Nervous System

Pathway of Cerebrospinal Fluid

CSF is formed within the choroid plexus of the right and left lateral ventricles and then flows into the third ventricle through the interventricular foramina, or the Foramina of Monro. The fluid then flows from the third ventricle through the cerebral aqueduct, or Aqueduct of Sylvius, into the fourth ventricle. CSF flows through two lateral foramina and one median foramen into the subarchnoid space. It goes down the posterior aspect of the brain and spinal cord before flowing back up the anterior aspect of the spinal cord and brain, where it is reabsorbed by the arachnoid villi of the superior sagittal sinus.

Foramina of the Brain

Connect the ventricles of the brain to each other. There are six foramina: the interventricular foramina, the cerebral aqueduct, the median foramen, and the two lateral foramina.

Function of the Peripheral Nervous System

Connects the CNS with the remaining parts of the body.

Cerebrospinal Fluid

Also known as cerebral spinal fluid, it is a clear, colorless fluid that bathes the entire surface of the central nervous system. It is produced in specialized cells within each ventricle called choroid plexus and nourishes and protects against chemical or physical injury. It acts to cushion a blow to the head to lessen the impact and protects the brain from damage. It continuously circulates through the subarchnoid space, around the brain and spinal cord, and through the ventricles. It is reabsorbed through ovoid structures within the superior sagittal sinus known as arachnoid villi.

Cerebral Aqueduct

Also known as the Aqueduct of Sylvius, it is a narrow slit located between the third and fourth ventricles.

Interventricular Foramina

Also known as the Foramina of Monro, they are the passageways between the lateral ventricles and the third ventricle.

Lateral Foramina

Also known as the lateral apertures or the Foramina of Luschka, they are two openings between the ends of each lateral recess of the fourth ventricle and the subarchnoid space.

Median Foramen

Also known as the median aperture or the Foramen of Magendie, it is the opening between the lower part of the roof of the fourth ventricle and the subarchnoid space.

Function of the Central Nervous System

Evaluates incoming information, formulates a response to them, and integrates various impulses. Also involved in thinking.

Trigeminal Nerves

Fifth pair of cranial nerves; sensations of head and face; chewing; proprioception.

Olfactory Nerves

First pair of cranial nerves; smell.

Ventricles of the Brain

Fluid-filled cavities within the brain through which cerebrospinal fluid flows. There are four ventricles: the right and left lateral ventricles, the third ventricle, and the fourth ventricle.

Trochlear Nerves

Fourth pair of cranial nerves; moves eyeballs; proprioception.

Adult Vertebral Column

Has 26 bones; seven cervical vertebrae, twelve thoracic vertebrae, five lumbar vertebrae, one sacrum, and one coccyx.

Meninges

Inner protective coverings over the brain, of which there are three: the pia mater, arachnoid, and dura mater.

Function of the Cerebrum

Intelligence, motor function, personality, reasoning, touch sensation, and interpretation of sensory impulses.

Cerebrum

Latin for "brain", it is the area for reasoning and intellect and provides us with the ability to read, write, speak, make calculations, compose music, remember the past, and make plans for the future. It is divided into two hemispheres: a right and left. They are connected to each other by the corpus callosum. Has four lobes, named for the cranial bones that cover them.

Cerebellum

Latin for "little brain", it is the second largest part of the brain and occupies the inferior and posterior aspect of the cranial cavity. It has two hemispheres and is smaller than the cerebrum, but contains more neurons or nerve cells.

Subdural Space

Located between the dura mater and the arachnoid, it contains a small amount of lubricating fluid.

Brachial Plexus

Located in the axilla, or armpit.

Spinal Cord

Located in the spinal cavity of the vertebral column, it is shorter than the vertebral column. Approximately 16-18 inches in length, it extends from the foramen magnum to the second lumbar vertebrae (L2). All nerves to the trunk and extremities emerge from the spinal cord. It is described as being a cylindrical structure, flattened in its anterior-posterior dimensions. It has two bulges, or enlargements, the cervical enlargement and the lumbar enlargement.

Epidural Space

Located outside the dura mater, but inside the bone. It contains a cushion of fat.

Subarachnoid Space

Located under the arachnoid, between the arachnoid and the pia mater, it contains significant amounts of cerebrospinal fluid.

Arachnoid Villi

Located within the superior sagittal sinus, they are ovoid structures that reabsorb cerebrospinal fluid.

Coccyx

Most inferior portion of the vertebral column.

Glossopharyngeal Nerves

Ninth pair of cranial nerves; sensations of the tongue; swallowing secretions of saliva.

Filum Terminale

Non-nervous, elastic fibrous tissue of the spinal cord, it extends inferiorly from the conus medullaris to the coccyx and serves to anchors the spinal cord to the coccyx.

Parietal Lobe

One of the four lobes of the cerebrum; responsible for processing information about touch reception and the evaluation of sensory information.

Occipital Lobe

One of the four lobes of the cerebrum; responsible for receiving and processing visual information.

Temporal Lobe

One of the four lobes of the cerebrum; responsible for receiving auditory signals.

Frontal Lobe

One of the four lobes of the cerebrum; responsible for voluntary motor function, motivation, aggression, mood, speech, and thought processes.

Vagus Nerves

Tenth pair of cranial nerves; sensations and movement of organs.

Cauda Equina

A tail-like collection of roots of spinal nerves, it is located at the inferior end of the spinal cord. They are actually the roots of the sacral and coccygeal nerves. The collection gets its name because of its resemblance to a horse's tail.

Dura Mater

Dura mater meaning "tough mother", it is the outer, most superficial layer and is composed of strong, dense, irregular connective tissue.

Auditory Nerves

Eighth pair of cranial nerves; also known as the vestibulocochlear nerves; hearing; balance (equilibrium).

Accessory Nerves

Eleventh pair of cranial nerves; also known as the spinal accessory nerves; shoulder movements; turning movements of head; movements of viscera; voice production.

Pia Mater

Pia mater meaning "delicate mother", it is the deep, inner, thin transparent connective tissue layer that adheres to the surface of the brain and spinal cord. It is rich in blood vessels.

Optic Nerves

Second pair of cranial nerves; vision.

Facial Nerves

Seventh pair of cranial nerves; facial expressions.

Abducens Nerves

Sixth pair of cranial nerves; abduction of the eyes.

Function of the Cerebellum

Skilled movements (from catching a ball to dancing), posture and balance, and coordination.

Choroid Plexus

Specialized cells responsible for the production of cerebrospinal fluid.

Peripheral Nervous System

The communicating portion of the nervous system, it connects the CNS with the rest of the body. It consists of all the nervous tissue outside the CNS, including the special sense organs and has 2 subdivisions: cranial nerves and spinal nerves.

Central Nervous System

The control center for the entire nervous system, it is the main network of coordination and control for the entire body. It consists of the brain (encephalon) and the spinal cord, which are protected and encased in bone. The brain and the spinal cord are continuous with each other at the foramen magnum.

Lumbar Enlargement

The inferior enlargement of the spinal cord, it extends from T9-T12. The nerves that supply the lower extremities arise from here.

Arachnoid

The middle layer, it is composed of delicate collagen fibers and some elastic tissue. It is called the arachnoid because of its spider web arrangement.

Pons

The middle portion of the brain stem, it is located directly superior to the medulla oblongata. It relays nerve impulses related to voluntary skeletal movements and helps control breathing.

Medulla Oblongata

The most inferior part of the brain stem, it is continuous with the superior portion of the spinal cord. It controls heart rate, respiration, digestion, and the constriction of blood vessels.

Peripheral Nervous System

The second subdivision of the nervous system, it consists of all nervous tissues outside the CNS, or the cranial nerves and spinal nerves.

Proprioception

The sense of the relative position of neighboring parts of the body and the strength of effort being employed in their movement.

Midbrain

The smallest and uppermost part of the brain stem, it is located superior to the pons. It conveys motor impulses and is the reflex center that controls movement of the eyeballs in response to visual stimuli. It also controls movement of the head and trunk in response to auditory stimuli, such as loud noises.

Brain Stem

The smallest portion of the brain, it is situated between the spinal cord and the cerebrum and consists of three portions (from inferior to superior): the medulla oblongata, the pons, and the midbrain.

Cervical Enlargement

The superior enlargement of the spinal cord, it extends from C4 to T1. The brachial plexus, a nerve bundle that supplies the upper extremities, arises from here.

Conus Medullaris

The tapered (conical) portion of the spinal cord, it is located inferior to the lumbar enlargement. It is the terminal end of the spinal cord.

Spinal Nerves

There are thirty-one pairs of nerves that extend from the spinal cord and communicate with the body below the head. These have no special names. They are numbered according to the level of the vertebral column at which they emerge from the spinal cavity. However, there are seven cervical vertebrae and eight cervical nerves. The reason is that the first pair of cervical nerves emerges above the first cervical vertebrae (between the skull and C1). So, there are eight pairs of cervical nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves.

Oculomotor Nerves

Third pair of cranial nerves; moves eyelids and eyeballs.

Hypoglossal Nerves

Twelfth pair of cranial nerves; tongue movements; proprioception.

Cranial Nerves

Twelve pairs of nerves known by name and number. The names suggest either their distribution or their function, while their number tells us the order in which they connect to the brain from anterior to posterior. They exit the skull through small foramen, allowing them to get to their destinations. They can be motor nerves, sensory nerves, or of mixed purpose (both sensory and motor). A helpful mnemonic device is: On Old Olympus' Tiny Tops, A Friendly Viking Grew Vines And Hops!

Superior Sagittal Sinus

Vein of the brain.