Nervous system : Difference between tract and nerve

Composition of nervous tissue :
1. neuron : excitable cell
2. Neuroglia : supporting cells
Parts of a neuron :

1. cell body 
2. processes : 2 in number 

i) dendrite: 1 or more than one in number

ii) Axon : usually one in number 

Axons are situated both CNS PNS
axon within the CNS is known as tract 
axons outside the CNS is known as nerve 

Topic                              Tract                                                 Nerve
location                          Mostly CNS                                   Part of PNS (peripheral NS)
myalination                     oligodendrocyte                           Schwann cells 
Type                   Ascending & descending tract    Sensory, motor and mixed both sensory& motor

Connective tissue composition: easy brief explaination

The main components of connective tissue is  cells (different types of cells with different functions)
Cells of connective tissue produce fibres (protein ) and ground substance ( a protein - carbohydrate composition )

Cells of connective tissue are two types

Connective tissue fibers are formed within connective tissues cells(fibroblast) ,
after formation they leave the cells and
become part of extra cellular matrix
collagen and reticular fibres are formed by collagen proteins 
elastic fibres are formed by elastin protein 

Ground subtances also secretion of connective tissue cells
They are nothing but a protein-carbohydrate complex
they consists of
1. proteoglycans
2. Glycosaminoglycans
3. Glycoprotein

easy and brief difference between tissues

Tissue means
group of cells and their extra cellular matrix ,
They do specific function or functions
Tissue : 4 types
1. epithelial tissue
2. connective tissue
3. muscular tissue
4. nervous tissue
Features of tissues :
Tissue                                     Cells                          extra-cellular matrix 
epithelium                        large number of cell                little
connective                        small number of tissue            large amount
muscular                           specialized cells                       moderate in amount
nervous                            neuron & neuroglia                  no extra cellular matrix

What is grey matter and white matter ?

One of the important  and vital questions of nervous system:
what is grey and white matter ?
Before explaining this we need to know about a neuron
  A neuron has two part
cell body and
processes : dendrites and an axon

if we arrange several neuron in single layer like following picture, we see cell body of neuron make a layer and processes of neuron makes a layer
Both this layer contain neuroglia and blood vessels

So, composition of grey and white matter is : 

•Gray matter:  Neuron cell  bodies

                            Neuroglial cells

                            Blood vessels

•White matter:  Processes  of neuron

                             Neuroglial cells

                             Blood vessels

Location of gray & white matter in the CNS

•Cerebrum and cerebellum ,

•Outer gray matter

•Inner white matter

•Spinal cord,

•outer part white matter

•Inner gray matter

  Why location of grey and white matter differ in different parts of CNS.

Glandular epithelium is developed from covering epithelium

Mechanism of formation of exocrine glands from covering epithelium
epithelial tissue broadly classify into two group
1. covering epithelium
2. glandular epithelium
Glandular epithelium with duct is known as exocrine glands
Glandular epithelium without duct is known as endocrine glands
Both exocrine and endocrine glands are developed from covering epithelium
exocrine glands remain their contact with covering epithelium but endocrine glands lost the contact .

Gastrointestinal tract related with different exocrine glands.
in generally, there are four histological layers of gastrointestinal tract
1. mucosa : is formed by  three layers
a) lining epithelium
b) lamina propria : connective tissue
c) muscularis mucosae: smooth muscle cells
2. submucosa : connective tissue
3. muscles layer: smooth muscle cells
4. serosa : formed by connective tissue and simple squamous epithelium (mesothelium)
From the lining epithelium of gastrointestinal tract glandular epithelium begin to form
some exocrine gland enter into lamina propria ex: gastric glands, intestinal gland etc
some are enter into submucosa ex: Brunner;s gland
some are go out side of gut wall ex: liver, pancreas
So, all glandular epithelium is originate from covering epithelium

Classification of epithelium

Classification of epithelium 

Atlanto‐occipital joint

Type: ‐ Synovial joint of Ellipsoid variety

 Articular surface‐

• Above: convex occipital condyles

• Below: Concave superior articular facet of  atlas

       Important relation of atlas: Inferolateral free margin of altas arches over the vertebral artery and first cervical nerve

•       Blood supply: Vertebral artery

•       Nerve supply of joint:  C1 nerve

•       Movements of joint:

•       • Ellipsoid joint ( biaxial joint)

•       • Flexion / extension (nodding)‐ transverse axis

•       • Lateral flexion‐ antero-posterior axis

•       The atlantoaxial joint :

•       is a joint in the upper part of the neck between the first and second cervical vertebrae; the atlas and axis.

•       The atlantoaxial joint is of a complicated nature. It consists of three joint:

•       Comprise of

•       A pair of lateral atlantoaxial joints: (Plane joint) between inferior facets of atlas and superior facets of axis.

•        A median atlanto-axial joint: (pivot joint) between the dens and anterior arch and transverse ligament of atlas

•       Movements:

•        All three joints produce rotatory movement around a vertical axis (No movement)

•        Movement is limited by alar ligament

•        Muscles producing movement are: Rectus capitis posterior major, obliquis capitis inferior, splenius capitis of one side along with sternomastoid of other side

(The median atlantoaxial joint is sometimes considered a double joint:

•       one between the posterior surface of the anterior arch of atlas and the front of the odontoid process

•       one between the anterior surface of the ligament and the back of the odontoid process)  

The ligaments connecting these bones are:

1. Articular capsules
2. Anterior atlantoaxial ligament
3. Posterior atlantoaxial ligament
4. Transverse ligament of the atlas

Bones of superior extremity :an easy and useful handout on Radius

An easy and useful handout on radius 

Radius

1. Write anatomical points of radius.

Round head lies superiorly

Dorsal tubercle lies posteriorly at the lower part of radius

Sharp interosseous border lies medially 

2. Upper end :

                                I.                              Head of radius is covered by ………………cartilage which is articulate with ……………of humerus and take part in formation of ……………. Joint

                             II.        Neck: it is surrounded by …………………………ligament. ……………………..muscle is inserted in lateral, anterior and posterior surfaces of  neck.

                           III.                  Tuberosity : it has two part. Posterior rough part receive insertion of the …………………………………..muscle and anterior smooth part is related to a ……………………

3. Shaft :

                                                       I.      It has three borders.

Border	Name of attached structure	Attachment area
Interosseous border	Interosseous membrane	Lower ¾ part of interosseous border
Anterior	Flexor digitorum superficialis	Arises from upper and middle parts of the anterior border
	Extensor retinaculum	Arises from lower part of anterior border
Posterior	-----	----

                                                    II.      it has three surfaces

Surfaces	Name of attached structure	Attachment area
Anterior surface	Flexor pollicis longus	Arises from upper 2/3 part of  anterior surface
	Pronator quadratus	Inserted into lower ¼ part of anterior surface
Posterior surface	Abductor pollicis longus	Arises from the upper part of posterior surface
	Extensor pollicis brevis	Arises from the part of posterior surface just below the abductor pollicis longus
Lateral surface	Supinator	Inserted into upper part of lateral surface Also ant & pos surface of neck
	Pronator teres	Inserted into middle part of lateral surface

4. Lower end : it has five surfaces

Surfaces	Attached area	Attachment
Lateral surface	Styloid process	Radial ligament of wrist joint
	Area above the styloid process	Insertion of brachioradialis
	Two groove lateral to styloid process	Tendons of Abductor pollicis longus and extensor pollicis brevis are related
Medial surface	Bear an ulnar notch	Articulate with head of ulna and forms  inferior radio-ulnar joint
	Lower part of ulnar notch	Articulate with articular disc of inferior radio-ulnar joint
Inferior surface	Medial quadrangular part	Articulate with lunate
	Lateral triangular part	Articulate with scaphoid
posterior surface	Dorsal tubercle	Attachment  of extensor retinaculum
	A groove medial to the dorsal tubercle	Lodges tendon of extensor pollicis longus
	A groove lateral to the dorsal tubercle	Lodges tendon of extensor carpi radialis longus and extensor carpi radialis brevis
Anterior surface	--	--

features of epithelial tissue

Features of epithelial tissue 

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1. avascular ( contain no blood vessels, get nutrition by diffusion)
2. has nervous  innervation 
3. each epithelial cell has one apical surface, two lateral surfaces and one basal surface 
4. basal surface of it rest on a basement membrane (a layer form by collagen fibril, and protein, carbohydrate combination) 
5. if basement membrane is intact the epithelial cells grown normally
6. cells of epithelial tissue tightly bind with each other by junctional complex
7. apical surface of epithelial cells modify and formed microvilli, cilia, stereocilia etc.
8. there are many functions of epithelium : absorption, secretion, diffusion etc