أسباب وأعراض الحمل خارج الرحم

 💢 فسيو العصبي 12,, motor 2

#Physiology_of_CNS 12

#CNS

*⃣ Muscle Sensor:

##هل عضلات جسمنااااا تشعررر مثلا بالالم 🤔 او بغيره ؟ اذا كانت الاجابة ب نعم 😎 طيب هاد معناه انه لا بد من وجود مستقبلاااات عليها ثح👌🤔😄 ؟ وكذلك توجد انواع مختلفة من انواع ال muscle sensors فخليكم معناااا👌😎😄🏃🏃🏃🏃

🔷Types of muscle sensors:👇

## وهم عبارة عن 4 انواع:👇👇👇

0⃣Muscle spindles (groups Ia and II afferents) are arranged in parallel with extrafusal  

fibers. They detect both static and dynamic changes in muscle length👌

1⃣Golgi tendon organs (group Ib afferents) are arranged in series with extrafusal muscle  

fibers. They detect muscle tension👌

2⃣Pacinian corpuscles (group II afferents) are distributed throughout muscle. They detect vibration👌

3⃣Free nerve endings (groups III and IV afferents) detect noxious stimuli👌

*⃣Type of muscle Fibers:👇

#⃣Extrafusal muscle fibers comprise the bulk of muscle and form the major force-generating structure.👌

#⃣Intrafusal muscle fibers are buried in the muscle, and they contain afferent receptors for stretch, but they also contain contractile elements.👌

🛑Extrafusal fibers:👇👇 👇

■ make up the bulk of muscle. 

■ are innervated by a-motoneurons. 

■ provide the force for muscle contraction .

🛑Intrafusal fibers:👇👇👇

■ are smaller than extrafusal muscle fibers. 

■ are innervated by g-motoneurons. 

■ are encapsulated in sheaths to form muscle spindles. 

■ run in parallel with extrafusal fibers, but not for the entire length of the muscle. 

■ are too small to generate significant force. 

*⃣Muscle spindles :👇👇👇

🔴consist of small, encapsulated intrafusal fibers connected in parallel with large (force generating) extrafusal fibers .👌

قد يعجبك ايضا

*⃣Types of intrafusal fibers in muscle spindles :👇👇

1⃣Nuclear bag fibers:👇👇

■ detect the rate of change in muscle length (fast, dynamic changes)👌

■ are innervated by group Ia afferents👌

■ have nuclei collected in a central “bag” region👌

2⃣ Nuclear chain fibers:👇👇

■ detect static changes in muscle length👌

■ are innervated by group II afferents👌

■ are more numerous than nuclear bag fibers👌

■ have nuclei arranged in rows. 

*⃣How the muscle spindle works??🤔

⚪️✔️Muscle spindle reflexes oppose (correct for) increases in muscle length (stretch)👌

0⃣ Sensory information about muscle length is received by group Ia (velocity) and  

group II (static) afferent fibers.

 

1⃣When a muscle is stretched (lengthened), the muscle spindle is also stretched, stimulating group Ia and group II afferent fibers👌 

2⃣Stimulation of group Ia afferents stimulates α-motoneurons in the spinal cord. This stimulation in turn causes contraction and shortening of the muscle. Thus, the original stretch is opposed and muscle length is maintained👌

#⃣Remember that👌👇👇

*⃣Function of g-motoneurons:👇👇👇👇👇

 

1. innervate intrafusal muscle fibers👌

2.adjust the sensitivity of the muscle spindle so that it will respond appropriately during muscle contraction👌

3.a-Motoneurons and g-motoneurons are coactivated so that muscle spindles remain sensitive to changes in muscle length during contraction👌

## ودمتم سالمين🏃🏃🚪