nervous (CNS) Flashcards
Includes the brain and spinal cord
Central Nervous System
➢ So, called because of its appearance and preponderance of nerve cell bodies and true dendrites.
➢ Outer part in brain; inner part in spinal cord
Gray matter
Central nervous system is divided grossly into:
❖ Gray matter
❖ White matter
➢ Composed chiefly of myelinated nerve fibers
➢ Inner part in brain; outer part in spinal cord
White matter
Group or aggregates of nerve cell bodies outside the Central Nervous System
Ganglion/Ganglia Cells
- The _________ is a vital part of the central nervous system (CNS) contained within the skull.
- Complexity: It is the most complex and largest mass of nervous tissue in the body, comprising billions of nerve cells (neurons).
Brain
- Weight: The average weight of the adult human brain is approximately: ?
o Male: ?
o Female: ?
2% OF OUR BODY WEIGHT
1380 grams
1250 grams
Embryological Divisions of the Brain
- Forebrain (Prosencephalon)
- Midbrain (Mesencephalon)
- Hindbrain (Rhombencephalon)
o Telencephalon (Cerebrum)
o Diencephalon (Thalamus, Hypothalamus, Epithalamus, Subthalamus)
Forebrain (Prosencephalon)
o Corpora Quadrigemina (Tectum)
- Superior Colliculi: Involved in visual reflexes
- Inferior Colliculi: Involved in auditory reflexes
o Cerebral Peduncles
o Vertebral Aqueduct of Sylvius (Iter)
Midbrain (Mesencephalon)
o Metencephalon (Cerebellum, Pons)
o Myelencephalon (Medulla Oblongata)
Hindbrain (Rhombencephalon)
➢ Function: Involved in various higher functions including:
o Discriminatory identification
o Integration of sensory information
o Memory
o Reasoning
o Language usage
o Emotional behavior
o Initiation of movement
Cerebrum (Telencephalon)
_________ and _________ of the Cerebrum
- Fissures
- Sulci
Shallower grooves (sulcus is singular, sulci is plural).
Sulci
Deep depressions in the cerebral cortex.
Fissures
Types of Fissures
- Longitudinal Fissure:
- Lateral (Sylvian) Fissure:
- Central Sulcus (Rolandic Fissure):
- Transverse Fissure:
- Parieto-occipital Fissure:
- Calcarine Fissure:
- Superior Temporal Sulcus:
➢ Separates the two cerebral hemispheres.
Longitudinal Fissure
➢ Divides the frontal and parietal lobes from the temporal lobe.
➢ End: Supramarginal Gyrus.
➢ Anterior Median Fissure: A deep groove along the spinal cord.
➢ Dorsal Median Fissure: A shallower groove; the middle cerebral artery emerges here.
Lateral (Sylvian) Fissure:
➢ Separates the frontal lobe from the parietal lobe.
Central Sulcus (Rolandic Fissure):
➢ Separates the occipital lobe from the parietal lobe.
Parieto-occipital Fissure:
➢ Separates the cerebellum from the cerebrum.
- Cerebellum: “Little brain”
- Cerebrum: “Big brain”
Transverse Fissure:
➢ Located in the occipital lobe; contains the visual center (calcarine area).
- Visual Areas: Includes the Cuneus and Lingual gyrus.
Calcarine Fissure:
➢ Located in the temporal lobe; leads to the Angular Gyrus.
Superior Temporal Sulcus:
Lobes of the Cerebral Cortex:
- Frontal Lobe:
- Parietal Lobe:
- Temporal Lobe:
- Occipital Lobe:
- Insula (Island of Reil):
➢ Located anterior to the central sulcus and above the lateral sulcus.
➢ Functions in motor control and personality.
Frontal Lobe:
➢ Located posterior to the central sulcus and above the lateral fissure.
➢ Functions in sensory processing.
Parietal Lobe:
➢ Located beneath the lateral sulcus.
➢ Involved in hearing and olfaction.
Temporal Lobe:
➢ Occupies the posterior part of the cerebral hemisphere.
➢ Functions as the visual center.
Occipital Lobe:
➢ Exposed when the lateral sulcus is separated.
➢ Located deep within the lateral sulcus.
Insula (Island of Reil):
Functional Areas of the Cerebrum
- Primary Motor Area (Pre-Central Gyrus):
- Pre-Motor Area:
- Pre-Frontal Area:
- Primary Sensory/Somesthetic Area (Post-Central Gyrus):
- Motor Speech Area:
➢ Controls voluntary movements on the opposite side of the body.
➢ Brodmann’s Area: 4
Primary Motor Area (Pre-Central Gyrus):
➢ Located anterior to the motor area.
➢ Coordinates an orderly series of movements.
Pre-Motor Area:
➢ Responsible for behavior, character, emotional state, foresight, good judgment, and abstract thinking.
Pre-Frontal Area:
➢ Located in the inferior frontal gyrus of the dominant hemisphere.
➢ Controls muscles used for speech.
➢ Brodmann’s Areas: 44 (Pars Opercularis), 45 (Pars Triangularis), Broca’s Area (Brodmann’s Areas 44 & 45).
Motor Speech Area:
➢ Located in the parietal lobe behind the central sulcus.
➢ Processes sensations of pain, temperature, pressure, touch, position, and movement from the opposite side of the body.
➢ Brodmann’s Areas: 3, 1, 2
Primary Sensory/Somesthetic Area (Post-Central Gyrus):
Diencephalon components:
- Thalamus:
- Hypothalamus:
- Corpus Callosum:
- Cingulate Gyrus and Sulcus:
➢ Acts as a relay center for sensory impulses (excluding olfactory) from peripheral receptors to the cerebral cortex.
Thalamus
➢ Regulates body temperature, feeding activities, biorhythms, and emotions.
Hypothalamus
➢ Cingulate Gyrus: Located above the corpus callosum.
➢ Cingulate Sulcus: A depression above the cingulate gyrus.
Cingulate Gyrus and Sulcus:
➢ Comprises the largest commissural fibers connecting the two cerebral hemispheres.
Corpus Callosum:
- Structure: Oval-shaped with a central constriction (vermis) and expanded lateral portions (hemispheres).
Cerebellum
Lobes of cerebellum:
o Anterior Lobe:
o Posterior Lobe:
o Flocculonodular Lobe:
Regulates muscle tone.
Anterior Lobe
Coordinates voluntary motor activity.
Posterior Lobe
Concerned with equilibrium, posture, and balance.
Flocculonodular Lobe
Links the forebrain and hindbrain; important for motor coordination.
Midbrain (Rhombencephalon)
Midbrain (Rhombencephalon) Components:
Cerebral Peduncles:
Corpora Quadrigemina:
Cylindrical bodies made of nerve fiber tracts
connecting the forebrain to the hindbrain.
Cerebral Peduncles
Hindbrain (Prosencephalon) components:
- Pons
- Medulla Oblongata
- Cerebrospinal Fluid (CSF)
Contains:
- Superior Colliculi: Involved in visual reflexes.
- Inferior Colliculi: Involved in auditory reflexes.
Corpora Quadrigemina
- Anterior to the cerebellum and between the midbrain and medulla.
- A bridge-like structure primarily made of white matter, linking various parts of the brain.
Pons
- Continuous with the spinal cord, lies ventral to the cerebellum.
- Contains vital regulatory and reflex centers controlling the circulatory system, breathing, swallowing, vomiting, coughing, and sneezing.
Medulla Oblongata
- Circulates within the brain’s ventricles, central canal of the spinal cord, and the subarachnoid space.
- Production: By the choroid plexus in all brain ventricles.
- Provides nutrition and immune functions; it is colorless and similar in composition to lymph.
Cerebrospinal Fluid (CSF)
- Absorption: Through Arachnoid villi or Arachnoid granulations.
Ventricles of the Brain:
Ventricles of the Brain:
o Lateral Ventricle:
o Third Ventricle:
o Fourth Ventricle:
➢ Located within the cerebral hemispheres; communicates with the third ventricle via the Interventricular Foramen (Foramen of Monroe).
Lateral Ventricle
➢ Positioned between the two thalamic nuclei; continuous with the cerebral aqueduct of Sylvius.
Third Ventricle:
➢ Communicates with the subarachnoid space through the Foramen of Luschka and Magendie; connected to the third ventricle via the Iter (cerebral aqueduct of Sylvius).
Fourth Ventricle:
- Three membranes that protect the brain and spinal cord.
➢ Dura Mater:
➢ Arachnoid Mater:
➢ Pia Mater:
Meninges
Outermost layer (subdural space beneath it).
Dura Mater
Middle layer (subarachnoid space beneath it).
Arachnoid Mater
Innermost layer, closely adherent to the brain.
Pia Mater
➢ Continuous with the medulla oblongata; extends from the foramen magnum to the lower border of the first lumbar vertebra in adults (L3 in children).
➢ Average Length: Approximately 45 cm.
Spinal Cord
Enlargements of spinal cord:
- Cervical Enlargement:
- Lumbar Enlargement:
Supplies nerves to the arms (C4 to T2).
Cervical Enlargement:
Supplies nerves to the legs (widest at T12).
Lumbar Enlargement:
The tapering.
Conus Medullaris
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