Hertwig's Epithelial Root Sheath- HERS

Hertwig's epithelial root sheath

• It originates from the cervical portion of the enamel organ.
• It plays an important role in determining shape length size and number of roots.
• It is a double layer of cells which consists of outer enamel epithelium and inner enamel epithelium.
• Root sheath extends around dental papilla and separates it from surrounding dental follicle all through except the Basil portion.
• Inner enamel epithelial layer of root sheath influences the formation of odontoblast from the outer portion of the radicular dental papilla. 
• These odontoblasts lead to the formation of the first layer of radicular dentin.

As the first layer of radicular dentin is laid down:

• HERS loses its continuity 
• The cells of the dental follicle or dental sac invade double layer of HERS 
• Root sheath degenerates to form epithelial Islands

Therefore, it allows connective tissue of dental follicle to come in contact with newly formed radicular dentin. 

This causes differentiation of cementoblast from dental follicle which deposits cementum on newly formed radicular dentin.

Transitory Sutures

Transitory Sutures are found in cap stage of tooth development

Enamel Knot: Enamel organ cells form a knob-like extension which extends to the underlying dental papilla.

Enamel cord: it is a vertical extension of enamel knot

Enamel septum: when enamel cord extends to meet outer enamel epithelium it divides stellate reticulum into two parts

Enamel navel: Depression present at the junction of enamel septum and Outer enamel epithelium is known as enamel navel and it resembles umbilicus

Enamel Knot signals determine the shape of the tooth
Enamel Knot and Enamel cord act as a reservoir of dividing cells 

- Written By Anisha Valli

Human Papilloma Virus mnemonics

To remember that HPV vaccination starts at 11 years old and that HPV is the most common STD in the US, use the following mnemonics:

=> Write Human Papilloma Virus with 11 instead of the 2 Ls so it becomes as follows:
Human Papi11oma Virus

the 11 in papilloma will remind you of number 11 :)

=> remember HPV as the Highest Prevalent Virus :P
so this will remind you that it is the commonest STD

and that's it

-Murad

MDMA mnemonic

Hello! 

This post is about MDMA.

MDMA? Yep. It's short for 3,4-methylenedioxymethamphetamine.

Commonly called “Molly” or “ecstasy”.

MDMA can elicit feelings of euphoria, wakefulness, intimacy, and disinhibition.

Intoxication causes dangerous side effects such as:

Hypertension
Hyperthermia
Delirium
Psychomotor agitation
Hyponatremia
Intracranial hemorrhage
Myocardial infarction
Aortic dissection
Disseminated intravascular coagulation
Rhabdomyolysis
Seizures
Serotonin syndrome

Here's a mnemonic!

That's all!

-IkaN

Conjunctival xerosis mnemonics

Conjunctival Xerosis

Hello everyone today let's discuss the causes and treatment of conjunctival xerosis.

So basically there are two types of conjunctival xerosis.
a. Epithelial xerosis
b. Parenchymatous xerosis

Epithelial xerosis.
The most common example is Xerophthalmia i.e. Vitamin A deficiency.

Let us discuss Xerophthalmia.

The cause of vitamin A deficiency is mostly its dietary deficiency or defective absorption.

The new WHO classification of Xerophthalmia

XN:   Night Blindness
X1A: conjunctival xerosis
X1B: bitots spots
X2:   corneal xerosis
X3A: keratomalacia <1/3rd of cornea
X3B: keratomalacia >1/3rd of cornea   
XS: corneal scar
XF: fundal changes – known as Uyemura spots, these are defects in the Retinal
Pigment Epithelium.

Treatment:
It consists of local ocular therapy with artificial tears along with vitamin A therapy.
Schedule for vitamin A is as follows :

>1 year of age – 1lakh IU i.m. given on 0 1 14 days
                                OR
 2lakh IU orally given on 0 1 14 days

<1 year of age – half the dose.

This has to be carried along with treatment of underlying causes like malnutrition or other disorders like diarrhoea dehydration.

Other causes of night blindness:
1. High myopia
2. Late stage of angle closure glaucoma
3. Oguchi syndrome
4. Gyrate atrophy of choroid
5. Retinitis pigmentosa

Parenchymatous Xerosis
It mainly involves the adenoid layer of the conjunctiva.
It can take place due two main reasons     holla! We have a mnemonic here
1. Due to cicatrizing disorders  (cicatrizing disorders turn conjunctiva reasonably shrivelled)
2. Due to over exposure to atmosphere ( marked exposure causes parenchymatous xerosis)

Cicatrizing disorders
1. Cicatricial phemphigoid
2. Diptheric membranous conjunctivitis
3. Trachoma
4. Chemical burns
5. Radiotherapy
6. Stevens-johnson syndrome


Overexposure to atmosphere
1. Marked proptosis
2. Ectropion
3. Coma (lack of blinking)
4. Palsy of cranial nerve 7 (facial palsy)

That’s all for now,
Stay Awesome!
Keep calm and keep studying!

- Ashish G. Gokhale

Step 2 CK: Blunt abdominal trauma

Hello!

When you are presented with a case of blunt abdominal trauma (BAT) in your exam, first determine whether the patient is stable or unstable.

Medicowesome secret project: Long Distance Metastasis

What is the secret project? How can I participate?

USMLEowesome: Basics about the Step 2 CS exam

Hello!

In this video I will cove the basics about the Step 2 CS exam:

Medicowesome secret project: Trouble in St. Bowel High School

What is the secret project? How can I participate?

Coronary circulation: Fun fact about blood flow to the myocardium

Hello everyone, here is a post busting a myth about coronary circulation.

Many of us have always thought that the heart itself receives blood during diastole which is only partially true. Here is the complete story.

Getting back to basics, let us revise a bit about the cardiac anatomy.

Medicowesome secret project: Calcified hearts

What is the secret project? How can I participate?

USMLEowesome: United States Clincal Experience (USCE), electives and obs...

United States Clinical Experience - An overview

Intended audience: Those who want to know more about USCE

What this video will cover:
Why do you need USCE?
Types of USCE
Deciding where to apply, which electives?
Paperwork required for electives (brief overview)
Strong letter (applicable for USCE and the match)
CV (brief overview)
Visa interview: Important! Do not mess it up!
If you are not accepted: Have back ups!
If you are accepted: Video for another time :)

Links from the video:

Types of USCE:
http://www.medicowesome.com/2016/03/a-short-post-on-how-to-apply-for.html
http://www.medicowesome.com/2016/04/dr-thinker-united-states-clinical.html
http://www.medicowesome.com/2017/06/my-elective-experience.html
http://electives.us/typesofusce.html

Paperwork:
http://www.medicowesome.com/2016/03/a-short-post-on-how-to-apply-for.html
http://electives.us/electiveapplication.html 

Read this before your visa interview: http://electives.us/usvisaandelectives.html

Link to the powerpoint:
https://drive.google.com/open?id=1aRH5u4Vk7RfHIKrBsDl0TjTMtuVmlVnW

That's all!

-IkaN

USMLEowesome: Studying for the USMLE Step 1 exam

Hello!

The intended audience for this video is those who have decided to give the exam and are starting to study for it.