The upper third of the oesophagus (esophagus) contains striated (voluntary) muscle.
Here's a more detailed breakdown:
The oesophagus is not uniform in its muscular composition along its length. It transitions from voluntary to involuntary muscle as it descends. This is functionally important for swallowing.
- Upper Third: Primarily composed of striated muscle, which is under voluntary control. This allows us to consciously initiate swallowing.
- Middle Third: Contains a mixture of both striated and smooth muscle (involuntary).
- Lower Third: Composed entirely of smooth muscle, which is involuntary. Peristalsis, the rhythmic contractions that propel food to the stomach, is primarily controlled by this smooth muscle.
The transition from striated to smooth muscle allows for both conscious initiation of swallowing and unconscious propulsion of food down the esophagus. Additionally, sphincters made of circular muscles are located at both ends of the esophagus to control the passage of food and prevent reflux.
