Showing posts with label Embryology. Show all posts
Showing posts with label Embryology. Show all posts

Saturday, November 2, 2019

Platypnea-Orthodeoxia Syndrome in interatrial right-to-left shunt

Hi everyone! This is a short post :)

Platypnea (flat breathing): Dyspnea induced by upright posture and relieved by recumbency.

Orthodeoxia: Arterial oxygen desaturation accentuated by upright posture and improved by recumbency.

Sunday, August 4, 2019

Tetralogy of Fallot: The Basics

Hey guys, this post highlights the important points discussed in the accompanying video.

Sunday, April 1, 2018

Neural Crest Cells : Mnemonic

Hi everyone !
Here's a short mnemonic post !

Neural Crest Cells are very special cells that form at around 2-3 weeks of gestation.
They're right next to the Neural folds of the Neural tube to begin with and then eventually come to lie lateral to the tube, after which they migrate to various parts of the body giving rise to a bunch of things.

It's kind of SUPER IMPORTANT to memories what structures arise out of the Crest cells.
One of the reasons for it is that neural crest cell tumors will express certain neuroendocrine markers and that will make it easier to detect them on histopathology.
The other reason is that it's literally the most favorite embryology question - whether it's  NEET PG or Step1!

So here goes :

Mnemonic - LAMAS BABy

L - Lepto meninges (Pia + Arachnoid)
A - Adrenal Medulla
M - Melanocytes
A - ANS Ganglia
S - Schwann Cells

B - Branchial Arches
A - Aortopulmonary windows + Endocardial Cushions
B - Bronchogenic cells - Pneumocytes
Y - Yo

This will also help you understand why Melanomas , Bronchogenic Carcinoma , Schwannoma, Pheochromocytoma and even Neuroblastoma are all positive for similar markers and have similar appearances at times along with similar histopathological fetaures.

Hope this list covers them all!
Happy Studying!
Stay Awesome!

~ A.P. Burkholderia

Saturday, February 17, 2018

Kallman syndrome mnemonic

Kallman Syndrome (also known as Olfactogenital dysplasia/syndrome or anosmic idiopathic hypogonadotropic hypogonadism)

Let's​ get down with the mnemonics!

'Kallman' kinda rhymes with 'Tallman', right? Well, "man" for it's more common in boys and Tall these individuals are of normal or even increased height (Tall).

The other features are:

K - kinda looks like an X so it's X-linked
K also sounds like C for Colorblindness
A - anosmia
L - lip (cleft lip and cleft palate)
N - nerve deafness
A - ataxia (cerebellar ataxia)
M - midline defects (cleft palate, cleft lip)

Other important points are:
- The defect is in the KAL gene which codes for the protein anosmin.
- It can be due to autosomal dominant or recessive inheritance.

That's all!

Stay awesome 

This post is written by Nikhil as part of the MSGAI.

Wednesday, January 24, 2018

Neural crest (clinical aspect)

Hello Awesomites! :D

Let us go back to the contribution of neural crest cells to many different systems (neural, skin, teeth, head, face, heart, adrenal glands, and gastrointestinal tract).

Neural crest forms neural and non-neural population.
-Cranial neural crest
-cardiac neural crest
-trunk neural crest
-Vagal neural crest

Malformations of NC origin
-Facial clefts, ear malformations, and other Facial defects 
-Branchial fistulae and anomalies of pharyngeal arch derivatives
-Cardiovascular malformations 
-Pigmentary disorders
-Abnormal enteric innervation 
-Hemangiomas and vascular malformations

1. Facial clefts, ear malformations, and other facial defects-
 The shaping of the face is therefore patterned under the influence of the NC.
The more common malformations of the region
-preauricular tags
-cleft lip, and cleft palate
-CHARGE association
-Treacher Collins, or Goldenhar syndrome.

2. Branchial fistulae and anomalies of pharyngeal arch derivatives 
-Malformations of the endocrine glands that are derived from the pharyngeal arches and pouches have the same origin. That is:-
The paired thymus which originate from the third pharyngeal pouch on each side,
The parathyroids, derived from the third (lower glands) and fourth pharyngeal pouches (upper glands) ,
C-cells of the thyroid (derived from the ultimobranchial body in the fifth pouch)
-Branchial cyst

3. (IMPORTANT) Cardiovascular malformations
TA, DORV, Tetralogy of Fallot (TOF), narrow outflow pulmonary tract (NOPT), transposition of the great vessels, perimembranous ventricular septal defect (VSD), and other heart defects are the result of defective NC influence on the region.

4. Pigmentary disorders 
-Neurocutaneous melanoses 
-neurofibromatosis of Von Recklinghausen 
-Tuberous sclerosis and all the gastrointestinal polyposes in which there are mucosal or cutaneous pigmentary spots (Peutz Jeghers, Cowden, Cronkhite- Canada etc.)
-neurofibromatosis albinism

5. Abnormal enteric innervation
-Hirschsprung disease
- Neuronal intestinal dysplasia

6. Tumors
Due to abnormal proliferation of NC cells
-Peripheral neuroectodermal tumor

7. Hemangiomas and vascular malformations 
The concept that hemangiomas and vascular malformations are derived from the NC is relatively new, but accepted. The flat vascular malformations that are located in the areas corresponding to the cutaneous innervation of the cranial nerves may have intracranial extension (Sturge-Weber syndrome) and are of this origin.

In next post, I will discuss NEUROCUTANEOUS SYNDROME as an extension of this post.
Feel connected: D

-Upasana Y. :)

Monday, October 2, 2017

Corpus Callosum - Let's connect

Hey Awesomites
Jas here
I am back :)

Let's talk about the largest connective pathway in the brain, the Corpus Callosum that is made up of more than 200 million nerve fibres, connecting our left brain to the right.

Sunday, June 4, 2017

Tetralogy of fallot mnemonic


Here is a short note on tetralogy of fallot. Tetralogy of fallot is a congenital disorder of heart. It shows four signs, as indicated in it's name (tetra).

Mnemonic for it is - PRVO virus ( parvo virus )

1. Pulmonary stenosis
2. Right ventricular hypertrophy
3. Ventricular septal defect
4. Overriding of aorta.

That's all :)


Saturday, June 3, 2017

Ano-Rectal anatomy: Above and below pectinate line

Here's an illustration I made :)

It shows the embryology, pathology, innervation, blood supply, venous drainage and lymphatic drainage on the rectum above and below pectinate line.

Wednesday, May 31, 2017

Tetrology of Fallot Causes : Mnemonic and discussion

Hello everyone !

Tetrology of Fallot refers to the tetrad of features occuring in the heart -

1. Ventricular septal defect
2. Pulmonary stenosis
3. Right Ventricular Hypertrophy
4. Overriding aorta.

Now. The factors associated with this disease include a decent bit of things.  And while I was revising I remembered I didn't remember them at all. :) :) :) :) :)


So here's a mnemonic.

CATCH = CATCH 22 Syndrome
(DiGeorge Syndrome is represented by CATCH 22 popularly).

N - NOTCH 1 Gene mutations.
A - Alagille syndrome - Associated with a very peculiar set of features - Bile duct hypoplasia. So random .
T - Trisomies 13,18,21
E - Et cetera = Maternal Diabetes , Maternal progesterone , Drugs like Retinoic acid.

Hope this helped !
Stay awesome!
~ A.P.Burkholderia

Cauda equina syndrome


What is cauda equina syndrome (CES)?
The cauda equina syndrome is caused by an intraspinal lesion caudal to the conus that injures two or more of the 18 nerve roots constituting the cauda equina within the lumbar spinal canal.

Cauda equina syndrome causes

Tuesday, May 23, 2017

Motor nuclei in the brainstem : An overview

Hi everyone. Just thought of doing an overview of the various motor nuclei of cranial nerves in the brain stem.

So we can classify the motor nuclei into 3 groups -
1. Somatic motor efferent - 4
2. Branchial motor efferent - 4
3. Visceral motor efferent - 4
Now how are these classified ?

1. Somatic Motor Efferent

- In the embryological stage , there are certain precursors to muscle and skin segment groups called 'Somites'. These are processes of the paraxial mesoderm.
- Sach somite gives rise to a particular set of muscles called its myotome. 
- There 4 such important somite groups -->

A. Pre otic somites = 3.
So this is simple.
There are 3 pre otic somites giving rise to distinct groups of extraocular muscles supplied by their own cranial nerve.

Somite 1  =
Muscles -
All Extra ocular muscles except Lateral Rectus and Superior oblique.
Nerve -
Oculomotor nerve (III)
Nucleus -
Oculomotor nucleus in the Upper Midbrain.

Somite 2  =
Muscles -
Superior oblique.
Nerve -
Trochlear nerve (IV)
Nucleus -
Trochlear motor nucleus in the Lower Midbrain.

Somite 3  =
Muscles -
Lateral Rectus.
Nerve -
Abducent nerve (VI)
Nucleus -
Abducent motor nucleus in the Pons.

(I'm sure you remember the popular mnemonic - LR6 SO4)

B. Occipital somites
Muscles -
All muscles of the tongue except Palatoglossus
Nerve -
Hypoglossal I'm nerve (XII)
Nucleus -
Hypoglossal nucleus in the Medulla.

Since these nuclei represent the motor innervation to the derivatives of Somites , they're called Somatic Motor or General Somatic Efferent (GSE) Fibres. 

2. Branchial Motor Efferent - 

- In the embryological stage , there are various branchial or Pharyngeal arches that give rise to muscles , bones and cartilage supplied by a particular nerve of that arch.

- Each nucleus that supplies the muscles from such a Branchial arch is called Branchiomotor Efferent or Special Visceral Efferent. (SVE) 
- There are 4 such important arches - 

A. 1st Pharyngeal arch (mandibular arch)
Muscles -
All muscles of mastication + TT (Tensor tympani + Tensor veli Palatini) + Digastric anterior belly. ( And Meckel cartilage)
Nerve -
Mandibular branch of Trigeminal
Nucleus - 
Trigeminal motor nucleus in Pons 

B. 2nd Pharyngeal arch (hyoid arch) 
Muscles -
All muscles of facial expressions + Stapedius + Digastric posterior belly.  ( And Reichter cartilage)
Nerve -
Facial nerve (VII)
Nucleus - 
Facial motor nucleus in Pons 

C. 3rd Pharyngeal arch
Muscles -
(And the hyoid bone funnily.)
Nerve -
Glossopharyngeal nerve (IX)
Nucleus - 
Nucleus Ambiguus in Medulla

D. 4th and 6th Pharyngeal arches
Muscles -
- All muscles of  Soft palate ( except Tensor veli which is up in the 1st arch) by the 4th. + cricothyroid muscle of Larynx. 
- All muscles of Larynx by the 6th except cricothyroid which is by the 4th. 
(All laryngeal cartilage as well)
Nerve -
4th arch - Superior laryngeal nerve of the Vagus.(X)
6th arch - Recurrent laryngeal nerve of the Vagus (X)
Nucleus - 
Nucleus Ambiguus of Medulla 

Now there's another Motor nucleus - The Accessory nerve. It supplies Trapezius and Sternomastoid muscles but it's doubtful if it's Branchial or Somatic. 

3. Visceral Motor Efferent - General

- These nuclei are parasympathetic and stimulate a particular gland to secrete or a ganglion to function. 
- These are called Secretomotor or General Visceral Efferent Fibres 

Again , there are 4 of these. 

A. Ciliary ganglion 
Function mediated by - 
Sphincter pupillae - Constricts pupil 
(Mnemonic = Remember C and C - Cholinergic Constricts )
Nerve -
Oculomotor nerve
Nucleus - 
Edinger Westphal in Midbrain 

B. Pterygopalatine ganglion 
Function mediated by - 
Lacrimal glands, nasal mucosal, sinuses mucosal glands and pharynx mucosal - Secretomotor. 
Nerve -
Facial nerve  (Greater Petrosal)
Nucleus - 
Superior salivatory nucleus - Pons. 

C. Submandibular ganglion 
Function mediated by - 
Submandibular glands , sublingual glands - Secretomotor.
Nerve -
Facial nerve  (Chorda tympani)
Nucleus - 
Superior salivatory nucleus - Pons. 

D. Otic ganglion 
Function mediated by - 
Parotid gland
Nerve -
Glosspharyngeal nerve  (Lesser Petrosal)
Nucleus - 
Inferior salivatory nucleus - Pons. 

The Vagus nerve has the largest parasympathetic discharge and supplies a lot of visceral with this input in the guy as well.

Hope this helps you to re-orient yourself to neuroanatomy and grasp the roles of various brainstem structures ! 
Happy studying ! 
~ A.P.Burkholderia

Monday, May 15, 2017

A neonate with cyanotic heart disease (Case #2)

A 3 day old new born is found to have cyanosis. On examination, a II/IV holosystolic murmur is heard. CXR shows decreased pulmonary vascular markings and cardiomegaly. ECG shows tall P waves and left axis deviation. Diagnosis?

Similar to the case we discussed last time (A neonate with cyanotic heart disease #1), let's narrow our differential.

Tuesday, March 7, 2017

Study group discussion: PGE and congenital heart diseases

We had a discussion on this question on our study group today :)

PGE causes clinical worsening in an infant with?
A. PS without VSD
B. Hypoplastic left heart syndrome
C. Obstructive TAPVC
D. Obstruction in Aorta

Let's work this out - choice by choice!

Saturday, February 11, 2017

Fact of the day: Handedness arises from genes in the spinal cord

Handedness is an asymmetry arising due to left-right differences in the development of nervous system. Evidences suggest that a human embryo of eight weeks is able to move its right arm more than the left arm.

Well, if you know something about neurologic development in-utero, you must know that at eight weeks signals are not transmitted from the brain yet. Instead the signals travel from the spinal cord.

The left side of the cord matures faster than the right cord. This means the genes that control growth and development are activated faster on the left cord than the right one. In the hindbrain, it is the other way around.

That's all
- Jaskunwar Singh

Wednesday, February 1, 2017

A neonate with cyanotic heart disease (Case #1)

A 24-hour-old newborn, born to a diabetic mother, appears blue in all extremities. He is found to have a single, loud S2 murmur. He is given NICU support. CXR hows cardiomegaly with, an apparent narrowing of the superior mediastinum and increased pulmonary vasculature markings.

Diagnosis? Treatment till surgery is performed?

Monday, January 9, 2017

Tetralogy of fallot

Hello  readers today's blog is small one -Fallot's tetralogy .

What is Fallot's tetralogy?
   It is a congenital disorder of heart .It is caused to foetus may be because of  alcoholic mother or who has  diabetes or may be due to rubella infection caused during pregnancy.It is caused due to deletion of chromosome 22

Signs and symptoms:-
As the name suggest ,there are four signs
All four of them are related to heart .
Mnemonic is PVR -f cinema.
-Pulmonary stenosis
-Ventricular septal defect .
-Right ventricular hypertrophy
-Over-riding of aorta ,due to which blood from both the ventricles may enter aorta.

Due to defect in heart ,there is low oxygen supply to tissue this may lead to cyanosis when there is high amount of pulmonary stenosis but when there is moderate amount of pulmonary stenosis this may lead to pink tit that is pinkish colouration of skin.There is also clubbing  .

Open heart surgery is only treatment for fallots tetralogy  .
The appropriate time for surgery depends on the pulmonary stenosis .
However patient should be on life long medication for healthy life

That's all :)
Have a happy day.


Friday, November 25, 2016

Cleft lip and palate

Hi friends,

Here's a quick way to remember the cause of Cleft lip and Cleft palate.

Cleft Lip - failure of fusion of Maxillary and median Nasal prominences!

Cleft Palate - failure of fusion of two Palatine Processes!

That's all!


Monday, November 21, 2016

Role of Glucocorticoids in Developmental events

Glucocorticoids in the fetus are either of maternal origin or syntheiszed from placental progesterone in the fetal adrenal cortex(which lacks zona reticularis). Glucocorticoids are essential for a lot of developmental events, but three of them are most important which goes as follows.

Tuesday, October 11, 2016

Two interesting facts.

Hey awesomites! Happened to read two interesting things today-

1. The Y sperm is relatively lighter due to the acrocentric chromosome, amounting to the relatively skewed sex ratio towards males across the globe.

2. Homeobox gene 8 controls the expression of forelimbs, messing with it causes alters the position of the forelimbs.

That's all!