smooth muscle (unstriated/unstriped/visceral muscle)

Introduction

One of the muscle fibers of the internal organs, blood vessels, hair follicles, etc.

Structure

• contractile elements are elongated, generally spindle-shaped with centrally located nuclei.
• fiber length varies from 20 to 200 uM, even longer in the pregnant uterus.
• both thin & thick myofibrils occur, but transverse striations are lacking
• fibers are bound together into sheets or bundles by reticular fibers & frequently elastic nets

Pathology

• see anti-smooth muscle antibody

More general terms

• muscle

More specific terms

• arrectores pilorum muscles
• ciliary muscle (Bowman's muscle)
• dartos muscle
• detrusor muscle (musculi detrusor vesicae)
• dilator pupillae (dilator iridis)
• levator prostatae (puboprostaticus)
• ligament of Treitz
• muscularis
• muscularis mucosa
• myometrium
• rectococcygeus
• rectourethralis
• rectouterine muscle
• sphincter pupillae
• superior tarsal muscle (Muller muscle)
• trachealis muscle
• tunica media
• tunica muscularis; circular/longitudinal muscle of esophagus

Additional terms

• anti-smooth muscle antibody (ASMA)