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Anatomy and Physiology

16.1 Overview of the Neurological Exam

Anatomy and Physiology16.1 Overview of the Neurological Exam
  1. Preface
  2. Unit 1: Levels of Organization
    1. 1 An Introduction to the Human Body
      1. Introduction
      2. 1.1 Overview of Anatomy and Physiology
      3. 1.2 Structural Organization of the Human Body
      4. 1.3 Functions of Human Life
      5. 1.4 Requirements for Human Life
      6. 1.5 Homeostasis
      7. 1.6 Anatomical Terminology
      8. 1.7 Medical Imaging
      9. Key Terms
      10. Chapter Review
      11. Interactive Link Questions
      12. Review Questions
      13. Critical Thinking Questions
    2. 2 The Chemical Level of Organization
      1. Introduction
      2. 2.1 Elements and Atoms: The Building Blocks of Matter
      3. 2.2 Chemical Bonds
      4. 2.3 Chemical Reactions
      5. 2.4 Inorganic Compounds Essential to Human Functioning
      6. 2.5 Organic Compounds Essential to Human Functioning
      7. Key Terms
      8. Chapter Review
      9. Interactive Link Questions
      10. Review Questions
      11. Critical Thinking Questions
    3. 3 The Cellular Level of Organization
      1. Introduction
      2. 3.1 The Cell Membrane
      3. 3.2 The Cytoplasm and Cellular Organelles
      4. 3.3 The Nucleus and DNA Replication
      5. 3.4 Protein Synthesis
      6. 3.5 Cell Growth and Division
      7. 3.6 Cellular Differentiation
      8. Key Terms
      9. Chapter Review
      10. Interactive Link Questions
      11. Review Questions
      12. Critical Thinking Questions
    4. 4 The Tissue Level of Organization
      1. Introduction
      2. 4.1 Types of Tissues
      3. 4.2 Epithelial Tissue
      4. 4.3 Connective Tissue Supports and Protects
      5. 4.4 Muscle Tissue and Motion
      6. 4.5 Nervous Tissue Mediates Perception and Response
      7. 4.6 Tissue Injury and Aging
      8. Key Terms
      9. Chapter Review
      10. Interactive Link Questions
      11. Review Questions
      12. Critical Thinking Questions
  3. Unit 2: Support and Movement
    1. 5 The Integumentary System
      1. Introduction
      2. 5.1 Layers of the Skin
      3. 5.2 Accessory Structures of the Skin
      4. 5.3 Functions of the Integumentary System
      5. 5.4 Diseases, Disorders, and Injuries of the Integumentary System
      6. Key Terms
      7. Chapter Review
      8. Interactive Link Questions
      9. Review Questions
      10. Critical Thinking Questions
    2. 6 Bone Tissue and the Skeletal System
      1. Introduction
      2. 6.1 The Functions of the Skeletal System
      3. 6.2 Bone Classification
      4. 6.3 Bone Structure
      5. 6.4 Bone Formation and Development
      6. 6.5 Fractures: Bone Repair
      7. 6.6 Exercise, Nutrition, Hormones, and Bone Tissue
      8. 6.7 Calcium Homeostasis: Interactions of the Skeletal System and Other Organ Systems
      9. Key Terms
      10. Chapter Review
      11. Review Questions
      12. Critical Thinking Questions
    3. 7 Axial Skeleton
      1. Introduction
      2. 7.1 Divisions of the Skeletal System
      3. 7.2 The Skull
      4. 7.3 The Vertebral Column
      5. 7.4 The Thoracic Cage
      6. 7.5 Embryonic Development of the Axial Skeleton
      7. Key Terms
      8. Chapter Review
      9. Interactive Link Questions
      10. Review Questions
      11. Critical Thinking Questions
    4. 8 The Appendicular Skeleton
      1. Introduction
      2. 8.1 The Pectoral Girdle
      3. 8.2 Bones of the Upper Limb
      4. 8.3 The Pelvic Girdle and Pelvis
      5. 8.4 Bones of the Lower Limb
      6. 8.5 Development of the Appendicular Skeleton
      7. Key Terms
      8. Chapter Review
      9. Interactive Link Questions
      10. Review Questions
      11. Critical Thinking Questions
    5. 9 Joints
      1. Introduction
      2. 9.1 Classification of Joints
      3. 9.2 Fibrous Joints
      4. 9.3 Cartilaginous Joints
      5. 9.4 Synovial Joints
      6. 9.5 Types of Body Movements
      7. 9.6 Anatomy of Selected Synovial Joints
      8. 9.7 Development of Joints
      9. Key Terms
      10. Chapter Review
      11. Interactive Link Questions
      12. Review Questions
      13. Critical Thinking Questions
    6. 10 Muscle Tissue
      1. Introduction
      2. 10.1 Overview of Muscle Tissues
      3. 10.2 Skeletal Muscle
      4. 10.3 Muscle Fiber Contraction and Relaxation
      5. 10.4 Nervous System Control of Muscle Tension
      6. 10.5 Types of Muscle Fibers
      7. 10.6 Exercise and Muscle Performance
      8. 10.7 Cardiac Muscle Tissue
      9. 10.8 Smooth Muscle
      10. 10.9 Development and Regeneration of Muscle Tissue
      11. Key Terms
      12. Chapter Review
      13. Interactive Link Questions
      14. Review Questions
      15. Critical Thinking Questions
    7. 11 The Muscular System
      1. Introduction
      2. 11.1 Interactions of Skeletal Muscles, Their Fascicle Arrangement, and Their Lever Systems
      3. 11.2 Naming Skeletal Muscles
      4. 11.3 Axial Muscles of the Head, Neck, and Back
      5. 11.4 Axial Muscles of the Abdominal Wall, and Thorax
      6. 11.5 Muscles of the Pectoral Girdle and Upper Limbs
      7. 11.6 Appendicular Muscles of the Pelvic Girdle and Lower Limbs
      8. Key Terms
      9. Chapter Review
      10. Review Questions
      11. Critical Thinking Questions
  4. Unit 3: Regulation, Integration, and Control
    1. 12 The Nervous System and Nervous Tissue
      1. Introduction
      2. 12.1 Basic Structure and Function of the Nervous System
      3. 12.2 Nervous Tissue
      4. 12.3 The Function of Nervous Tissue
      5. 12.4 The Action Potential
      6. 12.5 Communication Between Neurons
      7. Key Terms
      8. Chapter Review
      9. Interactive Link Questions
      10. Review Questions
      11. Critical Thinking Questions
    2. 13 Anatomy of the Nervous System
      1. Introduction
      2. 13.1 The Embryologic Perspective
      3. 13.2 The Central Nervous System
      4. 13.3 Circulation and the Central Nervous System
      5. 13.4 The Peripheral Nervous System
      6. Key Terms
      7. Chapter Review
      8. Interactive Link Questions
      9. Review Questions
      10. Critical Thinking Questions
    3. 14 The Somatic Nervous System
      1. Introduction
      2. 14.1 Sensory Perception
      3. 14.2 Central Processing
      4. 14.3 Motor Responses
      5. Key Terms
      6. Chapter Review
      7. Interactive Link Questions
      8. Review Questions
      9. Critical Thinking Questions
    4. 15 The Autonomic Nervous System
      1. Introduction
      2. 15.1 Divisions of the Autonomic Nervous System
      3. 15.2 Autonomic Reflexes and Homeostasis
      4. 15.3 Central Control
      5. 15.4 Drugs that Affect the Autonomic System
      6. Key Terms
      7. Chapter Review
      8. Interactive Link Questions
      9. Review Questions
      10. Critical Thinking Questions
    5. 16 The Neurological Exam
      1. Introduction
      2. 16.1 Overview of the Neurological Exam
      3. 16.2 The Mental Status Exam
      4. 16.3 The Cranial Nerve Exam
      5. 16.4 The Sensory and Motor Exams
      6. 16.5 The Coordination and Gait Exams
      7. Key Terms
      8. Chapter Review
      9. Interactive Link Questions
      10. Review Questions
      11. Critical Thinking Questions
    6. 17 The Endocrine System
      1. Introduction
      2. 17.1 An Overview of the Endocrine System
      3. 17.2 Hormones
      4. 17.3 The Pituitary Gland and Hypothalamus
      5. 17.4 The Thyroid Gland
      6. 17.5 The Parathyroid Glands
      7. 17.6 The Adrenal Glands
      8. 17.7 The Pineal Gland
      9. 17.8 Gonadal and Placental Hormones
      10. 17.9 The Endocrine Pancreas
      11. 17.10 Organs with Secondary Endocrine Functions
      12. 17.11 Development and Aging of the Endocrine System
      13. Key Terms
      14. Chapter Review
      15. Interactive Link Questions
      16. Review Questions
      17. Critical Thinking Questions
  5. Unit 4: Fluids and Transport
    1. 18 The Cardiovascular System: Blood
      1. Introduction
      2. 18.1 An Overview of Blood
      3. 18.2 Production of the Formed Elements
      4. 18.3 Erythrocytes
      5. 18.4 Leukocytes and Platelets
      6. 18.5 Hemostasis
      7. 18.6 Blood Typing
      8. Key Terms
      9. Chapter Review
      10. Interactive Link Questions
      11. Review Questions
      12. Critical Thinking Questions
    2. 19 The Cardiovascular System: The Heart
      1. Introduction
      2. 19.1 Heart Anatomy
      3. 19.2 Cardiac Muscle and Electrical Activity
      4. 19.3 Cardiac Cycle
      5. 19.4 Cardiac Physiology
      6. 19.5 Development of the Heart
      7. Key Terms
      8. Chapter Review
      9. Interactive Link Questions
      10. Review Questions
      11. Critical Thinking Questions
    3. 20 The Cardiovascular System: Blood Vessels and Circulation
      1. Introduction
      2. 20.1 Structure and Function of Blood Vessels
      3. 20.2 Blood Flow, Blood Pressure, and Resistance
      4. 20.3 Capillary Exchange
      5. 20.4 Homeostatic Regulation of the Vascular System
      6. 20.5 Circulatory Pathways
      7. 20.6 Development of Blood Vessels and Fetal Circulation
      8. Key Terms
      9. Chapter Review
      10. Interactive Link Questions
      11. Review Questions
      12. Critical Thinking Questions
    4. 21 The Lymphatic and Immune System
      1. Introduction
      2. 21.1 Anatomy of the Lymphatic and Immune Systems
      3. 21.2 Barrier Defenses and the Innate Immune Response
      4. 21.3 The Adaptive Immune Response: T lymphocytes and Their Functional Types
      5. 21.4 The Adaptive Immune Response: B-lymphocytes and Antibodies
      6. 21.5 The Immune Response against Pathogens
      7. 21.6 Diseases Associated with Depressed or Overactive Immune Responses
      8. 21.7 Transplantation and Cancer Immunology
      9. Key Terms
      10. Chapter Review
      11. Interactive Link Questions
      12. Review Questions
      13. Critical Thinking Questions
  6. Unit 5: Energy, Maintenance, and Environmental Exchange
    1. 22 The Respiratory System
      1. Introduction
      2. 22.1 Organs and Structures of the Respiratory System
      3. 22.2 The Lungs
      4. 22.3 The Process of Breathing
      5. 22.4 Gas Exchange
      6. 22.5 Transport of Gases
      7. 22.6 Modifications in Respiratory Functions
      8. 22.7 Embryonic Development of the Respiratory System
      9. Key Terms
      10. Chapter Review
      11. Interactive Link Questions
      12. Review Questions
      13. Critical Thinking Questions
    2. 23 The Digestive System
      1. Introduction
      2. 23.1 Overview of the Digestive System
      3. 23.2 Digestive System Processes and Regulation
      4. 23.3 The Mouth, Pharynx, and Esophagus
      5. 23.4 The Stomach
      6. 23.5 The Small and Large Intestines
      7. 23.6 Accessory Organs in Digestion: The Liver, Pancreas, and Gallbladder
      8. 23.7 Chemical Digestion and Absorption: A Closer Look
      9. Key Terms
      10. Chapter Review
      11. Interactive Link Questions
      12. Review Questions
      13. Critical Thinking Questions
    3. 24 Metabolism and Nutrition
      1. Introduction
      2. 24.1 Overview of Metabolic Reactions
      3. 24.2 Carbohydrate Metabolism
      4. 24.3 Lipid Metabolism
      5. 24.4 Protein Metabolism
      6. 24.5 Metabolic States of the Body
      7. 24.6 Energy and Heat Balance
      8. 24.7 Nutrition and Diet
      9. Key Terms
      10. Chapter Review
      11. Review Questions
      12. Critical Thinking Questions
    4. 25 The Urinary System
      1. Introduction
      2. 25.1 Physical Characteristics of Urine
      3. 25.2 Gross Anatomy of Urine Transport
      4. 25.3 Gross Anatomy of the Kidney
      5. 25.4 Microscopic Anatomy of the Kidney
      6. 25.5 Physiology of Urine Formation
      7. 25.6 Tubular Reabsorption
      8. 25.7 Regulation of Renal Blood Flow
      9. 25.8 Endocrine Regulation of Kidney Function
      10. 25.9 Regulation of Fluid Volume and Composition
      11. 25.10 The Urinary System and Homeostasis
      12. Key Terms
      13. Chapter Review
      14. Review Questions
      15. Critical Thinking Questions
    5. 26 Fluid, Electrolyte, and Acid-Base Balance
      1. Introduction
      2. 26.1 Body Fluids and Fluid Compartments
      3. 26.2 Water Balance
      4. 26.3 Electrolyte Balance
      5. 26.4 Acid-Base Balance
      6. 26.5 Disorders of Acid-Base Balance
      7. Key Terms
      8. Chapter Review
      9. Interactive Link Questions
      10. Review Questions
      11. Critical Thinking Questions
  7. Unit 6: Human Development and the Continuity of Life
    1. 27 The Reproductive System
      1. Introduction
      2. 27.1 Anatomy and Physiology of the Male Reproductive System
      3. 27.2 Anatomy and Physiology of the Female Reproductive System
      4. 27.3 Development of the Male and Female Reproductive Systems
      5. Key Terms
      6. Chapter Review
      7. Interactive Link Questions
      8. Review Questions
      9. Critical Thinking Questions
    2. 28 Development and Inheritance
      1. Introduction
      2. 28.1 Fertilization
      3. 28.2 Embryonic Development
      4. 28.3 Fetal Development
      5. 28.4 Maternal Changes During Pregnancy, Labor, and Birth
      6. 28.5 Adjustments of the Infant at Birth and Postnatal Stages
      7. 28.6 Lactation
      8. 28.7 Patterns of Inheritance
      9. Key Terms
      10. Chapter Review
      11. Interactive Link Questions
      12. Review Questions
      13. Critical Thinking Questions
  8. References
  9. Index
By the end of this section, you will be able to:
  • List the major sections of the neurological exam
  • Explain the connection between location and function in the nervous system
  • Explain the benefit of a rapid assessment for neurological function in a clinical setting
  • List the causes of neurological deficits
  • Describe the different ischemic events in the nervous system

The neurological exam is a clinical assessment tool used to determine what specific parts of the CNS are affected by damage or disease. It can be performed in a short time—sometimes as quickly as 5 minutes—to establish neurological function. In the emergency department, this rapid assessment can make the difference with respect to proper treatment and the extent of recovery that is possible.

The exam is a series of subtests separated into five major sections. The first of these is the mental status exam, which assesses the higher cognitive functions such as memory, orientation, and language. Then there is the cranial nerve exam, which tests the function of the 12 cranial nerves and, therefore, the central and peripheral structures associated with them. The cranial nerve exam tests the sensory and motor functions of each of the nerves, as applicable. Two major sections, the sensory exam and the motor exam, test the sensory and motor functions associated with spinal nerves. Finally, the coordination exam tests the ability to perform complex and coordinated movements. The gait exam, which is often considered a sixth major exam, specifically assesses the motor function of walking and can be considered part of the coordination exam because walking is a coordinated movement.

Neuroanatomy and the Neurological Exam

Localization of function is the concept that circumscribed locations are responsible for specific functions. The neurological exam highlights this relationship. For example, the cognitive functions that are assessed in the mental status exam are based on functions in the cerebrum, mostly in the cerebral cortex. Several of the subtests examine language function. Deficits in neurological function uncovered by these examinations usually point to damage to the left cerebral cortex. In the majority of individuals, language function is localized to the left hemisphere between the superior temporal lobe and the posterior frontal lobe, including the intervening connections through the inferior parietal lobe.

The five major sections of the neurological exam are related to the major regions of the CNS (Figure 16.2). The mental status exam assesses functions related to the cerebrum. The cranial nerve exam is for the nerves that connect to the diencephalon and brain stem (as well as the olfactory connections to the forebrain). The coordination exam and the related gait exam primarily assess the functions of the cerebellum. The motor and sensory exams are associated with the spinal cord and its connections through the spinal nerves.

This figure shows a picture of the brain connected to the spinal cord.
Figure 16.2 Anatomical Underpinnings of the Neurological Exam The different regions of the CNS relate to the major sections of the neurological exam: the mental status exam, cranial nerve exam, sensory exam, motor exam, and coordination exam (including the gait exam).

Part of the power of the neurological exam is this link between structure and function. Testing the various functions represented in the exam allows an accurate estimation of where the nervous system may be damaged. Consider the patient described in the chapter introduction. In the emergency department, he is given a quick exam to find where the deficit may be localized. Knowledge of where the damage occurred will lead to the most effective therapy.

In rapid succession, he is asked to smile, raise his eyebrows, stick out his tongue, and shrug his shoulders. The doctor tests muscular strength by providing resistance against his arms and legs while he tries to lift them. With his eyes closed, he has to indicate when he feels the tip of a pen touch his legs, arms, fingers, and face. He follows the tip of a pen as the doctor moves it through the visual field and finally toward his face. A formal mental status exam is not needed at this point; the patient will demonstrate any possible deficits in that area during normal interactions with the interviewer. If cognitive or language deficits are apparent, the interviewer can pursue mental status in more depth. All of this takes place in less than 5 minutes. The patient reports that he feels pins and needles in his left arm and leg, and has trouble feeling the tip of the pen when he is touched on those limbs. This suggests a problem with the sensory systems between the spinal cord and the brain. The emergency department has a lead to follow before a CT scan is performed. He is put on aspirin therapy to limit the possibility of blood clots forming, in case the cause is an embolus—an obstruction such as a blood clot that blocks the flow of blood in an artery or vein.

Interactive Link

Watch this video to see a demonstration of the neurological exam—a series of tests that can be performed rapidly when a patient is initially brought into an emergency department. The exam can be repeated on a regular basis to keep a record of how and if neurological function changes over time. In what order were the sections of the neurological exam tested in this video, and which section seemed to be left out?

Causes of Neurological Deficits

Damage to the nervous system can be limited to individual structures or can be distributed across broad areas of the brain and spinal cord. Localized, limited injury to the nervous system is most often the result of circulatory problems. Neurons are very sensitive to oxygen deprivation and will start to deteriorate within 1 or 2 minutes, and permanent damage (cell death) could result within a few hours. The loss of blood flow to part of the brain is known as a stroke, or a cerebrovascular accident (CVA).

There are two main types of stroke, depending on how the blood supply is compromised: ischemic and hemorrhagic. An ischemic stroke is the loss of blood flow to an area because vessels are blocked or narrowed. This is often caused by an embolus, which may be a blood clot or fat deposit. Ischemia may also be the result of thickening of the blood vessel wall, or a drop in blood volume in the brain known as hypovolemia.

A related type of CVA is known as a transient ischemic attack (TIA), which is similar to a stroke although it does not last as long. The diagnostic definition of a stroke includes effects that last at least 24 hours. Any stroke symptoms that are resolved within a 24-hour period because of restoration of adequate blood flow are classified as a TIA.

A hemorrhagic stroke is bleeding into the brain because of a damaged blood vessel. Accumulated blood fills a region of the cranial vault and presses against the tissue in the brain (Figure 16.3). Physical pressure on the brain can cause the loss of function, as well as the squeezing of local arteries resulting in compromised blood flow beyond the site of the hemorrhage. As blood pools in the nervous tissue and the vasculature is damaged, the blood-brain barrier can break down and allow additional fluid to accumulate in the region, which is known as edema.

The left panel of this image shows an image of the brain with a region in red. Arrows pointing towards this region indicate a hemorrhage associated with a stroke. The right panel shows a hemorrhage as it might appear on a CT scan.
Figure 16.3 Hemorrhagic Stroke (a) A hemorrhage into the tissue of the cerebrum results in a large accumulation of blood with an additional edema in the adjacent tissue. The hemorrhagic area causes the entire brain to be disfigured as suggested here by the lateral ventricles being squeezed into the opposite hemisphere. (b) A CT scan shows an intraparenchymal hemorrhage within the parietal lobe. (credit b: James Heilman)

Whereas hemorrhagic stroke may involve bleeding into a large region of the CNS, such as into the deep white matter of a cerebral hemisphere, other events can cause widespread damage and loss of neurological functions. Infectious diseases can lead to loss of function throughout the CNS as components of nervous tissue, specifically astrocytes and microglia, react to the disease. Blunt force trauma, such as from a motor vehicle accident, can physically damage the CNS.

A class of disorders that affect the nervous system are the neurodegenerative diseases: Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis (ALS), Creutzfeld–Jacob disease, multiple sclerosis (MS), and other disorders that are the result of nervous tissue degeneration. In diseases like Alzheimer’s, Parkinson’s, or ALS, neurons die; in diseases like MS, myelin is affected. Some of these disorders affect motor function, and others present with dementia. How patients with these disorders perform in the neurological exam varies, but is often broad in its effects, such as memory deficits that compromise many aspects of the mental status exam, or movement deficits that compromise aspects of the cranial nerve exam, the motor exam, or the coordination exam. The causes of these disorders are also varied. Some are the result of genetics, such as Huntington’s disease, or the result of autoimmunity, such as MS; others are not entirely understood, such as Alzheimer’s and Parkinson’s diseases. Current research suggests that many of these diseases are related in how the degeneration takes place and may be treated by common therapies.

Finally, a common cause of neurological changes is observed in developmental disorders. Whether the result of genetic factors or the environment during development, there are certain situations that result in neurological functions being different from the expected norms. Developmental disorders are difficult to define because they are caused by defects that existed in the past and disrupted the normal development of the CNS. These defects probably involve multiple environmental and genetic factors—most of the time, we don’t know what the cause is other than that it is more complex than just one factor. Furthermore, each defect on its own may not be a problem, but when several are added together, they can disrupt growth processes that are not well understand in the first place. For instance, it is possible for a stroke to damage a specific region of the brain and lead to the loss of the ability to recognize faces (prosopagnosia). The link between cell death in the fusiform gyrus and the symptom is relatively easy to understand. In contrast, similar deficits can be seen in children with the developmental disorder, autism spectrum disorder (ASD). However, these children do not lack a fusiform gyrus, nor is there any damage or defect visible to this brain region. We conclude, rather poorly, that this brain region is not connected properly to other brain regions.

Infection, trauma, and congenital disorders can all lead to significant signs, as identified through the neurological exam. It is important to differentiate between an acute event, such as stroke, and a chronic or global condition such as blunt force trauma. Responses seen in the neurological exam can help. A loss of language function observed in all its aspects is more likely a global event as opposed to a discrete loss of one function, such as not being able to say certain types of words. A concern, however, is that a specific function—such as controlling the muscles of speech—may mask other language functions. The various subtests within the mental status exam can address these finer points and help clarify the underlying cause of the neurological loss.

Interactive Link

Watch this video for an introduction to the neurological exam. Studying the neurological exam can give insight into how structure and function in the nervous system are interdependent. This is a tool both in the clinic and in the classroom, but for different reasons. In the clinic, this is a powerful but simple tool to assess a patient’s neurological function. In the classroom, it is a different way to think about the nervous system. Though medical technology provides noninvasive imaging and real-time functional data, the presenter says these cannot replace the history at the core of the medical examination. What does history mean in the context of medical practice?

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