The Brain

• Endoderm
• Mesoderm
• Ectoderm
• --Formed through gastrulation

• Starting layer that can become something else
• All tissues of the body originate from this

• Primary germ levels
• Blue: ectoderm
• Red: mesoderm; mesoderm in the middle is the notochordal plate
• Yellow: endoderm

• Forms the dervous system
• Epidermis of skin and its derivatives
• Epithelial lining of the mouth

• Begins in early week 3 of development 
• Occurs in the ectoderm
• Cell signaling starts this change

• 1. Formation of neural plate
• 2. Shaping of neural plate (tube)
• 3. Invagination of neural plate
• 4. Closure of neural groove
• -- Forms the neural tube and neural canal

• Two parts of the ectoderm:
• Light blue: Neural ectoderm- comprises the central nervous system
• Dark blue: Surface ectoderm- covers the outside of the body

• Proliferating cells in the neural tube
• Cranial end forms the brain
• Caudal end forms the spinal cord

Neural canal-- opening in the tube

Excitable cells

Supportive cells

• Nucleus
• Tract or fasciculus

• Ganglion
• Nerve

• Composed primarily of myelinated axons
• Allows nerve impulse to move quicker
• Fatty makes it white

• Composed of neuronal cell bodies, dendrites, unmyelinated axons, & neuroglia
• No mylein

Central cavity surrounded by gray matter surrounded by white matter

• Central cavity surrounded by a gray matter core with white matter external to the gray matter

Similar to spinal cord but there is scattered gray matter within the white matter

• The cerebrum and cerebellum have this outer layer of gray matter
• Its an extra layer of gray matter

Elevated fold of the brain i.e top folded region

Shallow/Deep groove that help separate gyri

• Insular hemisphere is inside the lateral fissure

• Anterior cranial fossa=Frontal lobe
• Middle cranial fossa=Temporal lobe
• Posterior cranial fossa=Cerebellum

• Yellow: Transverse Fissure
• Green: Longitudinal Fissure

• Precentral gyrus: closer to the frontal lobe; primary motor cortex
• Postcentral gyrus: primary sensory cortex

Parieto-occipital sulcus

• Calcarine sulcus
• Surrounded by the primary visual cortex

• Motor areas: initiation of voluntary movement (ex precentral gyrus) 
• Sensory areas: reception of sensory information and perception i.e temperature or touch (ex postcentral gyrus) 
• Association areas: complex integrative functions i.e speech which requires multiple actions

Each hemisphere is responsible for managing the motor and sensory functions of the opposite side

• Primary Somatosensory Area
• Postcentral Gyrus

Primary Visual Area

Primary Motor Area (precentral gyrus)

Broca's Speech Area

Prefrontal Cortex

Primary Auditory Area

• "Little man" represents a schematic illustration of body parts on the cortex
• The body parts are oriented according to their region of control or interpretation (bigger the body part, the more the senses)

• Fibers connecting gray areas between the two hemispheres
• Communication between hemispheres
• Ex: Corpus callosum (cut to help prevent spreading of seizures)

• Fibers connecting different parts of the same hemisphere
• Ex: General cerebral white matter

• Fibers connecting the cerebral cortex to the other parts of the CNS
• Ex: Spinal Tracts (top: corona radiata/bottom: internal capsule)

• Collection of nerve cell bodies deep in the cerebrum (white matter) i.e caudate nucleus, putamen and globus pallidus
• Function: influence motor function, inhibits extraneous muscle contraction and helps maintain motor control
• Writing/playing piano

• Top: Claudate
• Middle: Putamen
• Bottom: Globus pallidus

All three make up the basal nuclei (ganglia)

• It may have lead to muscle rigidity and/or resting tremors
• Ex: Parkinson's disease and Huntington's disease
• Can't turn off bad shaking

• Parts of the diencephalon

• Major relay center for all sensation entering the cerebral cortex except olfaction
• Grand central station-- info arrives/is processed/leaves

• Regulator of the body's internal environment
• Maintaining homeostasis and hormones
• Flight/flight, rest/digest

• Helps regulate sleep-wake cycle with the hypothalamus
• Pineal body secretes melatonin

• Parts of the brain stem
• Yellow: midbrain
• Blue: pons
• Red: medulla oblongata (connects directly to the spinal cord)

• Produces autonomic behaviors necessary for survival (heartrate/respiration)
• Provides a pathway for axons acending and descending
• Nuclei for CN III-XII are in this

• Cerebrals Peduncles (ventral surface)
• Superior Colliculi (dorsal surface)
• Inferior Colliculi (dorsal surface)

• Yellow: Oculomotor N
• Green: Trochlear N

• Higher brain centers and the spinal cord
• Motor cortex and cerebellum

• Trigeminal (V)
• Abducens (VI)
• Facial (VII)
• Vestibulocochlear (VIII)

Pons

• Yellow: Trigeminal N (CN V); has 3 divisions
• Orange: Abducens N (CN VI); inbetween pons and medulla
• Blue: Facial N (CN VII)
• Purple: Vestibulocochlear N (CN VIII)

Autonomic reflex center such as cardiovascular and respiratory centers

• Pyramids (ventral surface): big yellow star
• Gracile tubercle (dorsal surface): small yellow star
• Cuneate tubercle (dorsal surface): purple star

• Hypoglossal N
• CN XII
• Comes off of the pyramid

• Accessory N
• CN XI
• Comes off of the spinal cord as well as from the brain stem

• Vestibulocochlear N
• CN VIII

• Glossopharyngeal N
• CN IX

• Vagus N 
• CN X

• Provides timing and patterns for smooth and coordinated movements.
• Also error correcting (i.e balance)

• Arbor Vitae is the white matter
• Folia is the gray matter