Human Nervous System and Sensory Anatomy Explained

Nervous System Fundamentals

• Nervous System Function: Control and communication.
• Autonomic Nervous System: Regulates internal organs.
• Central Nervous System (CNS): Controls most functions of the body and mind (brain and spinal cord).
• Peripheral Nervous System: Connects the CNS to limbs and organs (cranial and spinal nerves).

Brain and Spinal Structures

• Cerebrum: Senses, thoughts, and movements (frontal, parietal, temporal, occipital lobes).
• Cerebellum: Balance, coordination, and speech (anterior lobe, posterior lobe, primary fissure).
• Diencephalon (Thalamus): Processes sensory and motor signals.
• Diencephalon (Hypothalamus): Links the nervous system to the endocrine system.
• Medulla Oblongata: Controls breathing, swallowing, and heart rate.
• Pons: Connects upper and lower parts of the brain.
• Ventricles: Communicating network of the brain.
• Cerebrospinal Fluid: Cushions the brain.
• Meninges: Protect the central nervous system (dura mater, arachnoid mater, pia mater).
• Spinal Cord: Comprised of 8 cervical, 12 thoracic, 5 lumbar, and 5 sacral segments.
• Dorsal Root: Sensation.
• Ventral Root: Carries signals from limbs and organs to the spinal cord and brain.

Neurons and Neurotransmission

• Cell Body: The factory of the neuron.
• Neuron Axon: The main conducting unit.
• Neuron Dendrite: Functions as an antenna.
• Synapse: Transfers electric activity.
• Neurotransmitters (Acetylcholine): Activates muscles.
• Neurotransmitters (Adrenaline): Controls heart rate.
• Neurotransmitter Blocking Agents: Phentolamine, propranolol, haloperidol, methysergide.

Cranial Nerves

• Sensory (S): Olfactory, Optic, Vestibulocochlear.
• Motor (M): Oculomotor, Trochlear, Abducens, Spinal Accessory, Hypoglossal.
• Mixed: Trigeminal, Facial, Glossopharyngeal, Vagus.

Sensory Anatomy

The Ear

• External Ear (Pinna): Collects sound.
• External Ear (Auditory Canal): Passageway for sound.
• External Ear (Eardrum): Transmits sound.
• Middle Ear (Ossicles): Amplification.
• Middle Ear (Eustachian Tube): Ventilates the middle ear space.
• Inner Ear (Semicircular Canals): Motion sensor.
• Inner Ear (Cochlea): Transforms sound into neural messages.

The Eye

• Scleroid Coat: Holds the eye together.
• Choroid Coat: Where the optic stalk connects.
• Cornea: Outer coat of the eye.
• Aqueous Humor: Fills the anterior and posterior chambers.
• Iris/Pupil: The opening of the eye.
• Vitreous Humor: Fills the space between the lens and retina.
• Retina: Receives light focused by the lens.
• Optic Nerve: Transfers visual information.