Lecture 3 Neuroanatomy

Question 1

Neuroanatomical Directions

Answer 1

Rostral = towards the “beak” or front end

Caudal = towards the tail or back end

Dorsal = top of head

Ventral = part facing the ground

Lateral = towards the side

Medial = towards the midline

Question 2

Neuroanatomical Planes

Answer 2

Question 3

4 Lobes Of The Brain and their main functions

Answer 3

• Frontal lobe - important for cognitive functions and control of voluntary movement or activity.
• Parietal lobe - processes information about temperature, taste, touch and movement.
• Occipital lobe - primarily responsible for vision.
• Temporal lobe - processes memories, integrating them with sensations of taste, sound, sight and touch.

Question 4

What types of Cognitive Planning does the Frontal lobe help us perform?

Answer 4

• strategic and coordinated planning.
• Verbal activities (such as planning a lecture) involve more left hemisphere regions, whereas spatial activities (such as planning a garden) involve more right hemisphere regions.
• The more challenging the planning of the activity, the greater the number of frontal lobe regions participate in the planning process.
• Example: Child who wants to go skiing.
• Difficulties in planning are common in Alzheimer’s

and other dementias.

• Effects of stress/anxiety, schizophrenia.

Question 5

What is the role of the Parietal Lobe?

Answer 5

• Processes information about temperature, taste, touch and movement.
• Sensory information goes through the thalamus to the parietal lobe, where it is processed and potentially integrated with the visual system.
• Includes the somatosensory cortex. Basically a map of the sensory representation of body parts.
• Several areas of the parietal lobe are important in language processing eg. Cognitive processing of language in the angular gyrus and sensorimotor control of writing.

Question 6

Damage to the right parietal lobe can result in:

Answer 6

• Neglecting part of the body or space (contralateral neglect), which can impair many self-care skills such as dressing and washing.
• Can also cause difficulty in making things (constructional apraxia), denial of deficits (anosagnosia) and drawing ability.

Question 7

What is Gerstmann’s Syndrome?

Answer 7

• Damage to the left parietal lobe:
• Includes right-left confusion, difficulty with writing (agraphia) and difficulty with mathematics (acalculia).
• Can also produce disorders of language (aphasia) and the inability to perceive objects normally (agnosia).

Question 8

What is Balint’s Syndrome?

Answer 8

• Bi-lateral damage.
• A visual attention and motor syndrome.
• Characterized by the inability to voluntarily control the gaze (ocular apraxia), inability to integrate components of a visual scene (simultanagnosia), and the inability to accurately reach for an object with visual guidance (optic ataxia).

Question 9

Explain neurological basis for Dyslexia and what it really is.

Answer 9

• Dyslexia is an often-misunderstood, confusing term for reading problems. It is neurobiological in origin.
• One of the most common misunderstandings about this condition is that dyslexia is a problem of letter or word reversals (b/d, was/saw) or of letters, words, or sentences “dancing around” on the page.
• Left parietotemporal system is important for word analysis. This region is critical in the process of mapping letters and written words onto their sound correspondences – letter sounds and spoken words. This area is also important for comprehending written and spoken language.
• People with dyslexia have less gray matter in the left parietotemporal area than nondyslexic individuals. Thought to lead to problems processing the sound structure of language.
• Many people with dyslexia also have less white matter in this same area than average readers; more white matter is correlated with increased reading skill.

Question 10

Brodmann area for V1 (or primary visual cortex)

Where does it project?

Answer 10

Brodmann area 17

V1 projects to occipital areas of the ventral stream and occipital areas of the dorsal stream

Question 11

What is the extrastriate cortex and what are these regions for?

Answer 11

•Visually driven regions outside V1 are called extrastriate cortex. There are many extrastriate regions, and these are specialized for different visual tasks, such as visuospatial processing, color differentiation, and motion perception.

Question 12

main functions of temporal lobe, 3 areas within and their functions

Answer 12

Involved in processing sensory input for the appropriate retention of visual memory, language comprehension, and emotion association

• 1. The temporal lobe holds the primary auditory cortex, which is important for the processing of semantics in both speech and vision in humans.
• 2. Wernicke’s area, which spans the region between temporal and parietal lobes, plays a key role in speech comprehension.
• 3. The medial temporal lobes are thought to be involved in encoding declarative long term memory.
• The medial temporal lobes include the hippocampi, which are essential for memory storage; damage to this area can result in impairment in new memory formation leading to permanent or temporary anterograde amnesia.

Question 13

Define Gyri and name some

Answer 13

A ridge or fold between two clefts on the cerebral surface in the brain

Question 14

Define Sulci and name 2 sulci and 3 fissure (4 total with one overlapping)

Answer 14

Question 15

Define Interneuron

Answer 15

Connectors (relay or association neurons) between the sensory and motor neuron pathways

Found exclusively in the CNS

Question 16

How many spinal nerves and what do they do?

Answer 16

• Carry motor, sensory, and autonomic signals between the spinal cord and the body.
• In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column.

Question 17

Spinal Cord organization

Answer 17

• Spinal cord is organised into dorsal root ganglia (somatosensory) and ventral root ganglia (motor). The dorsal root (posterior) enters the spinal cord and the ventral roots (anterior) exit the spinal cord.
• Each of the 31 dorsal roots innervate different areas of the skin referred to as dermatomes.
• When a dorsal root is cut, the spinal cord can no longer obtain info from that nerve.
• Spinal interneurons – form synapses with motor neurons which can mediate the motor response of sensory stimuli.

Question 18

What is the brainstem?

What does it do?

Answer 18

• The central trunk of the mammalian brain, consisting of the medulla oblongata, pons, and midbrain, and continuing downwards to form the spinal cord.
• Regulates the central nervous system,
• Provides the main motor and sensory nerve supply to the face and neck via the cranial nerves.
• Plays an important role in the regulation of cardiac and respiratory function.

Question 19

What are Cranial nerves?

How many originate in the brainstem?

Which two don’t?

Answer 19

• Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), in contrast to spinal nerves (which emerge from segments of the spinal cord).
• 10 of the cranial nerves originate in the brainstem.

From the Cerebrum:

The first and second cranial nerves derive from the telencephalon and diencephalon respectively and are considered extensions of the central nervous system: olfactory nerve (CN I), optic nerve (CN II)

Question 20

What is the Reticular Formation?

Answer 20

•Clusters of neurons that are interconnected within the brainstem.

•

•Thought to be responsible for mediating quite different behaviour eg. Sleep, respiration, habituation.

Question 21

What is the Medulla Oblongata?

What happens if it’s damaged?

Answer 21

• Controls autonomic functions such as breathing, digestion, heart and blood vessel function, swallowing, and sneezing.
• Relay of nerve signals between the brain and spinal cord.
• Coordination of body movements.
• Regulation of mood.

Damage:

•May result in a number of sensory-related problems eg. numbness, paralysis, difficulty swallowing, acid reflux, and lack of movement control.

Question 22

What is the Pons?

Answer 22

• Helps relay messages from the cortex and the cerebellum.
• Basically a messaging station.

Question 23

What is the Mesencephalon?

Answer 23

• Also known as the midbrain.
• Associated with vision, hearing, motor control, sleep/wake, arousal and temperature regulation.

Question 24

What is the Diencephalon?

Answer 24

• Includes the thalamus, the hypothalamus, the epithalamus and the subthalamus.
• Information processing and relay centre.

Question 25

What is the Hypothalamus, Role?

Answer 25

What is it?

• Area of brain that contains a number of small nuclei with a variety of functions.
• Located below the thalamus.

•

What is its role?

• Links the nervous system to the endocrine system via the pituitary gland.
• Releases hormones.
• Regulates body temperature.
• Maintains daily physiological cycles.
• Manages sexual behavior.
• Controls appetite.

Question 26

What happens to the Brainstem when a person experiences trauma?

How do we combat it?

What is the role of therapy when someone is in a hyperaroused state?

Answer 26

• When a person experiences a traumatic event, adrenalin rushes through the body and areas such as the brainstem get over-activated.
• To calm those deeper regions of the brain, we start with “bottom-up processing”.
• When someone is in an activated or hyperarousal state, the goal for therapeutic interventions is to bring oxygen and blood flow back to the brain, so we can start deactivating the fight/flight response and accessing the higher regions of the brain.

Question 27

What happens when Brainstem is damaged?

Answer 27

• A stroke in the brain stem can interfere with vital functions such as breathing and heartbeat.
• Other functions that we perform without thinking, such as eye movements and swallowing, can also be altered.
• Brain stem stroke can also impair your speech and hearing, and cause vertigo.
• Can cause you to lose your sense of smell and taste.
• Coma and locked-in syndrome.

Question 28

What is “Locked in Syndrome” aka___________, and what causes it?

Answer 28

• Also known as pseudocoma
• A condition in which a patient is aware but cannot move or communicate verbally due to complete paralysis of nearly all voluntary muscles in the body except for vertical eye movements and blinking.
• The individual is conscious and sufficiently intact cognitively to be able to communicate with eye movements.

Caused by:

• Brainstem stroke.
• Poisoning cases – More frequently from a krait bite and other neurotoxic venoms, as they cannot usually cross the blood-brain barrier.
• Damage to nerve cells, particularly the destruction of the myelin sheath.
• Traumatic brain injury.

Question 29

Role of the Cerebellum, how many neurons?

Answer 29

• Does not initiate movement, but receives information from the sensory systems and the spinal cord and then regulates motor movements.
• Coordinates voluntary movements such as posture, balance, coordination, and speech, resulting in smooth and balanced muscular activity.
• Contains roughly half of the brain’s neurons.

Question 30

What happens when the Cerebellum is damaged?

Answer 30

• Loss of coordination of motor movement (asynergia).
• The inability to judge distance and when to stop (dysmetria).
• The inability to perform rapid alternating movements (adiadochokinesia).
• Movement tremors (intention tremor).
• Staggering, wide based walking (ataxic gait).
• Tendency toward falling.
• Weak muscles (hypotonia).
• Slurred speech (ataxic dysarthria).
• Abnormal eye movements (nystagmus).
• Rain man?

Question 31

asynergia

Answer 31

Loss of coordination of motor movement

Question 32

dysmetria

Answer 32

The inability to judge distance and when to stop

Question 33

adiadochokinesia

Answer 33

The inability to perform rapid alternating movements

Question 34

intention tremor

Answer 34

Movement tremors

Question 35

ataxic gait

Answer 35

Staggering, wide based walking

Question 36

hypotonia

Answer 36

Weak muscles

Question 37

ataxic dysarthria

Answer 37

Slurred speech

Question 38

nystagmus

Answer 38

Abnormal eye movements

Question 39

How many layers of the Cerebral Cortex?

Answer 39

• Consists of six layers.
• Most of the neurons in the cerebral cortex are arranged vertically.
• Most abundant neurons are the efferent pyramidal cells (very large giant pyramidal cells found in the layer V).

•

Six layers of the cerebral cortex:

I. Molecular layer - consists only a few nerve cells.

II. External granular layer – relatively thin layer consisting of numerous small, densely packed neurons.

III. Pyramidal layer or external pyramidal layer - is composed of medium-sized pyramidal nerve cells.

IV. Inner granular layer - contains small, irregularly shaped nerve cells.

V. Ganglionic or inner pyramidal layer - includes large pyramidal cells.

VI. Multiform layer - small polymorphic and fusiform nerve cells.

Question 40

Basic Prefrontal Cortex functions

Answer 40

•Responsible for complex cognitive behaviour, social behaviour, making decisions, and forming memories.

•

•This region is highly interconnected with other regions involved in emotion, such as the hypothalamus, which controls the body’s stress responses, and the insula, which represents bodily states.

Question 41

What is the Basal Ganglia?

Answer 41

• Includes the ventral striatum, the dorsal striatum (caudate and putamen), substantia nigra and the globus pallidus.
• Primarily involved in the integration of input from cortical areas, particularly from the motor cortex.
• Involved in the generation and control of motor behavior and action selection.

Question 42

What happens when the Basal Ganglia is damaged?

Answer 42

• A person with basal ganglia dysfunction may have difficulty starting, stopping, or sustaining movement.
• May cause problems controlling speech, movement, and posture.
• This combination of symptoms is called parkinsonism.

Question 43

What is the limbic system? (Role and structures)

Answer 43

What is it?

•A collection brain structures including the amygdala, hippocampus, hypothalamus and thalamus.

•

What is its role?

• Supports a wide variety of functions including emotion, behaviour, long-term memory and motivation.
• Integrating the sensory, affective, and cognitive components of pain and processes information regarding the internal bodily state.

Question 44

what is the hippocampus?

Answer 44

• Located near the center of the brain.
• Stores memories and regulates the production of a hormone called cortisol.
• Releases cortisol during times of physical and mental stress, including during times of depression.
• In a healthy brain, neurons are produced throughout a person’s adult life in a part of the hippocampus called the dentate gyrus.

Question 45

What is the Amygdala?

Answer 45

• The part of the brain that facilitates emotional responses, such as pleasure and fear.
• Processes emotionally salient stimuli and initiates the appropriate behavioral response eg. fear/anxiety.
• Responsible for the expression of fear, aggression and defensive behavior; plays a role in formation and retrieval of emotional and fear-related memories.
• It receives input from the hippocampus, thalamus, and hypothalamus.

Question 46

What happens when Limbic system is damaged?

Answer 46

• Damage to various areas of the limbic system disturbs many behaviors related to motivation and emotion.
• Amygdala damage has been shown to disrupt emotional reactions in monkeys and makes them social outcasts. The problem appears to be that monkeys without the amygdala cannot recognize the meaning of emotionally and socially important signals from other monkeys.
• Mental heath issues.
• HM.

Question 47

What protects the brain?

Answer 47

• Hair
• Scalp
• Skull
• Meninges – the membranes covering the brain and spinal cord:
• Dura mater – “hard matter”. Tough and covers the inside of the skull. Has indentations which limit the movement of the brain.
• Arachnoid mater – covers over the sulci. Filled with cerebrospinal fluid.
• Pia Mater – immediate covering which covers brain very closely and covers all sulci and fissures.

Question 48

What and where are the ventricles?

Why necessary?

Answer 48

• Cavities in brain where cerebrospinal fluid is found.
• Lateral ventricles right and left (one for each hemisphere), third ventricle and fourth ventricle.
• Cerebrospinal fluid makes the brain lighter and buoyant.

Question 49

Types of brain injury

Answer 49

•Closed head injury (can include TBI, tumour, haemorrhage, stroke, encephalitis, and epilepsy). An insult to the brain which does not penetrate skull or any of the meninges.

•

•Penetrating head injury (anything that physically penetrates brain or meninges).

Question 50

What is TBI? How does it occur?

Categorization

When is it important to recieve treatment?

Most TBI’s are ______

Answer 50

• Occurs when an external force injures the brain.
• Categorised into mild, moderate, and severe.
• Symptoms depend on the part of the brain that was injured.
• Important to receive treatment during “golden hour”.
• Most TBIs are mild and do not cause long term disability, however every severity level of TBI has the potential to cause significant long lasting disability.

Question 51

How TBI affects Daily Life

(by area)

Answer 51

Question 52

Closed Head Injury: Coup-Countrecoup

Answer 52

• A contusion, or a coup-contrecoup injury, is a bruise of the brain tissue.
• Injuries can also be lateral or side-to-side.
• This is the type of injury that can occur in a car crash, where the head is propelled forward and accelerated and then moved back in deceleration.

Question 53

Treatment/therapy for TBI

Answer 53

Immediate:

• Main focus is to ensure proper oxygen supply and maintain adequate blood flow to the brain.
• Involves controlling raised intracranial pressure (ICP), since high ICP deprives the brain of badly needed blood flow and can cause deadly brain herniation.

•

Long term:

• Depends on the TBI.
• Multidisciplinary.

Question 54

Closed Head Injury:

Encephalopathy

Encephalitis

Hydrocephalus

Answer 54

Encephalopathy:

•Inflammation of the CNS caused by reaction to chemical, toxic or physical agents.

•

Encephalitis

• Inflammation of the brain resulting from the cells of immune tissues, fluid and protein moving out of the blood vessels.
• Can be caused by viruses.

•

Hydrocephalus

• Increase in volume of the ventricles due to overproduction of CSF, causes pressure on the walls of the ventricles.
• Due to different causes.

Question 55

Encephalopathy General Symptoms

Answer 55

• The hallmark of encephalopathy is an altered mental state or delirium.
• Impairment of the cognition, attention, orientation, sleep–wake cycle and consciousness.
• Hypervigilance.
• Headache, epileptic seizures, myoclonus (involuntary twitching of a muscle or group of muscles) or asterixis (“flapping tremor” of the hand when wrist is extended).
• Subtle personality changes.
• Inability to concentrate.

Question 56

•Stroke:

Acronym of symptoms

Answer 56

•Stroke: a sudden loss of blood supply to the brain, or bleeding into the brain tissue.

Question 57

Causes of stroke

Answer 57

•Hypertension -an increase in blood pressure due to the constriction of small blood vessels.

•

•Ruptured aneurysm - ballooning/rupture of an artery wall.

•

•Arteriovenous malformation (angioma) - collection of abnormal blood vessels which produce abnormal blood supply.

Question 58

Closed Head Injury: Epilepsy

What is it?

Answer 58

•Seizures cased by abnormal electrical discharges/neuronal activity in the grey matter of the brain.

•

•Many factors can cause seizures in people with a low threshold of neuronal excitability eg. low blood sugar, flickering lights, drowsiness, and sleep.

Question 59

Causes of Epilepsy:

Answer 59

Mechanism:

• A group of neurons begin firing in an abnormal, excessive and synchronized manner.
• This results in a wave of depolarization.
• This then results in a specific area from which seizures may develop, known as a “seizure focus”.

•

Eliptogenesis:

• Cases which occur as the result of brain injury, stroke, brain tumors, infections of the brain, and birth defects.
• Mechanism thought to result due to up-regulation of excitatory circuits or down-regulation of inhibitory circuits following an injury to the brain.

Question 60

What are Focal seizures:

Answer 60

• These start in a particular part of one brain hemisphere.
• They can cause both physical and emotional effects and make you feel, see, or hear things that aren’t there eg. Burning toast.
• About 60% of people with epilepsy have this type of seizure.

Question 61

3 categorizations of Focal Seizures:

Answer 61

•Simple focal seizures: They change how your senses read the world around you.

•

•Complex focal seizures: These usually happen in the part of your brain that controls emotion and memory.

•

•Secondary generalized seizures: These start in one part of your brain and spread to the nerve cells on both sides.

Question 62

6 Types of generalized Seizures:

Answer 62

Generalized seizures: These happen when there is widespread seizure activity in the left and right hemispheres of the brain.

Types:

• Tonic-clonic (or grand mal) seizures: Most noticeable; body stiffens, jerks, and shakes, and person may lose consciousness/lose control of bladder or bowels. Usually last 1 to 3 minutes.
• Clonic seizures: Muscles have spasms; face, neck, and arm muscles jerk rhythmically. May last several minutes.
• Tonic seizures: Muscles in arms, legs, or trunk tense up. These usually last less than 20 seconds and often happen during sleep. But if you’re standing up at the time, you can lose your balance and fall.
• Atonic seizures: Muscles suddenly go limp. These usually last less than 15 seconds, but some people have several in a row.
• Myoclonic seizures: Muscles suddenly jerk as if they have been shocked.
• Absence (or petit mal) seizures: Person will seem disconnected from others and unresponsive. May stare blankly into space, and eyes might roll back in your head. They usually last only a few seconds.

Question 63

Case study:

Joe visits his GP because he is having trouble with his vision and this concerns him as he is a truck driver. He appears very disorganized in his presentation with a dishevelled appearance and is late for the appointment. He notes that his wife complains that his personality is “all over the place” lately and she finds him unpredictable.

What type of head injury do you think this person has? Describe the brain area(s) and hypothesise as to how he may have undergone the injury.

Answer 63

discussion

Question 64

Ataxia

Answer 64

Ataxia is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in eye movements.