Skull Anatomy Terms (2)

Articulation

a joint between bones or cartilage

Suture

an immovable articulation; typically between flat bones

Process

a projection or prominence of a bone; often for muscle attachment

Condyle

a smooth, rounded projection of a bone; for articulation with another bone

Fossa

depression or indentation in a bone; often a site of articulation

Foramen (plural, foramina)

an opening; typically, a round passageway in a bone for a blood vessel or nerve

Fissure

a cleft, slit or gap between bones or parts of a bone

Meatus

a canal or duct in a bone

Sinus

cavity or space within a bone

Ramus

wide projection or elongated process

Fontanel

a membrane-covered space between bones of the fetal or infant skull; “soft spot”

Nerve

bundle of processes from neurons; transmit information to and from brain or spinal cord

Artery

a blood vessel that carries blood away from the heart to organs and tissues

Vein

a blood vessel that carries blood from the tissues back to the heart

Cranium

a collection of bones that cover and protect the brain

Frontal bone (with frontal sinuses)

forehead to anterior scalp area

paired frontal bones in the fetal skull fuse into a single bone in the adult skull

Supraorbital foramen

opening above orbit for passage of blood vessels and nerves

Parietal bones

cover the superior part of the brain

right and left parietal bones join at the sagittal suture

Temporal bones

on the lateral sides of the brain

joins to the parietal bone at the squamosal suture on both right and left sides

Squamous part

flat part of the temporal bone that connects through the squamosal suture to the parietal bone

Petrous part

dense, thick “rock-like” portion of the temporal bone that extends in a pyramidal shape to form a ridge in the cranial floor; contains the internal hearing and equilibrium organs

External auditory meatus

canal within the temporal bone allowing sound waves to reach the tympanic membrane (eardrum)

Internal auditory meatus

passage of the temporal bone from the internal ear for the Vestibulocochlear nerve (CN VIII), which carries the senses of hearing and equilibrium to the brain; and also for passage of the Facial nerve (CN VII), sending impulses from the brain for control of facial expression muscles

Mandibular fossa

depression in temporal bone for articulation with the mandibular condyle in the temporomandibular joint (TMJ, only freely movable articulation in the skull)

Mastoid process

rounded “bump” of the temporal bone posterior and inferior to external auditory meatus; contains sinuses that drain into the pharynx

Styloid process

delicate, curved “tooth-like” projection on the temporal bone medial and anterior to the mastoid process; attachment for ligaments and muscles associated with the hyoid bone and the tongue

Stylomastoid foramen

small opening in temporal bone between the styloid and mastoid processes; for passage of the Facial nerve (CN VII), which controls movement of the muscles of facial expression

Zygomatic process

thin extension of the temporal bone that joins with the temporal process of the zygomatic bone to form the zygomatic arch; a large chewing muscle (temporalis m.) passes under the zygomatic arch

Jugular foramen

opening in temporal bone medial to the styloid process; for passage of the internal jugular vein which drains blood from the brain and returns it to the heart

Carotid canal

opening in temporal bone anterior to the jugular foramen; for passage of the internal carotid artery delivering blood to the brain, which travels in this canal medially and anteriorly before entering the cranial cavity lateral to the sella turcica

Occipital bone

single bone covering the posterior part of the brain; connects to the parietal bones by the lambdoidal suture

Foramen magnum

large opening in occipital bone for the passage of the brainstem (medulla oblongata) to connect to the spinal cord; also passage of accessory nerves (CN XI) and vertebral and spinal arteries

Occipital condyles

paired inferior smooth projections in occipital bone, anterior and lateral outside the foramen magnum; for articulation with the first cervical vertebra (C1 = atlas)

External occipital protuberance

small, rough, midline projection in occipital bone: for neck muscle attachment

Sphenoid bone (with sphenoidal sinus)

butterfly or wing-shaped bone in the center of the skull; articulates with many other bones

Lesser wings

superior and anterior area of the sphenoid, form the posterior part of the anterior cranial fossa

Greater wings

in the sphenoid bone lateral to the sella turcica

Sella turcica (“Turkish saddle”) with the Pituitary fossa (depression in center)

in the sphenoid bone, location of the pituitary gland

Optic foramen

round canal in the medial orbit; for passage of the Optic nerve (CN II) , for vision

Superior orbital fissure

irregular slit in the superior orbit of the sphenoid bone; for passage of the Oculomotor nerve (CN III), Trochlear nerve (CN IV), Abducens nerve (CN VI) – which all control muscles for eye movement, and the Ophthalmic division of Trigeminal nerve (CN V) – for upper face sensation (also for passage of the ophthalmic artery)

Foramen rotundum

for passage of the maxillary division of the Trigeminal nerve (CN V) in sphenoid bone

Foramen ovale

oval opening in sphenoid bone lateral to the sella turcica; for passage of the mandibular division of the Trigeminal nerve (CN V) – for lower face sensation and control of the muscles of mastication = chewing

Foramen spinosum

for passage of the middle meningeal blood vessels

in sphenoid bone

Pterygoid processes (plates)

(from the inferior view) posterior and superior to the last molars on each side, two sets of plates (medial and lateral) for the attachment of chewing muscles

in sphenoid bone

Ethmoid bone (with ethmoid air cells)

delicate, irregularly shaped bone; forms part of the nasal cavity and medial orbits

Crista galli

anterior “crest of the cock” vertical projection into the anterior cranial cavity; for attachment of the dura mater covering over the brain

in the ethmoid bone

Cribriform plate

perpendicular and lateral on either side to the crista galli; separates the nasal cavity from the anterior cranial cavity

in the ethmoid bone

Olfactory foramina

many openings for passage of the Olfactory nerve (CN I) fibers , for the sense of smell

in the ethmoid bone and Cribriform plate

Perpendicular plate of the ethmoid

vertical plate separating the right and left nasal cavities; superior part of the nasal septum

Superior and middle nasal conchae (singular, concha)

paired “shell-shaped” projections located in the lateral walls of each nasal cavity; increase the surface area of the nasal mucosa in contact with inhaled air

Sutures

immovable articulations between flat bones of the cranium

Sagittal suture

superior, midline; joins R+L parietal bones

Coronal suture

superior; joins frontal bone to both parietal bones

Lambdoidal suture

posterior; joins occipital bone to both parietal bones

Squamosal sutures

lateral; each joins a temporal bone to a parietal bone

Maxillary bone (with maxillary sinus)

central portion of the face and upper jaw

Alveolus of maxillary bone(plural, alveoli)

socket for tooth

Alveolar processes of maxillary bone

inferior ridge that contains alveoli

Palatine processes

horizontal plates that form the anterior ~2/3 of the hard palate separating the nasal and oral cavities, in maxillary bone

Infraorbital foramen

opening below orbit for passage of blood vessels and nerve, in maxillary bone

Mandible

lower jaw; freely articulates with the maxilla at the temporomandibular joint

Body

U-shaped anterior portion of mandible; superior part contains teeth in alveoli

Ramus (plural, rami)

lateral flat region on mandible that connects to the body on each side at the angle, at a right angle

Angle

inferior region where a ramus connects to the body, mandible

Coronoid process

flat tapered process that extends from the superior, anterior ramus; site of mastication/chewing muscle attachment

Condyloid process or mandibular condyle

smooth, rounded process for articulation with the mandibular fossa of the temporal bone in the freely movable temporomandibular joint

Mental foramen

small opening on mandible on both sides of anterior body; for passage of nerves and blood vessels

Mandibular foramen

opening on medial side of each ramus; for passage of alveolar nerves and blood vessels to lower teeth

Alveolus of mandible (plural, alveoli)

socket for tooth

Alveolar processes of mandible

superior ridge that contains alveoli

Nasal bones

small, paired bones form the bony bridge of the nose

Lacrimal bones

each forms a small part of the medial orbit; inferior portion forms the nasolacrimal canal with the maxilla, for the passage of tears into the nasal cavity

Zygomatic bones

“cheek bones” lateral to the maxilla on each side; forms the inferior-lateral wall of the orbit; articulates with the temporal bone through the zygomatic arch

Palatine bones

horizontal plates form the posterior about 1/3 of the hard palate separating the oral from the nasal cavities

Vomer bone

single, midsagittal bone that forms the inferior and posterior portion of the nasal septum

Inferior nasal conchae (singular, concha)

on the lateral wall of each nasal cavity; inferior to the middle and superior nasal conchae of the ethmoid bone

the orbit direction

clockwise from about 2 o’clock looking at the right eye

Optic foramen

round canal in the medial orbit; for passage of the Optic nerve (CN II), for vision

Nasolacrimal canal

inferior, medial opening formed by the lacrimal and maxillary bones, allows tears to exit the orbit into the nasal cavity, inferior and lateral to inferior nasal concha

Inferior orbital fissure

irregular gap between the maxilla and sphenoid in the lateral, inferior orbit; for passage of the maxillary division of the Trigeminal nerve (CN V), for middle face sensation

Superior orbital fissure

irregular slit in the superior orbit; for passage of the Oculomotor nerve (CN III), Trochlear nerve (CN IV), Abducens nerve (CN VI) which all control muscles for eye movement, and the Ophthalmic division of Trigeminal nerve (CN V) for upper face sensation

NASAL SEPTUM

separates the R+L nasal cavities

Perpendicular plate of the ethmoid

vertical plate separating the right and left nasal cavities; superior part of the nasal septum

Vomer bone

single, midsagittal bone that forms the inferior and posterior portion of the nasal septum

PARANASAL (AIR) SINUSES

group of air-filled spaces that surround the nasal cavities; lined by mucus membranes that communicate with the nasal cavities

Frontal sinuses

medial spaces in the inferior part of the frontal bone

Maxillary sinuses

largest sinuses lateral to the nasal cavities; floor contains alveolar nerves and blood vessels to upper teeth

Ethmoid air cells

pockets of small sinuses located medial to or between the orbits

Sphenoidal sinuses

cavities inferior to the sella turcica in the sphenoid; below the pituitary gland

FETAL SKULL

fetal bones are not fused, allowing some flexibility passing through the birth canal as well as for future growth; fibrous connective tissue connects flat bones of the cranium

Anterior fontanel

“soft spot” membrane between the frontal and parietal bones

Metopic suture

fibrous membrane between the two frontal bones

Posterior fontanel

“soft spot” membrane between the occipital and parietal bones