title: Regional Variations in Orbicularis Oculi Histology.
abstract: OBJECTIVE
  To investigate and compare the histologic compositions of the pretarsal, preseptal, and orbital orbicularis oculi muscle (OOM) using nonpreserved, fresh-frozen, human cadavers.
  
  
  METHODS
  The OOM was exposed using sharp and blunt dissection. A metric ruler was used to measure and mark 0.5 cm × 1 cm samples from each portion of the right, superior OOM. Samples were excised, fixed in formalin, and completely embedded in paraffin. Five-micrometer-thick, hematoxylin- and eosin-stained sections were generated for each sample and analyzed by an anatomical pathologist. The relative percentages of the 4 main tissue types (skeletal muscle, fibrous tissue, adipose tissue, and neurovascular tissue) were quantified.
  
  
  RESULTS
  Forty-two samples were obtained from 14 Caucasian cadavers. On average, the pretarsal samples were composed of 83.5% skeletal muscle, 0.0% adipose, 5.0% neurovascular, and 11.5% fibrous tissue. Average preseptal OOM was 46.5% skeletal muscle, 12.7% adipose, 9.2% neurovascular, and 31.5% fibrous tissue. The orbital OOM was, on average, 42.7% skeletal muscle, 32.7% adipose tissue, 6.9% neurovascular, and 17.7% fibrous tissue.
  
  
  CONCLUSIONS
  The OOM represents a histologically heterogeneous structure.
authors: *Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio and †Department of Anatomic Pathology, Cleveland Clinic, Cleveland, Ohio; ‡Casey Eye Institute, Oregon Health and Science University, Portland, Oregon; §Department of Anatomy, Cleveland Clinic Lerner College of Medicine, Cleveland, Ohio; ‖Lorain Institute, Cleveland Clinic, Lorain, Ohio.
authors: Bryan R
authors: BR
authors: Costin
authors: Thomas P
authors: TP
authors: Plesec
authors: Laura J
authors: LJ
authors: Kopplin
authors: Rao V
authors: RV
authors: Chundury
authors: Jennifer M
authors: JM
authors: McBride
authors: Mark R
authors: MR
authors: Levine
authors: Julian D
authors: JD
authors: Perry
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000033:anatomy & histology*; D009915:Orbit / Q000033:anatomy & histology*; D009929:Organ Size; D044465:White People