IVRI Anatomy
A free veterinary anatomy learning platform for B.V.Sc., M.V.Sc., DVM and veterinary medicine students worldwide, developed at the Veterinary Anatomy Section, ICAR-Indian Veterinary Research Institute, Bareilly—covering VCI/MSVE and international university curricula through regional anatomy, histology, embryology, comparative biomechanics, clinical notes, quizzes and revision.
The ethmoid is a complex, cuboidal bone located deep between the orbits, separating the nasal cavity from the cranial cavity. It is the osseous center for olfaction.
Cribriform Plate (Lamina cribrosa): A horizontal sieve-like plate located at the deepest part of the cranial fossa. It is perforated by numerous foramina transmitting the olfactory nerve fascicles (CN I) from the nasal mucosa to the olfactory bulbs.
Crista Galli: A median, vertical bony ridge projecting into the cranial cavity from the cribriform plate. In the ox, it is distinct but relatively short and thick compared to the spine-like process in the pig. It serves as an anchor for the falx cerebri.
Perpendicular Plate (Lamina perpendicularis): A median vertical plate that extends rostrally to form the caudal osseous portion of the nasal septum. It articulates with the vomer ventrally and the frontal bone dorsally.
Ethmoidal Labyrinth: A dense mass of delicate bony scrolls known as ethmoturbinates:
| OX (BOS TAURUS) | Large labyrinth; 5 endoturbinates, ~18 ectoturbinates. Crista galli present; thick and low ridge. Perpendicular plate extensive; forms large part of septum. Lateral masses (lamina papyracea) present. Deep olfactory fossae. |
| HORSE (EQUUS CABALLUS) | Extensive labyrinth; 6 endoturbinates, ~25 ectoturbinates. Crista galli present; prominent. Perpendicular plate extensive. Deep. |
| DOG (CANIS LUPUS) | Complex labyrinth; 7 endoturbinates, ~20 ectoturbinates. Crista galli present; high and ridge-like. Perpendicular plate extensive. Very deep; houses large olfactory bulbs. |
| PIG (SUS SCROFA) | Massive labyrinth; highly complex lamellae for macrosmatic olfaction. Crista galli absent or vestigial. Perpendicular plate extensive. Deep. |
| FOWL (GALLUS DOMESTICUS) | Reduced; simple structure, olfaction is less critical. Very prominent; spine-like projection. Thin; membranous/cartilaginous. Small olfactory lobes. |
Explore the hidden mechanics of why structures are present, absent or modified across domestic and wildlife species—and how each anatomical design supports movement, function and clinical practice.
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