1. The Central Nervous System (CNS) – The Brain and Spinal Cord
Anatomy Ch. 7 Part 2
The Central Nervous System (CNS) – The Brain and Spinal Cord

2. Cerebrum Contains 2 divisions called the cerebral hemispheres.
Largest part of the brain
Contains 4 lobes: frontal, parietal, temporal, occipital
Surface features:
Gyri
ridges
Sulci
shallow grooves
divide the lobes of the brain
Fissures
deep grooves
divide the right and left hemispheres

3. Cerebral Cortex Outer region of the cerebrum Composed of gray matter
Functions:
Speech
Memory
logical and emotional responses
Consciousness
interpretation of sensations
voluntary movement.

4. Functional Regions of the Cerebral Cortex
Primary Somatic Sensory Area
Located in the parietal lobe
Interprets information from sensory receptors
All sensory pathways are crossed
Specialized cortex areas
Occipital lobe: vision
Temporal lobe: smell and hearing

5. Primary Motor Area Broca’s Area Located in the frontal lobe
Movements of skeletal muscles
All motor pathways are crossed
Broca’s Area
Specialized area that is involved in ability to speak
Left side of the frontal lobe

6. Anterior Association Area
Frontal lobe: reasoning and behavior
Frontal and temporal lobes: complex memories
Posterior Association Area
Combination of lobes: faces and patterns

7. Gray matter makes up the cortex of the cerebrum and white matter makes up the deeper regions.
The 2 hemispheres of the cerebrum are connected by a large nerve tract called the corpus callosum.

8. Diencephalon Sits on top of the brain stem
Enclosed by the cerebral hemispheres
Divided into 3 regions:
Thalamus
Relay station for sensory impulses passing to the sensory cortex
Provides a crude recognition of whether a sensation will be pleasant or unpleasant.

9. Hypothalamus Epithalamus
Plays a role in body temperature, water balance, and metabolism
Center for many drives and emotions
Regulates the pituitary gland
Epithalamus
Contains the pineal gland and capillaries that form CSF.

10. Limbic System Plays a role in emotions and memory
Found between the temporal lobes on both sides of the thalamus.
Closely associated with the diencephalon.
Consists of the amygdala and hippocampus
Amygdala: the emotion center of the brain
Hippocampus: formation of memories

11. Brain Stem Produces behaviors necessary for survival
Controls activities such as breathing and blood pressure.
Composed of 3 regions

12. Midbrain Pons Medulla Oblongata
connects ventricles in the brain which contain CSF
conducts impulses
contains reflex centers for vision and hearing
Pons
Controls breathing
Medulla Oblongata
Merges into the spinal cord
Contains centers that control heart rate, blood pressure, breathing, and swallowing.

13. Reticular Formation entire length of the brain stem
Motor control of organs
Consciousness
Wake/sleep cycles

14. Cerebellum Below the occipital lobe Similar structure to cerebrum
Hemispheres are connected by the vermis
Assists with skeletal muscle activity
Controls balance

15. Protection Meninges 3 membranes that cover and protect the CNS
Dura Mater
Outermost layer
Means tough mother
Double layered

16. Arachnoid Mater Pia mater Subarachnoid space Middle layer Weblike
Means gentle mother
Inner layers that clings tightly to the brain and spinal cord
Subarachnoid space
Found between the arachnoid and pia mater
Contains CSF

17. Cerebrospinal Fluid (CSF)
Watery substance similar to blood plasma
Continually formed from blood
Forms a watery cushion that protects nervous tissue from trauma
Continually circulates inside the brain in the ventricles and in the subarachnoid space

18. Blood-Brain Barrier
Composed of the least permeable capillaries in the whole body
Only water, glucose, and essential amino acids pass through easily
Metabolic wastes such as urea, toxins, proteins, and most drugs are prevented from entering

19. Nonessential amino acids and potassium are not only prevented from entering but are also actively pumped from the brain.
However this barrier is useless against fats, respiratory gases, and fat soluble molecules.
This explains why alcohol, nicotine, and anesthetics can affect the brain.

20. The Spinal Cord
Provides a 2 way conduction pathway to and from the brain
Major reflex center
Enclosed within the vertebral column
Protected by the same 3 layers of meninges as the brain.

21. Spinal Nerves Humans have 31 pairs of spinal nerves
The spinal cord is enlarged in the cervical and lumbar regions.
Cervical: upper limbs
Lumbar: lower limbs

23. Anatomy of the Spinal Cord
The gray matter is found on the inside of the spinal cord and is shaped like a butterfly.
The gray matter has 2 dorsal horns and 2 ventral horns
Dorsal horns: Sensory input
Ventral horns: Motor output
The gray matter surrounds a central canal which contains CSF.

24. White matter surrounds the gray matter of the spinal cord
The white matter contains myelinated fiber tracts
Dorsal tracts
sensory (afferent) information
ascending
Lateral and ventral tracts
Sensory (afferent) and motor (efferent) information
Ascending and descending

26. Cranial Nerves 12 pairs primarily serve the head and neck
Only the vagus nerve extends to the thoracic and abdominal cavities.
Cranial nerves are numbered and the name reveals the most important structures they control.
All cranial nerves have sensory and motor functions but 3.
The 3 that are only sensory are the optic, olfactory, and vestibulocochlear

27. General Description of the Cranial Nerves
I – Olfactory: smell II – Optic: vision III – Occulomotor: movement of the eye IV – Trochlear: movement of the eye V – Trigeminal: face, nose, mouth, chewing VI – Abducens: movement of the eye VII – Facial: face, glands, taste buds VIII – Vestibulocochlear: balance, hearing IX – Glossopharyngeal: throat, taste buds, artery pressure X – Vagus: throat, larynx, abdominal and thoracic organs XI – Accessory: sternocleidomastoid and trapezius XII – Hypoglossal: tongue

29. Spinal Nerves
31 pairs
Named for the region of the spinal cord from which they arise.
Groups of spinal nerves that service the same area are called plexuses.

30. Spinal Nerve Plexuses Cervical Plexus Brachial Plexus Lumbar Plexus
C1 – C5
Serves the head and neck
Brachial Plexus
C5 – C8 and T1
Shoulders and arms
Lumbar Plexus
L1 – L4
Abdominal and pelvic area
Sacral Plexus
L5 and S1 – S4
legs

31. T2 – T12 Do not form plexuses Intercostal nerves
Organs of the thorax and abdomen

33. Autonomic Nervous System