Editing Oesophagus (section)

== '''Tissue architecture''' ==

* Two main layers (no serosa,     unlike the rest of the alimentary tract)
** '''Mucosa''' - mostly stratified      squamous non-keratinizing epithelium, up to the Z-line, where it      transitions to cardiac mucosa/junctional columnar epithelium
*** Four distinct layers within       the mucosa:
**** Epithelium
**** Basement membrane
**** Lamina propria
**** Muscularis mucosae -        longitudinal fibres
** '''Submucosa''' is found deep to muscularis      mucosae - strongest layer for holding sutures
*** Lymphatic and vascular       networks
*** Mucous glands
*** Meissner neural plexus
*** Fibrous tissue
** '''Muscularis      propria'''
*** Inner circular layer       (continuation of cricopharyngeus)
**** Transitions from the        circular muscles of the oesophagus to the oblique muscles of the        stomach at the incisura, known as the collar of Helvetius
*** Thin septum of connective       tissue, which also contains the Auerbach plexus (interconnected ganglia)
*** Outer longitudinal muscle       layer
**** Begins at back of cricoid        cartilage by a tendon which gives rise to two fasciculi which spread        out to constitute the longitudinal muscle
**** Extends into abdomen,        becoming the longitudinal muscle of the cardia of the stomach
*** Proximal third       predominantly striated muscle; distal third entirely smooth muscle;       middle third a mixture
* Final outside layer of '''fibroalveolar     adventitia'''

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