The Structure and Function of Circular and Longitudinal Muscles Differ

The circular muscle layer is thicker than the longitudinal layer and more powerful in exerting contractile forces on the contents of the lumen. The long axis of the muscle fibers of circular muscle is oriented in the circumferential direction. Consequently, contraction reduces the diameter of the lumen of an intestinal segment and increases its length. Because the long axis of the muscle fibers is oriented in the longitudinal direction, contraction of the longitudinal muscle coat shortens the segment of intestine where it occurs and expands the lumen.

Longitudinal muscle

Longitudinal muscle

Structure Longitudinal Muscles

^FGUREISll^k Structural relationship of the intestinal musculature and the enteric nervous system.

Ganglia and interganglionic fiber tracts form the myenteric plexus between the longitudinal and the circular muscle layer and form the submucosal plexus between the mucosa and circular muscle layer.

^FGUREISll^k Structural relationship of the intestinal musculature and the enteric nervous system.

Ganglia and interganglionic fiber tracts form the myenteric plexus between the longitudinal and the circular muscle layer and form the submucosal plexus between the mucosa and circular muscle layer.

Both longitudinal and circular muscle layers are innervated by motor neurons of the ENS. The longitudinal muscle layer is innervated mainly by excitatory motor neurons,- the circular muscle layer by both excitatory and inhibitory motor neurons. Nonneural pacemaker cells and excitatory motor neurons activate contraction of the circular muscle, and excitatory motor neurons are the main triggers for contraction of the longitudinal muscle. More gap junctions between adjacent muscle fibers are found in the circular layer than in the longitudinal muscle layer. Calcium influx from outside the muscle cells is important for excitation-contraction coupling in longitudinal muscle fibers. Intracellular release from internal stores is more important for excitation-contraction coupling in the muscle fibers of the circular layer.

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Responses

  • belba
    What muscle is circular and longitudinal layered?
    7 years ago
  • TOMMASO
    What muscles form the circular layer of the musculature?
    7 years ago
  • angela
    Where are circular muscle fibers found?
    7 years ago
  • adalrico
    Which sructure would smooth muscle layer that are arranged in circular and longitudinal?
    6 years ago
  • kisanet
    Which of the layers has a longitudinal and circular layer of smooth muscle cells?
    6 years ago
  • Teagan Shaw
    Which is thicker circular or longitudinal muscles?
    2 years ago
  • anja
    What is the function of circular muscles?
    2 years ago
  • HARRISON
    Where is longitudinal skeletal muscle found?
    12 months ago
  • SINIT
    What is the function of the smooth circular muscle?
    12 months ago
  • giraldo
    What is the reason for both longitudinal and circular layer of muscle in the digestive tract?
    10 months ago
  • sabina
    Are the circular muscles of the body powerful?
    7 months ago
  • tiffany
    What parts of the body have longitudinal and circular muscles?
    6 months ago
  • Juha Ven
    How can a combination of circular and longitudinal muscles cause this action?
    5 months ago
  • beatrice
    What happens with damage to the longitudinal smooth muscle function?
    5 months ago
  • Medhane
    Where is longitudinal and circular muscles located?
    5 months ago
  • marigold
    Is longitudinal muscle innervated by excitatory and inhibitory?
    4 months ago
  • kifle
    How to work circular muscles?
    4 months ago
  • maximilian
    What is the relationship between structure and function in Muscle Skeletal Longitudinal Section ?
    17 days ago

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