Frontal bone
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View Tariq Walizai's current disclosures- Os frontale
The frontal bone is a skull bone that contributes to the cranial vault. It contributes to form part of the anterior cranial fossa.
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Gross anatomy
The frontal bone has two portions:
vertical portion (squama): has external/internal surfaces
horizontal portion (orbital): has superior/inferior surfaces
The external surface of the vertical portion features:
frontal/metopic suture
frontal eminence (tuber frontale)
superciliary arches which join to form the glabella
supraorbital notch/foramen containing the supraorbital nerve and vessels
supratrochlear notch/foramen containing the supratrochlear nerve and vessels
zygomatic process laterally
upper and lower temporal lines run backwards and are the sites of attachment for the temporalis fascia and temporalis muscle, respectively
nasal part features the nasal notch, nasion (middle of frontonasal suture), and nasal process (sharp spine, forms part of nasal septum)
Internal surface of the vertical portion features:
sagittal sulcus: vertical groove for the superior sagittal sinus
frontal crest: ridge, formed from edges of sulcus that gives attachment to the falx cerebri
foramen cecum: small notch, converted into foramen, emissary vein from nose
groove for anterior meningeal artery (branch of anterior ethmoidal artery)
The horizontal portion is composed of two thin, orbital plates separated by the ethmoidal notch.
The inferior surface of the horizontal portion is smooth and concave. It features:
lacrimal fossa: lateral shallow depression for lacrimal gland
fovea trochlearis / trochlear spine near nasal part, for attachment of cartilaginous pulley for superior oblique muscle
The superior surface of the horizontal portion is convex and contains depressions for cerebral convolutions. It features:
openings for the frontal sinuses on either side of the nasal process; each frontal sinus communicates with the ipsilateral middle nasal meatus via a frontonasal duct
two grooves converted into anterior and posterior ethmoidal canals when articulating with the ethmoid bone
Articulations
The frontal bone articulates with twelve bones.
Unpaired bones include:
ethmoid: via ethmoidal notch
-
greater wings via the border of squama
lesser wings via posterior borders of orbital plates
Paired bones include:
nasal: via either side of the midline of the nasal notch
frontal process of the maxilla: via the lateral portion of nasal notch
lacrimal: via lateral portion of nasal notch
parietal: via border of squama
zygomatic: via zygomatic processes
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Variant anatomy
hypoplasia/aplasia of the frontal sinus(es)
Development
The frontal bone undergoes intramembranous ossification. The metopic suture fuses in 2nd year but may persist.
References
- 1. Henry Gray, Patricia Collins. Gray's Anatomy. (2005) ISBN: 0443071683 - Google Books
Incoming Links
- Coronal suture
- Glabella
- Falx ossification
- Hyperostosis frontalis interna
- Intramembranous ossification
- Maxilla
- Ethmoid bone
- Parietal bone
- Craniofacial fibrous dysplasia
- Transcranial Doppler sonography (ultrasound)
- Sphenofrontal suture
- Frontal sinus
- Frontal lobe
- Base of the skull
- Supraorbital foramen
- Lamina papyracea
- Fovea ethmoidalis
- Skull vault osteoma
- Skull vault bones (mnemonic)
- Frontomaxillary suture
Related articles: Anatomy: Head and neck
- skeleton of the head and neck
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cranial vault
- scalp (mnemonic)
- fontanelle
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sutures
- calvarial
- facial
- frontozygomatic suture
- frontomaxillary suture
- frontolacrimal suture
- frontonasal suture
- temporozygomatic suture
- zygomaticomaxillary suture
- parietotemporal suture (parietomastoid suture)
- occipitotemporal suture (occipitomastoid suture)
- sphenofrontal suture
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- basal/internal
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- frontal bone
- temporal bone
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facial bones
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cranial vault
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facial muscles
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buccolabial muscles
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orbicularis oris muscle
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orbicularis oris muscle
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suboccipital muscles
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deep spaces of the neck
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- ear
- paranasal sinuses
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- viscera of the neck
- blood supply of the head and neck
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arterial supply
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common carotid artery
- carotid body
- carotid bifurcation
- subclavian artery
- variants
-
common carotid artery
- venous drainage
-
arterial supply
- innervation of the head and neck
-
cranial nerves
- olfactory nerve (CN I)
- optic nerve (CN II)
- oculomotor nerve (CN III)
- trochlear nerve (CN IV)
-
trigeminal nerve (CN V) (mnemonic)
- trigeminal ganglion
- ophthalmic division
- maxillary division
- mandibular division
- abducens nerve (CN VI)
- facial nerve (CN VII)
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vestibulocochlear nerve (CN VIII)
- vestibular ganglion (Scarpa's ganglion)
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- greater occipital nerve
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cervical plexus
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- scalenes
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ansa cervicalis
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- contribution to the accessory nerve (CN XI)
- cutaneous branches
- muscular branches
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cranial nerves
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