Contains the frontal paranasal sinuses

Has 2 primary centers that ossify along the frontal suture (metopic) in the 2nd year

Helps form the foramen cecum, which allows passage of an emissary vein that connects to the superior sagittal sinus

There is 1 frontal bone

The largest part of the frontal bone

Forms the majority of the forehead

Forms the supraorbital margin and the superciliary arch

The zygomatic process of the frontal bone extends from the posterior part of the supraorbital margin

Arachnoid foveae —depressions caused by arachnoid granulations that push on the dura mater, causing bone resorption on the endocranial surface

The trochlea of the orbit articulates with the orbital portion

Articulates with the nasal bones and the frontal process of the maxilla to form the root of the nose

Forms the majority of the cranial vault

Provides for the attachment of the temporalis muscle

The 4 corners of the parietal bone are not ossified at birth and give rise to the fontanelles

There are 2 parietal bones

The 4 corners:

Frontal—located at bregma

Sphenoid—located at pterion

Occipital—located at lambda

Mastoid—located at asterion

Relatively square, forming the roof and sides of the cranial vault

Endocranial surface is filled with grooves made by branches of the middle meningeal a.

Sigmoid sulcus is a groove on each side of the skull interior formed by the sigmoid sinus, a continuation of the transverse sinus; it begins where the lambdoid suture joins the occipital bone to the right and left parietal and temporal bones

Forms the posterior part of the cranial vault

Articulates with the atlas

The squamous and lateral portions normally ossify together by year 4

The basilar portion unites to this section at year 6

There is 1 occipital bone

Articulates with the temporal and parietal bones

The largest portion of the occipital bone

Located posterior and superior to the foramen magnum

Has the external occipital protuberance (more pronounced in males)

Has the superior and the inferior nuchal lines

Has grooves on the internal surface for 3 of the sinuses forming the confluence of the sinuses (the superior sagittal and the right and left transverse sinuses)

The depression superior to the transverse sinus is for the occipital lobes of the brain

The depression inferior to the transverse sinus is for the cerebellum

Articulates with the temporal bone

Is the portion lateral to the foramen magnum

Has the occipital condyles that articulate with the atlas

Contains the hypoglossal canal

Forms a portion of the jugular foramen

Articulates with the petrous part of the temporal and the sphenoid bones

Is the portion immediately anterior to the foramen magnum

Pharyngeal tubercle is part of the basilar portion that provides attachment for the superior constrictor

Internal surface of the basilar portion is called the clivus, and part of the brainstem lies against it

The paired temporal bones:

Help form the base and the lateral walls of the skull

House the auditory and vestibular apparatuses

Contain mastoid air cells

Each bone has 8 centers of ossification that give rise to the 3 major centers observed before birth

There are 2 temporal bones

Intramembranous

Endochondral

The largest portion of the bone

3 portions to the squamous part:

Temporal portion

Zygomatic process

Glenoid fossa

Temporal portion is the thin large area on the squamous part of the temporal bone

On the internal surface of the temporal portion lies a groove for the middle meningeal a.

Zygomatic process extends laterally and anteriorly from the squamous portion; it articulates with the temporal process of the zygomatic bone to make the zygomatic arch

Glenoid fossa is inferior and medial to the zygomatic process; it articulates with the mandibular condyle, forming the temporomandibular joint

Forms the solid portion of bone

The auditory and vestibular apparatuses are located within the petrous part

Helps separate the temporal and the occipital lobes of the brain; it extends anteriorly and medially

The medial part articulates with the sphenoid bone to form the foramen lacerum

Internal acoustic meatus is observed on the medial side of the petrous part

Carotid canal lies on the inferior part of the petrous part

Petrotympanic fissure lies between the petrous part of the temporal bone and the tympanic part of the temporal bone

On the medial portion of the petrous part lie grooves for the superior and inferior petrosal sinuses

On the posterior inferior surface of the petrous part lies the jugular fossa

Between the jugular fossa and the carotid canal is the tympanic canaliculus

The mastoid process extends posteriorly and has large mastoid air cells

A projection from the temporal bone

The stylomastoid foramen lies posterior to this process

Forms the majority of the middle portion of the cranial base

Forms the majority of the middle cranial fossa

Contains the sphenoid paranasal sinus

There is 1 sphenoid bone

The center of the sphenoid

Anterior portion of the body helps form part of the nasal cavity

Superior part of the body, known as the sella turcica, is saddle shaped and possesses the anterior and posterior clinoid processes

Hypophyseal fossa, the deepest part of the sella turcica, houses the pituitary gland

Dorsum sellae is a square-shaped part of the bone that lies posterior to the sella turcica

Clivus is the portion that slopes posterior to the body

Body contains the sphenoid paranasal sinuses

Lateral portion of the body is covered by the cavernous sinus

Optic canal is found in the body of the sphenoid

Endochondral

Intramembranous

Extends laterally and anteriorly from the posterior portion of the body of the sphenoid

Endocranial portion helps form a large part of the middle cranial fossa

Lateral portion is the infratemporal surface

Anterior portion lies in the orbit

Contains 3 foramina:

Foramen spinosum

Foramen rotundum

Foramen ovale

Extends laterally and anteriorly from the superior portion of the sphenoid body

Separated from the greater wing by the superior orbital fissure

Arises from the inferior surface of the body

There are 2 pterygoid processes

Each has a:

Lateral pterygoid plate

Medial pterygoid plate

Pterygoid hamulus extends from the medial pterygoid plate

2 canals are associated with the pterygoid process:

Pterygoid canal

Pharyngeal canal

Lacrimal bone is small and rectangular in shape and very thin and fragile

There are 2 lacrimal bones

Forms a small portion of the medial wall of the orbit

Articulates with the frontal process of the maxilla, orbital plate of the ethmoid bone, the frontal bone, and the inferior nasal concha

The region that articulates with the frontal process of the maxilla forms the lacrimal fossa, the location of the lacrimal sac

The inferior part of the lacrimal forms a small portion of the lateral wall of the nasal cavity

Inferior portion forms the superior margin of the nasal aperture

Forms the bridge of the nose

There are 2 nasal bones

Articulates with the nasal bone of the opposite side, the nasal portion of the frontal bone, the frontal process of the maxilla, and the perpendicular plate of the ethmoid

Inferior portion of the nasal bones attaches with the lateral nasal cartilages and septal cartilage

3 foramina in the zygoma:

Zygomatico-orbital foramen

Zygomaticofacial foramen

Zygomaticotemporal foramen

There are 2 zygomatic bones

A porous bone that forms the major portion of the middle part of the face between the orbits

Helps form the orbit, nasal cavity, nasal septum, and anterior cranial fossa

There is 1 ethmoid bone

A flat plate that descends from the cribriform plate to form part of the nasal septum

Articulates with the vomer inferiorly

A horizontal bone that forms the superior surface of the ethmoid

Contains numerous foramina for the olfactory n.

Crista galli is a vertical plate that extends superiorly from the cribriform plate, providing attachment for the falx cerebri of the meninges

Associated with a small foramen cecum

The largest part of the ethmoid bone

Descends inferiorly from the cribriform plate

Ethmoid paranasal sinuses are located within the ethmoid labyrinth

Ethmoid labyrinth forms 2 major structures within the nasal cavity:

Superior nasal concha

Middle nasal concha

Ethmoid bulla is the large elevation of bone located by the middle ethmoid paranasal sinuses

Uncinate process is a curved piece of bone

Between the uncinate process and the ethmoid bulla is the hiatus semilunaris