Transcript Brain Info

Chapter 15 Lecture
HUMAN ANATOMY
Fifth Edition
Chapter 15
The Nervous System:
The Brain and Cranial Nerves
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings
Frederic Martini
Michael Timmons
Robert Tallitsch
Introduction
• The brain is far more complex than the
spinal cord.
• The brain contains roughly 20 billion
neurons.
- Excitatory and inhibitory interactions among
the extensively interconnected neuronal pools
ensure that the response can vary to meet
changing circumstances.
Embryology of the Brain
Table 15.1 Development of the Human Brain
Fig
15.1
Fig
15.11
White matter
Grey matter
Ventricles
Fig
4 fluid filled cavities in the brain
Lined by ependymal cells
Contain cerebrospinal fluid
15.2
Protection and support of the brain
• Bones of the skull
• cranial meninges
• cerebrospinal fluid
• blood-brain barrier
Cranial Meninges
• Protective layers of the brain & spinal cord
- Provide physical stability and shock absorption
• Outermost
- Dura mater-Tough fibrous layer
• Middle
- Arachnoid
• Innermost
- Pia mater
The Cranial Meninges
Figure 15.4a Superior Cut away
The Cranial Meninges
Figure 15.3c Midsagittal View
• Deep to
arachnoid
is subarachnoid
space
- Network of
collagen and
elastin fibers
(arachnoid
trabeculae)
- Contains CSF
The Cranial Meninges
Figure 15.4b,c Coronal Section
Cerebral Spinal Fluid
• Cushions the CNS
• Supports the brain-the brains is floating in
the CSF
• Transport nutrient/wastes etc.
Choroid plexus
• Produces CSF 500 ml/day
• Composed of ependymal cells and
capillaries (CSF is very different from plasma)
• Found in each ventricle
• Floor of lateral ventricles (2)
• Roof of 3rd ventricle
• Roof of 4th ventricle
Fig
15.5
CSF circulation
Blood supply to the
brain is from the
internal carotid and
vertebral arteries
Blood brain barrier
• Maintained by astrocytes
• Not found in:
- the hypothalamus
- Pineal gland
- Roof of 3rd & 4th ventricles
The Cerebrum
Figure 15.8a,b The Cerebral Hemispheres, Superior and Anterior Views
The Cerebrum
Figure 15.8c Posterior View
Figure 15.9a Lateral View
Functions of the Cerebrum
Table 15.2 The Cerebral Cortex
Motor and Sensory Areas
of the Cerebral Cortex
Figure 15.9b Functional Areas of the Cortex
Central White Matter of the Brain
Figure 15.10a Lateral View
Figure 15.10b Anterior View
Basal Nuclei
Figure 15.11b,c Coronal View
The Limbic System
Figure 15.12a Lateral View
Figure 15.12b Close up
Sectional View Inside the Brain:
The Diencephalon
Figure 15.13a Midsagittal View
Sectional View Inside the Brain:
The Diencephalon
Figure 15.13b Coronal Section
The Diencephalon: Thalamus
Table 15.6 The Thalamus
The Mesencephalon
Figure 15.16a Lateral View
Figure 15.16c Posterior View
Copora
quadrigemina
Fig
15.15
Cerebral
peduncles
Aqueduct of midbrain
or
Cerebral aqueduct
The Pons
Figure 15.18 The Pons
The Cerebellum
Figure 15.19a Posterior, Superior Surface
The Cerebellum
Figure 15.19b Sagittal Section of Cerebellum
Fig
15.13
The Cranial Nerves
• Cranial nerves are components of the
peripheral nervous system that connect to
the brain rather than to the spinal cord.
- There are twelve pairs of cranial nerves.
- Cranial nerves are numbered using Roman
numerals.
• Each cranial nerve attaches to the brain
near the associated sensory or motor
nuclei.
1-12
Old
12 pairs of
Cranial
nerves
Fig
Owls
On
15.21
Tree
Tops
Are
Forever
Viewing
Green
Valleys
12
11
And
Hills
The Olfactory Nerve (N I)
• Primary function:
- Special sensory (smell)
• Origin:
- Receptors of olfactory epithelium
Figure 15.22 The Olfactory Nerve
The Olfactory Nerve (N I)
• Passes through:
- Cribriform plate of ethmoid
• Destination:
- Olfactory bulbs
Figure 15.22 The Olfactory Nerve
The Optic Nerve (N II)
• Primary function:
- Special sensory (vision)
• Origin:
- Retina of eye
• Passes through:
- Optic canal of sphenoid
• Destination:
- Diencephalon by way of the optic chiasm
The Optic Nerve (N II)
Figure 15.23 The Optic Nerve
The Oculomotor Nerve (N III)
• Primary function:
- Motor, eye movements
• Origin:
- Mesencephalon
• Passes through:
- Superior orbital fissure of sphenoid
The Oculomotor Nerve (N III)
• Destination:
- Somatic motor:
• Superior, inferior, and medial rectus muscles; the
inferior oblique muscle; the levator palpebrae
superioris muscle
- Visceral motor:
• Intrinsic eye muscles
The Oculomotor Nerve (N III)
Figure 15.24 The Oculomotor Nerve
The Trochlear Nerve (N IV)
• Primary function:
- Motor, eye movements
• Origin:
- Mesencephalon
• Passes through:
- Superior orbital fissure of sphenoid
• Destination:
- Superior oblique muscle
The Trochlear Nerve (N IV)
Figure 15.24 The Trochlear Nerve
The Trigeminal Nerve (N V)
• Primary function:
- Mixed (sensory and motor)
- Ophthalmic and maxillary branches sensory
- Mandibular branch mixed
The Trigeminal Nerve (N V)
• Origin:
- Ophthalmic branch (sensory):
• Orbital structures, nasal cavity, skin of forehead,
superior eyelid, eyebrow, and part of the nose
- Maxillary branch (sensory):
• Inferior eyelid, upper lip, gums, and teeth; cheek;
nose, palate, and part of the pharynx
- Mandibular branch (mixed):
• Sensory from lower gums, teeth, and lips; palate
and tongue (part); motor from motor nuclei of pons
The Trigeminal Nerve (N V)
• Passes through:
- Ophthalmic branch through superior orbital
fissure
- Maxillary branch through foramen rotundum
- Mandibular branch through foramen ovale
• Destination:
- Ophthalmic, maxillary, and mandibular
branches to sensory nuclei in the pons
- Mandibular branch also innervates muscles of
mastication
The Trigeminal Nerve (N V)
Figure 15.25 The Trigeminal Nerve
The Abducens Nerve (N VI)
• Primary function:
- Motor, eye movements
• Origin:
- Pons
• Passes through:
- Superior orbital fissure of sphenoid
• Destination:
- Lateral rectus muscle
The Abducens Nerve (N VI)
Figure 15.2 The Abducens Nerve
The Facial Nerve (N VII)
• Primary function:
- Mixed (sensory and motor)
• Origin:
- Sensory from taste receptors on anterior twothirds of tongue
- Motor from motor nuclei of pons
• Passes through:
- Internal acoustic meatus of temporal bone,
along facial canal to reach stylomastoid
foramen
The Facial Nerve (N VII)
• Destination:
- Sensory to sensory nuclei of pons
- Somatic motor: muscles of facial expression
- Visceral motor: lacrimal (tear) gland and nasal
mucous glands via pterygopalatine ganglion;
submandibular and sublingual salivary glands
via submandibular ganglion
The Facial Nerve (N VII)
Figure 15.26 The Facial Nerve
The Vestibulocochlear Nerve (N VIII)
• Primary function:
- Special sensory:
• Balance and equilibrium (vestibular branch) and
hearing (cochlear branch)
• Origin:
- Receptors of the inner ear (vestibule and
cochlea)
• Passes through:
- Internal acoustic meatus of the temporal bone
The Vestibulocochlear Nerve (N VIII)
• Destination:
- Vestibular and cochlear nuclei of pons and
medulla oblongata
The Vestibulocochlear Nerve (N VIII)
Figure 15.27 The Vestibulocochlear Nerve
The Glossopharyngeal Nerve (N IX)
• Primary function:
- Mixed (sensory and motor)
• Origin:
- Sensory from posterior one-third of the
tongue, part of the pharynx and palate, the
carotid arteries of the neck
- Motor from motor nuclei of medulla oblongata
• Passes through:
- Jugular foramen between occipital and
temporal bones
The Glossopharyngeal Nerve (N IX)
• Destination:
- Sensory fibers to sensory nuclei of medulla
oblongata
- Somatic motor:
• Pharyngeal muscles involved in swallowing
- Visceral motor:
• Parotid salivary gland, after synapsing in the otic
ganglion
The Glossopharyngeal Nerve (N IX)
Figure 15.28 The Glossopharyngeal Nerve
The Vagus Nerve (N X)
• Primary function:
- Mixed (sensory and motor)
• Origin:
- Visceral sensory from pharynx (part), auricle,
external acoustic meatus, diaphragm, and
visceral organs in thoracic and
abdominopelvic cavities
- Visceral motor from motor nuclei in the
medulla oblongata
The Vagus Nerve (N X)
• Passes through:
- Jugular foramen between occipital and
temporal bones
• Destination:
- Sensory fibers to sensory nuclei and
autonomic centers of medulla oblongata
- Somatic motor to muscles of the palate and
pharynx
- Visceral motor to respiratory, cardiovascular,
and digestive organs in the thoracic and
abdominal cavities
The Vagus Nerve (N X)
Figure 15.29 The Vagus Nerve
The Accessory Nerve (N XI)
• Primary function:
- Motor
• Origin:
- Motor nuclei of spinal cord and medulla
oblongata
• Passes through:
- Jugular foramen between occipital and
temporal bones
The Accessory Nerve (N XI)
• Destination:
- Internal branch innervates voluntary muscles
of palate, pharynx, and larynx
- External branch controls sternocleidomastoid
and trapezius muscles
The Accessory Nerve (N XI)
Figure 15.30 The Accessory Nerve
The Hypoglossal Nerve (N XII)
• Primary function:
- Motor, tongue movements
• Origin:
- Motor nuclei of the medulla oblongata
• Passes through:
- Hypoglossal canal of occipital bone
• Destination:
- Muscles of the tongue
The Hypoglossal Nerve (N XII)
Figure 15.30 The Hypoglossal Nerve