Let us examine the structure of the frontal bone (os frontale). Its main function is protecting the frontal lobes of the brain from all kinds of damage. The bone is also involved in the formation of the orbit and the anterior cranial fossa.

The frontal bone consists of several parts:

• squamous part (squama frontalis)

• orbital part (pars orbitalis)

  

• nasal part (pars nasalis)

  

  The squamous part consists of two surfaces:

• external surface (facies externa)

  

• internal surface (facies interna)

  

  The external surface forms what is commonly referred to as the forehead. The inferior part of the squamous part is called the supraorbital margin (margo supraorbitalis).

  

  There is a supraorbital notch (incisura supraorbitalis) on this margin closer to the nasal part. The supraorbital vessels and nerve pass here.

  

  In some people, this notch closes and becomes a supraorbital foramen (foramen supraorbitale).

  

  Medial to the supraorbital notch is a small cavity called the frontal notch (incisura frontalis). It contains blood vessels and a nerve.

  

  Around the midline on the external surface of the squamous part, there is the so-called frontal suture (sutura metopica), which is a trace of the fusion of the frontal bones in the prenatal period.

  

  From the supraorbital margin extends the zygomatic process (processus zygomaticus), which is connected with the zygomatic bone.

  

  A small temporal surface (facies temporalis) and temporal line (linea temporalis) can be distinguished upwards from the zygomatic process. The temporal fascia is attached to the latter.

  

  

  Upward from the supraorbital margin, there is the superciliary arch (arcus superciliaris). Between the left and right arches there is a protruding area — the glabella (glabella).

  

  

  Also on the external surface of the squamous part, we can distinguish a large elevation — the frontal tuber (tuber frontale).

  

  On the internal surface of the squamous part, the groove for the superior sagittal sinus (sulcus sinus sagittalis superioris) runs in the middle, which descends into the frontal crest (crista frontalis). The cranial dura mater is attached to this crest.

  

  

  At the base of the frontal crest lies the foramen caecum (foramen caecum).

  

  The orbital parts are sometimes called orbital plates, and they form nearly the entire superior wall of the orbit.

  The orbital part has two surfaces:

• orbital surface (facies orbitalis)

• cerebral surface (facies cerebralis)

The right and left orbital parts are separated by the ethmoidal notch (incisura ethmoidalis).

On the cerebral surface of the orbital parts, digitate impressions (impressiones digitatae) and impressions of cerebral gyri (juga cerebralia) can be distinguished. These are traces of adjoining of different cerebral structures.

Around the lateral angle lies the lacrimal fossa (fossa glandulae lacrimalis).

And closer to the center of the orbital part, we can see the trochlear fovea (fovea trochlearis), creating the attachment point of the obliquus capitis superior muscle.

Next to this fovea, the trochlear spine is located (spina trochlearis), to which the trochlea for the tendon of the superior oblique muscle is attached.

The nasal part of the frontal bone is located between the supraorbital margins. In front and on the sides, it bounds the ethmoidal notch. The nasal part itself is bounded laterally by the nasal margin (margo nasalis).

The nasal spine (spina nasalis) is derived from the nasal part.

The opening of the frontal sinus (apertura sinus frontalis) is located to the side of the spine (on each side).

The frontal sinus (sinus frontalis) is one of several pneumatized cranial cavities. The left and right frontal sinuses are separated by a septum.

This sinus is connected to the middle nasal meatus of the nasal cavity.

Dictionary

Frontal bone

frontal bone

os frontale

squamous part

squama frontalis

orbital part

pars orbitalis

nasal part

pars nasalis

external surface

facies externa

internal surface

facies interna

supraorbital margin

margo supraorbitalis

supraorbital notch

incisura supraorbitalis

supraorbital foramen

foramen supraorbitale

frontal notch

incisura frontalis

frontal suture

sutura metopica

zygomatic process

processus zygomaticus

temporal surface

facies temporalis

temporal line

linea temporalis

superciliary arch

arcus superciliaris

glabella

glabella

frontal tuber

tuber frontale

groove for superior sagittal sinus

sulcus sinus sagittalis superioris

frontal crest

crista frontalis

foramen caecum

foramen caecum

orbital surface

facies orbitalis

cerebral surface

facies cerebralis

ethmoidal notch

incisura ethmoidalis

digitate impressions

impressiones digitatae

impression of cerebral gyri

juga cerebralia

lacrimal fossa

fossa glandulae lacrimalis

trochlear fovea

fovea trochlearis

trochlear spine

spina trochlearis

nasal margin

margo nasalis

nasal spine

spina nasalis

opening of frontal sinus

apertura sinus frontalis

frontal sinus

sinus frontalis