NEET MDS Synopsis
The Middle Ear
AnatomyWalls of the Tympanic Cavity or Middle Ear
This cavity is shaped like a narrow six-sided box that has convex medial and lateral walls.
It has the shape of the biconcave lens in cross-section (like a red blood cell).
The Roof or Tegmental Wall
This is formed by a thin plate of bone, called the tegmen tympani (L. tegmen, roof).
It separates the tympanic cavity from the dura on the floor of middle cranial fossa.
The tegmen tympani also covers the aditus ad antrum.
The Floor or Jugular Wall
This wall is thicker than the roof.
It separates the tympanic cavity from the superior bulb of the internal jugular vein. The internal jugular vein and the internal carotid artery diverge at the floor of the tympanic cavity.
The tympanic nerve, a branch of the glossopharyngeal nerve (CN IX), passes through an aperture in the floor of the tympanic cavity and its branches form the tympanic plexus.
The Lateral or Membranous Wall
This is formed almost entirely by the tympanic membrane.
Superiorly it is formed by the lateral bony wall of the epitympanic recess.
The handle of the malleus is incorporated in the tympanic membrane, and its head extends into the epitympanic recess.
The Medial or Labyrinthine Wall
This separates the middle ear from the membranous labyrinth (semicircular ducts and cochlear duct) encased in the bony labyrinth.
The medial wall of the tympanic cavity exhibits several important features.
Centrally, opposite the tympanic membrane, there is a rounded promontory (L. eminence) formed by the first turn of the cochlea.
The tympanic plexus of nerves, lying on the promontory, is formed by fibres of the facial and glossopharyngeal nerves.
The medial wall of the tympanic cavity also has two small apertures or windows.
The fenestra vestibuli (oval window) is closed by the base of the stapes, which is bound to its margins by an annular ligament.
Through this window, vibrations of the stapes are transmitted to the perilymph window within the bony labyrinth of the inner ear.
The fenestra cochleae (round window) is inferior to the fenestra vestibuli.
This is closed by a second tympanic membrane.
The Posterior or Mastoid Wall
This wall has several openings in it.
In its superior part is the aditus ad antrum (mastoid antrum), which leads posteriorly from the epitympanic recess to the mastoid cells.
Inferiorly is a pinpoint aperture on the apex of a tiny, hollow projection of bone, called the pyramidal eminence (pyramid).
This eminence contains the stapedius muscle.
Its aperture transmits the tendon of the stapedius, which enters the tympanic cavity and inserts into the stapes.
Lateral to the pyramid, there is an aperture through which the chorda tympani nerve, a branch of the facial nerve (CN VII), enters the tympanic cavity.
The Anterior Wall or Carotid Wall
This wall is a narrow as the medial and lateral walls converge anteriorly.
There are two openings in the anterior wall.
The superior opening communicates with a canal occupied by the tensor tympani muscle.
Its tendon inserts into the handle of the malleus and keeps the tympanic membrane tense.
Inferiorly, the tympanic cavity communicates with the nasopharynx through the auditory tube.
Glasgow Coma Scale
Oral and Maxillofacial SurgeryGlasgow Coma Scale (GCS): Best Verbal Response
The Glasgow Coma Scale (GCS) is a clinical scale used to
assess a patient's level of consciousness and neurological function,
particularly after a head injury. It evaluates three aspects: eye opening,
verbal response, and motor response. The best verbal response (V) is one of the
components of the GCS and is scored as follows:
Best Verbal Response (V)
5 - Appropriate and Oriented:
The patient is fully awake and can respond appropriately to
questions, demonstrating awareness of their surroundings, time, and
identity.
4 - Confused Conversation:
The patient is able to speak but is confused and disoriented. They
may answer questions but with some level of confusion or incorrect
information.
3 - Inappropriate Words:
The patient uses words but they are inappropriate or irrelevant to
the context. The responses do not make sense in relation to the
questions asked.
2 - Incomprehensible Sounds:
The patient makes sounds that are not recognizable as words. This
may include moaning or groaning but does not involve coherent speech.
1 - No Sounds:
The patient does not make any verbal sounds or responses.
ANTIBIOTICS
Pharmacology
ANTIBIOTICS
Chemotherapy: Drugs which inhibit or kill the infecting organism and have no/minimum effect on the recipient.
Antibiotic these are substances produced by microorganisms which suppress the growth of or kill other micro-organisms at very low concentrations.
Anti-microbial Agents: synthetic as well as naturally obtained drugs that attenuate micro-organism.
SYNTHETIC ORGANIC ANTIMICROBIAL DRUGS
Sulfonamides
Trimethoprim-sulfamethoxazole
Quinolones – Ciprofloxacin
ANTIBIOTICS THAT ACT ON THE BACTERIAL CELL WALL
Penicillins
Cephalosporins
Vancomycin
INHIBITORS OF BACTERIAL PROTEIN SYNTHESIS
Aminoglycosides - Gentamicin
Antitubercular Drugs: Isoniazid & Rifampin
Tetracyclines
Chloramphenicol
Macrolides – Erythromycin, Azithromycin
Clindamycin
Mupirocin
Linezolid
ANTIFUNGAL DRUGS
Polyene Antibiotics (Amphotericin B, Nystatin and Candicidin)
Imidazole and Triazole Antifungal Drugs
Flucytosine
Griseofulvin
ANTIPROTOZOAL DRUGS
Antimalarial Drugs – Quinine, Chloroquine, Primaquine
Other Antiprotozoal Drugs – Metronidazole, Diloxanide, Iodoquinol
ANTIHELMINTHIC DRUGS
Praziquantel
Mebendazole
Ivermectin
ANTIVIRAL DRUGS
Acyclovir
Ribavirin
Dideoxynucleosides
Protease inhibitors
MANDIBULAR SECOND BICUSPID
Dental Anatomy
MANDIBULAR SECOND BICUSPID
Facial: From this aspect, the tooth somewhat resembles the first, but the buccal cusp is less pronounced. The tooth is larger than the first.
Lingual: Two significant variations are seen in this view. The most common is the three-cusp form which has two lingual cusps. The mesial of those is the larger of the two. The other form is the two-cusp for with a single lingual cusp. In that variant, the lingual cusp tip is shifted to the mesial.
Proximal: The buccal cusp is shorter than the first. The lingual cusp (or cusps) are much better developed than the first and give the lingual a full, well-developed profile.
Occlusal: The two or three cusp versions become clearly evident. In the three-cusp version, the developmental grooves present a distinctive 'Y' shape and have a central pit. In the two cusp version, a single developmental groove crosses the transverse ridge from mesial to distal
Contact Points; Height of Curvature: From the facial, the mesial contact is more occlusal than the distal contact.The distal marginal ridge is lower than the mesial marginal ridge
Root Surface:-The root of the tooth is single, that is usually larger than that of the first premolar
the lower second premolar is larger than the first, while the upper first premolar is just slightly larger than the upper second
There may be one or two lingual cusps
Mental Age Assessment
PedodonticsMental Age Assessment
Mental age can be assessed using the following formula:
Mental Age = (Chronological Age × 100) / 10
Mental Age Descriptions
Below 69: Mentally retarded (intellectual disability).
Below 90: Low average intelligence.
90-110: Average intelligence. Most children fall within
this range.
Above 110: High average or superior intelligence.
Iron deficiency anaemia
General PathologyIron deficiency anaemia.
Absorption of iron is affected by :
- Iron stores.
- Rate of erythropoiesis
- Acid pH aids absorption.
- Phosphates and phytates in diet impair absorption.
Causes of deficiency:
- Increased demand:
o Growth (in children)
o Menstruation, Pregnancy, lactation.
- Inadequate intake and absorption.
o Dietary deficiency.
o Achlorhydria or gastrectomy.
o Malabsorption states.
- Chronic blood loss
o Peptic ulcer, bleeding piles
o Menorrhagia.
o Hook worm infestation
Features:
- Anaemia.
- Koilonychia.
- Atrophic glossitis and angular stomatitis.
- Dysphagia-Plummer Vinson syndrome.
Blood findings:
- Microcytjc_hypochromic cells, ring cells and pessary cells.
- Anisocytosis and poikilocytosis.
- Low MCV. MCH and MCHC.
- Serum iron is low but iron binding capacity is increased
Bone marrow
Erythroid hyperplasia with imcronormoblasts. Iron stains reveal depleted stores
Differential diagnosis .-
- Sideroblastic anaemia which is also microcytic hypochromic but there is excess iron in the erythroid cells .Some are pyridoxine responsive.
- (ii) Thalassaemia
Sedative-Hypnotic and Anxiolytic Drugs
Pharmacology
Sedative-Hypnotic Drugs
Sedative drug is the drug that reduce anxiety (anxiolytic) and produce sedation and referred to as minor tranquillisers.
Hypnotic drug is the drug that induce sleep
Effects: make you sleepy; general CNS depressants
Uses: sedative-hypnotic (insomnia ), anxiolytic (anxiety, panic, obsessive compulsive, phobias), muscle relaxant (spasticity, dystonias), anticonvulsant (absence, status epilepticus, generalized seizures—rapid tolerance develops), others (pre-operative medication and endoscopic procedures, withdrawal from chronic use of ethanol or other CNS depressants)
1- For panic disorder alprazolam is effective.
2- muscle disorder: (reduction of muscle tone and coordination) diazepam is useful in treatment of skeletal muscle spasm e.g. muscle strain and spasticity of degenerative muscle diseases.
3-epilepsy: by increasing seizure threshold.
Clonazepam is useful in chronic treatment of epilepsy while diazepam is drug of choice in status epilepticus.
4-sleep disorder: Three BDZs are effective hypnotic agents; long acting flurazepam, intermediate acting temazepam and short
acting triazolam. They decrease the time taken to get to sleep They increase the total duration of sleep
5-control of alcohol withdrawals symptoms include diazepam, chlordiazepoxide, clorazepate and oxazepam.
6-in anesthesia: as preanesthetic amnesic agent (also in cardioversion) and as a component of balanced anesthesia
Flurazepam significantly reduce both sleep induction time and numbers of awakenings and increase duration of sleep and little rebound insomnia. It may cause daytime sedation.
Temazepam useful in patients who experience frequent awakening, peak sedative effect occur 2-3 hr. after an oral dose.
Triazolam used to induce sleep in recurring insomnia and in individuals have difficulty in going to sleep, tolerance develop within few days and withdrawals result in rebound insomnia therefore the drug used intermittently.
Drugs and their actions
1. Benzodiazepines: enhance the effect of gamma aminobutyric acid (GABA) at GABA receptors on chloride channels. This increases chloride channel conductance in the brain (GABA A A receptors are ion channel receptors).
2. Barbiturates: enhance the effect of GABA on the chloride channel but also increase chloride channel conductance independently of GABA, especially at high doses
3. Zolpidem and zaleplon: work in a similar manner to benzodiazepines but do so only at the benzodiazepine (BZ1) receptor type. (Both BZ1and BZ2 are located on chloride channels.)
4. Chloral hydrate: probably similar action to barbiturates.
5. Buspirone: partial agonist at a specific serotonin receptor (5-HT1A).
6. Other sedatives (e.g., mephenesin, meprobamate, methocarbamol, carisoprodol, cyclobenzaprine):
mechanisms not well-described. Several mechanisms may be involved.
7. Baclofen: stimulates GABA linked to the G protein, Gi , resulting in an increase in K + conductance and a decrease in Ca2+ conductance. (Other drugs mentioned above do not bind to the GABA B receptor.)
8. Antihistamines (e.g., diphenhydramine): block H1 histamine receptors. Doing so in the CNS leads to sedation.
9. Ethyl alcohol: its several actions include a likely effect on the chloride channel.
Cranial Nerves
Physiology
There Are 12 Pairs of Cranial Nerves
The 12 pairs of cranial nerves emerge mainly from the ventral surface of the brain
Most attach to the medulla, pons or midbrain
They leave the brain through various fissures and foramina of the skull
Nerve
Name
Sensory
Motor
Autonomic
Parasympathetic
I
Olfactory
Smell
II
Optic
Vision
III
Oculomotor
Proprioception
4 Extrinsic eye muscles
Pupil constriction
Accomodation
Focusing
IV
Trochlear
Proprioception
1 Extrinsic eye muscle (Sup.oblique)
V
Trigeminal
Somatic senses
(Face, tongue)
Chewing
VI
Abducens
Proprioception
1 Extrinsic eye muscle (Lat. rectus)
VII
Facial
Taste
Proprioception
Muscles of facial expression
Salivary glands
Tear glands
VIII
Auditory
(Vestibulocochlear)
Hearing, Balance
IX
Glossopharyngeal
Taste
Blood gases
Swallowing
Gagging
Salivary glands
X
Vagus
Blood pressure
Blood gases
Taste
Speech
Swallowing Gagging
Many visceral organs
(heart, gut, lungs)
XI
Spinal acessory
Proprioception
Neck muscles:
Sternocleidomastoid
Trapezius
XII
Hypoglossal
Proprioception
Tongue muscles
Speech
Many of the functions that make us distinctly human are controlled by cranial nerves: special senses, facial expression, speech.
Cranial Nerves Contain Sensory, Motor and Parasympathetic Fibers