Skull Anatomy PDF

Subdivided into 3 parts: Its divided by two imaginary lines The anterior line: passing along the posterior border of the hard palate. The posterior line: passing through the posterior border of the foramen magnum.  Anterior part of the norma basalis  Formed by : Hard pa...

Subdivided into 3 parts: Its divided by two imaginary lines The anterior line: passing along the posterior border of the hard palate. The posterior line: passing through the posterior border of the foramen magnum.  Anterior part of the norma basalis  Formed by : Hard palate Bounded anteriorly and laterally by alveolar arch of maxilla.  Bones forming : Palatine process of maxilla Horizontal plate of palatine bone  Sutures: Palato-maxillary suture Inter-maxillary suture  Some important features Alveolar margin (arch) : carries 16 sockets for the roots of upper teeth. Posterior border of the hard palate Posterior nasal spine Maxillary tuberosity  Foramina in the anterior part Incisive fossa ( contain 4 small foramina )  2 small median incisive foramina  2 lateral foramina Greater palatine foramen (Medial to the last molar ) Lesser palatine foramina 1  Middle part of norma basalis  Extended from the posterior border of the hard palate to the line passing through the anterior border of the foramen magnum.  Divided into : Median area , Lateral area  Bone forming it : Anterior ( middle) : vomer and body of sphenoid Anterior (lateraly ) :Ptytegoid process and infra temporal surface of greater wing of sphenoid. Posterio-lateraly :  Petrous part of temporal bone  Tympanic part of temporal bone  Mastoid part of temporal bone Posteriorly in the middle  Basilar part of occipital bone  2 lateral parts of occipital bone  Important particular features Posterior nasal openings (choana): separated from each other by vomer. A median vertical bony plate intervening between the 2 posterior nasal opening. Pterygoid process of Infratemporal surface of Petrous part of temporal sphenoid bone greater wing of sphenoid bone *Lateral pterygoid plate Bounded laterally by *Is wedged between greater *Medial pterygoid plate infra temporal crest. wing of sphenoid and basilar (posterior border) Bounded medially by part of occipital bone. pterygoid hamuls the groove for the *Contains : (upper end) pharyngo-tympanic tube Foramen lacerum scaphoid fossa It shows the spine of Rough quadrate area *Pterygoid fossa in sphenoid and two Carotid canal between which is a V foramen (oval and Jagular foramen shape spinosum) *It shows two processes : Styloid , Mastoid process 2   Basilar part of occipital bone  Important features Pharyngeal tubercle Articular parts (mandibular fossa, articular eminence, occipital condyle) Hypoglossal canal Posterior Condylar fossa Posterior Condylar canal Cranial Cavity (A) INNER SURFACE OF SKULL CAP (B) NORMA BASALIS INTERNA (A) INNER SURFACE OF SKULL CAP  Bones: Anteriorly: Frontal bone On the sides: parietal bones Posteriorly: squamous part of occipital bone Sutures: Coronal, Sagittal & Lambdoid.  Particular Features: 1. Frontal crest 2. Sagittal sulcus 3. Granular foveolae 4. parietal emissary foramen 5. Grooves for branches of middle meningeal vessels. (B) NORMA BASALIS INTERNA Divided into 3 Cranial Fossae:  Ant. cranial fossa  Middle cranial fossa  Post. cranial fossa 3 Anterior cranial fossa Middle cranial fossa Posterior cranial fossa The highest, smallest & It lies below the Ant. fossa The widest, deepest & most anterior one. & has a butter-fly shape. most post of the 3 fossae. Boundaries: The Middle Cranial Fossa is Bones forming its floor: Anteriorly and laterally - formed by: Anteriorly: The clivus The frontal bone 1. Body of sphenoid Posteriorly: Squamous Posteriorly - lesser wings 2. Greater wing of sphenoid part of occipital bone of the sphenoid bone 3. Petrous part of temporal Antro-laterally: Petrous Bones forming the floor bone part of temporal bone of the fossa: Boundaries: ,mastoid part of temporal Anteriorly: Anteriorly: post borders of bone 1. Orbital plates of lesser wings of sphenoid & frontal bone ant. clinoid processes. 2. Cribriform plate of Posteriorly: sup. borders of ethmoid bone petrous temporal bones & Posteriorly: dorsum sellae. 1. lesser wings of Bones forming its Floor: sphenoid Median part: 2. Jugum sphenoidal Sella turcica (Turkish (ant. part of body Saddle) formed by the body of sphenoid) of sphenoid. On either side: (1) greater wing of sphenoid: anteriorly. (2) Petrous temporal bone: posteriorly. (3) Squamous temporal bone: laterally. 4 Particular features: Particular features: Particular Features: (1) Orbital plates of Body of sphenoid includes: (a) Clivus frontal bones (a) Sella turcica or (b) Foramen magnum (2) Frontal crest Hypophyseal (pituitary) (c) Internal occipital crest (3) Cribriform plate of fossa (d) Internal occipital ethmoid (b) Tuberculum Sellae protuberance (4) Crista galli (c) Dorsum Sellae (e) Transverse sulcus (5) Jugum sphenoidal (d) Post. Clinoid processes (6) Lesser wing of (e) Sulcus Chiasmaticus sphenoid (f) Optic canal Greater wing of sphenoid: (a) Sup. orbital fissure (b) F. rotundum (c) f. Ovale Particular Features: (d) F. Spinosum (a)Groove for sigmoid (e) Vesalian F. venous sinus (f) F. innominatum (b)Internal acoustic Petrous temporal bone (its meatus ant. surface): (c) Hypoglossal canal (a) F. lacerum (d) Jugular foramen (b) Trigeminal depression Particular Features: (c) Arcuate eminence (a)Superior petrosal sulcus (d) Tegmen tympani (b)Inferior petrosal sulcus (e) Hiatus for greater (c)Mastoid emissary vein petrosal n. foramen (d)Posterior Condylar foramen (F) Hiatus for lesser petrosal n. 5