Bio211 Lecture 19

1
The Central Nervous System Brain II Cranial
Nerves
2
Lecture Overview

• Review/Questions from last lecture (Brain I)
• Brain II (pp. 84-87)
• Cerebrum
• Myelinated tracts
• Basal ganglia
• Sensory areas
• Motor areas
• Brain coverings (meninges)
• Cerebrospinal fluid (CSF)
• Ventricular System
• Cranial nerves

3
Review of Major Brain Areas
12
1
2
3
11
4
5
10 (White part)
6
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 (Embryology?) (Ventricles nearby?) 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 (Embryology?) (Ventricles nearby?) 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 (Embryology?) (Ventricles nearby?) 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?) (Ventricles nearby?)  
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
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

1. Receive input from entire cerebral cortex.
2. 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
3
2
9
40
(Gnostic)
44
39
22
18
42
10
41
43
17
19
Figure From Marieb Hoehn, Human Anatomy
Physiology, 9th ed., Pearson, 2013
Somatosensory (in figure) Somesthetic (in
your notes)
12
Meninges of the Brain
- 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)

14
Flow of CSF
(Monro)
(Luscka)
(Magendie)
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 Holes Human AP, 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

Whats a ganglion?
Figure from Martini, Anatomy Physiology,
Prentice Hall, 2001
22
Cranial Nerve V

• 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 Holes Human AP, 12th edition, 2010
Major sensory nerve of face
23
Cranial Nerve 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

• 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