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CT examination of the head of the Baikal seal ( Phoca sibirica )
Author(s) -
ENDO HIDEKI,
SASAKI HIROYUKI,
HAYASHI YOSHIHIRO,
PETROV EVAGENY A.,
AMANO MASAO,
SUZUKI NAOKI,
MIYAZAKI NOBUYUKI
Publication year - 1999
Publication title -
journal of anatomy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 118
eISSN - 1469-7580
pISSN - 0021-8782
DOI - 10.1046/j.1469-7580.1999.19410119.x
Subject(s) - anatomy , neurocranium , orbit (dynamics) , zygomatic arch , skull , cranial cavity , masticatory force , nasal cavity , biology , geology , medicine , orthodontics , engineering , aerospace engineering
We carried out a computerised tomographic (CT) examination to elucidate the modifications in the head related to orbital enlargement in the Baikal seal. Transverse CT images showed that (1) the external frontal contours and the frontal sinuses are compressed medially and ventrally by the orbital enlargement; (2) the caudal part of the nasal cavity and nasopharynx are compacted ventrally; and (3) the cranial cavity is displaced caudally. The neurocranium is obviously separated from the facial part in the transverse plane at the caudal region of the orbit. The disposition of the mandible, zygomatic arch, temporal bone, and the masseter, temporal, digastric and pterygoid muscles is changed by the enlarged orbit in the 3‐dimensional reorganisation of the head in this species. It is suggested that adaptation for the Lake Baikal environment primarily resulted in orbital enlargement, and that the altered orbital design may subsequently have influenced the form and function of the masticatory and respiratory system.