GLOSSARY
of Skullological Terminology
- Alveolus
- The socket into which the root of a tooth fits.
- Angle
- The lower back corner of the lower jaw.
- Anterior
- Towards the front.
- Ascending Ramus of Jaw
- The more or less vertical part of the jawbone which carries the joint with the skull.
- Brachycephalic
- Short-headed. Referring to breeds of dog such as boxers, with forshortened snouts.
- Braincase
- Part of the skull containing the brain.
- Bulla
- Bulbous part of the ear bones.
- Bunodont
- Low-crowned, rectangular grinding teeth, typical of the molars of omnivores such as bears and primates.
- Canines
- The four teeth in the front corners of the mouth. Usually large and pointed in carnivores, but may be small or absent in herbivores. They are the first teeth in the maxilla, called eye-teeth in humans.
- Carnassials
- Scissor-like teeth of carnivores specialised for shearing flesh. The last upper premolars and first lower molars.
- Carnivore dentition
- Tooth pattern found in most meat-eaters, featuring prominent canine teeth with shearing carnassial cheek teeth.
- Cheek teeth
- The teeth behind the canines, usually divided into molars and premolars.
- Choanae
- Where the rear edge of the palate has a central projection (e.g. in dogs), the choanae are the indentations on each side.
- Colonic Literature
- Academic papers incorporating in their titles a superfluous subtitle separated by a colon.
- Condylar process
- Smoothly rounded projection from the rear of the dentary where the lower jaw articulates with the skull.
- Condyle
- Smooth rounded projection of bone which forms a bearing or articulating surface in a moveable joint.
- Condylobasal length
- Coronoid process
- The back part of the lower jaw which rises up.
- Cranium
- The skull without the lower jaw.
- Dentary
- Bone forming one side of the lower jaw.
- Dentition
- The full set of teeth. Most mammals have specialised carnivore, herbivore or insectivore dentition. Dental formulas are given for most of the skulls illustrated.
- Diastema
- A long natural gap in a row of teeth, especially that between the incisors (or canines) and the cheek teeth in herbivores.
- Dolichocephalic
- Long headed. Referring to breeds of dog such as collies and greyhounds.
- Dorsal
- Concerning the top: e.g. "dorsal view" is a view from the top.
- Epiphysis
- The smooth, rounded or curved area at the end of a bone, forming an articulating surface of a joint. In young animals epiphyses are separated from the main body of the bone by a layer of cartilage, to allow for growth. The timing of their fusion gives a clue as to the age of the individual.
- Eurokaryotic
- Conforming to EU legislation on chromosome number.
- Foramen
- Hole in a bone for nerves and blood vessels.
- Foramen magnum
- Large opening in the back of the skull, through which the spinal cord leaves the brain. The occipital condyles lie on either side.
- Frontal bones
- Form the top, front part of the braincase.
- Herbivore dentition
- Tooth pattern found in typical plant-eaters such as cattle and rabbits. Prominent incisors are separated from the cheek teeth by a long diastema.
- Horn core
- Porous bone projecting from the frontal bone, on which the horn grows.
- Incisiform
- Shaped like an incisor. In some herbivores, especially deer, the lower canine teeth form part of the row of incisors instead of being cylindrical and pointed.
- Incisors
- Front teeth, between the canines. Upper incisors grow from the premaxilla, but other upper teeth grow from the maxilla.
- Infraorbital foramen
- A large hole in the side of the maxilla, usually in front of or below the orbit.
- Insectivore dentition
- Teeth mostly simple points, as in the hedgehog, mole and shrews.
- Interorbital width
- Interparietal bone
- Lies between the parietal bones and the occipital bone. Useful in separating rabbits and hares.
- Jaw length
- Lacrimal bone
- Forms the front edge of the orbit. Large and distinct in hoofed mammals, but small in most other species.
- Lacrimal pit
- A depression in the lacrimal bone.
- Lagomorph
- The group containing rabbits, hares and pikas.
- Lateral
- Concerning the side. e.g. "lateral view" is a view from the side.
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- Lophodont
- A tooth with the cusps elongated to form narrow ridges.
- Maxilla
- Bone forming the main part of the upper jaw on each side, supporting the canines and cheek teeth.
- Molars
- The rear cheek teeth which do not have equivalent milk teeth.
- Mustelid
- Sub-group of the Carnivores, including stoats, polecats, badgers and otters.
- Nasal bones
- Forming the upper surface of the muzzle.
- Nasal length
- Occipital bone
- Forming the back of the skull. Contains the foramen magnum.
- Occipital condyles
- Smooth, rounded knobs on each side of the foramen magnum, where the skull articulates with the first vertebra. Mammals have two occipital condyles, birds and reptiles have only one.
- Occipital crest
- A ridge formed where the parietal bones join the occipital bone, across the top, back part of the skull.
- Orbit
- The eye socket.
- Orbital diameter
- Orthodont
- Normal rodent upper incisors, pointing downwards. (see pro-odont)
- Palate
- The surface forming the roof of the mouth.
- Parietal bones
- Form the top, back part of the skull.
- Posterior
- Towards the rear.
- Postorbital process
- Projection from the frontal bone that marks the rear, upper edge of the eye socket.
- Postorbital constriction
- Premaxillas
- Bones forming the front tip of the upper jaw.
- Premolars
- Cheek teeth lying between the canines (or incisors, if canines are absent) and the molars.
- Pro-odont
- Rodent incisors which point forwards. (see orthodont)
- Ramus
- The main horizontal part of the lower jaw.
- Root
- The part of a tooth embedded in the jaw. Teeth may have from 1 to 5 roots.
- Rootless
- Continuously growing tooth which is the same in cross-section all the way down to the basewhere it is embedded in the jaw. The base of the tooth does not divide into roots.
- Rostrum
- Bones of the muzzle.
- Sagittal crest
- Ridge running lengthwise along the top of the braincase.
- Selenodont
- Teeth with a crown pattern of longitudinal crescentic ridges.
- Suture
- Immovable joint between bones.
- Temporal Ridge
- Ridge on the side of the cranium marking the upper limit of the temporalis muscle. In some species they develope with age, and may also migrate towards the top of the skull to form an interparietalridge (e.g. badger).
- Unicuspid
- Teeth with a single cusp or point, e.g. the simple conical teeth of insectivores.
- Ventral
- Concerning the underneath: e.g. a ventral view is a view from the bottom.
- Zygomatic Arch
- The cheekbone. Curved bone forming an arch along the side of the skull below the orbit.
- Zygomatic width
| SKULL MEASUREMENTS | ||
| Measurement | Abbreviation | Description |
| Condylobasal length | CB | The length of the skull, measured from the front of the premaxilliary bones to the rear surface of the occipital condyles. |
| Interorbital width | IW | Minimum distance between the upper edges of the orbits, measured across the top of the skull. |
| Jaw length | JL | The length of the lower jaw, from the front tip of the dentary bone to the angle. |
| Maximum palate width | PW | The maximum width across the alveoli of the cheek teeth. |
| Minimum palate width | MW | The minimum width across the palate, measured behind the canines. |
| Nasal length | NL | Overall length of the nasal bones. |
| Orbital diameter | OD | Maximum diameter of orbit, from rim to rim. May be specified as (horizontal) length or (vertical) height. |
| Overall length | OL | Maximum dimension of the skull when laid on level surface. |
| Palate length | PL | From the front of the alveolus of a first incisor, to one of the choanae on the same side at the rear of the palate. |
| Postorbital constriction | PC | Diameter of the narrowest part of the braincase immediately behind the orbits. |
| Zygomatic width | ZW | The maximum width across the zygomatic arches (cheekbones). |