NEET MDS Synopsis
Muscles Around the Eyelids
AnatomyMuscles Around the Eyelids
The function of the eyelid (L. palpebrae) is to protect the eye from injury and excessive light. It also keeps the cornea moist.
The Orbicularis Oculi Muscle
This is the sphincter muscle of the eye.
Its fibres sweep in concentric circles around the orbital margin and eyelids.
It narrows the eye and helps the flow of tears from the lacrimal sac.
This muscle has 3 parts: (1) a thick orbital part for closing the eyes to protect then from light and dust; (2) a thin palpebral part for closing the eyelids lightly to keep the cornea from drying; and (3) a lacrimal part for drawing the eyelids and lacrimal punta medially.
When all three parts of the orbicularis oculi contract, the eyes are firmly closed and the adjacent skin becomes wrinkled.
The zygomatic branch of the facial nerve (CN VII) supplies it.
The Levator Palpebrae Superioris Muscle
This muscle raises the upper eyelid to open the palpebral fissure.
It is supplied by the oculomotor nerve (CN III).
Prostaglandines
Pharmacology
Prostaglandines:
Every cell in the body is capable of synthesizing one or more types of PGS. The four major group of PGs are E, F, A, and B.
Pharmacological actions:
stimulation of cyclicAMP production and calcium use by various cells
CVS
PGE2 acts as vasodilator; it is more potent hypotensive than Ach and histamine
Uterous
PGE2 and PGF2α Contract human uterus
Bronchial muscle
PGF2α and thromboxan A2 cause bronchial muscle contraction.
PGE2 & PGI2 cause bronchial muscle dilatation
GIT: PGE2 and PGF2α cause colic and watery diarrhoea
Platelets
Thromboxan A2 is potent induce of platelets aggregation
Kidney
PGE2 and PGI2 increase water, Na ion and K ion excretion (act as diuresis) that cause renal vasodilatation and inhibit
tubular reabsorption
USE
PGI2: Epoprostenol (inhibits platelets aggregation)
PGE1: Alprostadil (used to maintain the potency of arterioles in neonates with congenital heart defects).
PGE2: Dinoproste (used as pessaries to induce labor)
Synthetic analogue of PGE1: Misoprostol (inhibit the secretion of HCl).
Ankylosing spondylitis
Orthopaedics
- Ankylosing spondylitis or AS, is a form of arthritis that primarily affects the spine, although other joints can become involved.
- It causes inflammation of the spinal joints (vertebrae) that can lead to severe, chronic pain and discomfort.
- Most people with AS have an antigen called HLA-B27
- Ankylosing spondylitis (AS) is a chronic, multisystem inflammatory disorder involving primarily the sacroiliac joints and the axial skeleton.
Key components of the patient history that suggest AS include the following:
• Insidious onset of low back pain - The most common symptom
• Onset of symptoms before age 40 years
• Presence of symptoms for more than 3 months
• Symptoms worse in the morning or with inactivity
• Improvement of symptoms with exercise
Complications
- AS can cause pain and inflammation in other parts of your body.
- Eyes. About 40% of people with AS have an eye problem called uveitis. It’s a painful inflammation that can blur your vision and make you sensitive to bright light.
- Heart valve. It’s not common, but AS can enlarge the aorta, the largest artery in your body. This can change the shape of the aortic valve, which can allow blood to leak back into your heart.
- Cancer. A large study found that people with AS are more likely to get certain types of cancers. They include bone and prostate cancers in men and colon cancer in women, as well as blood-related cancers in both sexes.
Types of Head Injury
General SurgeryTypes of Head Injury
1. Extradural Hematoma (EDH)
Overview
Demographics: Most common in young male patients.
Association: Always associated with skull fractures.
Injured Vessel: Middle meningeal artery.
Common Site of Injury: Temporal bone at the pterion
(the thinnest part of the skull), which overlies the middle meningeal
artery.
Location of Hematoma: Between the bone and the dura
mater.
Other Common Sites
Frontal fossa
Posterior fossa
May occur following disruption of major dural venous sinus.
Classical Presentation
Initial Injury: Followed by a lucid interval where the
patient may only complain of a headache.
Deterioration: After minutes to hours, rapid
deterioration occurs, leading to:
Contralateral hemiparesis
Reduced consciousness level
Ipsilateral pupillary dilatation (due to herniation)
Imaging
CT Scan: Shows a lentiform (lens-shaped or biconvex)
hyperdense lesion between the brain and skull.
Treatment
Surgical Intervention: Immediate surgical evacuation
via craniotomy.
Mortality Rate: Overall mortality is 18% for all cases
of EDH, but only 2% for isolated EDH.
2. Acute Subdural Hematoma (ASDH)
Overview
Location: Accumulates in the space between the dura and
arachnoid.
Injury Mechanism: Associated with cortical vessel
disruption and brain laceration.
Primary Brain Injury: Often associated with primary
brain injury.
Presentation
Consciousness: Impaired consciousness from the time of
impact.
Imaging
CT Scan: Appears hyperdense, with hematoma spreading
diffusely and having a concavo-convex appearance.
Treatment
Surgical Intervention: Evacuation via craniotomy.
Mortality Rate: Approximately 40%.
3. Chronic Subdural Hematoma (CSDH)
Overview
Demographics: Most common in patients on anticoagulants
and antiplatelet agents.
History: Often follows a minor head injury weeks to
months prior.
Pathology: Due to the tear of bridging veins leading to
ASDH, which is clinically silent. As the hematoma breaks down, it increases
in volume, causing mass effect on the underlying brain.
Clinical Features
Symptoms may include:
Headache
Cognitive decline
Focal neurological deficits (FND)
Seizures
Important to exclude endocrine, hypoxic, and metabolic causes in this
group.
Imaging
CT Scan Appearance:
Acute blood (0–10 days): Hyperdense
Subacute blood (10 days to 2 weeks): Isodense
Chronic (> 2 weeks): Hypodense
Treatment
Surgical Intervention: Bur hole evacuation rather than
craniotomy.
Anesthesia: Elderly patients can often undergo surgery
under local anesthesia, despite comorbidities.
4. Subarachnoid Hemorrhage (SAH)
Overview
Causes: Most commonly due to aneurysms for spontaneous
SAH, but trauma is the most common cause overall.
Management: Conservative treatment is often employed
for trauma cases.
5. Cerebral Contusions
Overview
Definition: Bruising of the brain tissue due to trauma.
Mechanism: Often occurs at the site of impact (coup)
and the opposite side (contrecoup).
Symptoms: Can range from mild confusion to severe
neurological deficits depending on the extent of the injury.
Imaging
CT Scan: May show areas of low attenuation (hypodense)
or high attenuation (hyperdense) depending on the age of the contusion.
Treatment
Management: Depends on the severity and associated
injuries; may require surgical intervention if there is significant mass
effect.
Natal and Neonatal Teeth
Pedodontics
Natal and neonatal teeth, also known by various synonyms such as congenital
teeth, prediciduous teeth, dentition praecox, and foetal teeth. This topic is
significant in pediatric dentistry and has implications for both diagnosis and
treatment.
Etiology
The etiology of natal and neonatal teeth is multifactorial. Key factors
include:
Superficial Position of Tooth Germs: The positioning of
tooth germs can lead to early eruption.
Infection: Infections during pregnancy may influence
tooth development.
Malnutrition: Nutritional deficiencies can affect
dental health.
Eruption Acceleration: Febrile incidents or hormonal
stimulation can hasten the eruption process.
Genetic Factors: Hereditary transmission of a dominant
autosomal gene may play a role.
Osteoblastic Activities: Bone remodeling phenomena can
impact tooth germ development.
Hypovitaminosis: Deficiencies in vitamins can lead to
developmental anomalies.
Associated Genetic Syndromes
Natal and neonatal teeth are often associated with several genetic syndromes,
including:
Ellis-Van Creveld Syndrome
Riga-Fede Disease
Pachyonychia Congenital
Hallemann-Steriff Syndrome
Sotos Syndrome
Cleft Palate
Understanding these associations is crucial for comprehensive patient
evaluation.
Incidence
The incidence of natal and neonatal teeth varies significantly, ranging from
1 in 6000 to 1 in 800 births. Notably:
Approximately 90% of these teeth are normal primary teeth.
In 85% of cases, the teeth are mandibular primary incisors.
5% are maxillary incisors and molars.
The remaining 10% consist of supernumerary calcified structures.
Clinical Features
Clinically, natal and neonatal teeth may present with the following features:
Morphologically, they can be conical or normal in size and shape.
The color is typically opaque yellow-brownish.
Associated symptoms may include dystrophic fingernails and
hyperpigmentation.
Radiographic Evaluation
Radiographs are essential for assessing:
The amount of root development.
The relationship of prematurely erupted teeth to adjacent teeth.
Most prematurely erupted teeth are hypermobile due to limited root
development.
Histological Characteristics
Histological examination reveals:
Hypoplastic enamel with varying degrees of severity.
Absence of root formation.
Ample vascularized pulp.
Irregular dentin formation.
Lack of cementum formation.
These characteristics are critical for understanding the structural integrity
of natal and neonatal teeth.
Harmful Effects
Natal and neonatal teeth can lead to several complications, including:
Laceration of the lingual surface of the tongue.
Difficulties for mothers wishing to breast-feed their infants.
Treatment Options
When considering treatment, extraction may be necessary. However, precautions
must be taken:
Avoid extractions until the 10th day of life to allow for the
establishment of commensal flora in the intestine, which is essential for
vitamin K production.
If extractions are planned and the newborn has not been medicated with
vitamin K immediately after birth, vitamin K supplements should be
administered before the procedure to prevent hemorrhagic disease of the
newborn (hypoprothrombinemia).
Periodontal Diseases Associated with Neutrophil Disorders
PeriodontologyPeriodontal Diseases Associated with Neutrophil Disorders
Acute Necrotizing Ulcerative Gingivitis (ANUG)
Description: A severe form of gingivitis
characterized by necrosis of the interdental papillae, pain, and foul
odor.
Association: Neutrophil dysfunction can exacerbate
the severity of ANUG, leading to rapid tissue destruction.
Localized Juvenile Periodontitis
Description: A form of periodontitis that typically
affects adolescents and is characterized by localized bone loss around
the permanent teeth.
Association: Impaired neutrophil function
contributes to the pathogenesis of this condition.
Prepubertal Periodontitis
Description: A rare form of periodontitis that
occurs in children before puberty, leading to rapid attachment loss and
bone destruction.
Association: Neutrophil disorders can play a
significant role in the development and progression of this disease.
Rapidly Progressive Periodontitis
Description: A form of periodontitis characterized
by rapid attachment loss and bone destruction, often occurring in young
adults.
Association: Neutrophil dysfunction may contribute
to the aggressive nature of this disease.
Refractory Periodontitis
Description: A form of periodontitis that does not
respond to conventional treatment and continues to progress despite
therapy.
Association: Neutrophil disorders may be implicated
in the persistent nature of this condition.
Tongue Thrust
OrthodonticsTongue Thrust
Tongue thrust is characterized by the forward movement of the tongue tip
between the teeth to meet the lower lip during swallowing and speech, resulting
in an interdental position of the tongue (Tulley, 1969). This habit can lead to
various dental and orthodontic issues, particularly malocclusions such as
anterior open bite.
Etiology of Tongue Thrust
Retained Infantile Swallow:
The tongue does not drop back as it should after the eruption of
incisors, continuing to thrust forward during swallowing.
Upper Respiratory Tract Infection:
Conditions such as mouth breathing and allergies can contribute to
tongue thrusting behavior.
Neurological Disturbances:
Issues such as hyposensitivity of the palate or disruption of
sensory control and coordination during swallowing can lead to tongue
thrust.
Feeding Practices:
Bottle feeding is more likely to contribute to the development of
tongue thrust compared to breastfeeding.
Induced by Other Oral Habits:
Habits like thumb sucking or finger sucking can create malocclusions
(e.g., anterior open bite), leading to the tongue protruding between the
anterior teeth during swallowing.
Hereditary Factors:
A family history of tongue thrusting or related oral habits may
contribute to the development of the condition.
Tongue Size:
Conditions such as macroglossia (enlarged tongue) can predispose
individuals to tongue thrusting.
Clinical Features
Extraoral
Lip Posture: Increased lip separation both at rest and
during function.
Mandibular Movement: The path of mandibular movement is
upward and backward, with the tongue moving forward.
Speech: Articulation problems, particularly with sounds
such as /s/, /n/, /t/, /d/, /l/, /th/, /z/, and /v/.
Facial Form: Increased anterior facial height may be
observed.
Intraoral
Tongue Posture: The tongue tip is lower at rest due to
the presence of an anterior open bite.
Malocclusion:
Maxilla:
Proclination of maxillary anterior teeth.
Increased overjet.
Maxillary constriction.
Generalized spacing between teeth.
Mandible:
Retroclination of mandibular teeth.
Diagnosis
History
Family History: Determine the swallow patterns of
siblings and parents to check for hereditary factors.
Medical History: Gather information regarding upper
respiratory infections and sucking habits.
Patient Motivation: Assess the patient’s overall
abilities, interests, and motivation for treatment.
Examination
Swallowing Assessment:
Normal Swallowing:
Lips touch tightly.
Mandible rises as teeth come together.
Facial muscles show no marked contraction.
Abnormal Swallowing:
Teeth remain apart.
Lips do not touch.
Facial muscles show marked contraction.
Inhibition Test:
Lightly hold the lower lip with a thumb and finger while the patient
is asked to swallow water.
Normal Swallowing: The patient can swallow
normally.
Abnormal Swallowing: The swallow is inhibited,
requiring strong mentalis and lip contraction for mandibular
stabilization, leading to water spilling from the mouth.
Management
Behavioral Therapy:
Awareness Training: Educate the patient about the
habit and its effects on oral health.
Positive Reinforcement: Encourage the patient to
practice proper swallowing techniques and reward progress.
Myofunctional Therapy:
Involves exercises to improve tongue posture and function, helping
to retrain the muscles involved in swallowing and speech.
Orthodontic Treatment:
If malocclusion is present, orthodontic intervention may be
necessary to correct the dental alignment and occlusion.
Appliances such as a palatal crib or tongue thrusting appliances can
be used to discourage the habit.
Speech Therapy:
If speech issues are present, working with a speech therapist can
help address articulation problems and improve speech clarity.
Monitoring and Follow-Up:
Regular follow-up appointments to monitor progress and make
necessary adjustments to the treatment plan.
Stationary Relationship
Dental Anatomy
Stationary Relationship
a) .Centric Relation is the most superior relationship of the condyle of the mandible to the articular fossa of the temporal bone as determined by the bones ligaments. and muscles of the temporomandibular joint; in an ideal dentition it is the same as centric occlusion.
(b) Canines may also be used to confirm the molar relationships to classify occlusion when molars are missing; a class I canine relationship shows the cusp tip of the maxillary canine facial to the mesiobuccal cusp of the first permanent molar
c) Second primary molars are used to classify the occlusion in a primary dentition
(d) In a mixed dentition the first permanent molars will erupt into a normal occlusion if there is a terminal step between the distal surfaces of maxillarv and mandibular second primary molars; if these surfaces are flush, a terminal plane exists and the first permanent molars will first erupt into an end-to-end relationship until there is a shifting of space or exfoliation of the second primary molar