Base Of Skull Anatomy PDF
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Dr Azizah Ahmad Fauzi
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Summary
This document provides an overview of the base of the human skull, focusing particularly on the various cranial fossae (anterior, middle, and posterior). It details the bones forming these fossae, their respective structures, foramina (openings), and associated nerves and blood vessels. It also touches upon potential fractures and their implications, including loss of sense of smell, CSF rhinorrhoea, haemorrhages, and leakage of CSF into specific locations.
Full Transcript
BASE OF SKULL Prepared by: Dr Azizah Ahmad Fauzi A) Base of skull (exterior view) Maxilla ◻ Incisive fossa (depression) 🡪 opens into incisive canals 🡪 transmit n/palatine n. Palatine process Median palatine suture / intermaxillary suture Palatine bone...
BASE OF SKULL Prepared by: Dr Azizah Ahmad Fauzi A) Base of skull (exterior view) Maxilla ◻ Incisive fossa (depression) 🡪 opens into incisive canals 🡪 transmit n/palatine n. Palatine process Median palatine suture / intermaxillary suture Palatine bone Tranverse palatine suture * Aperture = hole / gap Vomer - NASAL SEPTUM - - Flat - Trapezoidal shape Zygomatic bone ◻ acture - Maxillary process - Temporal process Zygomatic bone Zygomatic bone ◻ acture - Zygomaticomax suture - Temporozygomatic suture Tripod # ? Temporal bone Mandibular fossa Styloid process Tympanic plate Mastoid Laceru process m Carotid Stylomastoid canal Jugula f/men Sphenoid bone Hamulus – super. Constrictor mc. Plates - Medial pterygoid plate, Lateral pterygoid plate. Pterygoid fossa Scaphoid fossa -tensor veli palatini (mc of soft palate) Foramina – f. ovale >> V3, f. spinosum >> recurrent b. of V3 Spine of sphenoid (Post to f/men Occipital bone Pharyngeal tubercle Occipital condyle Hypogloss al canal f/men magnum External occipital crest External occ protuberance Frontal bone Ethmoid Sphenoid bone bone Parietal Sphenoid bone bone Temporal bone -squamous Occipital -petrous bone SKULL BASE (INTERNAL Anterior Cranial Fossa ▪Highest & shallowest ▪Formed by - Frontal bone - Ethmoid bone - lesser wing of sphenoid ▪Lodges frontal lobe of cerebrum ▪Forms roof of orbit ANTERIOR CRANIAL FOSSA Foramen Frontal caecum crest Orbital -emissary v to SSS plate -frontal crista galli - falx cerebri lobes Cribriform plate Ant clinoid process Boundaries Features Anterior Inner surface of frontal bone Frontal crest& Crista galli – attachment for falx cerebri Posterior Lesser wing of sphenoid Foramen caecum- transmits emissary veins to SSS Median Groove for optic chiasma Cribriform plate -olfactory N Floor - Orbital plate of frontal bone -roof of nasal cavity - Cribriform plate of ethmoid Anterior clinoid process- attachment for free border of tentorium cerebelli Fracture of anterior cranial fossa ▪Fracture of ethmoid bone - Anosmia (loss of sense of smell) - CSF rhinorrhoea (drainage of CSF through nose) ▪Fracture of frontal bone - Haemorrhage into orbital cavity 🡪 exophthalmos (bulging of eyeball) Middle Cranial Fossa ▪Butterfly-shaped ▪Formed by - Greater wing of sphenoid - Squamous & petrous part of temporal bone ▪Lodges temporal lobe of cerebrum Optic canal Superior orbital fissure - Optic nerve & opthalmic -Oculomotor CN III, artery trochlear CN IV, abducent CN VI, lacrimal, frontal & Foramen ovale nasociliary nerves - Mandibular nerve -Superior ophthalmic vein CN V3 - Accessory meningeal artery - Lesser petrosal nerve - Emissary vein Foramen spinosum - Middle meningeal artery Foramen rotundum - Maxillary nerve CN V 2 Foramen lacerum - Closed by fibrous tissue Boundaries Features Anterior Lesser wing of sphenoid Optic canal- optic N & ophthalmic A Superior orbital fissure- lacrimal, trochlear, oculomotor, abducent nerves, superior ophthalmic V Posterior Superior border of Foramen rotundum- maxillary N petrous part of temporal bn. Foramen ovale- mandibular N Foramen spinosum-middle meningeal Foramen lacerum Lateral Sq. part of temporal bn. -filled by cartilage in life Carotid canal Greater wing of sphenoid - opens lateral to foramen lacerum - transmits internal carotid artery Parietal bn. Sella turcica Fracture of middle cranial fossa (MCF) ▪Common 🡪 weakest part of base of skull ▪Characteristic features of MCF#? *Revise relations of MCF…. - MCF overlies middle ear cavity. MCF # leads to Leakage of CSF & blood 🡪 external auditory meatus - MCF overlies sphenoidal air sinuses MCF # leads to Leakage of CSF 🡪 sphenoidal air sinuses 🡪 nose Posterior cranial Fossa ▪Largest & deepest ▪Formed by - Occipital bone - Petrous & mastoid part of temporal bone ▪Lodges cerebellum, pons & medulla oblongata Internal acoustic meatus - Facial CN VII & vestibulocochlear CN VIII - Labyrinthine artery Jugular foramen Hypoglossal canal - Hypoglossal nerve (CN XII) Foramen magnum Clivus Internal occipital crest - Attachment for falx Groove for cerebelli transverse sinus Internal occipital protuberance Boundaries Features Anterior Superior border of petrous Foramen magnum-medulla part of temporal bn. oblongata with its surrounding meninges, ascending spinal parts of XI N, vertebral arteries Posterior Squamous part of occipital bn. Hypoglossal canal- 12 CN (Hypoglossal n.) Jugular foramen- Floor Occipital bone 9, 10, 11 CN (basilar / lateral / sq parts) sigmoid sinus becomes IJV Temporal bn. Internal acoustic meatus- (petrous & mastoid parts) vestibulocochlear N, motor & sensory roots of facial N. Roof Tentorium cerebelli
