Brain and Cranial Nerves

secondary vesicles that develop from the prosencephalon (superior/top)

1. Telencephalon →

   1. forms cerebrum

secondary vesicles that develop from the prosencephalon (after the telencephalon)

1. Diencephalon → forms the…

   1. Epithalamus

   2. Thalamus,

   3. Hypothalamus,

   4. pineal gland

Telecenphalon, Dicenphalon….what vesicle is after and what does it develop into?

• mesencephalon

  • midbrain

    • Tectal plate —> superior and inferior colliculi

    • cerebral aqueduct

secondary vesicles arise from the rhombencephalon (after mesencephalon…)

1. Metencephalon →

   1. Pons

   2. Cerebellum

2. Myelencephalon →

   1. Medulla Oblongata

3. spinal cord

structures found in gray matter

• Neuron cell bodies

• Dendrites

• Unmyelinated axons

superficial layer of gray matter

cortex

clusters of gray matter deep within the brain

Nuclei

Gray matter located in the brain

• Superficial (Cortex) →

  • Outer layer of cerebrum

• Deep (Nuclei) →

  • Embedded within white matter

three meninges from superficial to deep

• Dura mater (Superficial)

• Arachnoid mater (Middle)

• Pia mater (Deep)

What type of tissue is the dura mater made of?

Dense irregular connective tissue (CT)

What are the two layers of the dura mater?

• Periosteal layer – Attached to the skull

• Meningeal layer – Forms dural septa (folds that support the brain)

What is the function of dural septa?

Provides structural support by partitioning the brain

What is the middle meninge layer between the dura matter and pia matter?

1. Arachnoid matter (archne = spider )

   1. “web” of collagen elastic fiber

   2. Contains CFS in subarachnoid space

What is the intermost meninge layer (dura matter, archnoid mater…)

1. Pia matter (tender mother)

   1. areolar CT - thin/soft layer

   2. “form-fitting” to the brain

space is between the dura mater and the arachnoid mater

subdural space (contains cerebral spinal fluid)

What are ventricles in the brain?

Cavities within the brain filled with cerebrospinal fluid (CSF)

What are the four ventricles of the brain?

1. Lateral ventricles (1st & 2nd) – in each hemisphere

2. Third ventricle – in the diencephalon

3. Fourth ventricle – between the brainstem & cerebellum

Where are the lateral ventricles located?

In the cerebrum, one in each hemisphere

Where is the third ventricle located?

In the diencephalon, between the left & right thalamus

Where is the fourth ventricle located?

Between the brainstem & cerebellum

Where is cerebrospinal fluid (CSF) found?

1. Ventricles of the brain

2. Subarachnoid space (between arachnoid & pia mater)

What are the three main functions of CSF?

1. Cushioning (protection)

2. Buoyancy

3. Transport – Delivers nutrients & removes waste

Where is CSF produced?

Choroid plexus in the ventricles

What is the choroid plexus?

A network of blood capillaries & ependymal (glial) cells that produces CSF

Where is the choroid plexus located?

In each ventricle of the brain

What type of glial cells are involved in CSF production?

Ependymal cells – Line the ventricles & regulate CSF composition

Where does CSF drain after circulation?

Arachnoid villi → Dural venous sinuses → Bloodstream

What is the function of the blood-brain barrier (BBB)?

Prevents neuron exposure to harmful substances like toxins, drugs, and waste

What two structures form the BBB?

1. Astrocytes – Their end feet wrap around capillaries

2. Blood capillaries – Have tight junctions preventing leakage

What is the telencephalon?

• The largest part of the brain, also known as the cerebrum

  • Comprises 85% of the brain’s mass

What are the main functions of the cerebrum?

1. Conscious thought & intellectual functions

2. Intelligence & reasoning

3. Memory & judgment

4. Voluntary motor control

5. Processing of visual & auditory information

paired cerebral hemispheres are separated by a…

Longitudinal fissue

What are gyri (singular: gyrus)?

Ridges or folds on the brain’s surface that increase surface area for neurons

What are sulci (singular: sulcus)?

hallow grooves between gyri that help separate brain regions

What is the central sulcus

• deep groove separates the parietal from the frontal?

• Divides the

  • precentral gyrus from the postcentral gyrus

What is the precentral gyrus?

• Located in the frontal lobe

  • contains somatic motor cortex → Controls voluntary muscle movements

What is the postcentral gyrus?

• Located in the parietal lobe

  • Contains somatosensory cortex → Processes touch, temperature, pain, & proprioception

What is the insula?

• A deep lobe of the cerebrum hidden beneath the lateral sulcus

  • Plays a role in taste

What are the functions of the frontal lobe?

• Motor control (primary motor cortex)

• Decision-making & judgment

• Personality & impulse control

• Attention & problem-solving

What are the functions of the parietal lobe?

• Processes sensory information (touch, temp, pain)

• Helps understand spatial awareness & body position

What are the functions of the occipital lobe?

• Visual input (primary visual cortex)

• Visual memories

What are the functions of the temporal lobe?

• Language processing

• Auditory

• Emotion & smell processing (insula)

What are the three main motor areas in the frontal lobe?

• Primary (1°) Motor Cortex –

  • Controls voluntary movement of contralateral skeletal muscles

• Frontal Eye Field –

  • Controls eye movement for reading & binocular vision

• Motor Speech Area (Broca’s Area) –

  • Controls muscles for speech production

What are the main sensory areas in the brain?

• Primary Somatosensory Cortex –

  • Processes general sensory info

• Primary Visual Cortex –

  • (occipital lobe) Processes visual info

• Primary Auditory Cortex –

  • (temporal) Processes auditory info

• Primary Olfactory Cortex –

  • (temporal) Processes olfactory info from the nasal cavities

• Primary Gustatory Cortex –

  • (insula) Processes taste info

What are the main association areas

• Premotor cortex (somatomotorassociation area)

  • coordinating learned, skilled motor activities (e.g. reading, grasping)

• Somatosensory association area

  • understanding of the object producing the stimulus (e.g. texture, temperature, pressure, shape)

• Visual association area

  • color, movement, form, facial recognition

• Auditory association area

  • correlates with memories of sound

recognizing, understanding spoken/written language; composed

of parts of parietal and temporal lobes

Wernickearea

integrates all sensory input into a coherent whole by working with

the association areas within the parietal, occipital, and temporal lobes to produce

Gnostic area