Brain + Spinal Cord + Cranial Nerves + Sensory Receptors + Senses

a thick band of white matter that sits deep in the center of the brain, connecting the right and left hemispheres.

Corpus callosum

lie just ABOVE the corpus callosum

Cingulate gyrus

a curved bundle of nerve fibers beneath the corpus callosum, above the thalamus

Fornix

a paired, oval-shaped structure located deep within the center of the brain

Thalamus

Located INFERIOR to this important sensory structure (thalamus)

Hypothalamus

X shaped & where the optic nerves cross

Optic chiasm

a small pair of structures near the hypothalamus

Mammillary Bodies

a small, pinecone-shaped gland located near the center of the brain

Pineal gland

 a pea-sized gland hanging just below the hypothalamus

Pituitary gland

one of a pair of bumps on the top of the midbrain, part of the tectum roof of midbrain

Superior colliculi

the other pair of bumps on the lower part of the midbrain

Inferior colliculi

curved & deep within the temporal lobes, just above the brainstem, forming part of the limbic system. Wrap around the thalamus like a seahorse.

Hippocampus

an almond-shaped cluster deep in the temporal lobe, right next to the hippocampus

Amygdala

a rounded bulge on the front part of the brainstem, where SOME Cranial nerves originate,

Pons

located at the base of the brainstem, below the pons and above the spinal cord

Medulla Oblongata

a pair of large, C-shaped cavities, one in each hemisphere, containing CSF

Lateral Ventricles

a narrow midline cavity between the two halves of the thalamus, connecting to the cerebral aqueduct

3rd Ventricle

a diamond-shaped cavity between the cerebellum and brainstem, connecting to the spinal cord

4th Ventricle

Frontal Lobe

1. Primary motor cortex

2. Higher executive functions:

• Motor control, problem solving, emotional regulation, planning, and reasoning

Parietal Lobe

1. Primary somatosensory cortex

2. Sensory information

• Touch, temperature, pressure, and pain

Temporal Lobe

1. Primary auditory cortex

2. Sensory information

• Hearing, recognizing language, and forming memories

Occipital Lobe

1. Primary visual cortex

2. Visual processing

• Interpret depth, distance, location, and identity of seen objects

Functions of Brain

• Processes sensory information

• Initiates movement

• Stores memory

• Regulates homeostasis

CSF Functions

• Protection (shock absorber)

• Buoyancy (brain floats)

• Chemical stability

• Nutrient transport

• Waste removal

Dura Mater

• Tough outer layer

• Protection

Arachnoid Mater

• Middle layer

• Contains CSF (subarachnoid space)

Pia Mater

• Thin inner layer

• Adheres to spinal cord, provides nourishment

White Matter (Signal Highways)

• Myelinated axons

• Organized into tracts:

  • Ascending (sensory)

  • Descending (motor)

Gray Matter (Processing Center)

• Unmyelinated axons

• Posterior horn → sensory processing

• Anterior horn → motor output

• Lateral horn → autonomic (sympathetic)

• Gray commissure → connects sides

SAADI

Sensory Afferent Ascending Dorsal In 

MOVED

Motor Out Ventral Efferent Descending

Where does the spinal cord end?

L1-L2

What is filum terminale?

thin strand anchoring spinal cord

What is cauda equina?

bundle of spinal nerves below cord (looks like horse tail)

Which cranial nerves are associated with the Parasympathetic system?

• III ⛛ (3)

• VII ⛛ (7)

• IX ⛛ (9)

• X ⛛ (10)

Which cranial nerves are associated with the tongue?

• VII ☼ (7)

• IX ☼ (9)

• X ☼ (10)

LR6(SO4)3 stands for…

• Lateral rectus → VI (6)

• Superior oblique → IV (4)

• All others → III (3)

Limbic System (“emotional brain”)

1. amygdala → emotions

2. hippocampus → new long- term memories

3. hypothalamus → balance/ homeostasis

4. thalamus → relay sensory information

5. cingulate gyrus → emotional control/ decisions

6. fornix → communication pathway

A Happy Hippo Thinks Calmly First

Homunculus

a distorted representation of the body mapped onto the brain, where size reflects sensory sensitivity or motor control.

Anterior Spinothalamic Tract

Light touch and pressure sensations to the brain

Lateral spinothalamic Tract

Pain and temperature sensations to the brain.

Posterior column Tract

transmits proprioception, vibration, and fine touch sensations to the brain (Precise information)

Normal Consciousness

• Conscious

• Fully awake, alert, aware of self and environment, responds appropriately to stimuli.

Asleep

• Conscious (reversible)

• Reduced awareness; can be awakened easily by stimuli (sound, touch). Normal sleep cycle is temporary and reversible.

Stupor

• Mostly unconscious

• Only responds to strong, repeated, or painful stimuli. Very little awareness; returns to unresponsive state quickly

Coma

• Unconscious

• No wakefulness or awareness; does not respond to pain or external stimuli. Cannot be awakened.

Chronic Vegetative State

• Unconscious (wakeful but unaware)

• Has sleep-wake cycles (eyes may open), but no awareness of self or environment; no meaningful response to stimuli.

Sympathetic System (Thoracolumbar T1- L2)

• “Fight or flight”

• Origin: T1–L2

• Short preganglionic, long postganglionic

Parasympathetic (Craniosacral cranium- S2)

• “Rest and digest”

• Cranial nerves: III, VII, IX, X (3, 7, 9, 10)

• Long preganglionic, short postganglionic

Baroreceptors

• Classified by Location

• specialized mechanoreceptors that detect changes in blood pressure by responding to the stretch of blood vessel walls, particularly in the carotid sinus and aortic arch

Chemoreceptors

• Classified by Stimulus

• Respond to specific chemicals

Exteroceptors

• Classified by Location

• Respond to stimuli outside the body

Interoceptors

• Classified by Location

• Respond to stimuli inside the body

Mechanoreceptors

• Classified by Stimulus

• Respond to touch/ pressure

Nocioceptors

• Classified by Stimulus

• Respond to damaging stmuli

Proprioceptors

• Classified by Location

• Respond to stimuli in skeletal muscle and related connective tissue

Thermoreceptors

• Classified by Stimulus

• Respond to temperature changes

Photoreceptors

• Classified by Stimulus

• Respond to light

• Rods → low light, black & white vision

• Cones → color + sharp vision

General Senses (3)

• touch, temperature, pain, proprioception are distributed throughout the body, detecting stimuli via simple receptors in skin, muscles, and organs

Special Senses (5)

• vision, hearing and equilibrium/balance, olfaction/smell, gustation/taste are specialized, localized to complex head organs, and transmitted via cranial nerves.

Olfaction / Smell

1. Function of Olfactory glans (Bowman’s glands):

Produce mucus that: dissolves odor molecules, traps particles, and keeps olfactory epithelium moist

2. CN I involved in transmitting sensory signals from the olfactory receptors to the brain

3. Damage to Olfactory epithelium / Bowman’s glands of the olfactory system could directly affect mucus secretion and

   impair odor detection

4. Basal cells (replace olfactory receptor neurons) are responsible for the continuous regeneration

   of olfactory receptor neurons

5. Odor molecules typically reach the olfactory epithelium in the nasal cavity by dissolving in mucus after entering nasal cavity through inhaled air

Gustation / Taste

• Primary tastes: sweet, salty, sour, bitter, & umami (savory)

• anterior ⅔ of tongue is CN VII, posterior ⅓ is CN IX, very back of tongue is CN X

Hearing and equilibrium/balance

• CN VIII

• hearing is cochlea

• equilibrium/balance is vestibular system

• order of bones in ear is maleus→incus→stapes

• endolymph is in the scala media

• scala tympani and vestibuli has perilymph

Visual

1. Iris: Controls pupil size (color part)

2. Pupil: Opening that lets light in

3. Retina: Light-detecting layer (photoreceptors)

4. Choroid: Middle layer with blood supply

5. Cornea: Transparent front layer that bends light

6. Sclera: White outer protective layer

Layers of eye wall (S-C-R)

. 1. External (Fibrous tunic)

• sclera

• cornea

2. Middle (Vascular tunic)

• choroid

• iris

• ciliary body

3. Inner (Neural tunic)

• retina

  • contains photoreceptors:

    • rods

    • cones