1. Brain & Cranial Nerves

2. The Brain Ranges from 750 cc to 2100 cc
Contains almost 98% of the body’s neural tissue
Average weight about 1.4 kg (3 lb)

3. 6 Major Regions of the Brain
Cerebrum
Cerebellum
Diencephalon
Mesencephalon
Pons
Medulla oblongata

4. The Brain

5. Cerebrum Largest part of brain Controls higher mental functions
Divided into left and right cerebral hemispheres
Surface layer of gray matter (neural cortex)

6. Cerebral Cortex

7. 3 Functional Principles of the Cerebrum
1. Each cerebral hemisphere receives sensory information from, and sends motor commands to, the opposite side of body

8. 3 Functional Principles of the Cerebrum
2. The 2 hemispheres have different functions although their structures are alike

9. 3 Functional Principles of the Cerebrum
3. Correspondence between a specific function and a specific region of cerebral cortex is not precise

10. Motor & Sensory Areas of the Cerebral Cortex
Where are the motor, sensory, and association areas of the cerebral cortex, and what are their functions?

11. Central sulcus separates motor and sensory areas

12. Motor Areas Precentral gyrus of frontal lobe:
directs voluntary movements
Primary motor cortex:
is the surface of precentral gyrus
Pyramidal cells:
are neurons of primary motor cortex

13. Sensory Area Postcentral gyrus of parietal lobe:
receives somatic sensory information (touch, pressure, pain, vibration, taste, and temperature)
Primary sensory cortex:
surface of postcentral gyrus

14. Special Sensory Cortexes
Visual cortex:
information from sight receptors
Auditory cortex:
information from sound receptors
Olfactory cortex:
information from odor receptors
Gustatory cortex:
information from taste receptors

15. Sensory Association Areas
Somatic sensory association area:
interprets input to primary sensory cortex (e.g., recognizes and responds to touch)
Visual association area:
interprets activity in visual cortex
Auditory association area:
monitors auditory cortex

16. Other Integrative Areas
Speech center:
is associated with general interpretive area
coordinates all vocalization functions
Prefrontal cortex of frontal lobe:
integrates information from sensory association areas
performs abstract intellectual activities (e.g., predicting consequences of actions)

17. Hemispheric Lateralization
Functional differences between left and right hemispheres
Each cerebral hemisphere performs certain functions not performed by the opposite hemisphere

18. The Left Hemisphere
In most people, left brain (dominant hemisphere) controls:
reading, writing, and math
decision-making
speech and language

19. The Right Hemisphere Right cerebral hemisphere relates to:
senses (touch, smell, sight, taste, feel)
recognition (faces, voice inflections)

20. Cerebellum Second largest part of brain
Coordinates repetitive body movements
2 hemispheres
Covered with cerebellar cortex

21. The Cerebellum
An autonomic processing center

22. Functions of the Cerebellum
Adjusts postural muscles
Fine-tunes conscious and subconscious movements

23. Structures of the Cerebellum

24. Structures of the Cerebellum
Folia:
surface of cerebellum
highly folded neural cortex
Anterior and posterior lobes:
separated by primary fissure

25. Structures of the Cerebellum
Cerebellar hemispheres:
separated at midline by vermis
Vermis:
narrow band of cortex
Flocculonodular lobe:
below fourth ventricle

26. Purkinje Cells Large, branched cells Found in cerebellar cortex
Receive input from up to 200,000 synapses

27. Arbor vitae Highly branched, internal white matter of cerebellum
Cerebellar nuclei:
embedded in arbor vitae
relay information to Purkinje cells

28. The Peduncles
Tracts link cerebellum with brain stem, cerebrum, and spinal cord:
superior cerebellar peduncles
middle cerebellar peduncles
inferior cerebellar peduncles

29. Diencephalon
Composed of
Epithalmus
Hypothalamus
thalamus

30. The Thalamus Final relay point for ascending sensory information
Coordinates the activities of the cerebral cortex

31. Hypothalamus Controls somatic motor activities subconsciously
Rage, pleasure, pain, & sexual arousal
Controls autonomic function
Regulate heart rate, blood pressure, respiration, & digestive function
Coordinates activities of the nervous and endocrine systems
Inhibits or stimulates endocrine cells in the pituitary gland

32. Hypothalmus cont. Secrete 2 hormones
Antidiuretic hormone – restricts water loss at the kidneys
Oxytocin –stimulates smooth muscle contractions
Uterus/mammary glands
Prostrate gland
Produce emotions & behavioral drives
Feeding center, thirst center

33. Hypothalmus cont. Coordinate voluntary & autonomic functions
Think about a dangerous situation
Heart rate increases, respiratory rate goes up
Regulates body temperature
If temp. falls instructions sent to medulla oblongata to dialate blood vessels
Controls Circadian rhythms
24 hour, day-night cycle
Retina of the eye

34. Medulla Oblongata
Connects brain and spinal cord

35. The Pons Sensory & motor nuclei for 4 cranial nerves
Nuclei that help control respiration
Nuclei & tracts linking the cerebellum with the brain stem, cerebrum, and spinal cord
Ascending, descending & transverse tracts

36. Cranial Nerves I – olfactory nerves – sensory
Sense of smell
II – optic nerves – sensory
Visual information
III – oculomotor – motor
Motor eye movements
IV – Trochlear Nerves – motor
Superior oblique muscle

37. Cranial Nerves V - Trigeminal Nerves - mixed, sensory
Motor – jaw, mastication, eyelid, eyebrow, lips, gums. teeth, cheek
Sensory – forehead, palate, nasal cavity
VI - Abducen Nerves - motor
Motor eye movement, lateral rectus
VII - Facial – mixed
Sensory – anterior 2/3 of tongue
Motor – lacrimal gland, nasal mucous gland, submandibular & sublingual salivary glands

38. Cranial Nerves VIII – Vestibulocochlear Nerves - sensory
Special sensory – balance & equilibrium, hearing
IX – Glossopharyngeal – mixed
Sensory – posterior 1/3 of tongue, part of the pharynx & palate, carotid arteries
Motor – pharyngeal muscles, parotid salivary gland

39. Cranial Nerves X – Vagus – mixed XI – Accessory Nerves - motor
Sensory – pharynx, diaphragm,
Motor – pharyngeal muscles, visceral organs in thorax & abdominal cavity
XI – Accessory Nerves - motor
Muscles of neck & upper back
XII – Hypoglossal Nerves – motor
Tongue movement