The Brain and Eye Anatomy

The Brain: Central Nervous System (CNS)

• The brain consists of three major sections: the cerebrum, the cerebellum, and the brainstem.

Cerebrum

• The cerebrum consists of four lobes.
• Frontal Lobe: Primarily responsible for emotional regulation, planning, reasoning, and problem-solving.
• Temporal Lobe: Primarily responsible for hearing and some sensory feature processing.
• Occipital Lobe: Primarily responsible for receiving and processing signals from the optic nerve.
• Parietal Lobe: Primarily responsible for integrating sensory information, such as touch, temperature, pressure, and pain, and helps discern objects.

Brainstem

• The brainstem manages most involuntary functions such as heartbeat, sneezing, and breathing.

Cerebellum

• The cerebellum manages posture, balance, and coordination.

The Eye

• The eye is one of the two primary sense organs.
• Sight accounts for 80-90% of sensory input.

Parts of the Eye

• Choroid: Tissue layer surrounding the eye that prevents light from entering except through the pupil.
• Sclerotic Layer: Thick layer providing rigidity and protection to the eye.
• Cornea: Thin, clear tissue that prevents foreign pathogens from entering.
• Iris: Opaque tissue that dilates or contracts to change the size of the pupil.
• Lens: Convex-shaped tissue that reflects light onto the retina.
• Vitreous Humor: Gel-like substance that provides structure to the eye.
• Aqueous Humor: Gel-like substance that provides structure to the elements in front of the lens.
• Pupil: Hole in the eye that allows light to enter and dilates in darker environments.
• Suspensory Ligaments: Ligaments that hold the iris open by default.
• Ciliary Muscles: Muscles that contract or expand to adjust focus.
• Optic Nerve: Nerve that transmits visual information to the brain.
• Yellow Spot (Fovea): A spot with fewer color receptors.
• Retina: Layer of color detection cells across the back of the eye.
• Blind Spot: Spot in front of the optic nerve where no receptors are present.

Binocular Vision

• Binocular vision is the ability to see with two eyes facing in the same direction, facilitating depth perception.
• Either eye has a semi side view of any object using binocular vision.

Neurons

• There are 3 major types of neurons.

Sensory Neurons

• Sensory neurons detect changes to certain stimuli.
• Interneurons transmit signals between neurons.
• Motor neurons are different for different functions.

Receptors

• Photoreceptors: Detect light.
• Thigmoreceptors: Detect changes in pressure.
• Thermoreceptors: Detect changes in temperature.
• Nocireceptors: Detect pain.
• Mechanoreceptors: Detect movement.