Tongue (part-1)

Vaibhavi1 Comment

● Tongue is the muscular organ situated in the floor of the mouth

It has 2 surfaces

• Superior surface

• Inferior surface

● Superior surface is divided into 3 parts Anterior 2/3rd or oral part , posterior 1/3rd or pharyngeal part and base or root of the tongue

● Anterior 2/3rd and posterior 1/3rd are divided by V shaped sulcus terminalis, they are structurally and developmentally distinct.

● Inferior surface is covered by smooth mucous membrane. In midline a mucosal fold called frenulum connects tongue with floor of the mouth

● Lateral to frenulum deep lingual veins can be seen through mucosa lateral to lingual vein , mucosal fold called plica fimbriata is present

PAPILLAE OF TONGUE

Superior surface of tongue contains numerous papillae and have taste buds on their surface

Types of papillae

• Circumvalate papillae : present in front of sulcus terminalis , largest among papillae 8 to 12 in number

• Filliform papillae : Thin, long papillae with pointed ends. No taste buds. Identified by keratinization.

• Fungiform papillae: Slightly mushroom shaped , larger than Filliform papillae and present at apex of tongue and margins

• Foliate papillae : short vertical folds , present lateral to terminal sulcus and at margins

TASTE BUDS

Taste buds are sensory receptors for taste. Sensation of taste is called gustation.  Taste buds are located on surface of all papillae except Filliform papillae

Four taste sensation are sour, sweet, salty,  bitter and recently added is umami

MUSCLES OF TONGUE

● Intrinsic muscles: Main function is to alter the shape of the tongue ,they originate and insert within the tongue and no bony attachments.  ( 4) superior longitudinal,  inferior longitudinal,  vertical and transverse muscles

● Extrinsic muscles :  These muscles take origin from outside of the tongue and alter the shape as well.(4) Genioglossus, hyoglossus, styloglossus and palatoglossus

Superior longitudinal muscle: It lies just beneath dorsum of tongue. Action: It curls the tip upward and roll it posteriorly

Inferior longitudinal muscle : lies on each side lateral to the Genioglossus muscle. Action : To curl the tip of the tongue inferiorly

                                    

Transverse muscle: lies inferior to the superior longitudinal muscle and run from the septum to margins. Action : They narrow the tongue and increase the height

Vertical muscle: It lies inferolaterally to the Dorsum of tongue. Action : flattens the Dorsum

Genioglossus : origin- from superior mental spine and gets inserted into mucous membrane of tongue. It’s action is to protrude tongue, depress central part of tongue and increase the volume of sucking

Hyoglossus : origin- from greater horn and body of hyped bone and gets inserted to side of the tongue. It’s action is to depress side of the tongue assisting Genioglossus to enlarge the oral cavity

Styloglossus : origin- lower part of styloid process and upper part of stylohyoid ligament and inserts on side of the tongue. Action is to elevate and retract the tongue

Palatoglossus : origin- from soft palate and insertion lateral margin of tongue

♢ Styloglossus and palatoglossus attach the tongue Superiorly ,while Genioglossus and hyoglossus attached to the tongue inferiorly

♢ All the extrinsic and intrinsic muscles of tongue are supplied by hypoglossal nerve except palatoglossus supplied by vagus nerve

Movements of tongue

Reference: B.D chaurasia

GIANT CELLS

Dr.MehnazLeave a comment

PDF link below..⬇️

https://drive.google.com/open?id=1dow8Kc-EV3SNamk1lFlkj6gttzViwvrN

Link highlights:

• Definition

• Pathogenesis of Giant cells

• Types of giant cells - grossly classified into 2 types. –
• The giant cells which exist in normal tissue (physiological) e.g 
osteoclasts in bones, trophoblasts in placenta, odontoclast, straited muscle.

• The giant cells which exist pathological -eg. 
Foreign body giant cells
Langhan's giant cells
Touton giant cells
Aschoff giant cells
Anaplastic cancer giant cells Reed-Sternberg giant cells

Curated by: Dr. Tabassum Sayyad (Dental Intern – MARDC)

CYTOKINES

shweta170297Leave a comment

Cytokines are soluble protiens/polypeptides, produces by a variety of hematopoetic and non hematopoetic cell types. They are responsible for the regulation of immunological, inflammatory and reparative host responses.

Cytokines tend to bind to high affinity receptors and the target cells and mediate their effects. Specific cytokines mediate specific reactions.

Reference: Arvind Arora

Cytokines basically mediate immune response. But some cytokines are also pro inflammatory.

These are:-

Il-1, TNF alpha and IL-6.

IL-1 is the most important pro inflammatory cytokine.

Anti inflammatory cytokines are involved in the resolution of inflammation. These include:

IL-4, IL-10 IL-13 and TGF beta.

IL-4 has mainly anti-inflammatory properties with some pro-inflammatory properties.

TGF-beta is the most important fibrogenic factor.

Baroodontalgia

VaibhaviLeave a comment

• Baroodontalgia refers to baro- pressure odonto – teeth Algia- pain. It’s also called as Aerodontalgia or flyers tooth or tooth squeeze

• It is the pain in the teeth caused due to changes in pressure which may be seen in case of high altitude as seen in pilots and in deep sea divers who also see severe changes in pressure which lead to pain in the tooth.

• Baroodontalgia is usually seen in teeth which have pre existing dental pathology or have improper dental treatments such as chronic pulpitis is the primary culprit; Restored teeth are more likely to be involved ; Maxillary sinusitis; Improper fillings Carious teeth and periapical cysts

• Note that normal teeth without any underlying pathologies are not affected by any change in pressure.

• Baroodontalgia occurs during initial pressure from 14.7psi to 12- 18 psi.

Why there is pain in tooth due to pressure change?

• Due to change in external pressure there will be expansion of gas with compensatory increase in pressure within the pulp chamber and root canal of the tooth which is defective due to any underlying pathology

• Direct pressure in the exposed nerve endings and microleakage of Restorative material from a faulty restoration

• pain is most seen in maxillary posteriors and results from compromised blood supply to the tooth

• In pulpitis – pain on ascent and relief on descent and in Necrosis – pain on decent and relief on ascent

TREATMENT :

– Hyperbaric oxygen therapy is the treatment to avoid baroodontalgia where the person is put in a 100% compressed oxygen chamber which prepares the body for high pressures and compression

– Identification of underlying dental pathology and getting treated properly.

Source:- healthline.com

T- Cells

shweta170297Leave a comment

T- cells are among the two important cells of the adaptive immune system (others are B- Cells). T-cells arise in the bone marrow and mature in the thymus.

T- cells constitute 60-70% of the circulating peripheral lymphocytes.

T- cells categories:-

1.) Helper or Inducer T-cells:

60% of T- cells are helper T- cells. They have CD4 surface marker and are MHC II restricted. Types of CD4 helper cells are:

A) Effector cells- TH1, TH2 and TH17 cells. The TH1 cells are activated by IFN- gamma and themselves produce IL-2, IFN-gamma and IL-12. They are the primary cells involved in delayed hypersensitivity, cell mediated immunity, macrophage activation and killing of intracellular microbes. TH2 cells are activated by IL4 and themselves produce IL4, IL5, IL6 and IL13. They produce all antibodies except for IgG2b and also provide defence against helminthic parasites. TH17 cells are powerful recruiters of neutrophils and monocytes to play a role in severe inflammatory diseases.

B) Memory cells- They retain the antigenic affinity of previously activated T-cells and are used in a second immune response.

2.) Cytotoxic T-cells:

30% of the total T-cells. They have CD8 surface marker and MHC I restricted. They kill amd lyse target cells which include tumour cells, virus infected cells and allograft.

THE RATIO OF CD4:CD8 T-cell is normally 2:1.

3.) Suppressor T-cells:

They have CD8 surface marker and are MHC I restricted. They are responsible for down regulation of the immune response.

T–CELL RECEPTOR (TCR)

TCR is a molecule found on the T-cell which is responsible for recognising the antigen bound to MHC molecule. It is a heterodomer made up of an alpha and a beta chain. The presence of TCR gene rearrangements demonstrated by molecular analysis is a marker of T-cell lineage.

4th ventricle of brain

VaibhaviLeave a comment

• Ventricles are the sites for CSF production.

• lateral Ventricles are the largest and most proximal. Interventricular foramen of Monro connects lateral ventricle and third ventricle

• Third ventricle connects fourth ventricle through aqueduct of sylvius.CSF flows through the entire pathway and exits fourth ventricle into surrounding CNS tissue or through spinal cord.

STRUCTURE AND FUNCTION

• As said earlier , Ventricles are the sites for CSF production. Majority of CSF is produced by choroid plexus. Although lateral Ventricles also produce most of the CSF due to their larger surface area

• CSF gets produced in all Ventricles. CSF provides support to brain, absorbs shock during trauma,keeps neurons in homeostasis, provides nutrition and contain immune cells that fight against infections of nervous system

• fourth ventricle is most inferiorly located directly draining into spinal cord.

• Superiorly it connects third ventricle through cerebral aqueduct of sylvius. Anteriorly it’s surrounding by pons and medulla . Posteriorly by cerebellum and inferiorly by spinal cord.

• lateral apertures or foramen of luschka and median aperture or foramen of magendie. These apertures help the spread of CSF around the spinal cord and surrounding neural structures. All the CSF produced does not drain out of these aperture goes into central canal of spinal cord

EMBRYOLOGY

• Neural tube forms around 4th week of gestation. Three dilation that form neural tube are procencephalon, mesencephalon and rhombencephalon.

• Procencephalon or forebrain develops into telencephalon and diencephalon . Mesencephalon becomes the midbrain while rhombencephalon grows into metencephalon ( pons and cerebellum) and melencephalon (medulla)

• Within each of these dilations that develop from neural tube are cavities that become Ventricles

• The cavity located in rhombencephalon becomes fourth ventricle

BLOOD SUPPLY

posterior inferior cerebellar artery , anterior inferior cerebellar artery and superior cerebellar artery supplies majority of blood flow to fourth ventricle

CLINICAL SIGNIFICANCE

• Ependymomas are the third most common pediatric brain tumour. They are CNS malignancies that originate from the ependymal lining of Ventricles. These tumours are often treatable or require surgery to remove these tumors

• Hydrocephalus is presence of too much of CSF, which often results problem with CSF absorption. A condition called fourth ventricle outlet obstruction is a type of non communicating Hydrocephalus where there is disconnection between subarachnoid space and ventricular system

• Dandy walker malformation (DWM)that demonstrates a cystic enlargement of fourth ventricle and agenesis or hypoplasia of cerebellar vermis . CNS disorders associated with DWM include holoprosencephaly, neural tube defects and dysgenesis of corpus callosum

Reference :- B.D chaurasia