Activities of superior pharyngeal constrictor and levator veli palatini muscles related to respiration in dogs.
OBJECTIVE
This study, using mongrel dogs, attempted to delineate the respiratory activity of two closure muscles of the velopharynx, the levator veli palatini (LVP) and superior pharyngeal constrictor (PC) muscles.


METHODS
Fifteen mongrel dogs were given tracheotomies, with intratracheal tubes being connected to their respiratory circuits. Activities of the PC and LVP muscles were recorded electromyographically, and the effects of PaO2 and PaCO2 were analyzed along with the effects of lung inflation intratracheally with O2 and N2.


RESULTS
Under hypoxic conditions, expiratory LVP activity was observed while PC activity diminished. The effects of lung inflation on both LVP and PC activities were also studied. The activities of both muscles were enhanced by lung inflation.


CONCLUSIONS
It was thus suggested that the roles of both muscles during velopharyngeal closing movements are not the same.
Kogo
M
M
First Department of Oral and Maxillofacial Surgery, Osaka University, Faculty of Dentistry, Suita City, Japan.
Tanaka
S
S
Ishii
S
S
Hamaguchi
M
M
Iida
S
S
Matsuya
T
T
D000280:Administration, Inhalation; D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D004285:Dogs; D004576:Electromyography; D000860:Hypoxia / Q000503:physiopathology; D007320:Inspiratory Capacity / Q000502:physiology; D007442:Intubation, Intratracheal / Q000295:instrumentation; D008168:Lung / Q000502:physiology; D009584:Nitrogen / Q000008:administration & dosage; D010100:Oxygen / Q000008:administration & dosage / Q000097:blood; D010156:Palatal Muscles / Q000502:physiology*; D010160:Palate, Soft / Q000502:physiology; D010609:Pharyngeal Muscles / Q000502:physiology*; D012119:Respiration / Q000502:physiology*; D012121:Respiration, Artificial; D015656:Respiratory Mechanics / Q000502:physiology; D014140:Tracheotomy
D002245:Carbon Dioxide; D009584:Nitrogen; D010100:Oxygen