Optic nerve: easy and brief discussion

Optic nerve: 

Formation: by axon of ganglionic cells of retina 

Functional component: special somatic afferent 

Peculiarities of optic nerve: 

1. it is the prolongation of diencephalon 

2. it is the white matter of brain 

3. it is covered by three meninges of brain 

4. its myelination is derived from oligodendrocyte so it is devoid of neurolemma sheath and no regeneration 

5. pia mater project into nerve and carry blood vessels with it 

Blood supply of optic nerve: superior hypophyseal artery, ophthalmic artery and posterior ciliary artery 

parts of optic nerve with length :

1. intra orbital part : 25 mm
2. canalicular part : 5 mm 
3. intra cranial part  : 10 mm

Total length : 4 cm 

Intra orbital part is longer so eyeball can move without any tension. 

Human eye: viva questions with answer

Human eye:

1. How many layers of eye present from outside to inside? 

Ans: outside to inside: fibrous coat ( sclera and cornea ) , vascular coat( iris, ciliary body, choroid , nervous coat (retina)

2. how many layers present in cornea?

Ans: outside to inside

• lining epithelium: non-keranized stratified squmous epithelium 
• Bowman's membrane 
• substantia propria 
• Descemet's membrane 
• corneal endothelium 

3. Mention the name of neurons in retina 

Ans: Rods and cone cells, Amacrine, bipolar neuron, ganglionic cells

4. How optic nerve is formed?

Ans:  by axon of ganglionic cells

5. Mention the name of muscles present within the iris ?

Ans : sphincter pupillae and dilator pupillae

6. Mention the secretomotor pathway of the lacrimal gland 

Ans: the preganlionic fibres start in the lacrimatory nucleus(lower pons)
pass through nervus intermedius
the geniculate ganglion
the greater petrosal nerve
the nerve of pterygoid canal
pterygopalatine ganglion
post ganglionic fibres from pterygopalatine ganglion passage through zygomatic nerve
zygomaticotemporal nerve
lacrimal nerve
lacrimal gland

7. Mention the content of orbital cavity.

Ans: Content of orbit

1. eyeball 
2. two fascia : orbital and bulbar fascia 
3. extraocular muscles
4. Lacrimal glands
5. Artery: ophthalmic 
6. Veins: superior and inferior ophthalmic vein 
7. Nerves: sensory : optic nerve and ophthalmic nerve (branches of trigeminal nerve)            Motor: oculomotor(3rd cranial nerve), trochlear nerve (4th cranial nerve) and abducent nerve (6th cranial nerve) 
8. Ganglion : ciliary 
9. Orbital fat 

8. Give nerve supply of extraocular muscles

Ans: SO 4 , LR 6 and rest 3
 Trochlear nerve :Superior oblique
Abducent nerve: Lateral rectus
oculomotor nerve : medial, superior and inferior rectus and inferior oblique muscle

9. Mention the name of branches of ophthalmic artery

Ans: ophthalmic artery is the branch of internal carotid artery
its branches are:

1. central artery of retina 
2. supraorbital and supratrochlear artery 
3. anterior and posterior ethmoidal artery 
4. posterior ciliary artery
5. medial palpebral artery 
6. muscular artery 
7. lacrimal artery 

10. Why cornea is transparent ? 

Ans: Cornea is transparent. Because

• it is avascular 
• melanin absent in corneal epithelium
• in substantia propria, bundles of collagen fibrils (not fibre) and long slender fibroblasts are parallel in arrangement 
• The transparency of cornea requires precise regulation of the water content of the stroma, this function regulate by corneal endothelium , if water contain of cornea reduces , it causes aggregation of collagen fibres so cornea become opaque 

MS ophthalmology bd: Anatomy brief guide line

Bone :

Base of skull :

Orbit : 

1. boundary,
2.  walls, 
3. content, 
4. lacrimal gland: type of gland, nerve supply, it is related with which parasympathetic ganglion, it is related with which nucleus
5. Superior orbital fissure : structures passing through it 
6. optic canal : structures passing through it 

Frontal bone : orbital surface : important relation
Maxilla

General anatomy: 

Nervous system : 

1. classification of nervous system
2. composition of nervous system 
3. classification of neuron according to polarity, function,
4. What is nerve?Mention organization of nerve. 
5. Mention some special features of optic nerve 
6. classify neuroglia  with functions 

CVS: 

1. Define circulation. 
2. Define end artery . Classify end artery with example.
3. Why central artery of retina is known as true end artery 
4. define capillary . classify capillary with example
5. what do you mean by blood retinal barrier 

Muscular tissue : 

1. Classify muscle histologically 
2. Mention important features of skeletal , cardiac and smooth muscles 
3. Mention the types of Extraocular muscle and intraocular muscles

Nervous tissue: 

1. composition of nervous tissue 
2. classification of nervous tissue 
3. myelination in central and peripheral nervous system 
4. regeneration of peripheral nerve 

General histology : 

1. Define tissue. Mention the name of basic tissue 
2. Epithelium : definition, features, classification of epithelium, Classification of covering epithelium(both simple and stratified) , difference between non keratinized and keratinized stratified squmous epithelium, what is the lining epithelium of cornea, conjunctiva and corneal endothelium 
3. Connective tissue : composition of connective tissue , classify connective tissue proper , sclera : what types of tissue 

General embryology: 

1.  3rd week of development : development of neural tube 
2. name of brain vesicle and structure derived from it 
3. development of lens, cornea , retina , 

Viscera: 

Eyeball : 

anatomical position : 

1. Medial rectus muscle is near the sclero cornea junction 

2. optic nerve lies posterior inferiorly

1. Cornea: layers of cornea, which layer is thickest, why cornea is transparent, which layer maintain hydration of cornea, how cornea get nutrition , nerve supply of cornea 
2. Aqueous humor : formation, drainage, clinical anatomy : glucoma 
3. vascular coat: parts, formation and functions of iris and ciliary body 
4. retina : development, blood supply, name of neuron present within the retina, how optic nerve is formed ? 
5. Visual pathway: lesion in optic nerve,optic tract 
6. what is optic radiation?
7. what is lateral geniculate body
8. accommodation reflex 
9. pupillary light reflex

Brain: 

1. boundary of occipital lobe, 
2. show visual area 17, 18, 19 in superolateral surface and medial surface , 
3. what do you mean by macula sparing ? 
4. Mention the blood supply of occipital lobe.
5. parts of diencephalon, 
6. parts of thalamus , 
7. what is internal capsule ? 
8. blood supply of internal capsule. 

Cranial nerve: 

1. Why trochlear nerve is injured more frequently ? 
2. how can you diagnose trochlear nerve lesion? 
3. Facial colliculus is related with which nerve? how can you diagnose injury of that nerve? 
4. Which colliculus of mid brain is related with vision? 

Lacrimal apparatus : 

1. mention the name of different parts of it 
2. how this developed ?
3. where nasolacrimal duct is open? 
4. Relation of lacrimal sac.
5. nerve supply of lacrimal gland 
6. histological features of lacrimal gland 

Eyelid:

1. Mention the different layer of it 
2. how many glands are there in eyelid
3. Mention the name of muscle present in eyelid 
4. mention the nerve supply of upper and lower eyelid 

Short questions of thorax

Thorax: 

1. Mention the formation of thoracic cage ?

Ans: Anteriorly, sternum , laterally ribs with costal cartilage(hyaline cartilage) and posteriorly throcic vertebra with intervertebral disc

2. What is thoracic inlet and outlet? 

Ans: upper aperture of thoracic cage and lower aperture of thoracic cage 

3. which structures close the thoracic inlet and outlet?

Ans: The suprapleural membrane covers the thoracic inlet and the diaphragm covers the thoracic outlet. 

4. what is mediastinum? 

Ans: the space between two lungs is known as mediastinum 

5. mention the name of important nerve of thoracic region ?

Ans: Phrenic nerve , intercostal nerve, vagus nerves, recurrent lar;yngeal nerve (branches of vagus nerve) 

6. What do you mean by intercostal nerves? 

Ans: They are ventral rami of upper eleven thoracic spinal nerves 

7. What is the name of ventral ramus of 12th  thoracic spinal nerve?

Ans: Subcostal nerve 

8. Posterior relation of manubrium sternae? 

Ans: lower half arch of aorta and upper half branches of arch of aorta( brachiocephalic trunk, left common carotid and left subclavian artery) and left brachiocephalic vein

9. how sternocostal surface of heart is formed?  

Ans : this surface is formed by four chamber of heart

1. 2/3 right ventricle
2. 1/3 left ventricle
3. right atrium and auricle 
4. left auricle of left atrium 

10. how diaphragmatic surface of heart is formed?

Ans: 1/3 of right ventricle and 2/3 of left ventricles 

11. How base of heart is formed ?

Ans : By two atria, 2/3 by left atrium (because most of the part of left atrium is situated posteriorly )

and 1/3 of right atria (most of the part right atria is situated anteriorly)

  

Q: mention the anatomical point of heart 

Ans : this is the viscera of heart with root of the great vessels with pericardium (if present )

a) apex is directed downward, forward and to the left 

b) base is directed backward and to the right 

c) sternocostal surface of heart is directed anteriorly and the diaphragmatic surface of heart is directed inferiorly 

 Q: 

 

Ordinary connective tissue (connective tissue proper)

Ordinary connective tissue (connective tissue proper)

This types of connective tissue bears no special character or features.They only connect two types of tissue together. For example transitional epithelium of urinary bladder connected with smooth muscles layer by connective tissue known as lamina propria. 

Classification of ordinary connective tissue:

1. Loose connective tissue : why it is known as loose because it contain loosely arranged connective tissue fibres 

2. Dense connective tissue : why dense ? because it contain densely arranged connective tissue fibres. According to manner of arrangement of connective tissue fibres it is again two types:

Dense irregular connective tissue: dense connective tissue fibres arranged irregularly 

Dense regular connective tissue : dense connective tissue fibres arranged regularly   

Loose connective tissue contain large number of connective tissue cells but less and loosely arranged connective tissue fibres. Example: lamina propria of mucosa of intestine (it handle stress and allow distension)  

Dense irregular connective tissue : contain less connective tissue cells but densely and irregularly arranged connective tissue fibres: Example : dermis of skin ( irregularly arranged connective tissue fibres bear more stress from any direction ) 

Dense regular connective tissue contain less connective tissue cells but densely and regularly arranged connective tissue fibres  : example: tendon (it bear more stress but from particular direction ) 

Ganglia and nucleus : similarity and difference

Nucleus : 

collection of nerve cells bodies within the central nervous system.

SN:

1. Big collection of nerve cells body within the central nervous system is known as grey matter. 
2. Small collection of nerve cells body within the central nervous system is known as nucleus. 
3. Some time part of grey matter is also known as nucleus. 
4. Some time the axons of nucleus leaves the central nervous system as peripheral nerve

Ganglia : 

Collection of nerve cells bodies outside the central nervous system is known as ganglia.

SN:

Nerve cells bodies of ganglia some time synapses with axon of other neuron 

Some time axon of other neuron only passage through the ganglia 

Some time ganglia connect with each other so axon of one ganglia passage above ganglia or below ganglia 

Some ganglia near to central nervous system but some are nearer to target organ 

Similarity between nucleus and ganglia : both are collection of nerve cells bodies 

Difference between nucleus and ganglia: nucleus lies within CNS and ganglia lies within PNS  

Nucleus: at a glance

Nucleus 

Parts of nucleus

•      Nuclear membrane

•      Nucleolus

•      Chromatin &  nucleoplasm

Nuclear membrane

•      It is a double layer membrane. The outer layer of membrane attached with ribosomes and continuous with rER.

•      Pores present 

Nucleolus:  

1. It is a structure found in the nucleus of cells.

2. It is formed by proteins and nucleic acids. 

3. It is occupies about 25% of the volume of the cell nucleus.

Function:

 It transcribes ribosomal RNA (rRNA)

The synthesis of RNA is regulated by five different chromosomes (13, 14, 15, 21, and 22). 

 Malfunction of nucleoli : 

mutation causes malfunction  of nucleus and it is related to following disease like Weine syndrome, Treacher Collins Syndrome and dyskeratosis.

      Chromatin / Chromatin granule- 

        The readily stainable substance of a non dividing cell nucleus consisting of DNA and RNA and various     

            proteins; during mitotic division it condenses into chromosomes

•      They are two types: 

Heterochromatic

Densely packed portion of chromatin which is genetically inactive.

Bluish in colour. 

Euchromatic
 uncoiled portion of chromatin which is genetically active.
 Lightly stain 

What is chromosome?

•      it is  a  threadlike structures, which visible during cell division and is composed by

•      DNA,

•      Small RNA,

•       histone and non-histone protein. (consisting of genes that are responsible for the transmission of hereditary characteristics)

Types of chromosome:

 Autosomes chromosome:

•      The genes which regulate body character.

•      They are 22 pairs

 Sex chromosome: 

•      The genes which regulate sex character.

•      They are 1 pair

•      In male one X and one Y .

                  XY

•      In female two X.  

                        XX

Chromosomes number in human body

•      46

•      /23 pairs

•       22 pairs autosomes + 1pair sex chromosome

Diploid: A cell or an organism consisting of two sets of chromosomes:

Usually, one set from the mother and another set from the father.

In a diploid state, the haploid number is doubled, thus,

This condition is also known as 2n.

Haploid: The number of chromosomes in a gamete of an organism, symbolized by n. 

Parts of a chromosome

Each chromosome has a constriction point called the centromere, which divides the chromosome into two sections, or “arms.”

 The short arm of the chromosome is labeled the “p arm.”

The long arm of the chromosome is labeled the “q arm.

Chromatid - one of two identical strands into which a chromosome splits during mitosis