http://purl.obolibrary.org/obo/UBERON_0000009, http://purl.obolibrary.org/obo/UBERON_0006676

An outer layer of smooth muscle surrounding a hollow or tubular organ as the bladder, esophagus, large intestine, small intestine, stomach, ureter, uterus, and vagina that often consists of an inner layer of circular fibers serving to narrow the lumen of the organ and an outer layer of longitudinal fibers serving to shorten its length[BTO].

typically smooth muscle, but there may be exceptions - in the upper esophagus, part of the externa is skeletal muscle, rather than smooth muscle.

currently this class conflates a generic layer of muscle and a specific layer found lining the digestive tract (the muscularis externa), typically composed of circular and longitudinal layers (although this varies)

muscularis propria, tunica externa, muscularis externa, muscular coat, transverse muscular fibers, tunica muscularis, muscularis

uberon

UBERON:0006660

Muscle layer

• wall of ureter

• longitudinal muscle layer of muscular coat
• circular muscle layer of muscular coat