Esophagus: Muscularis externa
Muscularis externa is formed of inner circular and outer longitudinal muscle layers that produce propulsive peristaltic waves of contraction. In the upper third of the esophagus, these layers are formed of skeletal muscle, which is involved with swallowing, a voluntary action. In the middle one-third (seen here), skeletal and smooth muscles are intermixed. In the lower one-third, only smooth muscle is present. Innervation is provided by the myenteric (Auerbach’s) plexus. 400x
Submucosa
Muscularis externa is formed of inner circular and outer longitudinal muscle layers that produce propulsive peristaltic waves of contraction. In the upper third of the esophagus, these layers are formed of skeletal muscle, which is involved with swallowing, a voluntary action. In the middle one-third (seen here), skeletal and smooth muscles are intermixed. In the lower one-third, only smooth muscle is present. Innervation is provided by the myenteric (Auerbach’s) plexus. 400x
Muscularis externa
Muscularis externa is formed of inner circular and outer longitudinal muscle layers that produce propulsive peristaltic waves of contraction. In the upper third of the esophagus, these layers are formed of skeletal muscle, which is involved with swallowing, a voluntary action. In the middle one-third (seen here), skeletal and smooth muscles are intermixed. In the lower one-third, only smooth muscle is present. Innervation is provided by the myenteric (Auerbach’s) plexus. 400x
- Smooth muscle longitudinal section
Muscularis externa is formed of inner circular and outer longitudinal muscle layers that produce propulsive peristaltic waves of contraction. In the upper third of the esophagus, these layers are formed of skeletal muscle, which is involved with swallowing, a voluntary action. In the middle one-third (seen here), skeletal and smooth muscles are intermixed. In the lower one-third, only smooth muscle is present. Innervation is provided by the myenteric (Auerbach’s) plexus. 400x
- Skeletal muscle longitudinal section
Muscularis externa is formed of inner circular and outer longitudinal muscle layers that produce propulsive peristaltic waves of contraction. In the upper third of the esophagus, these layers are formed of skeletal muscle, which is involved with swallowing, a voluntary action. In the middle one-third (seen here), skeletal and smooth muscles are intermixed. In the lower one-third, only smooth muscle is present. Innervation is provided by the myenteric (Auerbach’s) plexus. 400x
- Smooth muscle cross section
Muscularis externa is formed of inner circular and outer longitudinal muscle layers that produce propulsive peristaltic waves of contraction. In the upper third of the esophagus, these layers are formed of skeletal muscle, which is involved with swallowing, a voluntary action. In the middle one-third (seen here), skeletal and smooth muscles are intermixed. In the lower one-third, only smooth muscle is present. Innervation is provided by the myenteric (Auerbach’s) plexus. 400x
- Skeletal muscle cross section
Muscularis externa is formed of inner circular and outer longitudinal muscle layers that produce propulsive peristaltic waves of contraction. In the upper third of the esophagus, these layers are formed of skeletal muscle, which is involved with swallowing, a voluntary action. In the middle one-third (seen here), skeletal and smooth muscles are intermixed. In the lower one-third, only smooth muscle is present. Innervation is provided by the myenteric (Auerbach’s) plexus. 400x
- Myenteric (Auerbach’s) plexus
Muscularis externa is formed of inner circular and outer longitudinal muscle layers that produce propulsive peristaltic waves of contraction. In the upper third of the esophagus, these layers are formed of skeletal muscle, which is involved with swallowing, a voluntary action. In the middle one-third (seen here), skeletal and smooth muscles are intermixed. In the lower one-third, only smooth muscle is present. Innervation is provided by the myenteric (Auerbach’s) plexus. 400x
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