ANATOMY: NERVOUS SYSTEM

1. Structure and Function:

a) Central Nervous System (CNS):

• Brain:

• Cerebrum:

• Cerebral Cortex:

• Consists of gray matter, the outermost layer of the brain.

• Function: controls conscious activities, thinking, language, memory, sensation, movement, etc.

• Cerebral Lobes:

• Frontal lobe: Controls behavior, voluntary movement, language, memory, etc.

• Parietal lobe: Receives tactile sensations, temperature, pain, pressure, etc.

• Temporal lobe: Receives auditory sensations, related to memory, language, etc.

• Occipital lobe: Receives visual sensations.

• Sulci and Gyri: Divide the brain into lobes and create a large surface area for the cerebral cortex.

• Sylvian fissure: Divides the frontal lobe and the temporal lobe.

• Rolandic fissure: Divides the frontal lobe and the parietal lobe.

• White matter:

• Consists of myelinated axons, connecting different brain regions and the brain to the spinal cord.

• Corticospinal tract: Conducts conscious motor impulses from the cerebral cortex to the spinal cord.

• Spinothalamic tract: Conducts sensory impulses from the spinal cord to the cerebral cortex.

• Cerebellum:

• Located in the cerebellar fossa of the occipital bone.

• Function: Regulates movement, maintains balance, coordinates movement activities.

• Brainstem:

• Located between the cerebrum and the spinal cord, includes:

• Midbrain:

• Function: Controls eye movement, regulates light reflex, etc.

• Corpora quadrigemina: Protrusions on the posterior surface of the midbrain.

• Cerebral peduncles: Located on the anterior surface of the midbrain, conducting impulses from the cerebrum to the spinal cord.

• Pons:

• Function: Connects the cerebrum to the cerebellum, conducts sensory impulses, etc.

• Middle cerebellar peduncle: Located on the posterior surface of the pons, conducting impulses from the pons to the cerebellum.

• Medulla oblongata:

• Function: Controls respiratory function, cardiovascular activity, etc.

• Anterior pyramids: Located on the anterior surface of the medulla, conducting conscious motor impulses from the cerebral cortex to the spinal cord.

• Medial lemniscus: Located just behind the anterior pyramids, conducting sensory impulses from the spinal cord to the cerebral cortex.

• Ventricles:

• Empty cavities containing cerebrospinal fluid.

• Ventricles I, II: Located within the cerebral hemispheres.

• Ventricle III: Located between the two hemispheres.

• Ventricle IV: Located between the cerebellum and the medulla oblongata, communicating with the subarachnoid space.

• Spinal cord:

• Located within the vertebral canal, extending from the foramen magnum to the second lumbar vertebra.

• Gray matter: Located in the center, shaped like an “H”, contains nerve cell bodies.

• White matter: Located around the gray matter, consists of nerve fibers bundles.

• Nerve roots: Emerge from the spinal cord, including:

• Anterior root: Motor in nature.

• Posterior root: Sensory in nature.

• Tracts:

• Motor tracts:

• Conscious motor tract: Cell bodies are in the precentral gyrus of the cerebral cortex, contacting neurons in the anterior horn of the spinal cord, crossing at the lower end of the medulla, forming the lateral corticospinal tract.

• Sensory tracts:

• Tactile sensory tract: Cell bodies are in the dorsal root ganglion, contacting neurons in the thalamus, then ascending to the cerebral cortex.

• Pain and temperature sensory tract: Cell bodies are in the dorsal root ganglion, contacting neurons in the posterior horn of the spinal cord, then ascending to the cerebral cortex.

b) Peripheral Nervous System (PNS):

• Cranial nerves:

• There are 12 pairs, originating from the brain, controlling muscles and sensory organs in the head, face, and neck.

• Cranial nerves III, IV: Have nuclei in the midbrain.

• Cranial nerve VI: Has a nucleus in the pons.

• Cranial nerves IX, X, XI, XII: Have nuclei in the medulla oblongata.

• Spinal nerves:

• There are 31 pairs, originating from the spinal cord, controlling muscles and sensory organs in the trunk and limbs.

• Nerve plexuses: Branches of spinal nerves combine to form plexuses, for example, cervical plexus, brachial plexus, lumbar plexus, sacral plexus.

2. Important concepts:

• Neuron: A nerve cell, responsible for transmitting nerve impulses.

• Reflex arc: Includes: sensory organ, afferent pathway, nerve center, efferent pathway, effector organ.

• Autonomic nervous system: Controls the activity of smooth muscles, endocrine glands, cardiovascular system, respiratory system, etc.

• White matter: Consists of myelinated axons.

• Gray matter: Consists of nerve cell bodies and unmyelinated axons.

3. Notes:

• Anatomical landmarks:

• Greater sciatic notch: Location for finding the sciatic nerve.

• Cubital fossa: Location for finding the radial nerve in the elbow.

• Bicipital groove: Location for finding the median nerve in the arm.

• Space between vertebrae L3 and L4: Location for performing a lumbar puncture in the spinal cord.

• Signs of nerve injury:

• “Claw hand”: Due to damage to the radial nerve in the axilla.

• “Ape hand”: Due to loss of conduction from two roots of the median nerve.

• “Drop hand”: Due to complete rupture of the deep branch of the radial nerve.

• Spinal cord segment landmarks:

• Upper thoracic region (from ThI-ThV): The number of spinal cord segments is 2 more than the number of the spinous process.

• Characteristics of vertebrae:

• Vertebra C7: Has the longest spinous process.

• Characteristics of the third ventricle:

• Anterior wall: From top to bottom, it has two columns of the vault, anterior margin, common lamella, and optic chiasm.

• Characteristics of the fourth ventricle:

• Communicates with the subarachnoid space via the foramen magnum and two lateral foramina, the cerebral aqueduct and the central canal of the spinal cord.

• Similarities between somatic and autonomic nervous systems:

• Both include central and peripheral nerves.

• Nerve cell bodies are only in the central part.

• Nerve fibers are only in the peripheral part.

• The autonomic nervous system cannot be perceived.

4. Additional information:

• The peripheral nervous system includes peripheral nerve fibers for sensation, movement, and autonomic function.

• The spinal cord is straight in the anteroposterior direction, with two swellings: the cervical and lumbar parts.

• The middle cerebellar peduncle is part of the pons.

• The posterior lobe of the pituitary gland secretes vasopressin and oxytocin, which are derived from neuroectoderm.

• The most important components of the nervous system are nerve cells.

5. Exercises:

• What are the functions of the cerebral lobes?

• List the signs of damage to the radial nerve.

• Explain the mechanism of nerve impulse conduction through a neuron.

• Compare and contrast the somatic and autonomic nervous systems?

Note:

• This article is just a basic introduction to the anatomy of the nervous system.

• To understand more about the structure and function of the nervous system, you need to refer to specialized materials, textbooks, or consult with experts.

• Self-diagnosis and treatment of nervous system problems is very dangerous.

• If you have any health concerns, please contact a doctor or healthcare professional immediately.