Brain Anatomy

• Brain has the consistency of unset gelatin

Meninges

• Dura mater is the thick outermost layer.
• Arachnoid layer is full of cerebrospinal fluid (CSF).
• Pia mater is the closest layer to the brain.

Ventricles & Subarachnoid Space:

• The ventricles and subarachnoid space, filled with CSF, makes the brain buoyant.

Brain Regions

• Cerebrum: responsible for higher processing, has 2 hemispheres and a corpus callosum
• Cerebellum: responsible for coordination
• Diencephalon: responsible for endocrine functions
• Brainstem: responsible for reflexes, heart rate, and blood pressure, all vital functions

Brainstem

• The midbrain regulates auditory and visual reflexes.
• Pons links the cerebellum and brainstem.
• Medulla Oblongata connects the brain and spinal cord, regulates heart rate, and blood pressure.

Diencephalon

• Epithalamus (pineal gland): produces melatonin
• Thalamus: responsible for visual and auditory processing
• Hypothalamus: produces many hormones

Limbic System

• Amygdala: controls fight or flight responses and emotional memory
• Hippocampus: responsible for learning and long-term memory
• Emotions are key for learning.

Cerebellum

• Functions for Coordination.
• Contains gray and white matter.
• Arbor Vitae ("tree of life")

Lobes and Cortices

• Frontal Lobe: Contains the primary motor cortex (precentral gyrus), which controls voluntary movement.
• Temporal Lobe: Responsible for auditory and olfactory processing.
• Parietal Lobe: Contains the primary somatosensory cortex (postcentral gyrus), which provides sensory awareness.
• Occipital Lobe: Responsible for visual processing.

Speech Areas

• Broca's Area: Responsible for speech production.
• Wernicke's Area: Responsible for language comprehension.

Cranial Nerves

• I: Olfactory nerve.
• II: Optic nerve.
• III-XII: Originate from the brainstem.

Sensory Concepts

• General senses: include touch, pressure, vibration, and proprioception.
• Receptive field: Smaller fields allow for easier stimulus localization.

Neurological Disorders

• Referred Pain: Pain felt in a location different from the actual source.
• Parkinson's Disease: Characterized by low dopamine levels and high muscle tone.
• ALS: Motor neuron degeneration.
• Alzheimer's: Causes dementia and poor neural communication.
• MS: Demyelination.
• Cerebral Palsy: Voluntary muscle pathway issues.
• Rabies: Viral, contracted from animal bites.

Nervous System

• Sympathetic: Fight/flight, increases in metabolism, heart rate, and blood pressure, and decreases in digestion and urination.
• Parasympathetic: Rest/digest, increases in digestion and urination, and decreases in heart rate and blood pressure.

Neurotransmitters

• Preganglionic neurons use Acetylcholine (ACh) in both sympathetic and parasympathetic systems.
• Sympathetic Ganglionic neurons use Norepinephrine (NE) and Epinephrine (E).
• Parasympathetic Ganglionic neurons use Acetylcholine (ACh).

Receptors

• Adrenergic receptors include alpha and beta types.
• Cholinergic receptors include nicotinic and muscarinic types.
• Autonomic Reflex Arcs: From receptor to effector.

Special Senses

• Olfaction: Smell receptor neurons transmit signals through the cribriform plate to the olfactory bulb, then to the olfactory tract, and finally to the cortex.
• Gustation: Tastes include sour, bitter, salty, sweet, and umami.
• Gustatory cells communicate with facial, glossopharyngeal, and vagus nerves.

Vision

• Eye accessories include the eyelid, eyelashes, conjunctiva, and lacrimal gland/sac.
• Eye layers: fibrous, vascular, and inner.
• Iris: Pigmented muscle controlling pupil size and its function is for light regulation.
• Lens: Focuses light via ciliary body.
• Retina: Contains photoreceptors (rods for dim light, cones for color vision).
• Optic Disk: Blind spot.
• Fovea Centralis: Area of clearest vision.
• Vision Issues: Emmetropia (normal), Hyperopia (farsighted), Myopia (nearsighted).

Ear

• External Ear: Includes the auricle, external acoustic meatus, and tympanic membrane.
• Middle Ear: Contains ossicles (malleus, incus, stapes) and the auditory tube.
• Inner Ear: Includes semicircular canals, vestibule, and cochlea.
• Functions include hearing and equilibrium.
• Hearing: Cochlea (Organ of Corti, hair cells).
• Equilibrium: Vestibule and semicircular canals (acceleration, rotation).