skull BY: DR.Yahya Alfarra CANADIAN BOARD IN DENTISTRY
Inferior aspect of skull(norma basalis) • It is the outer surface of skull base • For descriptive purposes, the norma basalis externa is divided into ant. , middle & post. Parts by 2 imaginary transverse lines : 1- ant. Transverse line: passing along the post. Border of the hard palate 2- post. Transverse line: passing through the post. Border of the foramen magnum of the skull
1- Ant. Part of norma basalis • It is formed by the hard(bony)palate which is bounded with in alveloar arch of maxilla • It is divided by the intermaxillary suture(?) into RT. & LT. halves • Each half is formed of 2 parts: 1) ant. 2/3 formed by the palatine process of maxilla (infront) 2) post. 1/3 formed by the horizontal plate of palatine bone(behind) • The 2 parts unite at the palato-maxillary suture.
Anatomical features: • palatine process of two maxilla infront & horizontal palate of 2 palatine bone behind. • incisive fossa to which nasopalatine N. passes from nose to palate. • greater palatine foramen which transmit greater palatine N. & V. • lesser palatine foramen that transmit lesser palatine nerve & vesseles.
post. Nasal spine * The most posterior part of alveolar process is called max. tuberosity.
They are sutured together at the median line. (intermaxillary suture).
2- middle part of norma basalis There are 2 large post. Nasal opening *lateral to post. Nasal opening, There is pterygoid process of sphenoid. anteriorly: it is separated from the back of maxilla by the pterygomaxillary fissure. Posteriorly: it presens: - medial pterygoid plate - lateral pterygoid plate in between pterygoid fossa.
The basilar part of occipital bone extend from vomer to foramen magnum. • Note: on each side of The basilar part of occipital bone, the petrous part of temporal bone is lies. • Lateral to petrous part of temporal bone found squamous part of temporal bone .
Lacerum foramen It’s transmit : * meningeal branch of ascending pharyngeal artery, *emissary vien from cavernous sinus to pterygoid plexus of vien. • Jugualr foramen It’s transmit : * Internal jugualr vien, glossopharyngeal nerve , nagus nerve , accessory nerve carotid canal it’s transmit: * Internal carotid artery, deep petrosal n.
* Foramen oval: - it’s oval in shape structure passing through Foramen oval: 1- mandibualr nerve 2- motor root of trigeminal nerve 3- middle meningeal vien 4- accessory meningeal artery • foramen spinosum it’s transmit • middle meningeal A. , nervous spinosum
* Stylomastoid foramen: it transmits: facial nerve which supply Mm of facial expression. * Mastoid notch * Occipital groove: a groove for occipital a. lying medial to the mastoid notch.
Mandibular fossa Articualr eminence occipital condyle 2 kidney-shaped condyles on each side of foramen magnum Note: occipital condyle articulate with upper surface of atlas to form atlanto-occipital joint *
Foramen magnum: * Above occipital condyle: ant. Condylar canal(hypoglossal canal) which transmit hypoglossal N. * Below occipital condyle:post. Condyalr foramen which transmit emissary vien. Note : Foramen magnum(structures passing) 1- vertebral artery 2- spinal artery 3- vertebral plexus of vien
3- post. Part of norma basalis It shows the following features: • Ext. occipital protuberance • Ext. occipitalcrest • Sup. Nuchal line • Inf. Nuchal line