233 Chapter 14
The Brain and Cranial Nerves
An Introduction to the Brain and Cranial Nerves
The Adult Human Brain
Volume ranges from 750 mL to 2100 mL
Contains almost 97 percent of the body’s neural tissue
Average weight about 1.4 kg (1400g or about 3 lbs.)
The Brain - Six Regions of the Brain
Cerebrum
Cerebellum
Diencephalon
Midbrain
Pons
Medulla oblongata
1. Cerebrum
Largest part of brain
Controls higher mental functions
Divided into left and right cerebral hemispheres
Surface layer of gray matter (neural cortex)
Cerebral cortex
Folded surface increases surface area
Elevated ridges (gyri)
Shallow depressions (sulci)
Deep grooves (fissures)
2. Cerebellum
Second largest part of brain
Coordinates repetitive body movements
Covered with cerebellar cortex
3. Diencephalon
Located under cerebrum
Links cerebrum with brain stem
Three divisions of the diencephalon
Left thalamus
Right thalamus
Hypothalamus
Diencephalon
Thalamus - Relays and processes sensory information
Hypothalamus
Hormone production
Emotion
Autonomic function
Diencephalon (continued)
Pituitary gland
Major endocrine gland
Connected to hypothalamus - Via infundibulum (stalk)
Interfaces nervous and endocrine systems
, The Brain (continued)
The Brain Stem
Processes information between: Spinal cord and cerebrum or cerebellum
Includes:
Midbrain
Pons
Medulla oblongata
4. Midbrain - Also called mesencephalon
Processes sight, sound, and associated reflexes
Maintains consciousness
5. Pons - Connects cerebellum to brain stem
Is involved in somatic and visceral motor control
6. Medulla Oblongata - Connects brain to spinal cord
Relays information
Regulates autonomic functions
Heart rate, blood pressure, and digestion
Ventricles of the Brain (4) – cavities in the brain, lined with ependymal cells and filled with CSF
Each cerebral hemisphere contains one large lateral ventricle (1 and 2)
Separated by a thin medial partition (septum pellucidum)
Third ventricle - Ventricle of the diencephalon
Lateral ventricles communicate with third ventricle
Via interventricular foramen (foramen of Monro)
Fourth ventricle - Extends into medulla oblongata
Becomes continuous with central canal of the spinal cord
Connects with third ventricle
Via (narrow canal in midbrain) the cerebral aqueduct
The Brain
The brain is a large mass of neural tissue
Containing internal chambers filled with cerebrospinal fluid
Each of the six major brain regions has specific functions
From the medulla oblongata to the cerebrum, brain functions become more complex and variable
Conscious thought and intelligence are produced in the neural cortex of the cerebral hemispheres
Brain Protection and Support
Physical Protection of the Brain
Bones of the cranium
Cranial meninges
Cerebrospinal fluid
Biochemical Isolation - Blood–brain barrier
The Cranial Meninges - Have three layers, continuous with spinal meninges, that protect the brain
from cranial trauma
Dura mater
Arachnoid mater
Pia mater
The Brain and Cranial Nerves
An Introduction to the Brain and Cranial Nerves
The Adult Human Brain
Volume ranges from 750 mL to 2100 mL
Contains almost 97 percent of the body’s neural tissue
Average weight about 1.4 kg (1400g or about 3 lbs.)
The Brain - Six Regions of the Brain
Cerebrum
Cerebellum
Diencephalon
Midbrain
Pons
Medulla oblongata
1. Cerebrum
Largest part of brain
Controls higher mental functions
Divided into left and right cerebral hemispheres
Surface layer of gray matter (neural cortex)
Cerebral cortex
Folded surface increases surface area
Elevated ridges (gyri)
Shallow depressions (sulci)
Deep grooves (fissures)
2. Cerebellum
Second largest part of brain
Coordinates repetitive body movements
Covered with cerebellar cortex
3. Diencephalon
Located under cerebrum
Links cerebrum with brain stem
Three divisions of the diencephalon
Left thalamus
Right thalamus
Hypothalamus
Diencephalon
Thalamus - Relays and processes sensory information
Hypothalamus
Hormone production
Emotion
Autonomic function
Diencephalon (continued)
Pituitary gland
Major endocrine gland
Connected to hypothalamus - Via infundibulum (stalk)
Interfaces nervous and endocrine systems
, The Brain (continued)
The Brain Stem
Processes information between: Spinal cord and cerebrum or cerebellum
Includes:
Midbrain
Pons
Medulla oblongata
4. Midbrain - Also called mesencephalon
Processes sight, sound, and associated reflexes
Maintains consciousness
5. Pons - Connects cerebellum to brain stem
Is involved in somatic and visceral motor control
6. Medulla Oblongata - Connects brain to spinal cord
Relays information
Regulates autonomic functions
Heart rate, blood pressure, and digestion
Ventricles of the Brain (4) – cavities in the brain, lined with ependymal cells and filled with CSF
Each cerebral hemisphere contains one large lateral ventricle (1 and 2)
Separated by a thin medial partition (septum pellucidum)
Third ventricle - Ventricle of the diencephalon
Lateral ventricles communicate with third ventricle
Via interventricular foramen (foramen of Monro)
Fourth ventricle - Extends into medulla oblongata
Becomes continuous with central canal of the spinal cord
Connects with third ventricle
Via (narrow canal in midbrain) the cerebral aqueduct
The Brain
The brain is a large mass of neural tissue
Containing internal chambers filled with cerebrospinal fluid
Each of the six major brain regions has specific functions
From the medulla oblongata to the cerebrum, brain functions become more complex and variable
Conscious thought and intelligence are produced in the neural cortex of the cerebral hemispheres
Brain Protection and Support
Physical Protection of the Brain
Bones of the cranium
Cranial meninges
Cerebrospinal fluid
Biochemical Isolation - Blood–brain barrier
The Cranial Meninges - Have three layers, continuous with spinal meninges, that protect the brain
from cranial trauma
Dura mater
Arachnoid mater
Pia mater
