Saturday, July 30, 2011

Complete denture Diagnosis and treatment Plan


Diagnosis is the evaluation of the existing condition, more specifically; it requires identifying and making judgment about departures from normal. It is:
·        The act or process of deciding the nature of a diseased condition by examination.
·        A careful investigation of the facts to determine the nature of a thing.
·        The determination of the nature, location and causes of a disease.

Diagnosis for the prosthodontic care requires the use of general diagnostic skills and accumulation of knowledge from other aspects of dentistry and its supporting sciences. Diagnosis in complete denture is a continuing process and is not accomplished in a short time. The dentist should be the first to recognize the problem and be ready to change the treatment plan to meet the new findings. These findings will be governed by:
1)   Patient's mental attitude.
2)   Patient's systemic status.
3)   Past dental history.
4)   Local oral conditions

Mental attitude (psychological factor)
The success of dental prosthesis is related to many factors, including functional, biological, technical, esthetic and psychological factors. Psychological factors include the preparedness of the patients and their mental attitudes towards dentures, their relationship with the dentist and their ability to learn how to use the dentures. Prosthodontists must fully understand their patients because such understanding predisposes the patient to accept the kind of the treatment they need. De Van said "meet the mind of the patient before meeting the mouth of the patient".
Patients seeking prosthodontic care usually arrive with accumulation of experiences and resulting attitude. These may range from optimism through resignation to despair; all may be set against a background of psychosis. In the discussion with the patient, the dentist must seek an understanding of the patient's health, particularly their attitude toward receiving new dentures. House classified the patients into 4 categories:
1.   Philosophical patients.
2.   Exacting patients.
3.   Indifferent patients.
4.   Hysterical patients.

Philosophical patients
These patients are rational, sensible, and calm and composed in a different situation. Their motivation is generalized as they desire dentures for the maintenance of health and appearance and feel that having teeth replaced is a normal acceptable process. These patients usually overcome conflicts and organize their time and habits; they eliminate frustrations and learn to adjust rapidly. The best mental attitude for denture acceptance is the philosophical type.
Exacting patients
These patients may have all of the good attributes of the philosophical type, however, they may require extreme care efforts and patience on the part of the dentist as they like each step in the procedure to be explained in details, and they require extra hours spent prior to the treatment in patient education until an understanding is reached.
Indifferent patients
These patients are apathic, uninterested and lack motivation. The do not care to their self image; they manage to survive without dentures and pay no attention to the instructions. They do not cooperate and mostly blame the dentists for their poor dental health. In most of them, questionable or unfavorable prognosis may be expected. For such patients, educational program in dental conditions and treatments is recommended before denture construction.
Hysterical patients
These patients are excitable, apprehensive, emotionally unstable and hypertensive. They are neglectful of their oral health and unwilling to try to adapt to wear dentures. Additional professional help is required prior to and during treatment. Although these patients may try to wear the denture, they fail to use it as they expect it to look and function like the nature teeth.
Social information
It is necessary as a first step of all patients. It is the establishment of their identity. Personal information as the name, address, telephone number, work and hours of work might help the dentist in the primary estimation of the dental health and prognosis. Social setting can help to understand the patient's expectation and the dental status developed. Social information may clarify some habits, specifically those might contribute of their present conditions and those might help ensure success or failure for the treatment. Modifications or reinforcements of these habits should be noted for the inclusion in the treatment plan.

Systemic-medical status
No prosthodontic procedure should be planned until the systemic status of the patient is evaluated. It must be realized that dentistry is part of health services and that oral health is closely associated with the general health of the patient. The dentist is not entitled to just make dentures; they are responsible on the well-being of the patient as a health professional. Except in cases of accident, individuals who are losing their teeth are manifesting pathological conditions because their loss may be as a result of systemic factors or associated with unfavorable systemic condition. Furthermore, these systemic factors must be considered in the treatment plan by the dentist. Many of the systemic diseases have local manifestations with no systemic symptoms and others have both local and systemic reactions. Some systemic diseases have a direct relation to the denture success even though, no local manifestations are apparent.
Debilitating diseases
These patients requires extra instructions in the oral hygiene and tissue rest, also frequent recall appointments should be arranged because the supporting bone may be affected to keep the denture bases adapted and the occlusion corrected. Debilitating diseases include, for example, diabetes, tuberculosis, blood diseases… etc.
Cardiovascular diseases
Patients with cardiovascular diseases may require consultation with cardiologist as some denture procedures may be contraindicated. Such patient must be controlled before dental treatment.
Joint diseases
Joint involvement, particularly osteoarthritis, presents different problems. If the disease involves the TMJ, alteration in the treatment plan may be essential. In extreme conditions, special impression tray and technique are often necessary because of the limited access from reduced ability to open the jaws. Furthermore, jaw relation records are difficult and occlusion correction must be made often because of the subsequent changes in the joints.
Neurological disorders
Some neurological involvement, as Bell's palsy or Parkinson's disease, requires some attention. The dentist has to deal with some problems related to the denture retention, maxillomandibular records and supporting musculature.
Skin diseases
Many of the dermatological diseases may have oral manifestations such as pemphigus vulgaris. Medical support mostly needed because these oral lesions are painful that prevent proper work. Other conditions, as congenital diseases, endocrine diseases, malignancy, menopause, psychological, nutritional deficiencies, and infectious diseases may require disease understanding to prepare for successful work.
Past dental history
Success or failure in the provision of prosthodontic care is frequently the direct result of the adequacy of taking the patient's dental history. By talking, the patients would provide the essence of a diagnosis of their dental health and needs.
An understanding of the etiology of teeth loss by a patient would help a dentist to estimate the patient's appreciation of the dentistry and contribute to the prognosis for prosthodontic success. Although patients can change their attitude and habits, it is reasonable to be suspicious that patients were lost their teeth in an accident might be much unhappy about their edentulous state than patients who lose their teeth as a consequence of decay resulting from neglect. Similarly, expectation of the amount of alveolar remaining would be greater for the patients with a history of rapid tooth loss from decay than for patient with a long history of progressive periodontal diseases.

Dental experiences may be the source of both good and bad habits. Patients may reveal instances of traumatic experiences dating to their first visit to the dentist. Traumatic experiences have very lasting effects and make the patient tense in the dental chair, this may lead to neglecting of the oral health by the patient and lead to negative attitude. Experiences with previous prosthodontic restorations, whether partial or complete, are important in determining the patient tolerance, tissue tolerance and esthetic acceptability and what the patient expect from the denture.
Any existing prosthesis must be examined thoroughly in an objective manner. Quality of the denture material, teeth type, occlusion and occlusal discrepancies between the teeth, occlusal plan, retention and stability, and the age of the denture can be estimated from the old denture. Patient oral hygiene can be reflected well by the old denture and the condition of the supporting tissues also can be expected. Evaluation of the esthetic of the existing denture should be approached from a professional judgment of the dentist and to correlate with the information about the natural teeth; this evaluation must take into consideration the patent's view.
Although it is important to strive to raise the quality of care to match the highest of the patient's expectations, also is appropriate to lower patient's expectations through education about denture wearing.
Local factors
Unfortunately, local factors are the only ones considered by many dentists. However, it is not enough to make a cursory examination and note the presence and absence of the teeth. Local factors that are considered to afford the ideal environment for complete dentures are:
1)   Broad square ridges devoid of undercuts and bony abnormalities.
2)   Definite cuspid eminences and alveolar tubercles, broad palate with uniform depth of vault in the maxillary arch.
3)   Broad buccal shelves and firm retromolar pads in the mandibular arch.
4)   A definite vestibular fornix devoid of muscle attachments.
5)   Frenum attachments high in the maxillary and low in the mandibular arches.
6)   A clearly defined and well-developed lingual sulcus.
7)   A lateral throat form that allows suitable extension into the retromylohyoid space.
8)   A firm mucosal covering over the denture-bearing area.
9)   Mucous membrane in the vestibular fornix and floor of the mouth, which is loosely movable and attached for denture seal.
10)   A gradually slopping palate with a passive reflection at the junction of the hard and soft palate.
11)   A tongue is normal in size, position and function.
12)   A normally-related maxilla to the mandible.
13)   Good muscular tone and coordination in the mandibular movement.
14)   Adequate inter-ridge space for a favorable placement of the teeth.
15)   Saliva is suitable in viscosity and quantity.
16)   Hard and soft palate tissues devoid of any signs of pathological disorder.

An appreciation of the influences of the local factors is based on the anatomy and physiology of the supporting tissues. Evaluation of the local factors would help in the selection of the type of the impression to be made, impression materials, method of making maxillo-mandibular relations, occlusion and even selection of the teeth.
Deviations from these ideal conditions are more often; this does not mean inability to do proper, successful dentures. Any deviations should be noted in the diagnosis, so appropriate procedures and modifications can be incorporated in the treatment plan. The local factors are usually evaluated during clinical examinations. Examination must divide into extraoral, which must exam the orofacial and oral surrounding structures (muscles of the face, TMJ, symmetry of the face, lips, and cheeks).
Intraoral examination must include the ridge form (square, round or v-shaped), mucous membrane (healthy firm, flabby, ulcerated, inflamed or normal or any other variations). Tongue position, size and function. The residual ridge if it is flat or not and palate height (high, shallow and medium). Saliva quality and quantity. The presence of retained roots and tori or any bony enlargement and sharpness.
Mostly, the clinical examination precedes radiographic examination, although in some cases, this order may be reversed. X-ray films (extra and intraorally) may provide additional information especially about the alveolar bone, joints, unerupted or retained roots and foreign bodies. It can be determined if the patient will accept or reject the dentures at the time of local factors evaluation. Other investigations may be decided individually according to the needs of the patient's case.
Diagnostic casts
In addition to the construction of the special tray, diagnostic cast is used for:
1.   It reveals new information or confirms that which has already been observed intraorally.
2.   It allows for an evaluation of the anatomy and relationships in the absence of the patient.
3.   The dentist will be able to look at each size and symmetry, interarch space, arch concentricity, anteroposterior jaw relationship, and lateral jaw relationships; especially posteriorly, where an occlusal crossbite might be present.
4.   Measurement and determination of other structures would assist in making a decision on preprosthodontic surgery.
5.   Undercuts may be observed unaided, or their significance can be determined more precisely with the aid of the dental surveyor.
6.   Education and explanation of some treatment steps would be easier by using diagnostic casts in some occasions.

Treatment plan
Treatment plan is a consideration of all of the diagnostic findings (systemic and local), which influence the surgical or any preprosthetic preparations of the mouth, impression making, maxillo-mandibular relations, occlusion, form and material of the artificial teeth and instructions in the use and care of the dentures. It is matching the possible treatment options with patient's needs and symmetrically arranging the treatment in order of priority but in keeping with logically or technically necessary sequences.
The process requires a broad knowledge of treatment possibilities and detailed knowledge of the patient's needs determined by a careful diagnosis, otherwise, the patient would be placed in jeopardy of receiving inadequate or inappropriate treatment. Treatment does not terminate with the construction and delivery of the complete denture and the patient should be so advised.
Treatment plan must have a parallel process of developing diagnosis; it is driven by the diagnosis but must take other factors, such as prognosis, patient health and attitude, into account. The patient must be informed about the time required for the procedure and expense. Limitation of the denture must be outlined for the patient with any expected problems.
Treatment plan is used to specifically state the treatment that would address a particular patient's need; this treatment must state in a logical sequences and care. Treatment plan is a problem-solving techniques; it involves a careful analysis of the problem, breaking to components, as possible, generating a list of possible component solutions are implemented; some believed that it is a mental exercise but written a list may assist thinking.
 

Efficacy of Root Planning

Definitions and Descriptions

Scaling: instrumentation of the crown and root surfaces of the teeth to remove plaque, calculus and stains from these surfaces.
  
           Root Planing:
a) A treatment procedure designed to remove cementum or surface dentin that is rough, impregnated with calculus, or contaminated with toxins or microorganisms. (Amer. Acad. of Perio.)

b) A technique of instrumentation by which the “softened” cementum is removed and the root surface is made “hard” and “smooth” (Lindhe’s textbook)

c) American Academy of Periodontology Description:
    " Periodontal scaling is a treatment procedure necessary to remove hard and soft deposits from the tooth surface.  It is performed on patients with periodontal disease and is therapeutic, not prophylactic in nature.  Periodontal scaling may precede root planing.  Root planing is a meticulous treatment procedure designed to remove bacterial plaque and its toxins, calculus, and diseased cementum and dentin from the root surface.  The procedure may be a definitive treatment in some stages of periodontal disease, may be a part of pre-surgical procedures in others and an essential part of maintenance care.  Root planing is arduous and time consuming.  It may be done by quadrant(s) or full mouth (note: not allowed by insurance), may need to be repeated, and may require local anesthetic."

d) Root Preparation: Use of instruments or chemicals on root to eliminate irritants, prevent bacterial accumulation, and encourage wound healing.  (Amer. Acad. of Perio.)

e) Root Debridement:  The mechanical removal or disruption of
irritants to the periodontium: bacterial plaque, LPS (lipopolysacchirides), deposits and other plaque retentive factors to establish an environment favorable to the health of the periodontal tissues that will facilitate plaque control by the patient. The endpoint of debridement is recognizable by the color of the lavage and the feel of the tooth. Clinical endpoints are evaluated at various times post treatment. (Various sources)


Initial Therapy Procedures That Reduce Inflammation and Tooth Mobility  
            A). Periodontal
                        a) oral hygiene instructions
b) scaling and root planing
c) adult prophylaxis (scaling and tooth polish)
d) occlusal therapy
                                    1) occlusal adjustment
                                    2)  occlusal splints and bite planes.

            B)  Non-periodontal
                        a) removal of overhangs
b) caries control
c) extraction of hopeless teeth
d) provisional restorations

Biological Basis for Root Planing
A) The role of calculus and altered cementum

B)  Terms for periodontal healing:
a) Repair: Healing of a wound by tissue that does not fully restore the architecture or the function of the part.

b) Reattachment: To attach again. The reunion of connective tissue with a root surface on which viable periodontal tissue is present. Not to be confused with new attachment.

c) New attachment:
1) True new attachment: The reunion of connective tissue with a root surface that has been deprived of its periodontal ligament.  This reunion occurs by the formation of new cementum with inserting collagen fibers.
2) Long junctional epithelium (epithelial attachment): Adhesion of the junctional epithelium to a root surface that has been deprived of its periodontal ligament or connective tissue attachment.
d) Regeneration: Reproduction or reconstitution of a lost or injured part.



C) Objectives in root planing:
a)    restore gingival health by completely removing tooth surface factors that promote gingival inflammation

b)    make the root surface biologically acceptable to the soft tissues.


Limitations in root planing as part of non-surgical periodontal therapy.



Decision-Making Regarding Response to Initial Therapy
            A)  periodontal surgery
B) periodontal maintenance         
A)   initial therapy end point not reached

Summary of Recent Literature


PERIODONTAL SCALING AND ROOT PLANING
SUMMARY OF ISSUES CONTROVERSIES IN THE LITERATURE


In the past 30 years there have been numerous studies designed to test the effectiveness of scaling and root planing as a method of controlling periodontal diseases.  If there is one area in dentistry that is evidence based, it is periodontal instrumentation, because of the extensive studies and literature.  However, because many issues are controversial with support on each sides, conclusive evidence is lacking. Therefore, periodontal scaling and root planing remains as much an art as a science despite the literature.  Some of the important issues are listed below.  In the 1989 World Workshop in Clinical Periodontics, it was emphasized that in many of the studies, instrumentation was performed by experienced periodontists with unlimited time.  Extrapolation from carefully controlled experimental studies to real-life clinical situations should be done cautiously. 

Surgical Vs. Non-surgical Therapy
There is support that in non-surgical scaling and root planing the deeper the pocket is, the more difficult it becomes to instrument non-surgically.  Rabbini (1981) had results that “demonstrated a high correlation between percent of residual calculus and pocket depth”.  It was shown that pockets less than 3 mm were the easiest sites for scaling and root planing.  Pocket depths between 3 to 5 mm were more difficult to scale and pockets deeper than 5 mm were the most difficult.  Sherman  (1990) evaluated the ability of experienced clinicians to detect residual calculus following subgingival scaling and root planing.  She compared the clinical detection with the microscopic presence of calculus.  The results showed that "there was a high false negative response (77.4% of the surfaces with microscopic calculus were clinical scores as being free of calculus) and a low false positive response (11.8% of the surfaces microscopically free of calculus were clinically determined to have calculus)."  Her study indicates the difficulties in clinically determining the thoroughness of subgingival instrumentation.  Kepic (1990) found that complete removal of calculus from a periodontally diseased root, even with an open (surgical) approach is rare.  Rateitschak (1992) found that in non-surgical therapy, curettes could not reach the bottom of deep pockets.   It may be concluded from the above studies that in deeper sites, periodontal surgery may be required to gain direct access to the root surface for debridement. 

Ultrasonics Vs. Hand Instrumentation
    a. Calculus removal
Most studies have found both ultrasonic/sonic and hand instrumentation to be equally effective in calculus removal.  Gellin (1986) found that the combination of sonic instrumentation and hand instrumentation to be better than either method alone.

    b. Rough vs. smooth roots and cementum removal
There is little question that root surfaces which have become rough due to exposure to the oral environment and calculus promote bacterial adherence, increased surface area.  Several S.E.M. studies have shown that hand instrumentation is more effective than ultrasonics in cementum removal and may result in a smoother root, although a few studies show equal effectiveness.  Improperly used hand instruments, ultrasonics or rotary instruments may induce root surface roughness which may in themselves cause future periodontal problems.  It can be concluded that when root roughness is present, hand instruments are more effective in making a rough root smoother.  When improperly used, hand instruments or ultrasonic instruments may gouge the root surface.  When scaling and root planing is done as a closed procedure, the smoothness of the root is one of the best ways to determine if a suitable end point is being reached.   Quirynen and Bollen (1995) extensively reviewed the literature on rough roots and the relationship to adhesion and retention of oral microbes.  Most of the studies they reviewed show rough roots lead to high-energy surfaces, which collect and bind more bacteria.  

   c. Difficult to reach areas
O'Leary found the most difficult sites to instrument completely are furcations, grooves, CEJ's and line angles.  Ultrasonic instrumentation seems to be superior in accessing difficult to reach areas, especially furcations, although neither technique can completely remove calculus in this area.  The new modified ultrasonic  tip (e.g.: slimline® tips) has made deep pockets more accessible. 

   d. Resolving inflammation
Some studies have shown that ultrasonic and hand instruments are both equally effective in reducing inflammation.  Badersten (1983) when evaluating reduction of inflammation on single rooted found " no differences in results could be observed when comparing hand versus ultrasonic instrumentation".  She also found that there was no advantage to repeated root planing and that improvement occurred over a 9 month period of time.

   e. Overall conclusion on hand vs. ultrasonic instrumentation
There is evidence in the literature that it makes good clinical sense to use both types of instrumentation, whenever possible, because the two methods supplement each other.


Cementum Removal and Endotoxin (LPS)
Endotoxin is the potent inflammatory stimulator that is released by gram negative bacteria on cell death and thought to contribute to the progression of periodontal disease through its absorption into the root.  Jones and O'Leary (1978) showed that scaling diseased roots (without root planing) only partly reduced endotoxin but root planing "was able to render diseased root surfaces approximately as free of detectable endotoxin as were uninvolved, healthy root surfaces of unerupted teeth".  Nishimine and O'Leary 1979 found hand instruments to be more effective than ultrasonics in removing endotoxin in vivo. Several recent studies have shown that ultrasonic instrumentation is effective at removing adsorbed endotoxins, but these studies are in vitro.   There is clinical support for the removal of some of the cementum but not to the extent of removing all of the cementum.  Endotoxin, originally believed to require extensive instrumentation to be removed from the root surface, is now believed to be more weakly adherent than originally believed.  Several more recent studies have shown that ultrasonics is quite effective in removing cementum bound endotoxins.  Nyman (1988) compared scaling and root planing with scaling and polish (without cementum removal) and found the same degree of improvement following periodontal surgery.   It may be concluded that it is clinically sound to remove enough cementum to make the root surface smooth and clean, but removal of all the cementum is not justified.

Root Planing At Shallow Versus Deep Sites
A few studies have shown that root planing healthy sites tends to result in clinical attachment loss, while root planing at sites deeper results in clinical attachment gain. The critical probing is the average probe depth below which there is attachment loss and above which there is attachment gain for a particular procedure.  Lindhe (1982) found the critical probing depth for periodontal scaling and root planing to be 2.9 mm on average (shallower sites show attachment loss; deeper sites show attachment gain).  The important message here is that root planing should be directed at sites with disease and not performed at healthy shallow sites.

The Role of Calculus in Periodontal Disease
In a 1985 Review article on the pathogenesis of periodontal disease entitled "Calculus Revisited", Irwin Mandel states that "since the accepted scenario is that apical growth of supragingival plaque precedes the formation of subgingival calculus, there is no longer an issue of whether subgingival calculus is the cause or the result of periodontal disease.  Subgingival mineralization results from the interaction of subgingival plaque with the influx of mineral salts that is part of the serum transudate and inflammatory exudate.   This however should not be the basis for relegating calculus to the ash heap.  Morphologic and analytical studies point to the porosity of calculus and retention of bacterial antigens and the presence of readily available toxic stimulators of bone resorption.  When coupled with the increased build up of plaque on the surface of the calculus, the combination has the potential for extending the radius of destruction and the rate of displacement of the adjacent junctional epithelium.  The centrality of thorough scaling and root planing in the successful maintenance of periodontal health supports the view the subgingival calculus contributes significantly to the chronically and progression of the disease, even if it can no longer be considered as responsible for initiation".

Gingival Curettage and Root Planing
The American Academy of Periodontology Glossary states "gingival curettage is the process of debriding the soft tissue wall of a periodontal pocket".  It involves removal of ulcerated sulcular epithelium and some of the inflamed connective tissue ("granulation tissue").  Inadvertent curettage is done when the trailing edge of the curet removes some of the pocket wall during root planing.  Intentional curettage is accomplished when the cutting edge of the curet is directed toward the pocket wall.  Since teeth that are curetted are always root planed and inadvertent curettage occurs during root planing the two procedures cannot be separated.  Moreover, curettage is difficult to accomplish effectively in deep pockets.   At the current time gingival curettage, as a separate procedure, apparently has no justifiable application during active therapy for chronic adult periodontitis.


Key Words : gum disease bleeding gums gums receding gums swollen gums sore gums healthy gums

The Spinal Cord and Spinal Nerves


  • The CNS is wrapped by layers called MENINGES
  • EPIDURAL SPACE: space just outside of the dura mater and within the vertebral foramen that houses the spinal cord and its meninges
  • DURA MATER: outermost of the meninges, it is made of collagen fibers and is therefore a mechanically protective covering
  • SUBDURAL SPACE: not usually a visible space - the arachnoid is in reality inflated right up against the dura mater.
  • SUBDURAL HEMATOMA: blood fills the subdural space and puts pressure on the spinal cord
  • ARACHNOID: a filmy, lightweight layer that, like a spiderweb, has microscopic extensions which gently hold the spinal cord in place
  • SUBARACHNOID SPACE: space between the arachnoid and the pia mater that is full of cerebrospinal fluid (CSF) in which the spinal cord floats - the subarachnoid space is a sort of hydraulic shock absorber for the CNS
  • PIA MATER: the layer that closely wraps the spinal cord (there is no space between the pia and the spinal cord)- contains blood vessels and supplies circulation to the CNS

Meninges can develop tumors called MENINGIOMAS
     - These are always benign tumors, but they can be dangerous or fatal if they start to displace other tissues and disrupt the spinal cord
  • HEMANGIOMA: an abnormal growth of blood vessels that would, if on the skin, is called a Port Wine Stain. May also be found growing in the vessels of the pia mater,and can be dangerous

  • SPINAL NERVES: run in/out of the spinal cord and extend to/from the body
     - Segmental - each nerve controls a segment of the body, or DERMATOME (a “slice” of skin)
     - Near the spinal cord, they branch to form a dorsal root and a ventral root, and then branch more to form rootlets which connect to the spinal cord
     - DERMATOMAL DISTRIBUTIONS: signs that is restricted to particular dermatomes in the skin
- Inflammation and pain in a particular dermatome is characteristic of shingles
- Numbness in a particular dermatome is a clue to a specific disc being herniated
  • CAUDA EQUINA: spinal nerves with roots that are found at the end of the spinal cord, and that extend downward and out through the sacral foramina
     - The nerves are “hanging” in an extension of the subarachnoid space, and are surrounded by CSF
  • SPINAL TAP: a lumbar puncture to draw CSF or to check spinal cord pressure in the safest region possible, the cauda equina

SPINAL CORD

  • GANGLION: cluster of cell bodies outside of the CNS
dorsal vs. ventral can always be distinguished by the “swelling” that is the dorsal root ganglion on the dorsal root just before the dorsal and the ventral roots meet to become the spinal nerve
  • WHITE MATTER: myelinated axons
  • GRAY MATTER: cell bodies

Three classes of neurons make up a REFLEX ARC:
     1. AFFERENT (SENSORY) NEURONS: can generate action potentials and carry a sensation to the CNS
            - bring impulses INTO the CNS
            - All afferent neurons enter the dorsal root
            - These are BIPOLAR type neurons, which have their cell body located in the dorsal root ganglion, and two axons which extend in opposite directions (one out to the extremity and the other to the CNS)
     2. EFFERENT (MOTOR) NEURONS: carry information/commands from the CNS out to the periphery
            - Cell bodies located in the ventral gray horns
            - All efferent neurons leave the CNS through the ventral root
     3. INTERNEURONS: distribute nerve impulses WITHIN the CNS
            - The most complicated type of all neurons; involved in processing
            - Cell bodies located in the dorsal gray horn and axons extend within the spinal
  cord
Reflexes are “hard-wired” as a consequence of the wiring patterns of efferent neurons,interneurons, and afferent neurons.
  • REFLEX ARCS are involved in fast, unconscious, involuntary reactions.
There is more gray matter in areas of the spinal cord where lots of reflexes are occurring
     - Cervical (arms), lumbar (legs), and sacral (bladder, rectum, sex organs) regions of the spinal cord
Syphilis and polio are two diseases that destroy opposite ends of a reflex arc (for instance, one destroys the sensory half, but leaves the motor half unaffected and vice versa). Multiple sclerosis is a disease that destroys the interneurons and thus the connection between the two halves of the arc.


  • TRACT: a group or "bundle" of axons traveling together
     - ASCENDING TRACTS: sensory
            1. DORSAL COLUMNS: the biggest ascending tracts that bring in information from the outside world
                 - Sensory information about the skin and body position
                 - If damaged, there would be a sensory deficit
            2. ANTEROLATERAL SPINOTHALAMIC TRACTS: send information about pain and temperature sensation to the thalamus
     - DESCENDING TRACTS: motor
            1. PYRAMIDAL TRACTS: voluntary muscle movement
            2. EXTRAPYRAMIDAL TRACTS: involuntary muscle movement
RAMUS: a branch off of a spinal nerve (plural = rami)

NERVES:
PHRENIC NERVE: controls the diaphragm and breathing
     - Out of C3, C4, and C5 - this is important because if the neck is broken below C5 then breathing is still possible
     - Right and left phrenic nerves run down between the heart and lungs to the diaphragm
     - breathing pacemaker: electrodes connect to the phrenic nerve
     - Hiccups: unexplained bursts of action potentials down the phrenic nerve cause spasms of the diaphragm
BRACHIAL PLEXUS: controls the arms
     - Out of C5, C6, C7, C8 and T1
     - Extensions of the brachial plexus:
            1. MUSCULOCUTANEOUS NERVE: controls the coracobrachialis, biceps
     brachi, and brachialis muscles
            2. ULNAR NERVE: runs down and behind the medial malleolus of the humerus to the little finger and part of the ring finger
            3. MEDIAN NERVE: controls lots of the flexor muscles of the hand
                 - comes off of the brachial plexus and runs down the middle of the ventral surface of the forearm
                 - carpal tunnel inflammation will put pressure on the median nerve and will cause loss of sensation in most of the hand and will also cause pain
            4. RADIAL NERVE: controls lots of the extensor muscles of the hand
                 - runs down behind the arm and down the extensor surface of the forearm
LUMBOSACRAL PLEXUS: out of L2, L3, L4, L5, S1, S2, S3, S4, and S5
     - Branches to form three nerves:
            1. FEMORAL NERVE: controls the quadriceps
            2. OBTURATOR NERVE: runs through the obturator foramen and controls the adductor muscles
            3. SCIATIC NERVE: the biggest, longest and fattest nerve in the body
                 - controls the butt, hamstrings, and calves
                 - becomes the POPLITEAL NERVE and then the TIBIAL and FIBULAR (Or PERONEAL) NERVES
                 - SCIATICA: pain and/or paralysis down the leg due to inflammation of or lack of circulation to the sciatic nerve


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