Brain & Cranial Nerves

Question 1

Principle parts of brain

Answer 1

• cerebrum
• diencephalon
  
  • thalamus and hypothalamus
• cerebellum
• brainstorm
  
  • medulla oblongata
  • pons
  • midbrain

Question 2

Protective Coverings of brain

Answer 2

• bone, meninges & fluid
• meninges same as around spinal cord
  
  • dura mater
  • arachnoid mater
  • pia mater

Question 3

Medulla Oblongata

Answer 3

• continuation of spinal cord
• ascending sensory tracts
• descending motor tracts
• cardiovascular centre
  
  • force & rate of heart beat
  • diameter of blood vessels
• respiratory centre
  
  • medullary rhythmicity area sets basic rhythm of breathing

Question 4

Central surface of medulla oblongata

Answer 4

• ventral surface bulge
  
  • pyramids - large motor tract
• decussation of most fibres
  
  • left cortex controls right muscles

Question 5

Dorsal surface of medulla oblongata

Answer 5

• nucleus gracious and nucleus cuneatus: sensory neurons

- relay information to thalamus on opposite side of brain

Question 6

Pons

Answer 6

• white fibre tracts ascend and descend
• pontine nuclei located in bulb of pons
• middle cerebellar peduncles carry cortical inputs to cerebellum
• bridge between cerebella hemispheres

Question 7

Midbrain

Answer 7

• superior and inferior colliculi
• extends from pons to diencephalon
• cerebral aqueduct connects 3rd ventricle above to 4th ventricle below

Question 8

Midbrain in section

Answer 8

• superior to colliculus
• substantial Nigra: help control subconscious muscle activity
• cerebral peduncles: contain descending axons from cerebral cortex

Question 9

Diencephalon

Answer 9

• surrounds 3rd ventricle
• superiors part is in the thalamus
• inferior part is in the hypothalamus

Question 10

Thalamic Nuclei

Answer 10

• Nuclei have different roles
  
  • relay auditory and visual impulses, taste, and somatic sensations
  • receives impulses from cerebellum and basal ganglia

Question 11

Hypothalamus

Answer 11

• dozen or so nuclei located ventral to thalamus
• controls autonomic functions - cardiorespiratory
• has direct and indirect influences on endocrine system
• plays an important role in emotions and behaviour and learning and memory (anger, pleasure, feeding, drinking and sleep)

Question 12

Cerebrum (cerebral cortex and basal nuclei

Answer 12

• cerebral cortex is gray matter overlying white matter
  
  • fold (gyri) and grooves (sulci) or fissures
• longitudinal fissure separates left hemisphere and right hemisphere
• gyri increase surface area

Question 13

Corpus callous

Answer 13

-band of white matter connecting left and right cerebral hemispheres

Question 14

Cerebrum

Answer 14

• each hemisphere is subdivided into lobes
• frontal lobe
• central sulcus (precentral and postcentral gyrus)
• parietal lobe
• parieto-occipital sulcus
• occipital lobe
• lateral sulcus
• temporal lobe

Question 15

Functional organization of cerebral cortex

Answer 15

• sensory areas: receive and interpret sensory and impulses
• motor areas: initiate movements
• association areas: integrative functions such as memory, emotions, reasoning, will, judgment, personality and intelligence

Question 16

Areas of cerebral cortex for speech and language

Answer 16

• Broca’s areas (in frontal lobe) formulates words for speech
• wernicke’s area (in temporal lobe) for interpretation of spoken words
• angular and supramarginal gyrus: integration

Question 17

Hemispheric lateralization

Answer 17

• although the 2 hemispheres share performance of many functions, each hemisphere also specializes in performing certain unique functions
• language is lateralized: hemisphere that is more important for the comprehension and production of language is called the dominant hemisphere
• non-dominant hemisphere although inferior in language functions superior in other functions

Question 18

Basal Nuclei

Answer 18

• control large autonomic movements of skeletal muscles, such as those used for standing and walking
• caudate, putamen and globus pallidus

Question 19

Lambic system

Answer 19

• medial fringe of brain, includes cortical and subcritical structures
• emotional brain: intense pleasure and intense pain
• strong emotions increase efficiency of memory

Question 20

Cerebellum

Answer 20

• 2 cerebellar hemispheres and vermis (central area)
• folia (gyri) and fissures and sulci
• correct voluntary muscle contraction and posture based on sensory data from body about actual movements
• sense of equilibrium
• concerned with:
  
  • coordination of muscular activity –> ataxia (in-coordination of movement)
  • propioception –> hypotonia and tremor
  • equilibrium –> vertigo

Question 21

Cerebellar Peduncles

Answer 21

• superior, middle, and inferior peduncles attach to brain stem
• inferior carries sensory information from spinal cord
• middle carries input from cerebral cortex and basal ganglia
• superior carries output to brain stem and thalamus

Question 22

Ventricular system

Answer 22

• system of spaces filled with CSF
• lateral ventricles
• 3rd ventricle
• 4th ventricle

Question 23

CSF

Answer 23

• 80-150ml
• clear liquid containing glucose, proteins, and ions
• mechanical protections: floats brain & softens impact with bony walls
• chemical protection: optimal ionic concentration for action potentials
• circulation: nutrients and waste products to and from bloodstream

Question 24

Origin of CSF

Answer 24

• made by choroid plexus (ependymal cells and capillaries
• located in lateral, 3rd and 4th ventricles
• cerebral aqueduct connects 3rd and 4th ventricles

Question 25

Drainage of CSF from ventricles

Answer 25

-one median aperture and 2 lateral apertures allow CSF to exit from the interior of the brain

Question 26

Reabsorption of CSF

Answer 26

- reabsorbed through arachnoid villi - grapelike clusters of arachnoid penetrate rural venous sinus - 20ml/hr reabsorption rate: same as production rate

Question 27

Blood supply to brain

Answer 27

- internal carotid arteries (contribute to circle of Willis) - vertebral arteries (contribute to circle of willis) - anastomotic network of arteries at base of brain - arterial blood supply is branches from circle of Willis on base of brain (internal carotid and vertebral arteries) - vessels on surface of brain: penetrate tissue - uses 20% of our bodies oxygen and glucose needs - blood flow to an area increases with activity in that area - deprivation of O2 for more than 4 mins does permanent damage - at that time lysosomes release enzymes

Question 28

Cerebrovascular accident (CVA)

Answer 28

-abrupt onset of neurological symptoms, such as paralysis or loss of sensation, that arise from destruction of brain tissue following intracerebral hemorrhage, emboli (blood clots), and atherosclerosis (formation of cholesterol-containing plaques that block blood flow) of the cerebral arteries

Question 29

Blood-brain barrier

Answer 29

- protects cells from some toxins and pathogens - proteins and antibiotics cannot pass but alcohol and anesthetics do - tight junctions seal together endothelial cells, continuous basement membrane, astrocytes processes covering capillaries

Question 30

Cranial Nerves

Answer 30

- 12 pairs of cranial nerves - most originate from brain stem and pass through foramina in skull - Olfactory (i) bulb - optic (ii) nerve - oculomotor (iii) nerve - trochlear (iv) nerve - trigeminal (v) nerve - abducens (vi) nerve - Facial (vii) nerve - vestibulocochlear (viii) nerve - glossopharyngeal (ix) nerve - vagus (x) nerve - accessory (xi) nerve - hypoglossal (xii) nerve

Question 31

Trigeminal Nerve (CN V)

Answer 31

- motor portion: muscles of mastication - sensory portion: touch, pressure, pain & temp receptors of the face - ophthalmic branch - maxillary branch - mandibular branch