Figure 10-2 Divisions of the Nervous System

Figure 10-1 • Nervous system.

The nervous system is a widespread body system that consists of the brain, spinal cord, and nerves that form a connected pathway along which nerve impulses travel throughout the body.

Figure 10-2 • Divisions of the nervous system.

The two main divisions of the nervous system are the central nervous system and the peripheral nervous system. The peripheral nervous system contains other subdivisions.

Figure 10-3 • Lobes of the cerebrum.

Each lobe of the cerebrum takes its name from the bone of the cranium that lies above it.

Figure 10-4 • Midline cut section of the brain.

This cut section shows the right half of the brain. The large size of the cerebrum is seen in comparison to the cerebellum and other structures. Many gyri and sulci are visible on the surface of the cerebrum. The lateral ventricle, thalamus, hypothalamus, midbrain, pons, and medulla oblongata are seen.

Figure 10-5 • Posterior half of the brain.

The anterior part of the cerebrum has been removed. The fissure that divides the right and left hemispheres of the cerebrum can be seen at the top. The corpus callosum is the white connecting bridge between the hemispheres. The right and left lateral ventricles and the small, central third ventricle can be seen. The medulla oblongata, the most posterior part of the brainstem, merges with the spinal cord.

Figure 10-6 • Left-brain thinking.

Left-brain thinking uses the left hemisphere, the site of mathematical and logical reasoning.

Pearson Education/PH College

Figure 10-7 • Meninges.

The three membrane layers of the dura mater, arachnoid, and pia mater make up the meninges. Between the arachnoid and the pia mater is the subarachnoid space, which is filled with cerebrospinal fluid.

Figure 10-8 • Spinal cord.

The spinal cord passes through the foramen of each vertebra. It is protected by the bony foramen as well as by the dura mater of the meninges.

Figure 10-9 • Spinal nerves.

The spinal nerves originate at regular intervals along the spinal column. Each spinal nerve consists of dorsal nerve roots that receive sensory information from the body and ventral nerve roots that carry motor commands to the body.

Figure 10-10 • Neuron.

A neuron consists of several dendrites, a cell body, and an axon. The dendrites receive nerve impulses from other neurons. The cell body contains the nucleus of the neuron. The axon transmits nerve impulses to other neurons (or to a muscle fiber, to a cell in an organ, or to a cell in a gland).

Figure 10-11 • Glioma.

This patient’s MRI scan of the brain shows a large glioma that is pressing on the cerebellum.

Simon Fraser/Photo Researchers, Inc.

Figure 10-12 • Cerebrovascular accident.

(a) A cerebrovascular accident on the left side of the brain affects the right side of the body and vice versa. (b) A hemorrhage of an aneurysm disrupts blood flow to the brain and causes a cerebrovascular accident. An embolus blocks blood flow to the brain and causes a cerebrovascular accident.

Figure 10-13 • Patient with a cerebrovascular accident.

This patient had a cerebrovascular accident on the left side of her brain that has paralyzed the right side of her body. Notice the drooping of the right side of her mouth and her right shoulder. The elbow and wrist of her right arm are covered with protective padding. She is using her good left hand to hold her right hand in her lap and move her right arm from time to time.

Michal Heron/PearsonEducation/PH College

Figure 10-14 • Concussion.

Although football helmets are padded and constructed to protect the head, this player has sustained a concussion with loss of consciousness. Repeated concussions can result in developing Alzheimer’s disease in middle age.

HENNY RAY ABRAMS/AFP/Getty Images

Figure 10-15 • PET scan of a normal brain.

A PET scan shows the metabolic activity of the brain. This patient’s scan shows large, symmetrical areas of metabolism and active brain cells. The bar at the right correlates colors on the scan with numerical measurements for the amount of metabolic activity. Areas with the highest metabolic activity appear yellow to red.

Science Photo Library/Custom Medical Stock Photo, Inc.

Figure 10-16 • PET scan of the brain in a patient with Alzheimer’s disease.

Notice the large areas that are without any evidence of metabolism or brain cell activity.

Science Photo Library/Custom Medical Stock Photo, Inc.

Figure 10-17 • Down syndrome.

This patient with Down syndrome shows the characteristic facial features (eyes and tongue) that accompany mental retardation.

Photo-Link/Getty Images—Photodisc-Royalty Free

Figure 10-18 • Dyslexia.

A patient with dyslexia may write certain alphabet letters backwards or may change the order of the letters in a word.

Will & Deni McIntyre/Photo Researchers, Inc.

Figure 10-19 • Epilepsy.

This physician is monitoring a patient who is having a seizure. The computer screen at the top shows the patient, who is in a hospital bed while having a seizure. The computer screen at the bottom shows the patient’s brain waves as they change from normal to abnormal with the onset of the seizure. The characteristic movements of the patient while having the seizure and the specific EEG pattern will lead to a diagnosis of the type of seizure disorder that the patient has.

Yoav Levy/Phototake NYC

Figure 10-20 • Subdural hematoma.

This patient developed a subdural hematoma after trauma to the side of the head. Also notice the hematoma of the scalp where blood has collected between the cranium and the skin. An MRI scan shows both hematomas and the extent of the compression of the brain.

ShoutPictures/Custom Medical Stock Photo, Inc.

Figure 10-21 • Hydrocephalus.

This infant has pronounced hydrocephalus. A light shown on the cranium reveals large areas of illumination where the enlarged ventricles are filled with cerebrospinal fluid and the more dense brain tissue has been pushed aside.

Barts Medical Library/Phototake NYC

Figure 10-22 • Parkinson’s disease.

Parkinson’s patients boxing legend Mohammad Ali and actor Michael J. Fox talk with each other before testifying at a Senate hearing on Parkinson’s disease research. Muhammad Ali has had Parkinson’s disease for many years, as evidenced by his advanced symptoms of an expressionless face and difficulty initiating movement of his hands.

AP Wide World Photos

Figure 10-23 • Meningocele.

Meningocele with the meninges in the hernia sac. The delicate tissues of the meningocele can be traumatized easily, allowing infection to enter and travel to the brain. Therefore, the meningocele is surgically closed shortly after birth.

JPD/CustomMedical Stock Photo, Inc.

Figure 10-24 • Radiculopathy.

The path of the sciatic nerve in the leg. A herniated nucleus pulposus presses on the sciatic nerve. The resulting area of pain, numbness, and tingling in the leg is shown in red.

Figure 10-25 • Spinal cord injury.

The level of the spinal cord where an injury occurs and whether the spinal cord was partially or completely transected determines how much of the body is affected and to what extent. Paraplegia affects the lower body and the legs. Quadriplegia affects the body from the neck down and all four extremities.

Figure 10-26 • Bell’s palsy.

This patient with Bell’s palsy has paralysis of the facial nerve on the right side of his face, as shown by drooping of his cheek and lips.

NIH/Phototake NYC

Figure 10-27 • Paresthesias.

This drug advertisement graphically shows the sensation that some patients have with paresthesias: a stabbing pain or shooting sensation. Other symptoms include burning pain, tingling, or numbness. Other advertisements for this drug show ants crawling on the feet or thumbtacks pricking the feet.

Figure 10-28 • Arteriogram.

The injected dye clearly outlines the patient’s left carotid artery and its many smaller branches within the cranial cavity. There is no evidence of carotid artery plaques or cerebral aneurysm.

Corbis RF

Figure 10-29 • Electroencephalography (EEG).

This boy is having an EEG done to diagnose what type of epileptic seizures he is having. Electrodes on his scalp pick up the electrical impulses of brain waves and display them on the computer screen.

Phanie/Photo Researchers, Inc.

Figure 10-30 • Positive Babinski’s sign.

This patient has a positive (abnormal) Babinski’s sign with extension of the great toe and fanning of the other toes laterally.

Pearson Education/PH College

Figure 10-31 • Lumbar puncture.

(a) For a lumbar puncture, the needle is inserted into the subarachnoid space where there is cerebrospinal fluid. (b) This patient is having a lumbar puncture. In this case, an upright position is being used, but this older patient does not have much flexibility of the spine and is only able to flex the head and shoulders forward. One physician is helping the patient to maintain this position while the other physician inserts the spinal needle. A white sterile drape covers the patient’s back except for a round opening in the drape where the needle is inserted.

Peres/Custom Medical Stock Photo, Inc.

Figure 10-32 • Spinal traction with tongs.

This patient’s spine is immobilized while a fractured vertebra heals. Notice the pins inserted into the cranium, tongs, and the rope that is connected to weights to exert steady and constant traction.

Vanstrum/Custom Medical Stock Photo, Inc.