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 constrictors muscles of pharynx

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Difference between constrictors muscles of pharynx

The constrictor muscles of the pharynx are three paired muscles that form the muscular wall of the pharynx and help in swallowing. They are:

1.     Superior Constrictor

o   Origin: it is originate from following structures : pterygoid hamulus, pterygomandibular raphe, posterior end of mylohyoid line of mandible, and side of tongue

o   Insertion: it is inserted in to the  pharyngeal raphe

o   Function: it initiates swallowing by constricting the upper part of the pharynx

o   Innervation: this muscle is supply by pharyngeal plexus of the vagus nerve (CN X)

2.    Middle Constrictor

o   Origin: it is originate from following structures:  stylohyoid ligament and hyoid bone (greater and lesser horns)

o   Insertion: it is also inserted into pharyngeal raphe

o   Function: this muscles narrows the pharyngeal lumen in the middle region, aiding in pushing food downward

o   Innervation: this muscle is also supplied by pharyngeal plexus of the vagus nerve (CN X)

3.    Inferior Constrictor

o   Origin: this muscle is originate from following laryngeal cartilages : Thyroid and cricoid cartilages

o   Insertion: like other two constrictors it is inserted into the  Pharyngeal raphe

o   Function: this muscle facilitates the passage of food into the esophagus by constricting the lower pharynx

o   Innervation: like other two constrictors it is also supply by p haryngeal plexus of the vagus nerve (CN X) but it is also supplied by  external and recurrent branches of the superior laryngeal nerve

Key Differences:

Feature

Superior Constrictor

Middle Constrictor

Inferior Constrictor

Origin

Pterygoid hamulus, pterygomandibular raphe, mylohyoid line

Stylohyoid ligament, hyoid bone

Thyroid and cricoid cartilages

Insertion

Pharyngeal raphe

Pharyngeal raphe

Pharyngeal raphe

Function

Initiates swallowing

Pushes food downward

Transfers food to the esophagus

Innervation

Pharyngeal plexus of CN X

Pharyngeal plexus of CN X

Pharyngeal plexus of CN X + external/recurrent branches of superior laryngeal nerve

 

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