Ch 8-12 Flashcards
2 ways the divisions of the nervous system can be classified by
Location Type of tissue supplied by the nerve cells in the division
2 neural structures the central nervous system (CNS) consists of
Brain Spinal cord
4 neural structures the peripheral nervous system (PNS) made up of
12 pairs of cranial nerves 31 pairs of spinal nerves Autonomic nerves Ganglia
2 neurons the PNS consists ofA
Afferent neurons Efferent neurons
Neurons that conduct impulses from peripheral receptors to the CNS
Afferent (sensory) neurons
Neurons that conduct impulses away from the CNS to the peripheral effectors
Efferent (motor) neurons
Supplies the striated skeletal muscles
Somatic nervous system (SNS)
Supplies smooth muscle, cardiac muscle, and glandular epithelial tissue
Autonomic nervous system (ANS)
Basic unit of the nervous system Consists of a cell body and two types of long, threadlike extensions
Neuron Nerve cell
Fatty covering that insulate the axons and increase the rate of transmission of nervous impulses
Myelin sheath
Deterioration of the fatty myelin sheath
Demyelination
The impulse conduction route to and from the CNS in involuntary reactions Basic ones consists of an afferent/sensory neuron, which conducts impulses to the CNS from the periphery; an an efferent/motor neuron which conducts impulses from the CNS to peripheral effectors (muscles or glandular tissue)
Reflex arc
Junction where impulses pass from one neuron to another Transmission here is a chemical reaction in which the termini of the axon release a neurotransmitter substance that produces an electrical impulse in the dendrites of the next axon; once the neurotransmitter has accomplished its task, its activity rapidly terminates so that subsequent impulses pass along this same route
Synapse
Largest part of the brain that consists of two cerebral hemispheres
Cerebrum
Elevations the surface of the cerebrum is highly convoluted with
Gyri
Shallow grooves the surface of the cerebrum is highly convoluted with
Sulci
Deeper grooves in the cerebrum that divide each cerebral hemisphere into lobes
Fissures
Outer portion of the cerebrum consists of a thin layer of gray matter where the nerve cell bodies are concentrated Responsible for receiving sensory information from all parts of the body and for triggering impulses that govern all motor activity Just posterior to the central sulcus, there are specialized areas to receive and precisely localize sensory information from the PNS
Cerebral cortex
Mass of white matter that connects the two cerebral hemispheres These extensive bundles of nerve fibers lie in the midline just above the roofs of the lateral ventricles
Corpus callosum
A few gray islands of gray matter deep within the white matter Help control position and automatic movements and consist of the caudate nuclei, the globus pallidus, and the putamen
Basal ganglia
3 parts of the brainstem (from top down) between the cerebrum and spinal cord
Midbrain Pons Medulla
Performs sensory, motor, and reflex functions, and contains the nuclei of the 12 cranial nerves and the vital centers controlling cardiac, vasomotor, and respiratory function
Brainstem
Responsible for such nonvital reflexes as vomiting, coughing, sneezing, hiccuping, and swallowing
Medulla
Second largest part of the brain located just below the posterior portion of the cerebrum that is composes of two large lateral masses: the hemispheres and a central section (vermis) Acts with the cerebral cortex to produce skilled movements by coordinating the activities of groups of muscles Coordinates skeletal muscles used in maintaining equilibrium and posture by functioning below the level of consciousness to make movements smooth rather than jerky, steady rather than trembling, and efficient and coordinated rather than ineffective and awkward
Cerebellum
Muscle incoordination
Ataxia
Lies between the cerebrum and midbrain and consists of several structures located around the third ventricle, primarily the thalamus and hypothalamus
Diencephalon
Primarily functions as a relay station that receives and processes sensory info of almost all kinds of sensory impulses before sending this info to the cerebral cortex
Thalamus
Extremely complex, tiny structure that functions as a link between the mind and body and is the site of “pleasure” or “rewards” centers for such primary drives as eating, drinking, and mating Plays a major role in regulating the body’s internal environment by coordinating the activities of the ANS and secreting the releasing hormones that control the secretion of hormones by the anterior and posterior portions of the pituitary gland Also important in helping to maintain a normal body temperature and in keeping the individual in a waking state
Hypothalamus
Lies within the vertebral column and extends from its junction with the brainstem at the foramen magnum to approximately the lower border of the first lumbar vertebra; consists of an inner core of gray matter surrounded by white matter tracts Its basic function is to conduct impulses up the cord to the brain (ascending tracts) and down the cord from the brain to spinal nerves (descending tracts); also serves as the center for spinal reflexes and involuntary responses (ex: knee jerk/patellar reflex)
Spinal cord
The inner coverings of brain and spinal cord
Meninges
3 layers of the meninges
Dura mater Arachnoid membrane Pia mater
Transparent innermost layer adhering to the outer surface of the brain and spinal cord
Pia mater
Tough outermost covering of the brain and spinal cord
Dura mater
Delicate, cobweb-like membrane between the pia and dura mater
Arachnoid membrane
3 extensions of the dura mater that separate portions of the brain
Falx cerebri Falx cerebelli Tentorium cerebellum
Extension of the dura mater that projects downward into the longitudinal fissure to separate the cerebral hemispheres
Falx cerebri
Extension of the dura mater that separates the two cerebellar hemispheres
Falx cerebelli
Extension of the dura mater that forms a tentlike covering over the cerebellum that separates it from the occipital lobe of the cerebrum
Tentorium cerebellum
After flowing through the ventricular system, the fluid circulates in this space between the pia mater and the arachnoid around the brain and spinal cord before being absorbed into venous blood through arachnoid villi
Subarachnoid space
An acute inflammation of the pia mater and arachnoid Infecting organisms can reach the meninges via infection in the middle ear, upper respiratory tract, or frontal sinus Spread through the bloodstream (hematogenously) Infection in the lungs (or other site)
Meningitis
2 things that cause meningitis
Bacteria Viruses
Most common form of meningitis
Bacterial meningitis (pyogenic)
Viral inflammation of the brain and meninges It produces a wide range of symptoms, ranging from mild headache and fever to severe cerebral dysfunction, seizures, and coma Herpes simplex virus can cause a sudden, severe, and fatal process
Encephalitis (meningoencephalitis)
Usually a result of chronic infections of the middle ear, paranasal sinuses, or mastoid air cells, of systemic infections (pneumonia, bacterial endocarditis, osteomyelitis)
Brain abscess
A suppurative process in the space between the inner surface of the dura and the outer surface of the arachnoid The most common cause is the spread of infection from the frontal or ethmoid sinuses Other causes: mastoiditis, middle ear infection, purulent meningitis, penetrating skull wounds, craniectomy, or osteomyelitis of the skull
Subdural empyema
Organisms that most commonly cause brain abscesses
Streptococci
Almost always associated with osteomyelitis in a cranial bone Originates from an infection in the ear or paranasal sinuses; the infection is outside the dural membrane and beneath the inner table of the skull The frontal region is usually affected because it is close to the frontal sinuses and the dura is easily stripped from the bone
Epidural empyema
Most commonly caused by direct extension of a suppurative process from the paranasal sinuses, mastoid air cells, or scalp Radiographic changes develop 1 to 2 weeks after the onset of clinical symptoms and signs
Osteomyelitis of the skull
8 CNS tumors
Glioma Meningioma Acoustic Neuroma Pituitary Adenoma Craniopharyngioma Pineal Tumors Chordoma Metastatic Carcinoma
The most common primary malignant brain tumors composed of glial cells (supporting connective tissues in the CNS) Spread by direct extension Can cross from one cerebral hemisphere to the other through connecting white matter tracts, such as the corpus callosum Peak age incidence: middle-age adults; infrequent in persons less than 30 years of age
Glioma
5 types of gliomas
Glioblastoma Astrocytoma Ependymoma Medulloblastoma Oligodendrocytoma
Highly aggressive gliomas that are predominately cerebral, although similar tumors may occur in the brainstem, cerebellum, or spinal cord
Glioblastoma
Most common gliomas (70%); slow-growing tumors that have an infiltrative character and can form large cavities or pseudocysts Favored sites are the cerebrum, cerebellum, thalamus, optic chiasm, and pons
Astrocytoma
A benign tumor that arises from arachnoid lining cells and is attached to the dura mater Most common sites: convexity of the calvaria, olfactory groove, tuberculum sellae, parasagittal region, sylvian fissure, cerebellopontine angle, and spinal canal
Meningioma
Slowly growing benign tumor May occur as a solitary lesion or as part of the syndrome of neurofibromatosis Arises from Schwann cells in the vestibular portion of the auditory (eighth cranial) nerve; most often originates in the internal auditory canal and extends into the cerebellopontine angle cistern
Acoustic neuroma
Usually arise in the anterior lobe Most common type: nonsecreting chromophobe adenoma (mass effect of tumor suppresses pituitary hormone secretions) Hormone-secreting ones produce symptoms related to excess hormones, rather than mass effect Gigantism in adolescents and acromegaly in adults
Pituitary adenomas
Most common types: germinoma and teratoma (both are rapidly growing germ cell tumors) Most common in males under age 25
Pineal tumors
Most common primary cancers to spread to the brain are lung and breast; usually reach the brain by hematogenous spread Melanomas, colon carcinomas, and testicular and kidney tumors also cause this
Metastatic carcinoma
3 types of skull fractures
Linear Diastatic Depressed
Appears on a plain radiograph as a sharp lucent line that is often irregular or jagged and occasionally branches
Linear skull fracture
A linear fracture that intersects a suture and courses along it, causing sutural separation
Diastatic skull fracture
More severe trauma, especially if localized to a small area of the skull, may force a fragment of bone to be separated and sunken into the cranial cavity The underlying dura is frequently torn, and there is a relatively high incidence of cerebral parenchymal injury They are often stellate (star shaped) with multiple fracture lines radiating outward from a central point When viewed en face, the fragment overlap makes the fracture line appear denser than the normal bone Tangential views are required to determine the amount
Depressed skull fracture
Caused by acute arterial bleeding, usually from a laceration to the middle meningeal artery Typically appears as a biconvex (lens-shaped), peripheral, high-density lesion
Epidural hematoma
Caused by venous bleeding; usually it is a vein between the dura and the other meninges Typically appears on CT scans as a crescent-shaped, peripheral zone of increased density Follows the surface of the brain and lies adjacent to the inner table of the skull
Subdural hematoma
Most common facial fractures Isolated ones vary from simple, nondisplaced linear fractures to comminuted lesions with depression of the septum and lateral splaying of the fracture fragments Best demonstrated on right and left (underexposed) soft tissue lateral projections, which also can define interruption of the anterior nasal spine Most fractures are transverse and tend to depress the distal portion
Nasal bone fractures
Caused by a direct blow to the front of the orbit of the eye that causes a rapid increase in intraorbital pressure Occurs in the thinnest, weakest portion of the orbit, which is the orbital floor just above the maxillary sinus
Blowout fracture
Plain radiographs that are the preferred screening study of blowout fractures
Modified Waters’ method
Zygomatic arch is vulnerable to a blow from the side of the face, which can produce a fracture with inward displacement of the central fragments and outward displacement of the fragments of the zygomatic and temporal ends of the arch Best demonstrated on underexposed images taken in the basal (submentovertex) projection (“jug-handle” view)
Zygomatic arch fractures
Consists of fractures of the zygomatic arch and the orbital floor or rim combined with separation of the zygomaticofrontal suture So named because it reflects separation of the zygoma from its three principal attachments Resulting free-floating zygoma may cause facial disconfiguration if the fracture is not diagnosed and properly treated
Tripod fracture
Mandible is a prominent, exposed segment of the facial skeleton and is thus a common site for both intentional and accidental trauma Demonstrated by plain radiographs with oblique views, combined with panoramic tomography Most common site is the angle, although fractures can involve any portion of the body and the condylar and coronoid processes Because the mandible functions as essentially a bony ring, bilateral ones are common
Mandibular fractures
Severe injuries in which separation at the fracture site results in the formation of a large, complex, detached fragment that is unstable and may have its position altered relative to the site of origin Involve bilateral and horizontal fractures of the maxillae and are classified as type I, II, or III depending on the extent of injury
Le Fort fractures
6 types of facial fractures
Nasal bone fracture Blowout fracture Tripod fracture Le Fort fracture Zygomatic arch fracture Mandible fracture
Denotes the sudden and dramatic development of a focal neurologic deficit Varies from dense hemiplegia and coma to only a trivial neurologic disorder Specific neurologic defect depends on the affected arteries Circulation of the internal carotids are most commonly involved and is seen with symptoms that include acute hemiparesis and dysarthria
Stroke (acute brain infarction)
Paralysis on one side of the body
Hemiplegia
Weakness of one side of the body
Hemiparesis
Difficulty speaking
Dysarthria
Focal neurologic deficits that completely resolve within 24 hours. They result from emboli originating from the surface of an arteriosclerotic, ulcerated plaque (embolic stroke) which causes temporary occlusion of cerebral vessels, or from stenosis of an extracerebral artery, which leads to a reduction in critical blood perfusion Almost 2/3 of strokes are preceded by these; important to diagnose since 5-year cumulative risk of stroke in patients with this may be as high as 50% Most common location of surgically treatable arteriosclerotic disease causing ones is the region of the carotid bifurcation in the neck
Transient ischemic attacks (TIA) Mini-strokes
Evidenced on images as enlargement of the ventricular system and sulci; caused by a gradual loss of neurons
Normal aging
A diffuse form of progressive cerebral atrophy that develops at an earlier age than the senile period CT and MRI demonstrate nonspecific findings of cerebral atrophy, including symmetrically enlarged ventricles with prominence of the cortical sulci
Alzheimer’s disease (presenile disorder)
Inherited (autosomal dominant) condition that predominantly involves men; presents in the early to middle adult years with dementia and typical choreiform movements (involuntary movements that are rapid, jerky, and continuous) Pathologic hallmark is atrophy of the caudate nucleus and putamen that produces appearance of focal dilatation of the frontal horns and a loss of their normal concave shape on CT images; generalized enlargement of the ventricles and dilatation of the cortical sulci can also occur
Huntington’s disease
Progressive, degenerative disease characterized by stooped posture, stiffness and slowness of movement, fixed facial expression, involuntary rhythmic tremor of the limbs that disappears with voluntary movement Shows up in middle or later life; very gradually progressive and exhibits a prolonged course
Parkinson’s disease (“shaking palsy”)
Caused by a viral upper respiratory infection that obstructs drainage and localized pain, tenderness, and fever. Radiographically it appears as a soft tissue density lining the walls of the involved sinuses An air-fluid level in a sinus is usually considered a manifestation of acute inflammatory disease
Sinusitis
Sinuses that are most commonly affected by sinusitis
Maxillary
Sinusitis is best visualized on a this projection
Waters
2 functions of blood
Bring oxygen, nutrients, salts, and hormones to the cells and to carry away the waste products of cellular metabolism Major defense against infection, toxic substances, and foreign antigens
Blood forming tissues of the body found in vertebrae, proximal femurs, and flat bones such as the sternum, ribs, skull, and pelvis, and lymph nodes
Red bone marrow
Red blood cells (RBCs) made in red bone marrow; contain hemoglobin
Erythrocytes
Platelets made in red bone marrow; smallest blood cells essential for blood clotting
Thrombocytes
White blood cells (WBCs) produced in both red marrow and lymphoid tissue Function as part of the immune system
Leukocytes
Iron-based protein that carries oxygen to the body’s tissues
Hemoglobin
5 types of leukocytes
Neutrophils Eosinophils Basophils Lymphocytes Monocyte
Decrease in the amount of oxygen-carrying hemoglobin in the peripheral blood that can be attributable to an increased rate of RBC destruction, improper formation of new RBCs, or a loss of RBCs as a result of prolonged bleeding Causes the person to appear pale, fatigue and muscular weakness and often to dyspnea
Anemia
Shortness of breath on exertion
Dyspnea
5 types of anemia
Iron-deficiency Hemolytic Megaloblastic Vitamin B12 deficiency A deficiency of folic acid (and vitamin B12) may also be related to intestinal malabsorption Imaging appearance: decrease or absence of the usually prominent rugal folds; gastritis Aplastic – bone marrow failure Myelophthisic – infiltration of bone marrow with nonhematopoietic cells
Most common cause/form of anemia; results from chronic blood loss (such as from an ulcer), a malignant tumor, or menorrhagia (excessive bleeding during menstruation)
Iron-deficiency anemia
Shortened RBC life span Most caused by hereditary defect
Hemolytic anemia
3 major hereditary hemolytic anemias
Spherocytosis Sickle cell anemia Thalassemia
Hemolytic anemia of the newborn can result when the mother is Rh-negative and the fetus has Rh-positive blood inherited from the father
Erythroblastosis fetalis
Vitamin B12 deficiency A deficiency of folic acid (and vitamin B12) may also be related to intestinal malabsorption Imaging appearance: decrease or absence of the usually prominent rugal folds; gastritis
Megaloblastic anemia
Bone marrow failure
Aplastic anemia
Infiltration of bone marrow with nonhematopoietic cells
Myelophthisic anemia
Anemia generally confined to African Americans with no cure
Sickle cell anemia
Increased production of erythrocytes, granulocytes, and platelets
Polycythemia
2 forms of polycythemia
Primary Secondary
Characterized by hyperplasia of the bone marrow Slowly progressive and produces symptoms associated with increased blood volume and viscosity Increased incidence of peptic ulcer disease Spleen is often massively enlarged and may be see as a LUQ mass
Primary polycythemia
Result of long-term inadequate oxygen supply in patients with severe chronic pulmonary disease or congenital cyanotic heart disease, or it may develop in persons living at high altitudes
Secondary polycythemia
Neoplastic proliferation of white blood cells Excessive WBCs’ circulating causes a decrease in circulating RBCs and platelets
Leukemia
2 major types of leukemia
Myelocytic leukemia Lymphatic leukemia
Cancer of the bone marrow
Myelocytic leukemia
Malignancy of the lymph nodes; the only white blood cells that dramatically increase are lymphocytes
Lymphatic leukemia
Neoplasms of the lymphoreticular system Mediastinal lymph node enlargement is the most common radiographic finding Approximately 5-10% of patients have involvement of the GI tract; skeletal involvement in the spine In practice, CT of the chest, abdomen, and pelvis is generally the first imaging procedure used in staging
Lymphoma
3 things the lymphoreticular system includes
Lymph nodes Spleen Lymphoid tissues of parenchymal organs, such as the gastrointestinal tract, lung, and skin
2 major types of lymphomas
Hodgkin’s Non-Hodgkin’s
90% of these lymphomas originate in the lymph nodes Dense vertebral sclerosis may develop
Hodgkin’s
Self-limited viral disease of the lymphoreticular system Primarily infects young adults Often termed the “kissing disease” but is not particularly contagious Blood tests show an elevated WBC count Epstein-Barr virus is thought to be the cause
Infectious mononucleosis
4 vague symptoms that characterize infectious mononucleosis
Mild fever Fatigue Sore throat Swollen lymph nodes
Blood coagulation
Clotting
Platelets, calcium, and 12 coenzymes and proteins
Coagulation factors
A deficiency in quantity or activity of coagulation factors may lead to an inability to control hemorrhage or even to spontaneous bleeding
Diseases of platelets (bleeding disorders)
Inherited (by a sex-linked recessive gene) anomaly of blood coagulation that appears clinically only in males, females are carriers Characterized by a decreased or absent serum concentration of antihemophilic globulin (factor VIII) A person who has this is prone to spontaneous hemorrhage or severe bleeding from even minor cuts or injuries for his or her lifetime Radiographic changes are complications of recurrent bleeding into the joints
Hemophilia
Biochemical communication network through which several small glands control a broad range of vital body activities; secretes hormones
Endocrine system
Chemical messengers which circulate in the blood and may affect single target organs or the entire body May be proteins (growth), steroids (cortisone), peptides (antidiuretic [ADH]), amino acids (thyroxine), or amines (epinephrine) Range from small to large molecules and have chemical structures of various complexities
Hormones
4 major endocrine glands
Pituitary Adrenal Thyroid Parathyroid
Inadequate production of hormones from the endocrine glands can give rise to a wide variety of clinical symptoms and radiographic abnormalities
Hypoactive
Excess production of hormones from the endocrine glands can give rise to a wide variety of clinical symptoms and radiographic abnormalities
Hyperactive
Secretes epinephrine and norepinephrine; these fight-or-flight hormones are secreted in stress situations when additional energy and strength are needed
Adrenal medulla
Adrenaline
Epinephrine
Tumors that grow rapidly; approximately half are functioning tumors that cause Cushing’s syndrome
Adrenal carcinoma
Excess production of glucocorticoid hormones may be attributable to generalized bilateral hyperplasia of the adrenal cortex, or it may be a result of functioning adrenal or even nonadrenal tumor
Cushing’s syndrome
6 primary tumors/carcinomas that most frequently metastasize to the adrenal gland (one of the most common sites of metastatic disease)
Lung Breast Kidney Ovary Gastrointestinal tract Melanomas
Highly malignant tumor of adrenal medullary origin, second most common malignancy in children Approximately 10% of these tumors arise outside the adrenal gland primarily in sympathetic ganglia in the neck, chest, abdomen, or pelvis
Neuroblastoma
Gland that secretes many hormones to control the level of most glandular activity throughout the body Tiny gland about the size of a pea that sits in the bony depression of the sella turcica
Pituitary gland Master gland
Results from an excess growth hormone produced by a tumor The development of this condition before endochondral bone growth has ceased results in gigantism and beginning after bone growth has stopped produces acromegaly Underlying abnormality is the generalized overgrowth of all the body tissues Excessive growth hormone in the anterior pituitary Imaging appearance: widened joints, thickened heel pad, thickened skull tables with frontal bossing, paranasal sinus enlargement, mandibular changes, vertebral enlargement with scalloping, hypertrophy of cartilage
Hyperpituitarism
Butterfly-shaped gland located in the neck at the level of the larynx; consists of two lobes, one on each side of the trachea Picks up iodine from the bloodstream and combines it the tyrosine to synthesize hormones
Thyroid gland
Loss of secretion of any anterior pituitary hormone Imaging appearance: skeletal changes in size; dwarfism
Hypopituitarism
Results from the excessive production of thyroid hormone, either from the entire gland or from one or more functioning adenomas
Hyperthyroidism
Excessive production of thyroid hormone from the entire gland
Graves’ disease
Can result from any structural or functional abnormality that leads to an insufficient synthesis of thyroid hormone
Hypothyroidism
3 major types of thyroid carcinomas
Papillary Follicular Medullary
Most common type of thyroid carcinomas that has peaks of adolescence and young adulthood and again later in life, during the third to fifth decades Usually slow growing and cystic, and it typically spreads to regional lymph nodes, where it may remain silent for years
Papillary carcinoma
Four tiny glands, two on each side, that lie behind the upper and lower poles of the thyroid gland; secrete parathomone
Parathyroid glands
Hormone which is responsible for regulating the blood levels of calcium and phosphate
Parathormone Parathyroid hormone (PTH)
Common endocrine disorder in which either beta cells in the islets of Langerhans of the pancreas fail to secrete insulin or target cells through the body fail to respond to this hormone
Diabetes mellitus
A lack of insulin prevents glucose from entering the cells, thus depriving them of the major nutrient needed for energy production and the blood glucose level rises Patients must also be wary of hypoglycemic shock
Hyperglycemia
Patients with diabetes must be wary of this shock which results from too much insulin, not enough food, or excessive exercise; patient feels lightheaded and faint, trembles, and begins to perspire In the radiology department, this condition may occur in diabetic patients who have not eaten or drunk before GI examinations or other special procedures Essential that this condition be rapidly recognized and that sugar be given, usually in the form of orange juice or candy
Hypoglycemic shock Insulin shock
2 types of diabetes mellitus
Type 1 Type 2
Chronic condition in which the pancreas produces little or no insulin, develops in childhood Requires the patient to undergo daily insulin injections
Type 1 diabetes Insulin-dependent diabetes Juvenile-onset diabetes
More common type of diabetes that tends to develop later in life which occurs when the body becomes resistant to insulin or does not make enough insulin Less severe and can often be controlled by diet alone
Type 2 diabetes Non-insulin-dependant diabetes
