MICROANATOMY

Detailed explanation-1: -The muscularis propria is comprised of a layer of circularly aligned muscle fibers within, and a layer of longitudinally aligned muscle fibers without, surrounding mucosal layers of loosely connected tissue. The muscle mass of the circular and longitudinal muscle layers is nearly the same.

Detailed explanation-2: -During peristalsis, the circular smooth muscle contracts behind (on the orad side) the bolus and relaxes in front (on the aborad side) of the bolus. At the same time, the longitudinal muscle relaxes orad to the bolus and contracts on the aborad side of the bolus.

Detailed explanation-3: -The smooth muscle in the intestine is arranged into two layers: an inner circular layer and an outer longitudinal layer. Note again the spindle-shaped cells and centrally located nucleus in each cell.

Detailed explanation-4: -In muscle: Muscle in soft animals. The longitudinal muscle fibres run lengthwise along the body, and the circular fibres encircle it. The body contents are liquids or tissues that can be deformed into different shapes, but they maintain a constant volume.