Skull Anatomy (PDF)

## Different Aspects of the Skull ### Norma Frontalis - **Identify the Bones:** - Frontal bone: upper part - Nasal bones: above the nasal opening - Zygomatic bones: lateral to the orbital opening - Maxilla: forming the upper jaw. - Mandible: forming the lower jaw. - **Identif...

## Different Aspects of the Skull ### Norma Frontalis - **Identify the Bones:** - Frontal bone: upper part - Nasal bones: above the nasal opening - Zygomatic bones: lateral to the orbital opening - Maxilla: forming the upper jaw. - Mandible: forming the lower jaw. - **Identify the Sutures:** - Coronal suture: between frontal & parietal - Metopic suture: in infant skull between the 2 halves of frontal bone. It disappears at the age of 2 - 6 years. The lower part persists in about 8% of adult skulls. - Frontonasal & frontozygomatic suture - Internasal suture - **Identify the Bony Landmarks:** - Frontal eminence: center of ossification - Superciliary arch: above the orbit - Glabella: elevation between the 2 superciliary arches - Nasion: depression at the frontonasal suture. - Nasal septum and anterior nasal spine - Middle and inferior nasal conchae. - Canine eminence: formed by root of the canine tooth - **Identify the Foramina:** - Supraorbital foramen: supraorbital nerve & vessels - Infraorbital foramen: infraorbital nerve & vessels - Zygomaticofacial foramen: zygomaticofacial nerve & vessels - Mental foramen: mental nerve & vessels ### Norma Verticalis Externa - **Identify the Bones:** - Frontal bone: anterior part - Occipital bone: posterior part - Parietal bones: one on each side - - **Identify the Sutures:** - Coronal suture: between the frontal & parietal bones - Sagittal suture: between the 2 parietal bones. - Lambdoid suture: between occipital & parietal bones - - **Identify the Bony Landmarks:** - Bregma: meeting of the sagittal & coronal sutures - Lambda: meeting of the sagittal & lambdoid sutures. - Parietal foramen: emissary vein between SSS & scalp v - Parietal eminence: site of the center of ossification. ### Norma Verticalis Interna - **Identify the Bones:** - Frontal bone: anterior part - Occipital bone: posterior part - Parietal bones: one on each side - - **Identify the Sutures:** - Coronal suture: between the frontal & parietal bones - Sagittal suture: between the 2 parietal bones. - Lambdoid suture: between occipital & parietal bones - - **Identify the Bony Landmarks:** - Bregma: meeting of the sagittal & coronal sutures - Lambda: meeting of the sagittal & lambdoid sutures. - Groove for superior sagittal sinus: in the middle - Grooves for the middle meningeal vessels - Granular foveolae: made by arachnoid granulations ### Norma Occipitalis - **Identify the Bones:** - Right & left parietal bones - Squamous part of the occipital bone - Mastoid process - **Identify the Sutures:** - Sagittal suture & Lambdoid suture. - Occipito-mastoid & Parieto-mastoid sutures - **Identify the Bony Landmarks:** - Externa occipital protuberance. Inion is the prominent point - External occipital crest - Lambda: meeting of the sagittal & lambdoid sutures. - Asterion: meeting of 3 bones: parietal, occipital and mastoid bones - 3 Nuchal lines: highest, superior & inferior. - Mastoid notch (digastric notch) - Mastoid foramen: emissary vein & meningeal branch of occipital artery ### Norma Lateralis - **Identify the Bones:** - Above: frontal, parietal & occipital bone - Zygomatic bone & zygomatic arch - Greater wing of sphenoid - Squamous part of the temporal bone - Mastoid process & Styloid process - Bones of the face: nasal & maxilla - Infratemporal fossa & pterygomaxillary fissure: deep to the ramus of the mandible - **Identify the Sutures:** - Coronal suture - Lambdoid suture. - Squamosal suture: between parietal & temporal bones - Occipitomastoid suture & mastoid foramen - Parietomastoid & frontozygomatic sutures ### What are the Fontanelles of the Newborn Skull & Their Location in the Adult Skull? - **Fontanelle** | **Location** | **Adult Skull** | **Ossification** --- | --- | --- | --- Anterior | Between frontal and parietal bones | Bregma | 18 months Posterior | Between parietal and occipital bones | Lambda | 6 months Anterolateral | Between frontal, parietal, GWS & temporal bones | Pterion | 3 monthes Posterolateral | Between parietal, temporal & occipital bones | Asterion | 3 monthes ### Norma Basalis Externa - **Divided into 3 Parts:** - **Anterior Part:** Is the hard palate - **Middle Part:** Between the hard palate and anterior margin of the foramen magnum - **Posterior Part:** Behind the anterior margin of the foramen magnum. It is the occipital bone and mastoid process ### Anterior Part: Hard Palate - **Identify Parts of the Hard Palate:** - Palatine process of the maxilla: anterior 2/3 - Palatine bone: posterior 1/3 - Posterior nasal spine: in the middle of the free posterior border. - - **Identify the Sutures & Foramina:** - Median palatine suture: in the midline. - Palato-maxillary suture: between the maxilla and the palatine bone. - Incisive foramen (fossa): transmits nasopalatine nerve and sphenopalatine vessels. - Greater palatine foramen: transmits greater palatine nerve and sphenopalatine vessels - Lesser palatine foramina: transmit lesser palatine nerve and vessels ### Middle Part: Sphenoid & Petrous Temporal Bone - **Identify the Bones & Foramina:** - **In the Midline:** - The vomer & body of the sphenoid - Occipitosphenoid suture: ossifies at 25 yrs - Basilar part of the occipital bone - Pharyngeal tubercle - **On Each Side:** - Medial & lateral pterygoid plates - Pterygoid fossa: between the 2 pt plates - Pterygoid hamulus & scaphoid fossa - Greater wing of the sphenoid: contains: - Foramen ovale: transmits "MALE" Mandibular nerve, Accessory meningeal art, Lesser petrosal nerve & Emissary vein - Foramen spinosum: middle meningeal artery & nervus spinosus. - Groove for auditory tube: behind f ovale - Petrous part of temporal bone: showing - Foramen lacerum: transmits ICA & DPN - Carotid canal: transmits ICA. - Jugular foramen - Styloid process - Articular tubercle & articular fossa ### Posterior Part: Occipital Bone & Mastoid Process - **Occipital Bone:** - Divided by foramen magnum into 3 parts: - Basilar part: in front of the foramen magnum - Squamous part: behind the foramen magnum - Condylar part: 2 occipital condyles - 2 Foramina: - Hypoglossal canal: above the occipital condyle Transmits the hypoglossal nerve - Posterior condylar canal: behind the condyle. Transmits emissary vein between the sigmoid sinus and suboccipital venous plexus. - **Mastoid Process:** - Mastoid notch: on the medial side (digastric) - Stylomastoid foramen: transmits facial nerve & styomastoid art from posterior auricular art - Mastoid foramen: transmits artery & vein - Groove for the occipital artery ### Orma Basalis Interna - **1. Anterior Cranial Fossa** - **2. Middle Cranial Fossa** - **3. Posterior Cranial Fossa** ### 1. Anterior Cranial Fossa - **Identify the Bones & Foramina:** - Frontal crest, foramen cecum & crista galli - Cribriform plate of the ethmoid bone - Orbital plate of the frontal bone - Lesser wing of the sphenoid bone - Anterior & posterior ethmoidal canals ### 2. Middle Cranial Fossa - **Identify the Bones & Foramina:** - Sella turcica: hypophyseal fossa, tuberculum sellae & dorsum sellae. - Anterior & posterior clinoid processes - Optic canal & sulcus chiasmaticus - Greater wing of the sphenoid: contains 3 foramina: Foramen rotundum, ovale & spinosum - Superior orbital fissure - Petrous temporal bone: trigeminal ganglion fossa, tegmen tympani, arcuate eminence; foramen lacerum ### 3. Posterior Cranial Fossa - **Identify the Bones:** - Basilar part of the occipital bone - Squamous part of the occipital bone - Clivus: formed of sphenoid & basilar part of occipital b - Internal occipital protuberance - Internal occipital crest - **Identify the Foramina:** - Foramen magnum - Jugular foramen: between occipital & petrous TB - Hypoglossal canal (anterior condylar canal) - Internal auditory meatus - Mastoid foramen: in the groove for sigmoid sinus - **Identify the Grooves for dural venous sinuses:** - Transverse sinus. - Sigmoid sinus - Superior petrosal sinus ### Foramina - Anterior ethmoidal canal: anterior ethmoidal nerve & vessels - Posterior ethmoidal canal: posterior ethmoidal nerve & vessels - Superior orbital fissure: Live Free To See No Insult at All+ OV Lacrimal n, Frontal n, Trochlear n, Sup division of III n, Nasociliary n, Inferior division of III n, Abducent n - F lacerum: ICA & deep petrosal n - Internal auditory meatus: VII n, VIII n & labyrinthine artery - Foramen magnum: 9 3 nervous: medulla to become SC, spinal accessory n, sympath fibers 3 arteries: 2 vertebral, 1 anterior spinal & 2 posterior spinal arteries 3 meninges: dura, arachnoid & pia - Foramen cecum: emissary vein between nasal vein and SSS - Cribriform plate: olfactory nerves - Optic canal: Optic nerve and ophthalmic artery - Foramen rotundum: maxillary n - Foramen ovale: "MALE" Mandibular nerve, Accessory meningeal art, Lesser petrosal n & Emissary vein of cavernous sinus - Foramen spinosum: middle meningeal art & nervus spinosus - Jugular foramen: 2 V & 3 N Anterior: inferior petrosal sinus Posterior: sigmoid sinus Middle: IX, X & XI nerves: - Hypoglossal canal: XII nerve