Week 9 - Brain & Spinal Cord

Question 1

What are the 5 secondary brain vesicles?

Answer 1

The telencephalon - develops into the cerebrum and lateral ventricles . The diencephalon - develops into the thalmus, hypothalamus, epithalamus, & 3rd ventricle. The mesencephalon - gives rise to the midbrain and aqueduct of the midbrain (cerebral aqueduct) . The metencephalon becomes the pons, cerebellum, and upper part of the fourth ventricle . The myelencephalon forms the medulla oblangata and lower part of the 4th ventricle

Question 2

What are the 4 major parts of the brain?

Answer 2

brain stem is continuous with the spinal cord and consists of the medulla oblongata, pons, and midbrain. Posterior to the brain stem is the cerebellum. Superior to the brain stem is the diencephalon, which consists of the thalamus, hypothalamus, and epithalamus. Supported on the diencephalon and brain stem is the cerebrum, the largest part of the brain.

Question 3

What are Ventricles, how many are there and what are they called?

Answer 3

4 Cerebrospinal Fluid (CSF) filled cavities in the brain. There is one lateral in each hemisphere of the cerebrum. Then there is the 3rd and 4th ventricles.

Question 4

What are the 5 Lobes of the Cerebrum?

Answer 4

Frontal, temporal, parietal, occipital, insular

Question 5

What is the structure of the Cerebrum?

Answer 5

Your cerebrum is the largest area of your brain. Your cerebrum divides your brain into two halves called hemispheres. The hemispheres are attached by a bundle of nerve fibers called the corpus callosum. The corpus callosum allows your two hemispheres to communicate with each other.

Question 6

What does the Cerebrum allow us to do?

Answer 6

Seat of intelligence’ - provides ability to read, write speak. Make calculations, compose music, create. Remember the past and plan for the future.

Question 7

What is the Cerebral Cortex?

Answer 7

Outer layer that lies on top of cerebrum

Question 8

What are the 3 kinds of functional areas contained in the Cerebral Cortex?

Answer 8

Motor, sensory and association

Question 9

What doe the motor areas do and where are they located?

Answer 9

control voluntary movement, mostly lie in the posterior part of the frontal lobes

Question 10

What is the function of the Primary Motor Cortex and where is it located?

Answer 10

The primary motor area (area 4) is located in the precentral gyrus of the frontal lobe. within which there is a ‘map’ of the entire body: each region within the area controls voluntary contractions of specific muscles or groups of muscles Different muscles are represented unequally in the primary motor area. More cortical area is devoted to those muscles involved in skilled, complex, or delicate movement.

Question 11

What is the function of the Broca’s Speech Area and where is it located?

Answer 11

Broca’s speech area is located in the frontal lobe close to the lateral cerebral sulcus. Speaking and understanding language are complex activities that involve several sensory, association, and motor areas of the cortex. From Broca’s speech area, nerve impulses pass to the premotor regions that control the muscles of the larynx, pharynx, and mouth. The impulses from the premotor area result in specific, coordinated muscle contractions.

Question 12

what is the function of the frontal I field and where is it located?

Answer 12

frontal eye field (FEF) is an area of the frontal cortex in animals over which electrical stimulation is able to trigger eye movements

Question 13

What are sensory areas concerned with and where do they occur?

Answer 13

They are concerned with conscious awareness of sensation, and occur in the parietal insular temporal and occipital lobes

Question 14

What is the function of the Primary Somatosensory Area/Cortex? What is its location?

Answer 14

primary somatosensory area (areas 1, 2, and 3) is located directly posterior to the central sulcus of each cerebral hemisphere in the postcentral gyrus of each parietal lobe. The primary somatosensory area receives nerve impulses for touch, pressure, vibration, itch, tickle, temperature (coldness and warmth), pain, and proprioception (joint and muscle position) and is involved in the perception of these somatic sensations. A ‘map’ of the entire body is present in the primary somatosensory area:

Question 15

What is the function of the Somatosensory Assoc. Area/Cortex? What is its location?

Answer 15

It is posterior to and receives input from the primary somatosensory area, as well as from the thalamus and other parts of the brain. This area permits you to determine the exact shape and texture of an object by feeling it, to determine the orientation of one object with respect to another as they are felt, and to sense the relationship of one body part to another. Another role of the somatosensory association area is the storage of memories of past somatic sensory experiences, enabling you to compare current sensations with previous experiences.

Question 16

What is the function of the primary visual area and where is it located?

Answer 16

primary visual area - located at the posterior tip of the occipital lobe, receives visual information

Question 17

What is the function of the visual association area and where is it located?

Answer 17

visual association area , located in the occipital lobe, receives sensory impulses from the primary visual area and the thalamus. Is essential for recognising and evaluating what is seen.

Question 18

what is the function of the primary auditory area and where is it located?

Answer 18

located in the superior part of the temporal lobe and receives sound information

Question 19

what is the function of the auditory assoc. area and where is it located?

Answer 19

located inferior and posterior to the primary auditory area in the temporal cortex, allows you to recognise a particular sound as speech, music, or noise.

Question 20

What is the fn of the primary olfactory area and where is it located?

Answer 20

located in the temporal lobe on the medial aspect (and thus may not be easily visible), receives impulses for smell and is involved in olfactory perception.

Question 21

What is the function of the primary gustatory area and where is located?

Answer 21

located at the base of the postcentral gyrus superior in the parietal cortex, receives impulses for taste and is involved in gustatory perception and taste discrimination.

Question 22

What are multimodal areas of the cortex?

Answer 22

Areas that receive inputs from multiple senses and send outputs to multiple areas

Question 23

How does information flow into and through the cortex?

Answer 23

Sensory Receptors > Primary Sensory Cortex > Sensory Association Cortex > Multimodal Association Cortex.

Question 24

What does the multimodal association area of the cortex allow us to do?

Answer 24

allows us to give meaning to the information we receive, store it in memory, tie it into previous experience and knowledge, and decide what action to take. Where sensations, thoughts and emotions become conscious.

Question 25

How many parts of the Multi modal areas are there?

Answer 25

Three, the anterior posterior and limbic areas

Question 26

What does the anterior part of the multimodal area allow us to do and where is it located?

Answer 26

• In the frontal lobe and also called the prefrontal cortex. • The most complicated cortical region of all, involved with intellect, cognition, recall and personality.• Contains working memory necessary for abstract ideas, judgement, reasoning, persistence and planning.• These abilities develop slowly in children, implying the prefrontal cortex matures slowly and depends heavily on feedback from our social environment.

Question 27

What does the posterior part of a multimodal associate area allow us to do and where is it?

Answer 27

• Encompasses parts of the temporal, parietal and occipital lobes. • Plays a role in identifying patterns and faces, localising us and our surroundings in space, and binding different sensory input into a coherent whole. • Also involved in understating written or spoken language

Question 28

What does the Limbic Association area allow us to do and where is it located?

Answer 28

Includes the cingulate gyrus, parahippocampal gyrus and hippocampus. • Provides the emotional impact that makes a scene important to us

Question 29

What is hemispheric lateralisation?

Answer 29

it describes the structural and functional asymmetry of the two hemispheres

Question 30

What is the difference between the grey and white cerebral matter?

Answer 30

The gray matter is the areas where the actual “processing” is done whereas the white matter provides the communication between different gray matter areas and between the gray matter and the rest of the body.

Question 31

During embryonic development, when brain size increases rapidly, the grey matter of the cortex enlarges much faster than the deeper white matter. What happens to it’s structure as a result?

Answer 31

the cortical region rolls and folds on itself. The folds are called gyri or convolutions The deepest grooves between folds are known as fissures ; the shallower grooves between folds are termed sulci.

Question 32

The cerebral white matter consists primarily of myelinated axons in three types of tracts. What are they and what do they do?

Answer 32

1. Association tracts contain axons that conduct nerve impulses between gyri in the same hemisphere. 2. Commissural tracts contain axons that conduct nerve impulses from gyri in one cerebral hemisphere to corresponding gyri in the other cerebral hemisphere. Three important groups of commissural tracts are the corpus callosum (the largest fibre bundle in the brain, anterior commissure , and posterior commissure . 3. Projection tracts contain axons that conduct nerve impulses from the cerebrum to lower parts of the CNS (thalamus, brain stem, or spinal cord) or from lower parts of the CNS to the cerebrum. eg internal capsule

Question 33

What are the basal nuclei or basal ganglia and what do they do?

Answer 33

Deep within each cerebral hemisphere are three nuclei (masses of grey matter) that are collectively termed the basal nuclei. They are primarily involved in the control of movement. Activity in the basil nuclei proceeds body movement and helps regulate initiation and termination of movement. May also have role initiating and terminating some cognitive processes including memory attention & planning and may act with limbic Press system to regulate emotional behaviours

Question 34

What three structures make up the diencephalon?

Answer 34

The thalamus hypothalamus and epithalamus

Question 35

What is the thalamus and what does it do?

Answer 35

makes up 80% of the diencephalon. Acts as the relay station for all information coming into the cerebral cortex. Afferent impulses from all senses and all parts of the body converge on the thalamus where the information is sorted out and ‘edited’. Other inputs, including emotion and visceral function from the hypothalamus, instructions that help direct motor activity from the cerebellum and basal nuclei and memory and sensory integration are also received.

Question 36

What is the epithalamus and what does it do?

Answer 36

Contains pineal gland, responsible for secreting melatonin, which helps regulate the sleep-wake cycle.

Question 37

What is the hypothalamus and what does it do?

Answer 37

The main visceral control centre of the body, vitally important to overall body homeostasis

Question 38

What are the 8 main functions of the hypothalamus?

Answer 38

Control the ANS (regulates smooth and cardiac muscle); Initiates the physical response to emotions eg pleasure, fear and rage; Regulates body temperature: The body’s thermostat. Monitors blood temp and receives input from brain/ body thermoreceptors; Regulates food intake in response to changing blood levels of nutrients; Regulates water balance and thirst: receives input from osmoreceptors and controls the release of ADH; Regulates sleep-wake cycles in response to daylight/darkness cues; Control endocrine system function through releasing and inhibiting hormones.

Question 39

Which three structures make up the brainstem?

Answer 39

The midbrain, the pons, the medulla oblongata

Question 40

What four part make up the midbrain and what do they do?

Answer 40

Cerebral peduncles conduct nerve impulses from motor areas in the cerebral cortex to the spinal cord, medulla and pons. Superior Colliculi are visual reflex centres that coordinate head and eye movements when we visually follow a moving object, even if not consciously looking at it. Inferior Colliculi are part of the auditory relay from the ear to the sensory cortex. Also act in reflexive responses to sound, such as the startle reflex causing you to turn your head in response to an unexpected noise. Substantia Nigra (deep to the cerebral peduncle) releases the neurotransmitter dopamine. Same functions as basal nuclei in controlling subconscious movements

Question 41

What 3 things does the pons do?

Answer 41

Chiefly composed of conduction tracts oriented in two different directions: 1. Deep projection fibres run longitudinally as part of the pathway between higher brain centres and the spinal cord.
2. Superficial ventral fibres run transversely and dorsally, connecting. They form the middle cerebellar peduncles, connecting the pons to the cerebellum. These relay ‘conversations’ between the motor cortex and cerebellum.
3. Also Contains the pontine respiratory group which helps control breathing with the medullary respiratory groups

Question 42

What is the function of the medulla oblongata?

Answer 42

Autonomic reflex centre involved in maintaining homeostasis. Contains important functional groups of visceral motor nuclei: 1. Cardiovascular centre: includes the cardiac centre which adjusts the force and rate of heart contraction to meet the bodies needs. 2. Respiratory c goentres: Generate respiratory rhythm and together with pontine centres, control the rate and depth of breathing. 3. Various other centres: regulate activities such as sneezing, vomiting, hiccupping, swallowing and coughing.Has overlap with the hypothalamus as the hypothalamus relays its instructions through the medullary reticular centres. Continuous with the superior aspect of the spinal cord so contains all sensory and motor tracts extended between all areas of the brain and the spinal cord

Question 43

What is the function of the reticula formation?

Answer 43

It is an intricate system composed of loosely class to neurons in what is otherwise white matter. It helps regulate awareness arousal attention and sleep

Question 44

What is the function of the limbic system?

Answer 44

The limbic system is the part of the brain involved in our behavioural and emotional responses, especially when it comes to behaviours we need for survival: feeding, reproduction and caring for our young, and fight or flight responses.. It also is involved in olfaction (smell) and memory.

Question 45

What four structures protect the brain?

Answer 45

Bone(the skull); Membranes (the meninges); CerebrospinalFluid; Blood brain barrier

Question 46

What do the Meminges do?

Answer 46

Three connective tissue membranes that cover and protect the CNS, protect blood vessels and enclose venous sinuses, contain CSF, and form partitions of the skull.

Question 47

From external to internal what are the three meninges?

Answer 47

Dura mater, arachnoid mater, pia mater

Question 48

What is cerebrospinal fluid what does it do and where is it located?

Answer 48

Cerebrospinal fluid (CSF) is a clear, colourless liquid composed primarily of water that protects the brain and spinal cord from chemical and physical injuries (located yeahin ventricles). It also carries small amounts of oxygen, glucose, and other needed chemicals from the blood to neurons and neuroglia.

Question 49

What are the three basic functions of the cerebro spinal fluid?

Answer 49

1. serves as a shock-absorbing medium The fluid also buoys the brain so that it ‘floats’ in the cranial cavity saving the brain collapsing in on itself. 2. The pH of the CSF affects pulmonary ventilation and cerebral blood flow, which is important in maintaining homeostatic controls for brain tissue. 3. CSF is a medium for minor exchange of nutrients and waste products between the blood and adjacent nervous tissue.

Question 50

How and where is cerebrospinal fluid made

Answer 50

CSF is produced mainly by the choroid plexus epithelium and ependymal cells of the ventricles. CSF is derived from blood plasma and is largely similar to it, except that CSF is nearly protein-free. A filtered form of plasma moves from fenestrated capillaries in the choroid plexus into an interstitial space. This fluid then passes through the epithelium cells lining the choroid plexus. However] Unlike blood passing from the capillaries into the choroid plexus, the epithelial cells lining the choroid plexus contain tight junctions between cells, which act to prevent most substances flowing freely into CSF

Question 51

What is the blood brain barrier?

Answer 51

is the specialized system of brain endothelial cells that shields the brain from toxic substances in the blood, supplies brain tissues with nutrients, and filters harmful compounds from the brain back to the bloodstream.

Question 52

how does the blood brain barrier work?

Answer 52

the blood–brain barrier is formed by endothelial cells of the capillary wall, astrocyte and pericytes embedded in the capillary basement membrane.[2] This system allows the passage of some small molecules by passive diffusion, as well as the selective and active transport of various nutrients, ions, organic anions, and macromolecules such as glucose and amino acids

Question 53

How do the endothelial cells astrocytes and pericytes help the blood brain Barrier work?

Answer 53

In the capillaries that form the blood–brain barrier, endothelial cells are wedged extremely close to each other, forming so-called tight junctions. The tight gap allows only small molecules, fat-soluble molecules, and some gases to pass freely through the capillary wall and into brain tissue. Astrocytes that press up against capillaries are involved in this process by secreting chemicals that maintain the permeability characteristics of the tight junctions. The basement membrane contains pericytes that destroy certain chemicals(such as epinephrine) that would otherwise activate brain neurons.

Question 54

What are the three things that protect the spinal-cord?

Answer 54

Bone (The vertebrae) 2. Meninges 3. CSF Meniges similar structure to brain, dura mater (single layer), arachnoid matter, pia mater. CSF is in the subarachnoid space and central canal.

Question 55

What two things divide the spinal cord in to left and right sides?

Answer 55

Anteriorly ventral median fissure Posteriorly dorsal median sulcus

Question 56

Which is on the inside of the spinal-cord and which is on the outside? Grey or white matter?

Answer 56

Grey matter is at the centre of the spinal-cord and white matter outside

Question 57

The grey matter forms 2 to 3 horns depending on the segment of the spinal-cord. What are they and what do they do?

Answer 57

1. the dorsal horn is composed of interneurons which receives input from sensory neurons 2. the ventral horn is made up of somatic motor neurons which affect afferent voluntary movement 3. lateral horn which is only found in the thoracic and superior lumber segments & is responsible for autonomic or visceral motor neurons

Question 58

What does Grey matter do and what does white-matter do?

Answer 58

Gray matter largely functions to receive information and regulate outgoing information, as it contains the cell bodies of neurons. White matter, which is largely composed of axons, serves to transmit signals to other regions of the brain, spinal cord, and body

Question 59

The fibres of the white matter of the spinal-cord run in three directions what are they and what do they do?

Answer 59

1. Ascending which carries sensory inputs up to higher centres. 2. Descending which carries motor down the cord. 3. Transcending which carries information from one side of the cord to the other

Question 60

White-matter is divided into three columns what are they called?

Answer 60

The dorsal funiculus, the ventral funiculus, and the lateral funiculus

Question 61

What would happen if the dorsal root are damaged?

Answer 61

dorsal roots (posterior roots) allow sensory neurons to enter the spinal cord. If it they damaged, the sensory information may be altered or not transmitted at all

Question 62

What would happen if the ventral roots are damaged?

Answer 62

ventral roots (anterior roots) allow motor neurons to exit the spinal cord. Therefore if they were damaged, the pathway of motor information would be cut off.. Therefore, whatever effectors that spinal nerve controlled would no longer work; it would be paralyzed.

Question 63

What is polio myelitis (polio)?

Answer 63

It is an infectious disease caused by poliovirus. Most people who catches are asymptomatic but it can produce mild moderate and even severe effects including paralysis and death. Once viral reproduction is established in the mucosal surfaces of the nasopharynx, poliovirus can multiply in specialized cells in the intestines and enter the blood stream to invade the central nervous system, where it spreads along nerve fibres. When it multiplies in the nervous system, the virus can destroy nerve cells (motor neurons) which activate skeletal muscles

Question 64

what is amyotrophic lateral sclerosis?

Answer 64

ALS, is a progressive nervous system disease that affects nerve cells in the brain and spinal cord, causing loss of muscle control. ALS is often called Lou Gehrig’s disease, after the baseball player who was diagnosed with it

Question 65

What four things are common to most spinal tracks or neuron pathways?

Answer 65

The spinal tracts or make up neuron pathways and connect the brain to the rest of the body. Theyre signified by decussation, relay, somatotopy, and symmetry. Most pathways cross from one side of the CNS to the other, which is described as decussation. Most also consist of a chain of several neurons contributing to successive pathway tracts in the relay of information. Most pathways have a precise spatial relationship among tract fibers (somatotopy), which resemble the body’s ordered mapping. Ascend-ing sensory tracts, for example, fibers that transmit inputs from sensory receptors in superior regions of the body, lie lateral to others that convey sensory infor-mation from inferior body regions. There is ­symmetry to all pathways and tracts. One member of each pair is present on either side of the brain or spinal cord.

Question 66

What is the somatosensory system, senses and pathways?

Answer 66

Somatic senses allow you to feel sensations from the external environment such as pain, temperature, touch, as well as proprioceptive information from muscles and joints. Somatic Sensory Tracts are ascending and travel through the white matter of the spinal cord, carrying somatosensory information up to the brain.

Question 67

What are neural pathways?

Answer 67

Neural pathways are groups of nerve fibers which carry information between the various parts of the CNS. Neural pathways that connect the CNS and spinal cord are called tracts. Ascending tracts run from the spinal cord to the brain while descending tracts run from the brain to the spinal cord.

Question 68

How are tracts formed?

Answer 68

Tracts are formed by neurons synapsing onto one another, and these neurons can be classified as first-order, second-order and third-order neurons depending on their location and order within the tract.

Question 69

How do 1st, 2nd and 3rd order neurons relate?

Answer 69

Each ascending pathway follows the same general structure as first-order, second-order and third-order neurons. First-order neurons are afferent in nature. The sensory input from the receptors is sent through the peripheral nerve to the spinal/dorsal root ganglion. The body of the first-order neuron, within the ganglia, projects its axons to the posterior gray horn of the spinal cord. Here, it synapses with second-order neurons that ascend along the spinal cord and project onto third-order neurons which are found in the subcortical structures of the brain, such as the thalamus. These third-order neurons pick up the neural impulse and carry it on to the cerebral cortex.

Question 70

What does the posterior dorsal column medial lemniscal pathways do?

Answer 70

They carry fine and discriminative touch as well as proprioceptive sensations.

Question 71

What does the spinothalamic pathway do?

Answer 71

There are two spinothalamic tracts: anterior and lateral. The anterior spinothalamic tract transports course touch and pressure sensation. The lateral spinothalamic tract carries pain and temperature sensations.

Question 72

how is the information from the dorsal column and spinothalamic path ways integrated with movement? For example, how can our fingers follow the rim of a glass, or how can we walk in a coordinated fashion?

Answer 72

These actions occur with the help of our spinocerebellar tracts. Spinocerebellar tracts sense proprioception from muscle spindles, Golgi tendon organs and joint receptors. As a result, they are involved in movement coordination and posture maintenance.

Question 73

What do the descending pathways of the spinal-cord do?

Answer 73

They are motor pathways that travel through the white matter of the spinal cord carrying information from the brain to peripheral effectors, the skeletal muscles. The descending tracts are involved in voluntary motion, involuntary motion, reflexes and regulation of muscle tone

Question 74

What is the difference between the pyramidal an extra pyramidal descending pathways?

Answer 74

The corticospinal and corticobulbar tracts form the pyramidal tract, which is under voluntary control. The remaining tracts are grouped together into the extrapyramidal system, which is under involuntary control.

Question 75

What do The corticospinal and corticobulbar tracts from the pyramidal tract do?

Answer 75

The corticospinal tract is involved with the speed and agility of voluntary movements. Corticobulbar tract controls the activity of muscles of the head, face and neck.

Question 76

Provide more detail about what the extra pyramidal descending tract does

Answer 76

The reticulospinal tract, which is part of this involuntary system, helps with motor regulation by facilitating or inhibiting voluntary and reflex actions. For example it helps maintain posture. It is also involved in breathing. The tectospinal tract is responsible for controlling the movement of the head in response to auditory and visual stimuli. The rubrospinal tract is considered to be responsible for the mediation of fine involuntary movement

Question 77

Explain how the neurons work in the descending pathways

Answer 77

Because the second-order neurons are insignificant, we use only a two-order system for the descending (motor) tracts. This way, the first neuron in the pathway (the upper motor neuron) arises in the cerebral cortex or brainstem, descends along the spinal cord and synapses in the anterior gray horn. The second neuron in the pathway (lower motor neuron) leaves the spinal cord through the anterior(ventral) root. In the cervical, brachial and lumbosacral regions the anterior roots combine to form the so-called nerve plexuses. Peripheral nerves emerge from the distal aspect of these plexus, or in the case of the thoracic region directly from the anterior roots. These efferent neurons subsequently travel all the way to a specific skeletal muscle or muscle group (myotome), innervating them.

Question 78

Name three clinical homoeostatic imbalances

Answer 78

1. Cerebral palsy 2. anencephaly 3. spina bifida

Question 79

What is cerebral palsy?

Answer 79

A neuromuscular disability in which the voluntary muscles are poorly controlled or paralysed as a result of brain damage. May be caused by a lack of oxygen during delivery. Can lead to spasticity speech difficulties (including some degree of deafness) Motor impairments and seizures

Question 80

What is anencephaly?

Answer 80

it’s where the cerebrum and part of the brain stem never develop in utero. The child is totally vegetative, unable to process sensory inputs and no voluntary movements possible. Child will be stillborn or die within hours of birth.

Question 81

What is spina bifida?

Answer 81

is a birth defect that occurs when the spine and spinal cord don’t form properly.
People with spina bifida higher on the spine (near the head) might have paralyzed legs.
Those with spina bifida lower on the spine (near the hips) might have more use of their legs and use crutches, braces, or walkers, or they might be able to walk without these devices.

Question 82

What does the cerebellum do?

Answer 82

It helps with the controls voluntary movements such as:
walking.
posture.
eye movements.
speech.

Question 82

What does the cerebellum do?

Answer 82

It helps with the controls voluntary movements such as:
walking.
posture.
eye movements.
speech.

Question 82

What does the cerebellum do?

Answer 82

It helps with the controls voluntary movements such as:
walking.
posture.
eye movements.
speech.