Brain Structure

02.04.2016

Nervous System

Nervous System

Central Nervous System

Brain Spinal Cord

Peripheral Nervous System

Cranial nerves, spinal nerves,

peripheral ganglia

Brain

Brain

Forebrain

Cerebral Cortex

Basal Ganglia

Limbic System

Brain Stem

Hindbrain Midbrain

Diencephalon

Meninges of Central Nervous System Meninges – protect and cover brain and spinal cord

1. Dura mater

2. Arachnoid membrane Subarachnoid space

3. Pia matter

https://www.youtube.com/watch?v=opfC4JIUPd0

Meninges of Peripheral Nervous System

1. Dura mater

2. Pia mater

Brain Ventricles

• Two lateral ventricles (1st and 2nd ventricles)

• 3rd ventricle

• 4th ventricle

• Cerebral aqueduct connects 3rd and 4th ventricle

https://www.youtube.com/watch?v=Zm-TsqsgCHc

Cerebro-Spinal FluidProtection1. reduce pressure (absorbs shock)2. nutrition3. waste removal

• Extracted from blood

• Manufactured by choroid plexus (in ventricles)

• Manufactured and reabsorbed continuously

• Reabsorbed into blood stream

https://www.youtube.com/watch?v=asQo6cmOjd0

Central Nervous System

• Brain

• Spinal cord

Brain – Gross Structure

Cerebral cortex:Gyrus

“Bump” on the brain’s surface

SulcusFold / groove between gyri

FissureA long, deep sulcus

Lobes of the Brain

Functional Brain Areas

Cerebral Cortex

• Divided into two hemispheres– Connected by corpus callosum

• Left hemisphere– Verbal, verbally mediated processes, analytical,

sequential information processing

• Right hemisphere– Non-verbal, holistic, simultaneous information processing

Corpus Callosum

• Largest white matter tract

• Connect corresponding parts of cortex in R and L hemispheres

– Anterior– Posterior– Body

Corpus Colostomy

• To prevent spread of epileptic activity

• Split brain (Roger Sperry 1913-1994):– Can not name image in left visual field– Can not name object touched by left hand– Personality, intelligence, emotions intact

https://www.youtube.com/watch?v=zx53Zj7EKQE

Forebrain

Basal Ganglia

• Multiple subcortical nuclei

• Main functions: motor control, eye movements, motivation

Basal GangliaParkinson’s disease Loss of Dopamine producing cells in substantia nigraNeurodegenerative disease

• Motor symptoms:– Tremor– Bradykinesia (slow movement)– Rigidity– Postural instability– Dysarthria, difficulty swallowing

• Cognitive symtoms:– Cognitive slowing, micrographia– Distractability, disorganization, forgetfulness, difficulty planning– Depression, apathy, anxiety

https://www.youtube.com/watch?v=3wg9ExKwZy4

Basal GangliaHuntington’s disease Striatum Neurodegenerative genetic disorder

Motor symptoms:– Uncontrollable jerky movements– Lack of coordination– Unsteady gait

Cognitive symptoms:– Memory, executive functions impairment– Anxiety, depression

https://www.youtube.com/watch?v=4HgFUvVyHYQ

Limbic system• Group of cortical

and subcortical structures

• Main functions: memory, emotions, arousal

https://www.youtube.com/watch?v=GDlDirzOSI8https://www.youtube.com/watch?v=PNx9m54fjao

Limbic System (functions of some structures)

Hippocampus • Learning new memories (transfer from short-term memory to long-term memory)• Spatial memory

Amygdala • Emotions (fear, anxiety)• Prepare body for emergency reactions• Attention• Autobiographical memory (in particular, emotional memories)• Social processing (in particular, recognition of emotions in others)

Thalamus• Subcortical sensory relay

Hypothalamus• Hormones production

Diencephalon

Thalamus – relays sensory and motor signals to cortex, regulates consciousness, sleep, alertness

Hypothalamus – part of endocrine system, links nervous system to endocrine system via pituitary gland• Four F’s

Brain Stem

Hindbrain

1. Metencephalon– Pons Varolii – cranial nerves for

equilibrium, hearing, taste, facial sensation& expressions

– Cerebellum – movement coordination

2. Myelencephalon (medulla oblongata)

- cranial nerves (VI-XII)- IV ventricle

3. Reticular formation - activation

Midbrain, MesencephalonTectum:

– Superior colliculi - vision– Inferior colliculi - hearing

Tegmentum

- Movements

Reticular formation - arousal

Spinal Cord

Bell-Magendie Law• Roots = bundles of axons

• Dorsal roots Axons entering spinal cord Carry sensory information

• Ventral roots Axons exiting spinal cord Carry motor information

Dorsal = Toward the backVentral = Toward the stomach

Signal Transmission from and to the Spine

The Cranial Nerves• 12 pairs of nerves (Left and Right)

Connect brain to receptors and muscles of head and internal organs

Originate in nuclei (groups of neurons) in brain

• Functions Sensation and movement in head

Parasympathetic nervous system

The Cranial NervesNumber and Name Major Functions

I. Olfactory Smell

II. Optic Vision

III. Oculomotor Control of eye movements, pupil constriction

IV. Trochlear Control of eye movements

V. Trigeminal Skin sensations from most of the face; Control of jaw muscles for chewing and swallowing

VI. Abducens Control of eye movements

VII. Facial Taste from the anterior 2/3 of the tongue; Control of facial expressions, crying, salivation, and dilation of the head’s blood vessels

VIII.Auditory/Vestibulocochlear

Hearing, equilibrium

IX. Glossopharyngeal Taste and other sensations from throat and posterior 1/3 of the tongue; Control of swallowing, salivation, throat movements during speech

X. Vagus Sensations from neck and thorax; Control of throat, esophagus, and larynx; Parasympathetic nerves to stomach, intestines, and other organs

XI. Spinal Accessory Control of neck and shoulder movements

XII. Hypoglossal Control of muscles of the tongue

The Cranial Nerves