1. The Central Nervous System
Brain II
Cranial Nerves
94 min, 51 slides

2. Lecture Overview Review/Questions from last lecture (Brain I)
Brain II (pp )
Cerebrum
Myelinated tracts
Basal ganglia
Sensory areas
Motor areas
Brain coverings (meninges)
Cerebrospinal fluid (CSF)
Ventricular System
Cranial nerves

3. Review of Major Brain Areas12 1 2 3 11 4 5 6
10 (White part) 7 8 9

4. Summary from Last Lecture
Part of Brain
Major Function
Brainstem
Medulla Oblongata
(Embryology?)
(Ventricles nearby?)
Contains cardiac, vasomotor, and respiratory control centers
Nucleus gracilis/cunneatus
Origin of CN 9, 10, 11, 12
Pons
Bridge between medulla and midbrain via transverse tracts (to cerebellum) and longitudinal tracts(to medulla/midbrain)
Helps regulate rate and depth of breathing
Origin of CN 5, 6, 7, 8
Midbrain
Major connecting center between spinal cord and brain and parts of brainstem
Contains corpora quadrigemina (visual and auditory reflexes)
Origin of CN 3 and 4
Location of red nucleus (rubrospinal tract)
Origin of substantia nigra
Cerebellum
Subconscious coordination of skeletal muscle activity, maintains posture
Hemispheres separated by falx cerebelli and vermis
Cerebellar peduncles (sup, middle, inf) attach to rest of brainstem
Diencephalon (Embryology?)
Thalamus
gateway (relay) for sensory impulses heading to cerebral cortex; hearing, vision, taste
Crude interpretation for pain, touch, pressure, and temperature
relay for motor information (voluntary)
Forms walls of third ventricle
Hypothalamus
Vital functions associated with homeostasis, ANS, psychosomatic illness, feeding/satiety
Connected to pituitary by infundibulum (pituitary stalk)

5. Brain - Cerebrum
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013
Over 85% of brain mass, with about 14 billion multipolar neurons in cortex
Lobes names for overlying bones. (See sulci above for divisions)

6. Brain - Cerebrum Lateral Sulcus
Upper figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013
Lateral Sulcus
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013

7. Dural Folds
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013
Falx Cerebri – within longitudinal fissure; separates cerebral hemispheres
Tentorium Cerebelli – above cerebellum; separates occipital lobe from cerebellum

8. Myelinated Tracts of Cerebrum
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013
Three types of myelinated tracts form cerebral white matter:
1. Association – same hemisphere
2. Commisural – between corresponding gyri in opposite hemispheres (corpus callosum)
3. Projection (Projector) – Ascending and descending tracts

9. Basal Nuclei (formerly basal ganglia)
nuclei are masses of gray matter in CNS
deep within cerebral hemispheres
three nuclei: caudate nucleus and putamen, (together called the striatum), and the globus pallidus
subconscious control certain muscular activities, e.g., learned movement patterns
Receive input from cerebral cortex, other subcortical nuclei, and each other. Output is through thalamus and (along with output from substantia nigra of midbrain) goes to the premotor and prefrontal cortex to influence muscle movement directed by primary motor cortex. Also seem to filter out incorrect or inappropriate responses of cognition and emotion.
Receive input from entire cerebral cortex.
Relay motor impulses originating in the substantia nigra (where is this?), along with their own output, through the thalamus to the motor cortex to influence muscle movement.

10. Basal Nuclei – Transparent View
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013

11. Brain – Sensory and Motor Areas* 4 6 1 5 8 7 2 3 9 40
(Gnostic) 44 39 22 10 42 18 43 41 19 17
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013
*Somatosensory (in figure) = Somesthetic (in your notes)

12. Meninges of the Brain *Singular of meninges is meninx
Dura mater – thick, collagenous membrane (about thickness of rubber kitchen glove)
Arachnoid mater – simple squamous epithelium; loose meshwork of collagenous and elastic fibers spanning the gap (subarachnoid space)
Pia mater – delicate membrane, close follows contours of nervous tissue that it covers.
- dura mater – outer, tough (anchoring dural folds)
- arachnoid mater – web-like
- pia mater – inner, delicate
*Singular of meninges is meninx
- Subdural space – like interstitial fluid
- Subarachnoid space – CSF
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013

13. Cerebrospinal Fluid
~500 ml/day secreted by choroid plexus of ventricles; only ~120 ml present in subarachnoid space at one time
circulates in all ventricles, cerebral aqueduct, central canal of spinal cord, and subarachnoid space
completely surrounds brain and spinal cord
clear liquid (more Na+ and Cl-, but less K+, Ca2+, glucose, and protein than plasma)
nutritive and protective (shock absorber)
About 500 ml of CSF produced per day; about ml present at any time.

14. Flow of CSF (Luscka) (Magendie) (Monro)
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013

15. Ventricles of the Brain
interconnected cavities
within cerebral hemispheres and brain stem
continuous with central canal of spinal cord
filled with cerebrospinal fluid (CSF)
lateral ventricles (2)
rt/lt cerebral hemispheres
under corpus callosum
third ventricle (1)
between thalamus
fourth ventricle (1)
between cerebellum and pons
cerebral aqueduct connect 3rd and 4th

16. Divisions of the Nervous System
You are here
CNS
PNS

17. Peripheral Nervous System
Cranial nerves arising from the brain
Somatic fibers connecting to the skin and skeletal muscles
Autonomic fibers connecting to viscera
Spinal nerves arising from the spinal cord
Somatic fibers connecting to the skin and skeletal muscles
Autonomic fibers connecting to viscera

18. Cranial Nerves
Paired. Numbered (roughly) in the order of their occurrence from anterior to posterior. Abbreviated using N or CN.
Figure from: Hole’s Human A&P, 12th edition, 2010

19. The Cranial Nerves Numeral Name Function
Sensory, Motor, or Both (Mixed Nerve) I
OLFACTORY (OLD)
OLFACTION/SMELL
SENSORY (SOME)  II
OPTIC (OPIE)
VISION
SENSORY (SAY) 
III
OCULOMOTOR (OCCASIONALLY)
MOVE EYE; ACCOMMODATION; PUPIL SIZE
MOTOR (MARRY) IV
TROCHLEAR (TRIES)
MOVE EYE (superior oblique)
MOTOR (MONEY) V
TRIGEMINAL (TRIGONOMETRY)
MAJOR SENSORY NERVE FROM FACE; MASTICATION (chewing)
BOTH (BUT) VI
ABDUCENS (AND)
MOVE EYE (lateral rectus)
MOTOR (MY)
VII
FACIAL (FEELS)
MAJOR MOTOR NERVE OF FACE
BOTH (BROTHER)
VIII
VESTIBULOCOCHLEAR (VERY) (ACOUSTIC)
HEARING AND EQUILIBRIUM
SENSORY (SAYS)  IX
GLOSSOPHARYNGEAL (GLOOMY)
MOVE MUSCLES OF TONGUE AND PHARYNX; CIRCULATORY AND ESPIRATORY REFLEXES
BOTH (BIG) X
VAGUS (VAGUE)
INNERVATE VISCERAL SMOOTH MUSCLE; MUSCLES OF SPEECH; CVS REFLEXES
BOTH (BOOBS) XI
ACCESSORY (AND)
MOVE NECK MUSCLES
MOTOR (MATTER)
XII
HYPOGLOSSAL (HYPOACTIVE)
MOVE TONGUE; SPEECH, MASTICATION, DELGLUTITION (swallowing)
MOTOR (MOST)

20. Cranial Nerves I and II Olfactory (I) sensory
fibers transmit impulses associated with smell
Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Optic (II)
sensory
fibers transmit impulses associated with vision

21. Cranial Nerves III, IV, and VI
Abducens (VI)
primarily motor
origin in pons
motor impulses to the lateral rectus (LR) muscles that move the eyes
Oculomotor (III)
primarily motor
origin in midbrain
motor impulses to muscles that
raise eyelids
move the eyes
focus lens
adjust pupil size
Trochlear (IV)
primarily motor
origin in midbrain
motor impulses to the superior oblique (SO) muscles that move the eyes
What’s a ganglion?
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

22. Cranial Nerve V Major sensory nerve of face Trigeminal (V)
both sensory and motor
origin in pons
opthalmic division
sensory from surface of eyes (cornea), tear glands, scalp, forehead, and upper eyelids
maxillary division
sensory from upper teeth, upper gum, upper lip, palate, and skin of face
mandibular division
sensory from scalp, skin of jaw, lower teeth, lower gum, and lower lip
motor to muscles of mastication and muscles in floor of mouth
Figure from: Hole’s Human A&P, 12th edition, 2010
Major sensory nerve of face

23. Cranial Nerve VII Major MOTOR nerve of face Facial (VII)
Figures From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013
Facial (VII)
both sensory and motor
sensory from taste receptors (ant. 2/3 tongue)
motor to muscles of facial expression, orbicularis oculi, tear glands, and submandibular and sublingual salivary glands
Major MOTOR nerve of face

24. Cranial Nerves VIII and IX
Vestibulocochlear (VIII)
sensory
origin in pons
sensory from equilibrium receptors of ear
sensory from hearing receptors
Glossopharyngeal (IX)
both sensory and motor
origin in medulla
sensory from pharynx, tonsils, tongue (post. 1/3), and carotid arteries
motor to parotid salivary gland and muscles of pharynx
Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001

25. Cranial Nerve X Vagus (X) both sensory and motor origin in medulla
somatic motor to muscles of speech and swallowing
autonomic motor (parasympathetic) to viscera of thorax and abdomen
CVS and respiratory reflexes
sensory from pharynx, larynx, esophagus, and viscera of thorax and abdomen
Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

26. Cranial Nerves XI and XII
Accessory (XI)
primarily motor
origin in medulla/spinal cord
motor to muscles of soft palate, pharynx, larynx, neck (sternocleidomastoid), and back (trapezius)
Hypoglossal (XII)
primarily motor
origin in medulla
motor to muscles of the tongue
impt in speech, mastication, and deglutition
Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004

27. Limbic System The motivational system Consists of
portions of frontal lobe
portions of temporal lobe
hypothalamus
thalamus
basal nuclei
other deep nuclei
associated with sense of smell (less significant)
Functions
controls emotions
produces feelings
interprets sensory impulses
facilitates memory storage and retrieval (learning!)
Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007
The motivational system