Morphology and Physiology

UNDER CONSTRUCTION

Skull and Head Morphology
Copyright Notice - If you use the photographs on this page, please credit them Copyright Coryi Foundation, Inc. 1994-2005

Dentition 

Dental Formula

Function of Teeth

Canines - killing, severing prey cervical vertebrae and spinal cord

Incisors - plucking fur and skin from prey

Molars - ripping meat from bone, shredding and chewing meat, crushing bone

Skull Nomenclature

Lateral	Lateral
Cranium Ventral View	Mandible Dorsal View
Dorsal View	Ventral View
Anterior View

terms used in the morphological study of skulls

Commons terms used in comparative anatomy and physiology pertaining to skull morphometrics and nomenclature.
(Numbered items correspond to numbers in photographs above)

Alveolus (1) - the socket in the alveolar bone into which the tooth’s root fits.
Apical Foramen -  the root canal of a tooth through which the major root nerve of the tooth passes from the jaw to the tooth.
Angle - the angle formed by the junction of the lower edge of the jawbone and the posterior edge of the ramus of the jawbone. Also called angle of mandible. 
Anterior - front end or near the front end.
Ascending Ramus of Jaw - an ascending ramus is a part of an irregularly shaped bone that is thicker than a process and forms an angle with the main body, especially the ascending part of the lower jaw that makes a joint at the temple. This then would be in the context of the jaw, that part of the mandible that rises vertically to form the joint with the skull.
Bead - a salient, rounded cordlike projecting ridge of bone, as in certain rodents where the superior border of the orbit is beaded.
Braincase - the part of the skull that encloses the brain; the cranium.
Bulbous (7) - from bulb - a globular or fusiform anatomical structure or enlargement, in this case, the enlarged portion of the audio bones in the ear.
Auditory bulla (plural, auditory bullae) - a hollow, bony prominence of rounded form (in most mammals formed by the tympanic bone) partly enclosing structures of the middle and inner ear.
Bunodont - having cheek teeth with low rounded cusps on the occlusal surface of the crown, as in mammals with mixed diet, such as swine, many rodents, and humans.
Bunodont dentition - referring to the cusp type of molars and/or premolars: cusps are low and rounded. The figure shows upper cheekteeth of a young domestic pig; some bunodont dentition, such as human teeth, are simpler; others are more complex.
Calcar - process connected with the calcaneum (heel bone) and extending into the uropatagium near its edge, helping to support the the uropatagium (the fold of skin that extends between the leg and tail). A keeled calcar is one with a definite flap of membrane posterior to the calcar extending beyond the general margin of the uropatagium. Seen in bats.
Canines (9) - maxillary teeth that are the first in the tooth row past the premaxillary suture (distal to the incisor farthest from the midline). The mandibular canine is the tooth that articulates directly mesial from the maxillary canine. Used by carnivores to kill prey. The two upper and two lower long sharp pointed teeth next to the incisors. Fangs. conical teeth which are longer than other teeth
Carnassials - the tooth adapted for tearing apart flesh. One of the last upper premolar or first lower molar teeth in carnivorous mammals. From French carnassier, carnivorous; from Provençal, from carnasso, meat in abundance, from carn, flesh, from Latin carō, carn-; these teeth operate in a scissor fashion as a means to shred tissue.
Carnivore dentition - dentition of species that hunt, kill, and consume other animals; characterized by well formed and accentuated canine teeth used to kill prey, and caranassial teeth used to shred and shear tissue.
Cephalic - associated with the head.
Cheek teeth - a tooth having a somewhat quadrangular crown with four or five cusps on the grinding surface; the root is bifid in the lower jaw, but there are three conical roots in the upper jaw; there are six molars in each jaw, three on either side behind the premolars in the permanent dentition; in the deciduous dentition there are but four molars in each jaw, two on either side behind the canines.
Choanae - a projection or indentation on opposing sides of the palate.
Condylar process (56) - the posterior process on the ramus of the mandible that articulates with the mandibular fossa of the temporal bone; condylar: condyloid, or articular. 
Condyle - a rounded projection ob a bone that forms the articulation point for movement in a joint.
Coronoid process - a sharp triangular projection from a bone; coronoid process of the mandible, the triangular anterior process of the mandibular ramus, giving attachment to the temporal muscle; coronoid process of the ulna, a bracket-like projection from the anterior portion of the proximal extremity of the ulna; its anterior surface gives attachment to the brachialis, its proximal surface enters into the formation of the trochlear notch. The upward projecting process of the posterior part of the mandible, giving attachment on its outward side to the masseter muscle and on its inner side to the temporal muscle.
Cranium (18) - the skull minus the mandible.
Dentary - an ossification center of the mandible, giving origin to the lower border and outer plate. Where the jaw bone of the lower jaw exists that bears teeth.19a. Dental formula (plural, formulae) - A brief method for expressing the number and kind of teeth of mammals. The abbreviations i. (incisor), c. (canine), p. or pm. (premolar), and m. (molar) indicate the kinds in the permanent dentition, and the number in each jaw is written like a fraction, the figures above the horizontal line showing the number in the upper jaw, and those below, the number in the lower jaw. For deciduous teeth, the abbreviation is preceded by "d".
Dentine - calcareous material, harder and denser than bone, which composes the principal mass of a tooth.
Dentition - the teeth in the dental arch; ordinarily used to designate the natural teeth in position in their alveoli. An individual’s set of teeth. Each order possess unique sets of dentition: e.g. carnivore, insectivore, and herbivore possesses distinct types and arrangements of teeth.
Deuterocone - one of the cusps of a premolar tooth of a mammal corresponding in position (anteromedial) to the protocone of a true molar.
Diastema (21) - a space between two adjacent teeth in the same dental arch.
Dilambdodont - molars with a W-shaped outer ridge.
Dorsal - anatomical; back or top of a structure; as in ‘dorsal’ fin – the fin on the back (top side) of a fish; as in dorsal thoracic – the back of a chordate (such as the back of a human).
Enamel - of teeth, the hardest substance of the mammalian body and forming a thin layer that caps or partly covers a tooth. 
Epiphysis - the growth area near the end of a bone; A part of a long bone where growth bone growth occurs from.
Foramen - canals in teeth or bones through which nerves pass.
Foramen magnum (25) - the large hole at the base of the skull which allows passage of the spinal cord at which point it becomes the medulla oblongata of the brain.
Frontal - pertaining to or designating the bone (paired) immediately in front of the parietal bone and behind the nasal.
Frontal bones - the large single bone forming the forehead and the upper margin and roof of the orbit on either side; it articulates with the parietal, nasal, ethmoid, maxillary, and zygomatic bones, and with the lesser wings of the sphenoid.
Herbivore dentition - pattern of teeth found in herbivores; characterized by teeth adapted for grazing, browsing, chewing; large gap (diastema) exist between incisors and cheek dentitions.
Horn core - position on frontal bones from which an ungulate's horn emanates.
Incisiform - chisel-like; used to describe teeth which are flattened and truncate with sharp edges like the front teeth of some mammals such as humans, also compressed and wedge-shaped; said of teeth with a cutting edge resembling incisors of higher vertebrates, such as ungulates (deer).
Incisors (30) - teeth that grow in the upper and lower jaw between canines in mammals.
Incisive foramen - The anterior palatine foramen, which are paired, are in the bony roof of the anterior part of the cavity of the mouth at the juncture of the premaxillary bones and maxillary bones; they transmit nasal branches of palatine arteries and nasopalatine ducts of Jacobson.
Infraorbital foramen - the external opening of the infraorbital canal on the front surface of the body of the maxilla located below the orbit. Also known as infraorbital canal - A canal through the maxillary bone from the orbit to the face.
Interorbital constriction - least amount of distance across the top of the skull between the orbits.
Interorbital region - region between the eye sockets; the region of the skull between the rostrum and the braincase.
Insectivore dentition - tooth pattern found in insectivores.
Interparietal bone - a large sutural bone occasionally found detached from the anterior portion of the os interparietale. (Interparietal - pertaining to or designating the bone (rarely paired) immediately in front of the supraoccipital bone and between the two parietal bones.)
Lacrimal bone - situated at the front part of the medial wall of the orbit; near the tear duct.
Lacrimal pit - opening in lacrimal bone containing tear duct.
Lagomorph - rabbits, hares and pikas.
Lateral - side view or positioned at the side of the plane that cuts the dorsal and ventral plane.
Lophodont - teeth having elongated ridges called lophs that run between cusps.
Mandible - lower Jaw.
Mastoid - designating or pertaining to the mastoid bone (paired) or its process. This bone is bounded by the squamosal bone, the exoccipital bone, and the tympanic bone.
Maxilla - bone of the upper jaw that supports the dentition of the upper jaw.
Maxillary toothrow - The row of teeth in one maxillary bone; in most mammals all the premolars and molars on one side of the upper jaw.
Molars - teeth that are at the outer areas of the dentition along the cheeks. Also, of or pertaining to a molar tooth. One of the teeth behind the premolar teeth; a molar tooth is not preceded in embryological development by a deciduous (milk) tooth.
Mustelid - any member of the family Mustelidae, fur-bearing carnivores including the weasels, skunks, badgers, and others (about 25 existing genera with about 70 species, and 47 to 73 extinct genera), characteristically possessing well-developed anal scent glands.
Nasal bones - bones comprising the nasal passage structures above the maxilla. Also, nasal - of or pertaining to the nose, as a nasal bone (paired) on the dorsal surface of the skull at its anterior end. A bony structure comprising the nasal.
Occipital bone - the back of the skull; contains the occipital sensory area of the brain.
Occipital condyles - protusions on the back of the skull which articulate with the vertebra of the backbone; two rounded projections on either side of the foremen magnum that fit into a pair of sockets on the top of the spine, thus articulating the skull with the spine.
Occipital crest - a ridge running from the internal occipital protuberance to the posterior margin of the foramen magnum, giving attachment to the falx cerebelli; runs lateral along the boundary between the parietal and occipital bones.
Occlusal - of or pertaining to the grinding or biting (occluding) surface of a tooth.
Orbit - the socket of the eye; plural: orbits
Orthodont - the upper incisors of order rodentia.
Osseous - composed of, or resembling, bone; bony. Osseous tissue is bony tissue.
P3 - designation of the third (next to last) premolar in the upper jaw of a mammal. Capital letters designate teeth in the upper jaw and lowercase letters designate teeth in the lower jaw.
Palate (49) - boney structure in the underlying portion of the roof of the mouth. The roof of the mouth, consisting of the structures that separate the mouth from the nasal cavity. The bony palate is composed of the following bones: premaxillae, maxillae, and palatines.
Palatal - of or pertaining to the palate (as generally used, the bony roof of the mouth made up of two palatine bones, two maxillary bones, and two premaxillary bones).
Parietal bones - bone of the skull going from the gyrus at the top of the head down to the occipital crest at the junction of the parietal bone with the occipital bone. Parietal - in reference to the parietal bone (paired) roofing the braincase. This bone is behind the frontal bone and in front of the occipital bones.
Pinna (pl, pinnae) - the projecting part of an ear.
Postauricular - situated behind the auricle (pinna) of the ear, e.g., postauricular patch; referring to a patch of fur differing in color from surrounding fur.
Posterior - of or at the rear of the medial axis of the body.
Postorbital process - portion of the frontal bone aft and above of the orbit. Contrast with postorbital: situated behind the eye, as postorbital process of the frontal bone or postorbital process of the jugal bone.
Premaxillas - a bone on either side of the middle line between the nose and mouth, forming the anterior part of each half of the upper jawbone; the intermaxilla. In man the premaxillae become united and form the incisor part of the maxillary bone. Contrast premaxillary - referring to the premaxilla, a bone in the mammalian skull bearing the incisor teeth of the upper jaw; the premaxilla is situated in front of the maxilla.
Premolars - the teeth between the molars and canines, or incisors if the species does not possess canines;  pertaining to one of the teeth (a maximum of 4 on each side of upper jaw and lower jaw of placental mammals, or 16 in all) in front of the true molars; when canine teeth are present, premolars are behind these teeth; premolars are preceded by deciduous teeth, and in the upper jaw are confined to the maxillary bone.
Pro-odont - incisors that point forward; as in rodentia.
Ramus (56) - one of the two prominent, projecting back parts of the horseshoe-shaped lower jaw bone.
Root - the dental structure seated in the jaw bone that possesses nerves and acts as the mounting portion for the tooth in the jaw.
Rootless teeth - ever-growing, continuously open root canal.
Rostrum - the bony portion of the nasal projection on the snout. It projects anteriorly in front of the orbits.
Sagittal crest - bony ridge along the top of the skull that increases in size due to a lifetime of skeletal-muscular flexing of the jaw; ridge of bone at the juncture of the two parietal bones resulting from the coalescence of the temporal ridges; in old individuals of many species of mammals, the crest extends from the middle of the lambdoidal crest anteriorly onto the frontal bones and divides there into two temporal ridges, each of which extends anterolaterally on the posterior edge of the postorbital process of the frontal bone.
Selenodont - denoting an animal, or man, having teeth, as the human molars, with longitudinal crescent-shaped ridges.
Subauricular spot - a hairy patch that is prominently colored immediately below the ear.
Supraorbital process of the frontal bone - the process of the frontal bone on the top rim of the orbit.
Suture - boundary of cranial bones; joints of the skull that do not move.
Temporal Ridge - upper reach of the temporalis muscle along the temporal lobe that increases with wear as does the saggiital crest; a curved, raised line on the side of the braincase marking the upper limit of attachment of the fascia of the temporal muscle; the temporal ridge is prominent on the parietal bone, frequently extends forward onto the frontal bone, and in some kinds of mammals extends backward onto the interparietal bone. When present, the sagittal crest is formed by the coalescence of the two temporal ridges.
Unicuspid Teeth - with one cusp, e.g. as is found in insectivores; usually applied to a set of teeth of shrews, but may be used for any such tooth, such as a canine tooth.
Ventral - bottom of tetrapods or front of bipeds; as in ventral portion of torso (chest and stomach).
Zygomatic Arch (66) - the arched bone below the orbit that is prominent and forms what is called the cheek bone.
Zalambdodont- Molars having a lateral, V-shaped ridge.

 

---

SKULL MEASUREMENTS

The terms and descriptions below are commonly used by anatomists to compare morphologies of individuals within sub-species to help to ascertain the phylogenetic origin of members of a clade.

Below are a few common measurements taken on skulls to assess some limited phylogeny and regional variations of sub-species. It must be emphasized that these morphometric parameters do not constitute a full set of markers required for establishing a phylogeny. Mitochondrial satellite DNA fingerprinting is also used by geneticists to establish blood lines and suggested histories of species and populations. However, morphometric parameters can be useful in the delineation of local variations among a species such as clades among puma within North America.

Alveolar length of molar toothrow (maxilla and mandible) - The length of the toothrow from the anterior surface of the first molar near its junction with the edge of alveolus to the posterior surface of the last molar near its junction with the edge of alveolus; the premolars are not included.
Bicanine breadth, bicanine width - The maximum breadth of the muzzle across the canine alveoli.
Biorbital breadth -The maximum horizontal distance between the outer margins of orbital rims.
Breadth of braincase - The maximum width across the braincase posterior to the zygomatic arches; greatest breadth of the brain-part of the head over the parietal or temporal bones; perpendicular to the midsagittal plane, and never taken on or below the ear-eye horizon even though the maximum width should occur there.
Canine length - Length from the canine tip to the gumline.
Canine width - The maximum width of the canine as measured at the gumline.
Condylo-basal length - Measured from the posteriormost projections of the occipital condyles to the anterior edge of the premaxillae bony structure.
Condylo-canine length - Measured from the anterior edges of the alveoli of the upper canines to the posterior edges of the occipital condyles. This measurement are typically taken instead of the condylobasal length in forms in which the premaxillae are frequently lost.
Diastema length, mandible - Measured from the posterior margin of the alveolus of the last incisor present to anterior margin of the alveolus of the first cheek tooth present.
Diastema length, maxilla - Measured from the posterior margin of the alveolus of the last incisor present to the anterior margin of the alveolus of the first cheek tooth present.
Greatest length of skull, maximum skull length, total skull length, maximum length of skull - Measured from the most anterior part of the rostrum (to not include teeth) to the most posterior point of the skull.
Interorbital width - Minimum distance between the upper tangential edges of the rims of the two orbits. It is measured across the top of the skull.
Jaw length - The length of the mandible from the front surface to the angle. (mandible length).
Least interorbital breadth  - The minimum interorbital distance.
Mastoid breadth - The maximum width of skull inclusive of the mastoid.
Maxillary breadth - The width of the skull across the maxilla.
Maximum palate width - The width between the alveoli of the cheek teeth at the maximum alveolar width.
Minimum distance between temporal lines - The shortest horizontal distance between median surfaces of the temporal lines.
Minimum palate width - The width of the palate on the posterior surface of the canines.
Nasal length - Distance from the anteriormost point of nasal bones to the posteriormost point, taken along the midline of the skull.
Nasal suture length - The maximum length of the suture along the midline of paired nasal bones.
Nasal width - The maximum width across the nasals.
Occipitonasal length - Least distance between two vertical lines, one touching the posteriormost part of the skull above the foramen magnum (opening for the spinal cord) and the other touching the anteriormost part of the nasal bones or a nasal bone.
Orbital diameter - The diameter of an orbit  that is maximum that is measured from the rim on one side of the orbit to the rim on the opposing side. This measurement needs to be specified as to whether it is the greatest or the horizontal distance.
Overall length - Maximum length of the skull.
Palate length - Distance from the posterior edges of alveolae of the first incisors to the anteriormost point on the posterior edge of palate.
Palate breadth - The widest breadth of palate from the outside to include the alveoli.
Postorbital constriction - The diameter of the prominent constriction in the skull immediately behind the orbits.
Postpalatal length - The length from the anteriormost point on the posterior edge of palate to the anteriormost point on the lower edge of the foramen magnum.
Tympanic bullae length - The greatest length of bullae.
Tympanic bullae width - The greatest width of bullae.
Zygomatic width, also referred to as breadth, bizygomatic breadth, bizygomatic width, or bimalar breadth - The greatest distance across the zygomatic arches of the cranium at right angles to the long axis of skull.