Comparison between tract and nerve

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  Comparison between tract and nerve Nerve Nerve contain bundle of axons (nerve fibers) in the peripheral nervous system (PNS) that transmits signals between the central nervous system (CNS) and other parts of the body. It is the most important part of peripheral nervous system Location: Peripheral nervous system. Structure: Made of axons, connective tissue layers (endoneurium: axon is surrounded by it , perineurium: bundle of axons are surrounded by it, epineurium: whole nerve trunk is surrounded by it), and blood vessels. It gets myelination by Schwann cell   Function: Carries sensory signals to the CNS (afferent) from peripheral part of body or motor signals carry from from the CNS (efferent) to target organs like skeletal muscle, cardiac muscle, smooth muscle or glands Example: Sciatic nerve, median nerve, except optic nerve (though optic nerve is technically part of CNS in develop...
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Difference between anterior and posterior fontanelle

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Difference between anterior and posterior fontanelle 

 

Anterior fontanelle

Posterior fontanelle

It is also known as bregmatic fontanelle, frontal fontanelle

It is alos known as lambdoid fontanelle, occipital fontanelle

It is a diamond-shaped membrane-filled space.

It  is triangle-shaped.

  It measures about 4 cm in its antero-posterior and 2.5 cm in its transverse diameter. 

Less than 1 cm

It is  located between the two frontal and two parietal bones of the developing fetal skull.

It is located between two parietal bones and occipital bone of the developing fetal skull

It is at the junction of the coronal suture and sagittal suture.

It lies at the junction between

the sagittal suture and lambdoid suture

The anterior fontanelle typically closes between the ages of 12 and 18 months

The posterior fontanelle generally closes 2 to 3 months after birth

 

 

The fetal anterior fontanelle may be palpated until 18 months. In cleidocranial dysostosis

The cranial point in adults corresponding the fontanelle is called 'lambda' A delay in closure is associated with congenital hypothyroidism.

·         The anterior fontanelle is useful clinically. Examination of an infant includes palpating the anterior fontanelle. A sunken fontanelle indicates dehydration  whereas a very tense or bulging anterior fontanelle indicates raised intracranial pressure.

Delay closer of posterior fontanelle one of the indication of hypothyroidism



















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