1. Hypothalamic Function
Regulates body temperature, food intake, water balance, and thirst
Regulates sleep and the sleep cycle
Controls release of hormones by the anterior pituitary
Produces posterior pituitary hormones

2. Pineal gland—extends from the posterior border and secretes melatonin
Epithalamus
Most dorsal portion of the diencephalon; forms roof of the third ventricle
Pineal gland—extends from the posterior border and secretes melatonin
Melatonin—helps regulate sleep-wake cycles

3. Cerebral hemisphere Septum pellucidum Corpus callosum Interthalamic
adhesion
(intermediate
mass of
thalamus)
Fornix
Choroid plexus
Thalamus
(encloses third
ventricle)
Interven-
tricular
foramen
Posterior commissure
Pineal gland
(part of epithalamus)
Anterior
commissure
Corpora
quadrigemina
Mid-
brain
Hypothalamus
Cerebral
aqueduct
Optic chiasma
Arbor vitae (of
cerebellum)
Pituitary gland
Fourth ventricle
Mammillary body
Choroid plexus
Pons
Cerebellum
Medulla oblongata
Spinal cord
Figure 12.12

4. Brain Stem
Three regions
Midbrain
Pons
Medulla oblongata

5. Brain Stem
Similar structure to spinal cord but contains embedded nuclei
Controls automatic behaviors necessary for survival
Contains fiber tracts connecting higher and lower neural centers
Associated with 10 of the 12 pairs of cranial nerves

6. Frontal lobe Olfactory bulb (synapse point of cranial nerve I)
Optic chiasma
Optic nerve (II)
Optic tract
Mammillary body
Midbrain
Pons
Temporal lobe
Medulla
oblongata
Cerebellum
Spinal cord
Figure 12.14

7. Oculomotor nerve (III) Trochlear nerve (IV)
View (a)
Optic chiasma
Optic nerve (II)
Diencephalon
Crus cerebri of
cerebral peduncles
(midbrain)
• Thalamus
• Hypothalamus
Thalamus
Mammillary body
Diencephalon
Hypothalamus
Oculomotor nerve (III)
Midbrain
Pons
Brainstem
Trochlear nerve (IV)
Medulla
oblongata
Trigeminal nerve (V)
Middle cerebellar
peduncle
Pons
Facial nerve (VII)
Abducens nerve (VI)
Vestibulocochlear
nerve (VIII)
Glossopharyngeal nerve (IX)
Hypoglossal nerve (XII)
Pyramid
Vagus nerve (X)
Ventral root of first
cervical nerve
Accessory nerve (XI)
Decussation of pyramids
Spinal cord
(a) Ventral view
Figure 12.15a

8. Superior cerebellar peduncle Pons Middle cerebellar peduncle
Crus cerebri of
cerebral peduncles
(midbrain)
Thalamus
View (b)
Infundibulum
Superior colliculus
Pituitary gland
Inferior colliculus
Trochlear nerve (IV)
Trigeminal nerve (V)
Superior cerebellar peduncle
Pons
Middle cerebellar peduncle
Facial nerve (VII)
Inferior cerebellar peduncle
Abducens nerve (VI)
Vestibulocochlear nerve (VIII)
Glossopharyngeal nerve (IX)
Olive
Hypoglossal nerve (XII)
Thalamus
Vagus nerve (X)
Diencephalon
Hypothalamus
Accessory nerve (XI)
Midbrain
Pons
Brainstem
Medulla
oblongata
(b) Left lateral view
Figure 12.15b

9. • Superior cerebellar peduncle Pons • Middle cerebellar peduncle
Thalamus
View (c)
Diencephalon
Midbrain
• Superior colliculus
Corpora
quadrigemina
of tectum
• Inferior colliculus
• Trochlear nerve (IV)
Pineal gland
• Superior cerebellar peduncle
Pons
• Middle cerebellar peduncle
Medulla oblongata
Anterior wall of
fourth ventricle
• Inferior cerebellar peduncle
• Facial nerve (VII)
• Vestibulocochlear nerve (VIII)
Choroid plexus
(fourth ventricle)
• Glossopharyngeal nerve (IX)
• Vagus nerve (X)
• Accessory nerve (XI)
Dorsal median sulcus
Thalamus
Dorsal root of
first cervical nerve
Diencephalon
Hypothalamus
Midbrain
Pons
Brainstem
(c) Dorsal view
Medulla
oblongata
Figure 12.15c

10. Located between the diencephalon and the pons
Midbrain
Located between the diencephalon and the pons
Cerebral peduncles
Contain pyramidal motor tracts
Cerebral aqueduct
Channel between third and fourth ventricles

11. Midbrain Nuclei
Nuclei that control cranial nerves III (oculomotor) and IV (trochlear)
Corpora quadrigemina—domelike dorsal protrusions
Superior colliculi—visual reflex centers
Inferior colliculi—auditory relay centers
Substantia nigra—functionally linked to basal nuclei
Red nucleus—relay nuclei for some descending motor pathways and part of reticular formation

12. Superior Tectum Dorsal colliculus Periaqueductal gray matter
Cerebral aqueduct
Oculomotor
nucleus (III)
Reticular formation
Medial
lemniscus
Red
nucleus
Substantia
nigra
Fibers of
pyramidal tract
Ventral
Crus cerebri of
cerebral peduncle
(a) Midbrain
Figure 12.16a

13. Pons Forms part of the anterior wall of the fourth ventricle
Fibers of the pons
Connect higher brain centers and the spinal cord
Relay impulses between the motor cortex and the cerebellum
Origin of cranial nerves V (trigeminal), VI (abducens), and VII (facial)
Some nuclei of the reticular formation
Nuclei that help maintain normal rhythm of breathing

14. Fourth ventricle Reticular formation Superior cerebellar peduncle
Trigeminal main
sensory nucleus
Trigeminal
motor nucleus
Middle
cerebellar
peduncle
Pontine
nuclei
Trigeminal
nerve (V)
Fibers of
pyramidal
tract
Medial lemniscus
(b) Pons
Figure 12.16b

15. Medulla Oblongata
Joins spinal cord at foramen magnum
Forms part of the ventral wall of the fourth ventricle
Contains a choroid plexus of the fourth ventricle
Pyramids—two ventral longitudinal ridges formed by pyramidal tracts
Decussation of the pyramids—crossover of the corticospinal tracts

16. Medulla Oblongata
Inferior olivary nuclei—relay sensory information from muscles and joints to cerebellum
Cranial nerves VIII, X, and XII are associated with the medulla
Vestibular nuclear complex—mediates responses that maintain equilibrium
Several nuclei (e.g., nucleus cuneatus and nucleus gracilis) relay sensory information

17. Autonomic reflex centers Cardiovascular center
Medulla Oblongata
Autonomic reflex centers
Cardiovascular center
Cardiac center adjusts force and rate of heart contraction
Vasomotor center adjusts blood vessel diameter for blood pressure regulation

18. Medulla Oblongata Respiratory centers Generate respiratory rhythm
Control rate and depth of breathing, with pontine centers

19. Additional centers regulate
Medulla Oblongata
Additional centers regulate
Vomiting
Hiccuping
Swallowing
Coughing
Sneezing

20. Hypoglossal nucleus (XII) Dorsal motor nucleus of vagus (X)
Fourth ventricle
Solitary
nucleus
Choroid
plexus
Hypoglossal nucleus (XII)
Dorsal motor nucleus
of vagus (X)
Vestibular nuclear
complex (VIII)
Inferior cerebellar
peduncle
Cochlear
nuclei (VIII)
Lateral
nuclear
group
Nucleus
ambiguus
Medial
nuclear
group
Reticular formation
Inferior olivary
nucleus
Raphe
nucleus
Pyramid
Medial lemniscus
(c) Medulla oblongata
Figure 12.16c

21. The Cerebellum
11% of brain mass
Dorsal to the pons and medulla
Subconsciously provides precise timing and appropriate patterns of skeletal muscle contraction

22. Anatomy of the Cerebellum
Two hemispheres connected by vermis
Each hemisphere has three lobes
Anterior, posterior, and flocculonodular
Folia—transversely oriented gyri
Arbor vitae—distinctive treelike pattern of the cerebellar white matter

23. Anterior lobe Cerebellar cortex Arbor vitae Cerebellar peduncles
Posterior
lobe
• Superior
• Middle
Choroid
plexus of
fourth
ventricle
• Inferior
Medulla
oblongata
Flocculonodular
lobe
(b)
Figure 12.17b

24. Anterior
lobe
Posterior
lobe
(d)
(d)
Vermis
Figure 12.17d

25. All fibers in the cerebellum are ipsilateral
Cerebellar Peduncles
All fibers in the cerebellum are ipsilateral
Three paired fiber tracts connect the cerebellum to the brain stem
Superior peduncles connect the cerebellum to the midbrain
Middle peduncles connect the pons to the cerebellum
Inferior peduncles connect the medulla to the cerebellum

26. Cerebellar Processing for Motor Activity
Cerebellum receives impulses from the cerebral cortex of the intent to initiate voluntary muscle contraction
Signals from proprioceptors and visual and equilibrium pathways continuously “inform” the cerebellum of the body’s position and momentum
Cerebellar cortex calculates the best way to smoothly coordinate a muscle contraction
A “blueprint” of coordinated movement is sent to the cerebral motor cortex and to brain stem nuclei

27. Cognitive Function of the Cerebellum
Recognizes and predicts sequences of events during complex movements
Plays a role in nonmotor functions such as word association and puzzle solving

28. Protection of the Brain
Bone (skull)
Membranes (meninges)
Watery cushion (cerebrospinal fluid)
Blood-brain barrier

29. Meninges
Cover and protect the CNS
Protect blood vessels and enclose venous sinuses
Contain cerebrospinal fluid (CSF)
Form partitions in the skull

30. Meninges
Three layers
Dura mater
Arachnoid mater
Pia mater

31. Skin of scalp Periosteum Bone of skull Dura Periosteal mater Meningeal
Superior
sagittal sinus
Arachnoid mater
Pia mater
Subdural
space
Arachnoid villus
Blood vessel
Subarachnoid
space
Falx cerebri
(in longitudinal
fissure only)
Figure 12.24

32. Dura Mater
Strongest meninx
Two layers of fibrous connective tissue (around the brain) separate to form dural sinuses

33. Dural septa limit excessive movement of the brain
Dura Mater
Dural septa limit excessive movement of the brain
Falx cerebri—in the longitudinal fissure; attached to crista galli
Falx cerebelli—along the vermis of the cerebellum
Tentorium cerebelli—horizontal dural fold over cerebellum and in the transverse fissure

34. Superior sagittal sinus Falx cerebri Straight sinus Crista galli
of the
ethmoid
bone
Tentorium
cerebelli
Falx
cerebelli
Pituitary
gland
(a) Dural septa
Figure 12.25a

35. Arachnoid Mater
Middle layer with weblike extensions
Separated from the dura mater by the subdural space
Subarachnoid space contains CSF and blood vessels
Arachnoid villi protrude into the superior sagittal sinus and permit CSF reabsorption

36. Skin of scalp Periosteum Bone of skull Dura Periosteal mater Meningeal
Superior
sagittal sinus
Arachnoid mater
Pia mater
Subdural
space
Arachnoid villus
Blood vessel
Subarachnoid
space
Falx cerebri
(in longitudinal
fissure only)
Figure 12.24

37. Pia Mater
Layer of delicate vascularized connective tissue that clings tightly to the brain

38. Cerebrospinal Fluid (CSF)
Composition
Watery solution
Less protein and different ion concentrations than plasma
Constant volume

39. Cerebrospinal Fluid (CSF)
Functions
Gives buoyancy to the CNS organs
Protects the CNS from blows and other trauma
Nourishes the brain and carries chemical signals

40. Right lateral ventricle (deep to cut)
Superior
sagittal sinus 4
Choroid
plexus
Arachnoid villus
Interventricular
foramen
Subarachnoid space
Arachnoid mater
Meningeal dura mater
Periosteal dura mater 1
Right lateral ventricle
(deep to cut)
Choroid plexus
of fourth ventricle 3
Third ventricle
CSF is produced by the
choroid plexus of each
ventricle. 1
Cerebral aqueduct
Lateral aperture
Fourth ventricle
CSF flows through the
ventricles and into the
subarachnoid space via the
median and lateral apertures.
Some CSF flows through the
central canal of the spinal cord. 2
Median aperture 2
Central canal
of spinal cord
CSF flows through the
subarachnoid space. 3
(a) CSF circulation
CSF is absorbed into the dural venous
sinuses via the arachnoid villi. 4
Figure 12.26a

41. Choroid Plexuses
Produce CSF at a constant rate
Hang from the roof of each ventricle
Clusters of capillaries enclosed by pia mater and a layer of ependymal cells
Ependymal cells use ion pumps to control the composition of the CSF and help cleanse CSF by removing wastes

42. containing glucose, oxygen, vitamins, and ions (Na+, Cl–, Mg2+, etc.)
Ependymal
cells
Capillary
Section
of choroid
plexus
Connective
tissue of
pia mater
Wastes and
unnecessary
solutes absorbed
CSF forms as a filtrate
containing glucose, oxygen,
vitamins, and ions
(Na+, Cl–, Mg2+, etc.)
Cavity of
ventricle
(b) CSF formation by choroid plexuses
Figure 12.26b

43. Blood-Brain Barrier
Helps maintain a stable environment for the brain
Separates neurons from some bloodborne substances

44. Blood-Brain Barrier Composition
Continuous endothelium of capillary walls
Basal lamina
Feet of astrocytes
Provide signal to endothelium for the formation of tight junctions

45. (a) Astrocytes are the most abundant CNS neuroglia.
Capillary
Neuron
Astrocyte
(a) Astrocytes are the most abundant CNS neuroglia.
Figure 11.3a

46. Blood-Brain Barrier: Functions
Selective barrier
Allows nutrients to move by facilitated diffusion
Allows any fat-soluble substances to pass, including alcohol, nicotine, and anesthetics
Absent in some areas, e.g., vomiting center and the hypothalamus, where it is necessary to monitor the chemical composition of the blood

47. Homeostatic Imbalances of the Brain
Traumatic brain injuries
Concussion—temporary alteration in function
Contusion—permanent damage
Subdural or subarachnoid hemorrhage—may force brain stem through the foramen magnum, resulting in death
Cerebral edema—swelling of the brain associated with traumatic head injury

48. Homeostatic Imbalances of the Brain
Cerebrovascular accidents (CVAs)(strokes)
Blood circulation is blocked and brain tissue dies, e.g., blockage of a cerebral artery by a blood clot
Typically leads to hemiplegia, or sensory and speed deficits
Transient ischemic attacks (TIAs)—temporary episodes of reversible cerebral ischemia
Tissue plasminogen activator (TPA) is the only approved treatment for stroke

49. Homeostatic Imbalances of the Brain
Degenerative brain disorders
Alzheimer’s disease (AD): a progressive degenerative disease of the brain that results in dementia
Parkinson’s disease: degeneration of the dopamine-releasing neurons of the substantia nigra
Huntington’s disease: a fatal hereditary disorder caused by accumulation of the protein huntingtin that leads to degeneration of the basal nuclei and cerebral cortex

50. Spinal Cord Location Functions Begins at the foramen magnum
Ends as conus medullaris at L1 vertebra
Functions
Provides two-way communication to and from the brain
Contains spinal reflex centers

51. Spinal Cord: Protection
Bone, meninges, and CSF
Cushion of fat and a network of veins in the epidural space between the vertebrae and spinal dura mater
CSF in subarachnoid space

52. Spinal Cord: Protection
Denticulate ligaments: extensions of pia mater that secure cord to dura mater
Filum terminale: fibrous extension from conus medullaris; anchors the spinal cord to the coccyx

53. Ligamentum flavum Lumbar puncture needle entering subarachnoid space
Supra-
spinous
ligament L5
Filum
terminale S1
Inter-
vertebral
disc
Cauda equina
in subarachnoid
space
Arachnoid
matter
Dura
mater
Figure 12.30

54. (a) The spinal cord and its nerve roots, with the bony vertebral
Cervical
spinal nerves
Cervical
enlargement
Dura and
arachnoid
mater
Thoracic
spinal nerves
Lumbar
enlargement
Conus
medullaris
Lumbar
spinal nerves
Cauda
equina
Filum
terminale
(a) The spinal cord and its nerve
roots, with the bony vertebral
arches removed. The dura mater
and arachnoid mater are cut
open and reflected laterally.
Sacral
spinal nerves
Figure 12.29a

55. Cervical and lumbar enlargements
Spinal Cord
Spinal nerves
31 pairs
Cervical and lumbar enlargements
The nerves serving the upper and lower limbs emerge here
Cauda equina
The collection of nerve roots at the inferior end of the vertebral canal

56. Cross-Sectional Anatomy
Two lengthwise grooves divide cord into right and left halves
Ventral (anterior) median fissure
Dorsal (posterior) median sulcus
Gray commissure—connects masses of gray matter; encloses central canal

57. (a) Cross section of spinal cord and vertebra
Epidural space
(contains fat)
Pia mater
Arachnoid
mater
Spinal
meninges
Subdural space
Dura mater
Subarachnoid
space
(contains CSF)
Bone of
vertebra
Dorsal root
ganglion
Body
of vertebra
(a) Cross section of spinal cord and vertebra
Figure 12.31a

58. (b) The spinal cord and its meningeal coverings
Dorsal median sulcus
Gray
commissure
Dorsal funiculus
Dorsal horn
White
columns
Ventral funiculus
Gray
matter
Ventral horn
Lateral funiculus
Lateral horn
Dorsal root
ganglion
Spinal nerve
Central canal
Dorsal root
(fans out into
dorsal rootlets)
Ventral median
fissure
Ventral root
(derived from several
ventral rootlets)
Pia mater
Arachnoid mater
Spinal dura mater
(b) The spinal cord and its meningeal coverings
Figure 12.31b

59. Gray Matter
Dorsal horns—interneurons that receive somatic and visceral sensory input
Ventral horns—somatic motor neurons whose axons exit the cord via ventral roots
Lateral horns (only in thoracic and lumbar regions) –sympathetic neurons
Dorsal root (spinal) gangia—contain cell bodies of sensory neurons

60. Dorsal horn (interneurons)
Dorsal root (sensory)
Dorsal root ganglion
Dorsal horn (interneurons)
Somatic
sensory
neuron
Visceral
sensory
neuron
Visceral
motor
neuron
Spinal nerve
Ventral horn
(motor neurons)
Ventral root
(motor)
Somatic
motor neuron
Interneurons receiving input from somatic sensory neurons
Interneurons receiving input from visceral sensory neurons
Visceral motor (autonomic) neurons
Somatic motor neurons
Figure 12.32

61. White Matter
Consists mostly of ascending (sensory) and descending (motor) tracts
Transverse tracts (commissural fibers) cross from one side to the other
Tracts are located in three white columns (funiculi on each side—dorsal (posterior), lateral, and ventral (anterior)
Each spinal tract is composed of axons with similar functions