Skull SHANDONG UNIVERSITY Liu Zhiyu Skull The skull

Skull SHANDONG UNIVERSITY Liu Zhiyu

Skull The skull is composed of 23 bones, which may be divided into the cerebral craniumand facial cranium

Skull Cerebral cranium (8) ―larger, upper and posterior part, contains and protects the brain n Single bones: include q q n frontal bone ethmoid bone sphenoid bone occipital bone Paired bones: include q q temporal bone parietal bone

Skull Bones of facial cranium (15) n ―smaller, lower, and anterior part, contains bones that surrounded the eye, nose and mouth Single bones: include q q q n mandible vomer hyoid bone Paired bones: include q q q maxilla nasal bone lacrimal bone palatine bone zygomatic bone inferior nasal concha

Bones of facial cranium

parietal bone Frontal bone Sphenoid bone Temporal bone Zygomatic bone Nasal bone Maxilla Mandible Occipital bone

Mandible Body of mandible n n n Superior border: alveolar arch Inferior border: base of mandible Outer surface: mental protuberance Mental foramen Inner surface: mental spine Digastric fossa

Mandible Ramus n n n n Mandibular notch Coronoid process Condylar process q head of mandible q neck of mandible Mandibular foramen Mandibular lingula Angle of mandible Masseteric tuberocity

The skull as a whole

Skull viewed from above (superior view) n Bones: q q q n Sutures: q q q n n frontal bone paired parietal bone occipital bone Coronal suture Sagittal suture Lambdoid suture parietal tuber parietal foramen

Skull viewed from above (superior view) Internal surface of the calvaria n sulcus for superior sagittal sinus n granular foveola n arterial grooves

Skull viewed from behind n n n External occipital protuberance Superior nuchal line Inferior nuchal line

Internal view of base of skull Base of skull forms three fossae n n n Anterior cranial fossa Middle cranial fossa Posterior cranial fossa

Internal view of base of skull

Anterior cranial fossa Formed by orbital part of frontal bone, cribriform plate of ethmoid, and lesser wings of sphenoid Structures: n n n frontal crest foramen cecum crista galli cribriform plate cribriform foramina

Meddle cranial fossa Formed by the body and greater wings of sphenoid, petrous part of temporal Structures: n n n n Body of sphenoid bone Hypophysial fossa Optic canal Anterior clinoid process Tuberculum sellae Dorsum sellae Posterior clinoid process Sella turcica

Meddle cranial fossa n n n Carotid sulcus Superior orbital fissure Foramen rotundum Foramen ovale Foramen spinosum Sulcus for middle meningeal artery Foramen lacerum Internal opening of carotid canal Trigeminal impression Arcuate eminence Tegmen tympani

Posterior cranial fossa Formed by occipital and the petrous part of temporal Structures: n n n n n foramen magnum clivus internal opening of hypoglossal canal internal occipital protuberance internal occipital crest sulcus for transverse sinus sulcus for sigmoid sinus jugular foramen internal acoustic pore internal acoustic meatus

Skull viewed from below (inferior view) n n n n alveolar arch bony palate median palatine suture incisive foramina incisive canal greater palatine foramen posterior nasal apertures pterygoid process occipital condyle external opening of hypoglossal canal external opening of carotid canal styloid process stylomastoid foramen mandibular fossa articular tubercle

Lateral view of the skull n n n External acoustic pore Mastoid process Zygomatic arch Temporal fossa Pterion Superior temporal line

Lateral view of the skull n n Infratemporal fossa pterygomaxillary fissure pterygopalatine fossa sphenopalatine foramen

Skull viewed from the front (anterior view) Frontal region: n n frontal squama frontal tuber superciliary arch glabella

Orbit pyramid-shaped paired cavities n n n Base: supraorbital notch infraorbital foramen Apex: optic canal Walls q q q Superior: fossa for lacrimal gland Medial: fossa for lacrimal sac Inferior: infraorbital fissure infraorbital groove infraorbital canal

Bony nasal cavity n n Roof: cribriform plate of ethmoid Floor: bony palate Medial wall ― bony septum of nose Lateral wall q q n n n Superior, middle and inferior nasal conchae Superior, middle and inferior nasal meatus (underlying each concha) Sphenoethmoidal recess above superior nasal concha Anterior ―piriform aperture Posterior ―posterior nasal aperture communicates with pharynx

n Paranasal sinuses Frontal sinus q q Lies in frontal bone, deep to superciliary arch Drain to anterior part of middle meatus

Paranasal sinuses n Maxillary sinus q q Largest paired sinus, lie in the body of maxilla; Opening into middle nasal meatus

Paranasal sinuses n Ethmoidal cellules q q Lie in ethmoidal bone, contains large number of air cells, divided into anterior, middle and posterior groups Anterior and middle groups drain into middle nasal meatus, while posterior group drains into superior nasal meatus

Paranasal sinuses n Sphenoidal sinus q q Lies in body of sphenoid bone Drain into sphenoethmoidal recess

General characters of the skull at birth n n n The skull at birth is large in proportion to rest of the skeleton ― 1/4 (adult 1/7) The facial portion equals about one eight that of the cranium in size, whereas in adult it is one half (1/4) Many bones consist of more than one piece

General characters of neonatal skull Cranial frontanelles ―unossified membrane between the bones at the angles of parietal n Anterior frontanelle n Posterior frontanelle n Mastoid fontanelle Sphenoidal fontanelle n ―closes during middle of 2 nd year ―closes by the end of 2 nd month after birth

Anteroposterior radiograph of skull.

Lateral radiograph of skull.

Horizontal CT at level of upper part of ramus of mandible showing relationships of the pterygoid plates.