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 malleus , incus and stapes

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1.      Difference between malleus , Incus and Stapes

Topics
Malleus
Incus
Stapes
Shape
like  mallet  
like premolar tooth (like anvil) 
it looks like stirrup
Length
Longest, about 8-9 mm
Medium
Shortest
Parts
Head: 
Neck: 
Handle:
Anterior process: 
Lateral process: 
Body
Short process : 
Long process : 
Head :
Neck :
Anterior &  posterior limbs
Base or foot- plate : 
Development
1st pharyngeal arch
1st pharyngeal arch
2nd pharyngeal arch
Cartilage
Develops from dorsal end of Meckel’s cartilage  
Develops from dorsal extremity of Meckel’s cartilage
Develops from hyoid arch cartilage
Muscle attachment
Tensor tympani
None
Stapedius
Nerve supply of attached muscles
Mandibular division of trigeminal nerve
None
Facial nerve
Functions of attached muscles
Damping high frequencing vibration /sound by tensing  the tympanic membrane
Damping high frequencing vibration /sound by drawing the base of stepes laterally
Important Relation
Chorda tympani nerve related with medial surface of neck of malleus
None
None
Articulation
Incudo-malleolar (saddle type of synovial joint)
Incudo-malleolar and incudo-stapedial   
Incudo-stapedial (ball and socket type of synovial joint )
Ossification
All part ossify from single endochondral centre at 4th month of intra-uterine life except anterior process which ossify from dense connective tissue at six months of intra-uterine life
All part ossify from single endochondral centre  except lentiform process 
All part ossify from single endochondral centre 


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