

The part of the brain responsible for conscious perception of auditory and olfactory stimuli.

Association Areas

Areas of the brain that interpret sensory information and coordinate complex activities.

Integrative Centers

Areas of the brain that receive information from association areas and direct complex activities.

Hemisphere Lateralization

Functional differences between the left and right hemispheres of the brain.

Reticular Formation and Activating System (RAS)

A network in the brainstem that regulates consciousness and sleep-wake cycles.

Electroencephalogram (EEG)

A test that monitors the electrical activity of the brain using electrodes on the skull.

Brain Waves

Patterns of electrical activity in the brain recorded by an EEG, including alpha, beta, theta, and delta waves.

Cranial Nerves

Twelve pairs of nerves that originate from the brain and brainstem, serving various sensory and motor functions.

Olfactory bulb

Termination point of the olfactory nerve (I) responsible for the sense of smell.

Optic nerve (II)

Cranial nerve responsible for vision, originating from the retina of the eye.

Oculomotor nerve (III)

Cranial nerve controlling eye movements, originating from the midbrain.

Trochlear nerve (IV)

Cranial nerve involved in motor functions for eye movements, originating from the midbrain.

Trigeminal nerve (V)

Cranial nerve with mixed sensory and motor functions to the face, having three branches.

Abducens nerve (VI)

Cranial nerve responsible for motor functions related to eye movements, originating from the pons.

Facial nerve (VII)

Cranial nerve with mixed sensory and motor functions to the face, controlling muscles of facial expression.

Vestibulocochlear nerve (VIII)

Cranial nerve for special sensory functions, with branches for balance and hearing.

Glossopharyngeal nerve (IX)

Cranial nerve involved in taste sensation and motor functions in the throat.

Vagus nerve (X)

Cranial nerve responsible for various autonomic functions in the body.

Accessory nerve (XI)

Cranial nerve controlling specific muscles in the neck and shoulders.

Hypoglossal nerve (XII)

Cranial nerve responsible for controlling the muscles of the tongue.

Glossopharyngeal Nerve (N IX)

A mixed nerve responsible for sensory and motor functions in the head and neck.

Vagus Nerve (N X)

Another mixed nerve with sensory and motor functions distributed in the thorax and abdomen.

Accessory Nerve (N XI)

A motor nerve controlling muscles in the neck and upper back.

Hypoglossal Nerve (N XII)

A motor nerve responsible for tongue movements.

Cranial Reflexes

Reflex arcs involving sensory and motor fibers of cranial nerves, crucial for checking nerve damage.

Cranial Reflexes

Reflexes that involve the cranial nerves and are responsible for various responses in the head and neck region.

Somatic Reflexes

Reflexes that involve the contraction of skeletal muscles in response to stimuli.

Corneal Reflex

A somatic reflex triggered by contact with the corneal surface, leading to blinking of the eyelids.

Tympanic Reflex

A somatic reflex in response to loud noise, resulting in reduced movement of auditory ossicles.

Auditory Reflexes

Reflexes triggered by sudden sounds, leading to eye and/or head movements.

Vestibulo-ocular Reflex

A reflex involving the vestibulocochlear nerve and controlling eye movements to stabilize the field of vision.

Visceral Reflexes

Reflexes that involve internal organs and their responses to stimuli.

Direct Light Reflex

A visceral reflex triggered by light striking the photoreceptors, causing constriction of the ipsilateral pupil.