Sphincter pupillae

Sphincter pupillae

Pupil is the central small aperture situated within the iris of eye. The size of it control by two muscles one is sphincter papillae and dilator papillae. So through pupil only the appropriate amount of light enters the eye .

    They are involuntary muscle fibers of the iris, which arranged circularly.

It is only present in papillary margin of iris. It is supplied by parasympathetic fibers from Edinger-westphal nucleus of oculomotor nerve.

Function: constrictor of the pupil in response to bright light. Failure of pupil to respond to light is an important clinical sign of the lack of nerve or brain function.

Erb's paralysis : brief and easy handout

Erb’s paralysis : it is also known as upper trunk plexus injury.

Cause of injury:  Upper trunk is ruptured due to forceful widening of the angle between the head and shoulder . traction of the arm during child birth and or by fall on the shoulder causes widening of angle between the head and shoulder. The root value of upper trunk is C5,6 .

In this paralysis, nerve roots involved: Mainly C5 and partly C6.

Muscles paralysed: Mainly biceps, deltoid,brachilais and brachioradialis.Partly supraspinatus, infraspinatus and supinator

Deformity: The deformity is known as "Policeman's tip hand" or "Porter's tip hand".

Loss of function:

Motor loss:

Arm: Hangs by the side, it is adducted due to paralysis of deltoid muscle. It is also medially rotated due to paralysis of supraspinatus, infraspinatus  and teres minor muscles

Forearm: Extended and pronated due to paralysis of biceps brachii.

Sensory loss:

The sensory loss of this clinical condition is minimal, only along the outer aspect of arm due to involvement of roots of C6 spinal nerve.

Moderator band / septomarginal trabeculum

Moderator band: (septomarginal trabeculum)

It is the unique features of the right ventricle , a thick muscular ridge extending from the ventricular septum to the base of the anterior papillary muscle.

 It conveys the right branch of the atrioventricular bundle (bundle of His) , a part of conducting system of the heart .

Function of the moderator band: it prevents the over distension of right ventricle. 

Easy handout of left ventricle of the heart

left ventricle:

 The wall of the left ventricle is thicker than the atrium and also  it is thicker than the right ventricle.

It contains two orifices

1.     Left  atrioventricular orifice: by this orifice oxygenated blood of left atrium enters into the left ventricle

2.      aortic orifice : by this orifice it sends it oxygenated blood to whole body via aorta.

Externally it forms some part of  the sternocostal surface and 2/3 of diaphragmatic surface. It also form apex, left border. It is separated from left atrium by atrioventricular sulcus /groove or coronary sulcus. It also separated from right ventricle by two groove anterior and posterior inter-ventricular groove. 

Internally it has two part inflowing rough part due to trabeculae carneae ( muscular ridges of the heart ) and outflowing smooth part also known as infundibulum. 

The cavity of the left ventricle is circular shape in cross section because the interventricular septum makes a bulge toward the right ventricle.

Trabeculae carneae of ventricles:

Three types of muscular projections are present in trabeculae carneae of left ventricle.

They are

1.     Ridges : fixed muscular elevations

2.     Bridges : two ends are fixed with central free portion

3.     Papillary muscles : in left ventricle it is two in number : anterior and posterior

Easy handout of right ventricle of the heart

Right ventricle of the heart:

The heart consists of four chambers:

·        Right and left atrium both are separated by interatrial septum

·        Right and left ventricle both are separated by interventricular septum

Right ventricle:

 The wall of the right ventricle is thicker than the atrium but it is less thick than the left ventricle.

It contains two orifices

1.     Right atrioventricular orifice: by this orifice deoxygenated blood of right atrium enters into the right ventricle

2.     Pulmonary orifice : by this orifice it sends it deoxygenated blood to the lung via pulmonary trunk for oxygenation.  

Externally it forms most the sternocostal surface and 1/3 of diaphragmatic surface. It also form inferior border. It is separated from right atrium by atrioventricular sulcus /groove or coronary sulcus. It also separated from left ventricle by two groove anterior and posterior interventricular groove . 

Internally it has two part inflowing rough part due to trabeculae carneae ( muscular ridges of the heart ) and outflowing smooth part also known as infundibulum. The two part are separated by a muscular ridge known as supraventricular crest.

The cavity of the right ventricle is crescent shape in cross section because  the interventricular septum make a bulge toward the right ventricle.

Moderator band: (septomarginal trabeculum)

it is the unique features of the right ventricle , a thick muscular ridge extending from the ventricular septum to the base of the anterior papillary muscle. It conveys the right branch of the atrioventricular bundle (bundle of His) , a part of conducting system of the heart .

function of the moderator band: it prevents the overdistension of right ventricle. 

Trabeculae carneae of right ventricle:

Three types of muscular projections are present in trabeculae carneae of right  ventricle.

They are

1.     Ridges : fixed muscular elevations

2.     Bridges : two ends are fixed with central free portion

3.     Papillary muscles of  right ventricle: are  three in number : anterior , posterior and septal. 

Interior of right ventricle of heart

Interior of right ventricle:

Internally it has two parts

1.     inflowing rough part due to trabeculae carneae  ( muscular ridges of the heart ) and

2.      outflowing smooth part also known as infundibulum. The two part are separated by a muscular ridge known as supraventricular crest.

The cavity of the right ventricle is crescent shape in cross section because the interventricular septum make a bulge toward the right ventricle.

Moderator band: (septomarginal trabeculum)

it is the unique features of the right ventricle , a thick muscular ridge extending from the ventricular septum to the base of the anterior papillary muscle. It conveys the right branch of the atrioventricular bundle (bundle of His) , a part of conducting system of the heart . 

Function : it prevent overdistension of heart 

Trabeculae carneae of right ventricle:

Three types of muscular projections are present in trabeculae carneae of right  ventricle.

They are

1.     Ridges : fixed muscular elevations

2.     Bridges : two ends are fixed with central free portion

3.     Papillary muscles of  right ventricle: are  three in number : anterior , posterior and septal. 

Different types of sulci on the brain

Different types of sulci on the  brain

Cranium contain limited space   so for accommodation, the cerebral cortex is folded into numerous gyri separated by sulci . For this region the total surface area of the cortex of human brain is increased to about 2200 cm^2. One third of cortex is exposed as gyri and two third of cortex is hidden in the sulci.

Development of sulci:

Upto the 3^rd months of inter uterine life:  the cerebral cortex remains smooth

During 4^th months of inter uterine life: lateral sulcus appears on the superolateral surface of cerebrum and insular cortex begins to submerge.

During the 6^th months of inter uterine life: central, parieto-occipital, calcarine and cingulate sulci appear.

During the 7^th months of inter uterine life: all sulcus appear

•       Types of sulci  : 

1. Limiting sulcus : central sulcus
2. Axial sulcus : calcarine sulcus
3. Operculated sulcus: lunate sulcus
4. Complete sulcus
5. Primary and secondary sulcus

Limiting sulcus :

It separates agranular  motor cortex  from  granular  sensory cortex  . Agranular cortex contain more pyramidal cell with less granule cell but granular cortex contain more granule cells with less pyramidal cells

Axial sulcus :

Calcarine sulcus presents an axial sulcus because visual cortex grow two side of this sulcus 

Operculated sulcus: 

•       lunate sulcus is operculated sulcus which separates visual area 17  from 19 and

•       floor & wall of lunate sulcus form area 18

Complete sulcus :

Some of the sulcus are called complete sulcus because it extend depth enough to produce elevation in lateral ventricle . The collateral and anterior part of the calcarine sulci are complete because the former produces the collateral eminence in the floor of the inferior horn of lateral ventricle and the later forms the calcar avis of the posterior horn of lateral ventricle

Primary and secondary sulcus :

 Most of the sulcus are primary sulcus since they develop independently but parieto occipital sulcus & lateral sulcus are secondary sulcus because they dependent on other factors. For example,  Shape of lateral sulcus depend on exposure of insular cortex. If insular cortex expose , can see easily from surface the lateral sulcus is wide open and thick .  If insular cortex buried well , cannot see from surface the lateral sulcus remain narrow.

The growth of corpus callosum causes obliteration of small sulci on the medial surface of cerebral hemisphere to form parieto-occipital sulcus .

•       Terminology :

•       Sulcus :  one sulcus 

•       Sulci: more than one sulcus

•       Gyrus : one gyrus

•       Gyri :  more than one gyrus