Anatomy books

Sunday, September 10, 2017

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 cm2. One third of cortex is exposed as gyri and two third of cortex is hidden in the sulci.
Development of sulci:
Upto the 3rd months of inter uterine life:  the cerebral cortex remains smooth
During 4th months of inter uterine life: lateral sulcus appears on the superolateral surface of cerebrum and insular cortex begins to submerge.
During the 6th months of inter uterine life: central, parieto-occipital, calcarine and cingulate sulci appear.
During the 7th 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




Friday, September 8, 2017

Summary of adipose tissue: special connective tissue

Adipose tissue
It is a specialized connective tissue which is composed of fat cells, reticular fibres and rich vascular supply.
In men of normal weight, adipose tissue represents 15-20% of the body weight;
in women of normal weight, it represents 20-25% of body weight.
 Adipose tissue is a very efficient storage tissue. It is in a state of continuous turnover and is sensitive to both nervous and hormonal stimuli.
 The sympathetic division of the autonomic nervous system richly innervates both uni-locular and multi-locular adipose tissues. In uni-locular adipose tissue, nerve endings are found only in the walls of blood vessels; the adipocytes are not directly innervated. Release of the neurotransmitter norepinephrine activates the hormone-sensitive lipase described above. This innervation plays an important role in the mobilization of fats.

Types:  
1.      White (unilocular) and
2.      Beige adipocyte
3.      Brown (multilocular).

White adipocyte :

These types of adipocytes are predominantly found in adult. White adipocytes are spherical, but they may appear polyhedral or oval when crowded together. It contains unilocular fat which store triglyceride, flatten nucleus, rim of cytoplasm. Adipocyte looks like signet ring so it also known as signet ring cell.  Early lipoblasts look like fibroblasts but develop small lipid inclusions and a thin external lamina.
Unilocular adipocytes are large cells, sometimes 100 µm or more in diameter. The lipid mass in the adipocyte is not membrane bounded. It thin cytoplasmic rim contain a Golgi complex, few poorly developed mitochondria, poorly developed cisternae of the rough endoplasmic reticulum, and free polyribosomes,  the lipid droplet contains cisternae of smooth endoplasmic reticulum and numerous pinocytotic vesicles. Each adipose cell is surrounded by a basal lamina.

Innervation: Few sympathetic nerve fibers
Secretions:  White adipose tissue produces a variety of hormones, growth factors, and cytokines.
ASP(Acylation-stimulating protein ) Influences the rate of triglyceride synthesis in adipose tissue
Insulinlike growth factor I (IGF-I) : Stimulates proliferation of a wide variety of cells and mediates many of the effects of growth hormone
Leptin Regulates appetite and body energy expenditure
Plasminogen activator inhibitor-1 (PAI-1):  Inhibits the fibrinolytic system
Elevated levels are associated with increased formation of blood clots
Prostaglandins I2 F2_, (PGI2 and PGF2_) Helps regulate inflammation, blood clotting, ovulation, menstruation,and acid secretion
Resistin:  Increases insulin resistance ,Linked to obesity and to type 2 diabetes
Distribution: subcutaneous tissue, breast, greater omentum, mesenteries, visceral pericardium, orbital cavity, retroperitoneal space, bone marrow
Metabolism:

It hydrolyzes the stored lipids into fatty acids and glycerol, which are released from the cell.

 Functions of white adipose tissue include
1.      metabolic energy storage,
2.      insulation,
3.      cushioning of vital organs, and
4.      secretion of hormones,
5.       Source of metabolic water.  
6.       Subcutaneous layers of adipose tissue help to shape the surface of the body, whereas deposits in the form of pads act as shock absorbers, chiefly in the soles and palms.


 Beige adipocytes:  Beige fat” is a new kind of energy-burning cell that prevent obesity and help weight loss for adults.
Distribution:  This new fat cell is found underneath the skin along the spine and in the proximal area of the collarbone in deposits resembling the size of a pea.
Microscopic features: Like brown fat, beige fat cells also have a plentiful amount of mitochondria and iron, giving them their darker color.
Function:
Prevent obesity
Increase insulin receptor sensivity
How this cell is formed? :
These beige fat cells are converted from white fat cells while exercising when muscles release a hormone called irisin.
Brown adipocyte :
Brown adipose tissue is present in humans during fetal life but diminishes during the first decade after birth. Brown adipose tissue makes up about 5% of the total body mass.

Microscopic features: Multilocular adipose tissue contains numerous fat droplets. Brown (multilocular) adipocytes are smaller in diameter (10–25 µm) than those of white adipose tissue.
Multilocular, spherical, round eccentric nucleus. The multilocular adipocyte contains numerous mitochondria, a small Golgi apparatus, and only small amounts of rER and sER. The mitochondria contain large amounts of cytochrome oxidase, which imparts the brown color to the cells.
Function: Brown adipose tissue is present in large amounts in the newborn, which  prevent  the extensive heat loss by heat production (thermogenesis) that results from the newborn’s high surface-to-mass ratio and avoid lethal hypothermia (a major risk of death for premature babies).
Distribution : It is located on the back, along the upper half of the spine, and toward the shoulders. In adult it is gradually decreases. At first decade of life it is situated in the cervical, axillary, paravertebral, mediastinal, sternal,and abdominal regions of the body.
It then disappears from most sites except for regions around the kidney, adrenal glands, large vessels (i.e., aorta), and regions of the neck (deep cervical and supraclavicular), regions of the back (interscapular and paravertebral), and thorax (mediastinum).
Metabolism: brown fat contain numerous mitochondria which are capable of uncoupling proton leakage and instead of producing adenosine triphosphate (ATP), they release heat, thus arousing the animal from hibernation.

Brown adipocyte : special connective tissue

Brown adipocyte :
Brown adipose tissue is present in humans during fetal life but diminishes during the first decade after birth. Brown adipose tissue makes up about 5% of the total body mass.

Microscopic features: Multilocular adipose tissue contains numerous fat droplets. Brown (multilocular) adipocytes are smaller in diameter (10–25 µm) than those of white adipose tissue.
Multilocular, spherical, round eccentric nucleus. The multilocular adipocyte contains numerous mitochondria, a small Golgi apparatus, and only small amounts of rER and sER. The mitochondria contain large amounts of cytochrome oxidase, which imparts the brown color to the cells.
Function: Brown adipose tissue is present in large amounts in the newborn, which  prevent  the extensive heat loss by heat production (thermogenesis) that results from the newborn’s high surface-to-mass ratio and avoid lethal hypothermia (a major risk of death for premature babies).
Distribution : It is located on the back, along the upper half of the spine, and toward the shoulders. In adult it is gradually decreases. At first decade of life it is situated in the cervical, axillary, paravertebral, mediastinal, sternal,and abdominal regions of the body.
It then disappears from most sites except for regions around the kidney, adrenal glands, large vessels (i.e., aorta), and regions of the neck (deep cervical and supraclavicular), regions of the back (interscapular and paravertebral), and thorax (mediastinum).
Metabolism: brown fat contain numerous mitochondria which are capable of uncoupling proton leakage and instead of producing adenosine triphosphate (ATP), they release heat, thus arousing the animal from hibernation.


Beige adipocyte : a new hope for losing weight

Beige adipocytes:  Beige fat” is a new kind of energy-burning cell that prevent obesity and help weight loss for adults.
Distribution :  This  new fat cell is found underneath the skin along the spine and in the proximal area of the collarbone in deposits resembling the size of a pea.
Microscopic features: Like brown fat, beige fat cells also have a plentiful amount of mitochondria and iron, giving them their darker color.
Function:
Prevent obesity
Increase insulin receptor sensitivity
How this cell is formed? : These beige fat cells are converted from white fat cells while exercising when muscles release a hormone called irisin. These beige cells then burn extra calories. It is speculated that these beige fat cells developed from shivering, which is categorized at a neuromuscular activity along with exercise.The embryonic origin of beige adipocytes is less clear. But recent study support that large unilocular white adipocytes transform into beige adipocytes in response to cold. Brown fat cells show high levels of UCP1, (a protein essential to mitochondria to generate heat and burn calories), where beige cells usually show lower levels of this protein. Beige cells are able to increase their level of this UCP1 protein, by releasing irisin or being exposed to the cold, making them just as effective as brown cells to burn calories. Beige fat cells behave like white fat cells until they’re activated through a process called “browning.” After they are browned, they start to behave like brown fat and burn other white fat for energy. Beige fat does a lot more than body weight. To take one example, it may also help improve insulin sensitivity.

Factors stimulate browning:
  • Social interaction. By increasing the levels of a protein called Brain-Derived Neurotrophic Factor, social interaction can “brown” white fat tissue.
  • Exercise. By releasing the hormone irisin, exercise can make cause fat browning. This is a major difference between beige and brown fat inrisin has no real effect on brown fat 
  • Cold exposure. Just like brown fat, beige fat gets “turned on” by cold.
  • Mild stress:   browning might be activated by mild stress. Mild stress causes small spikes in cortisol, but in chronic stress cortisol level remain high for most of the time that is not good for health. So occasional spikes in cortisol are good for health.
  • cancer is really great at browning white fat cells  which is one reason why people with cancer lose so much weight.
    Food stimulates browning:
1.      Green tea
2.      Garlic
3.      Red pepper
4.      Sea weed extract
5.      Fish/flaxseed oil
6.      Curcumin /tumaric
7.      Melatonin

8.      Resveratrol 

White adipocyte : easy and brief description

White adipocyte :

These types of adipocytes are predominantly found in adult. White adipocytes are spherical, but they may appear polyhedral or oval when crowded together. It contains unilocular fat which store triglyceride, flatten nucleus, rim of cytoplasm. Adipocyte looks like signet ring so it also known as signet ring cell.  Early lipoblasts look like fibroblasts but develop small lipid inclusions and a thin external lamina.
Unilocular adipocytes are large cells, sometimes 100 µm or more in diameter. The lipid mass in the adipocyte is not membrane bounded. It thin cytoplasmic rim contain a Golgi complex, few poorly developed mitochondria, poorly developed cisternae of the rough endoplasmic reticulum, and free polyribosomes,  the lipid droplet contains cisternae of smooth endoplasmic reticulum and numerous pinocytotic vesicles. Each adipose cell is surrounded by a basal lamina.


Innervation: Few sympathetic nerve fibers
Secretions:  White adipose tissue produces a variety of hormones, growth factors, and cytokines.
ASP(Acylation-stimulating protein ) Influences the rate of triglyceride synthesis in adipose tissue
Insulinlike growth factor I (IGF-I) : Stimulates proliferation of a wide variety of cells and mediates many of the effects of growth hormone
Leptin Regulates appetite and body energy expenditure
Plasminogen activator inhibitor-1 (PAI-1):  Inhibits the fibrinolytic system
Elevated levels are associated with increased formation of blood clots
Prostaglandins I2 F2_, (PGI2 and PGF2_) Helps regulate inflammation, blood clotting, ovulation, menstruation,and acid secretion
Resistin:  Increases insulin resistance ,Linked to obesity and to type 2 diabetes
Distribution: subcutaneous tissue, breast, greater omentum, mesenteries, visceral pericardium, orbital cavity, retroperitoneal space, bone marrow
Metabolism:

It hydrolyzes the stored lipids into fatty acids and glycerol, which are released from the cell.

 Functions of white adipose tissue include
1.      metabolic energy storage,
2.      insulation,
3.      cushioning of vital organs, and
4.      secretion of hormones,
5.       Source of metabolic water.  
6.       Subcutaneous layers of adipose tissue help to shape the surface of the body, whereas deposits in the form of pads act as shock absorbers, chiefly in the soles and palms.



Tuesday, September 5, 2017

Gray and white matter : composition , location and difference

Grey (British)  gray (American) matter and white matter are  found within the  central nervous system.
Composition of gray matter :
1.      Neuron cell body,
2.      Initial portion of dendrites and axon
3.      Neuroglia
4.      Blood vessels
Composition of white matter:
1.      White matter contain
2.      numerous dendrites and myelinated axons, 
3.      neuroglia, and
4.      blood vessels.
Colour:
Gray matter:  actually has a very light gray colour with yellowish or pinkish hues, which come
from blood vessels and neuronal cell bodies.
White matter:  the colour of white matter arises mainly from the whiteness of myelin.
Location
location of gray matter ::
In cerebrum and cerebrum gray matter situated in outer layer of these organs.
In spinal cord it is situated in inner layer of this organ .

A small collection of gray matter known as nuclei present within the white matter. Example :  basal nuclei/ nuclei: caudate nucleus, putamen, globus pallidus , substantia nigra, subthalamic nucleus , nucleus accumbens and  brain stem nuclei (red nuclei, cranial nerve nuclei) are spread within the cerebral white matter.

Cerebellar nuclei dentate nuclei, fastigi, emboliform etc are the small collection of gray matter present within the white matter of cerebellum .
Ganglia are small collection of gray matter (neuron cell body ) situated outside the central nervous system .
Location of white matter:
White matter forms the bulk of the deep parts of the cerebrum and cerebellum and the superficial parts of the spinal cord  
Difference between gray matter and white matter
Topics
Gray matter
White matter
Composition
Nerve cell body ,
Neuroglia,
Processes ,
Blood vessels
Neuroglia,
Processes ,
Blood vessels
Colour
Light grey
White
Percentage
Occupy 40% of brain
Occupy 60% of brain
Maturity
Girl  11 years
Boy 12 years 
Girl 25 years
Boy 20 years
Sex difference
Male 6.5 more gray matter
Female   contain 10 times more  white matter
Proportion of
Men have higher proportion of white matter
women have higher proportion of grey  matter
Function
It is the information processing region  of brain
It makes connection between different information processing region of brain
Oxygen use
It uses almost 95% of oxygen
It uses remaining  5%
Loss of volume
It volume losses constantly throughout the life
its volume losses start after mid age
Other name of
Gray matter also known as substantia grisea
White matter also known as substantia alba


Wednesday, August 23, 2017

Ear ossicles : malleus, incus ,stapes : short and easy description

Ear osssicles :
The middle ear cavity contains a chain of three small bones the malleus , the incus and the stapes .
Conduction of sound through the middle ear to internal ear is transmitted by these three ossicles. Each ear ossicles is ossified from one ossification centre in the fourth month of intra-uterine life and they attain adult size at birth .
Malleus :
It is the largest bone of middle ear.
Shape: like a round-headed club
Parts:
Head: it lies in the epi- tympanic part of middle ear cavity. Head articulate with the incus forming a siddle shaped synovial joint
Neck:  it situated in between head and handle and lies just medial to pars flaccida of tympanic membrane. Its medial side is related with chorda tympani nerve
Handle: it is attached with medial side of tympanic membrane and its upper part receives insertion of tendon of tensor tympani muscles.
Anterior process: situated just below the neck: it receives attachment of anterior ligament which extends up to spine of sphenoid. This ligament derived from perichondrium of 1st pharyngeal arch cartilage.
Lateral process: mallear folds are attached to the apex of the lateral process.


Incus
Shape : like premolar tooth
Development : 1st pharyngeal arch
Parts :
Body : articulate with head of malleus
Short process : directed posteriorly
Long process : it is situated parallel to the upper part of handle of malleus and tip of incus forms a knob known as lentiform nodule which articulate with head of stepes . 

Stepes:
Shape : it looks like stirrup
Development :2nd pharyngeal arch
Parts :
Head : articulate with lentiform nodule of incus
Neck : receive insertion of stepedius muscle
Anterior and posterior limbs
Base or foot- plate : it is attached with fenestra vestibule by annular ligament


What are the structure seen through auroscope
Lateral process of malleus
Long process of incus






Two small muscles are associate with ear ossicles
1.      Stapedius :
Attachement : origin : interior of hollow pyramid
Insertion : neck of stepes
Nerve supply :  facial nerve
Functions: contraction of this muscle draw the stapes laterally thus tilting its foot plate in the oval window.
 it prevent excessive movement of stapes so its paralysis leads  to uninhibited movement of stapes and excessive acuteness of hearing (hyperacusis) 
SN: paralysis of the stapedius causes an abnormally increased power of
2.      Tensor tympani:
Attachment : origin : bony part of auditory tube
Insertion : handle of malleus
Nerve supply : mandibular division of trigeminal nerve
Functions: contraction of this muscle draw the handle of malleus medially (inward) which makes tympanic membrane more concave laterally  and tense. It prevent wide excursions of the ear ossicles and potential damage to the inner ear when exposed to loud sounds

          Functions of both muscles: damp high frequency vibrations