Mammalian Skull Anatomy

auditory bulla

(also called typmanic bulla): a hard, compact structure that contains the inner ear structures

Maxilloturbinate, mTur

(in the nose) a labyrinth of thin bones, called turbinates, which are all lined by an epithelium. In the anterior part of the nose the bones are known as maxillo-turbinates, and they are lined by a respiratory type epithelium producing mucus.

Orbitosphenoid, Osp*

A bone in the floor of the mammalian cranium, in the region of the optic nerve.

Premaxilla, Pmx

Either of two bones located in front of and between the maxillary bones in the upper jaw of vertebrates.

Ceratohyal, cHyo*

Endochondral bone that is bilaterally paired and articulates with the hypohyal cartilage or bone, dorsal and ventral hypohyals, and epihyal posteriorly.

Thyrohyal, tHyo*

Oblique line of lamina of thyroid cartilage; inferior border of body of hyoid bone; elevates larynx or depresses hyoid bone

Cribiform plate, Crb*

The cribriform plate of the ethmoid bone (horizontal lamina) is received into the ethmoidal notch of the frontal bone and roofs in the nasal cavities.

Alisphenoid, Als*

The greater wing of the sphenoid bone; a bony process of the sphenoid bone; there is one on each side, extending from the side of the body of the sphenoid and curving upward, laterally, and backward.

Dentary, Den

The mandible of a vertebrate, or homologous bone in the lower jaw of ancestral and related animals, which holds teeth.

Tympanic, Tym

The tympanic part of the temporal bone is a curved plate of bone lying below the squama, in front of the mastoid process, and surrounding the external acoustic meatus.

Foramina (singular: foramen)

There are numerous small holes in the skull, providing places for either nerves or blood vessels to pass.

temporomandibular joint (TMJ)

This joint functions as a hinge for the jaw. In carnivores, it's typically a tight hinge. However, in other orders, the hinge is loose. A loose TMJ allows for sideways motion of the jaw which is important for animals such as cattle and sheep, which grind sideways when chewing their food. The TMJ is loose if the mandibular condyle is open and shallow, and if the mandibular condyle moves freely within the fossa.

Bassioccipital, Boc*

a bone in the base of the cranium immediately in front of the foramen magnum that is represented in humans by the basilar process of the occipital bone

Supraoccipital, Soc*

a bone on the dorsal side of the great foramen of the skull

nuchal crest

a crest that extends laterally across the back of the skull, forming an attachment point for strong neck muscles. The nuchal crest is also called the lambdoidal crest.

coronoid process

a flat structure sticking up from the mandible (lower jaw). The temporalis muscle attaches to the medial (inner) side of the coronoid process

Interparietal, Int

a median triangular bone lying at the junction of the parietal and occipital bones

Pterygoid, Pty

a paired bone forming part of the palate of many vertebrates, behind the palatine bones.

postorbital process of the frontal

a projection on the frontal bone near the rear upper edge of the eye socket. In many mammals, it reaches down to the zygomatic arch, forming the postorbital bar.

sagital crest

a ridge along the top of the head, formed where the parietal bones from each side meet in the middle. The sagittal crest forms an attachment point for extra-large temporalis muscles. The temporalis is one of the main muscles responsible for biting and chewing; it extends from the sagittal crest down to the coronoid process. An animal with a powerful bite is likely to have large temporalis muscles, a sagittal crest, and large coronoid processes. Many mammals do not have a sagittal crest; the muscles simply attach to the sides of the skull.

Vomer, Vom

a roughly triangular bone that forms the inferior and posterior of the nasal septum

occipital

a single trapezoid-shaped bone situated at the posterior and inferior part of the cranium

Tympanohyal, tHyo*

a small nodule of bone forming the base of the cartilaginous styloid process of the temporal bone

Lacrimal, Lac

a thin scalelike bone, roughly resembling a fingernail in size and shape, at the anterior part of the medial wall of the orbit, articulating with the frontal and ethmoidal bones and the maxilla and inferior nasal concha.

Zygomatic arch

also called the cheekbone. Formed by the zygomatic bone and part of the temporal bone, the zygomatic arch provides some protection for the eye and also provides an attachment point for the masseter muscle used for chewing. The other main jaw muscle, the temporalis, runs along the side of the skull from the temporal bone and sagittal crest to attach to the coronoid process of the jaw, and it passes inside the zygomatic arch. If the temporalis muscle is large, the zygomatic arch must be wide to accommodate its size.

angular process

an attachment point for the masseter muscle, which (along with the temporalis) helps in biting and chewing

fossa

an indentation in a bone. The fossa is the socket part of a ball-and-socket type joint

infraorbital foramen

an opening into the floor of the eye socket, is the forward end of a canal through which passes the infraorbital branch of the maxillary nerve, the second division of the fifth cranial nerve. It lies slightly below the lower margin of the socket.

Epihyal, eHyo*

an ossified stylomastoid ligament.

sphenoid

an unpaired bone of the neurocranium. It is situated in the middle of the skull towards the front, in front of the temporal bone and basilar part of the occipital bone. The sphenoid bone is one of the seven bones that articulate to form the orbit. Its shape somewhat resembles that of a butterfly or bat with its wings extended.

Jugal, Jug

another name for zygomatic bone; a bone on each side of the face below the eye, forming the prominence of the cheek; cheekbone.

process

any bony structure that sticks out, generally forming a place for a muscle to attach

Nasoturbinate, nTur

any of the scrolled spongy bones of the nasal passages in vertebrates.

Basihyal, bHyo*

bone at the ventral point of the hyoid arch

Basisphenoid, Bsp*

bone located at the base of the skull. It is immediately in front of the bone that contains the opening through which the brainstem projects to connect with the spinal cord.

mastication

chewing or biting

Frontal, Frn

forms the forehead, the roofs of the orbits, and most of the anterior part of the cranial floor

nasal

of or relating to the nose

mandibular condyle

on the mandible, the convex part of the hinge joint for the jaw

Mandibular fossa

on the skull, the concave part of the hinge joint for the jaw. The mandibular fossa is in the temporal bone, and the joint is called the temporomandibular joint.

temporal fossa

one of the two irregular bones on either side of the skull forming part of the lateral surfaces and base of the skull, and containing the organs of hearing. The temporal bones form the inferior sides of the cranium and part of the cranial floor

Parietal, Par

one of the two quadrilateral bones on either side of the cranium forming part of the superior and lateral surfaces of the skull, and joining each other in the midline at the sagittal suture. The parietal bones form the greater portion of the sides and roof of the cranial cavity

Palatine, Pal

one of two irregularly shaped bones (L-shaped) forming the posterior part of the hard palate, the lateral wall of the nasal fossa between the medial pterygoid plate and the maxilla, and the posterior part of the floor of the orbit. The posterior part of the hard palate, which separates the nasal cavity from the oral cavity, is formed by the horizontal plates.

Maxilla, Max

paired bones uniting to form the upper jawbone. The maxillae articulate with every bone of the face except the mandible, or lower jawbone.

occipital condyles

part of the joint between the skull and the first cervical (neck) vertebra

Ethmoid, Eth*

sieve-like spongy bone located in the anterior part of the floor of the cranium between the orbits. The ethmoid is the principal supporting structure of the nasal cavity.

Presphenoid, Psp*

the anterior part of the body of the sphenoid bone in front of the basisphenoid.

condyle

the convex part of the joint; the ball part in a ball-and-socket joint

external acoustic meatus

the ear canal

orbit

the eye socket. In a carnivore , the orbits face forward, providing good binocular vision. In a species that's more likely to be prey than predator (such as a rodent or a deer), the orbits face to the sides, providing a wide field of view but less effective binocular vision.

mandible

the lower jaw bone

Exoccipital, Exo*

the part of the occipital bone that lies on either side the foramen magnum

Ethmoturbinate, eTur

the scroll-like, papyraceous parts of the ethmoid bone occupying the caudal part of the nasal fossae.

Periotic, Per*

the single bone that surrounds the inner ear of mammals. It is formed from the fusion of the prootic, epiotic, and opisthotic bones.

Stylohyal, sHyo*

the styloid process of the temporal bone and to the hyoid bone.

Squamosal, Sqa

thin, scalelike portion of the temporal bone that is situated on the side of the skull above and behind the ear.

Nasal, Nas

two small oblong bones placed side by side at the middle and upper part of the face, and form, by their junction, "the bridge" of the nose.