IN THE NAME OF ALLAH

Facial Bones with glasses onFacial Bones with glasses on

The Skull

• 22 bones joined together by sutures

• Cranial bones surround cranial cavity– 8 bones

• Facial bones support teeth & form nasal cavity & orbit– 14 bones

Frontal Bone

• Forms forehead and part of the roof of the cranium

• Forms roof of the orbit• Contains frontal sinus

Parietal Bone

• Forms cranial roof and part of its lateral walls

• Bordered by 4 sutures– coronal, sagittal, lambdoid

and squamous

• Marked by temporal lines of temporalis muscleTemporal lines

Temporal Bone

• Forms lateral wall & part of floor of cranial cavity– squamous part

• zygomatic process

• mandibular fossa & TMJ

– tympanic part• external auditory meatus

• styloid process

– mastoid part• mastoid process

• mastoid notch– digastric muscle

Petrous Portion of Temporal Bone

• Forms part of cranial floor– separates middle from

posterior cranial fossa

• Houses middle and inner ear cavities

Openings in Temporal Bone

Occipital Bone

• Foramen magnum holds spinal cord

• occipital condyles

Sphenoid Bone

• Lesser wing

• Greater wing

• Body of sphenoid

• Medial and lateral pterygoid processes

Sphenoid Bone

• Body of the sphenoid– sella turcica contains deep

pit (hypophyseal fossa)

– houses pituitary gland

• Lesser wing– optic foramen contains optic

nerve & ophthalmic a.

Sphenoid Bone

• Sphenoid sinus

Ethmoid Bone

• Between the orbital cavities• Forms lateral walls and roof of nasal

cavity• Cribriform plate & crista galli• Ethmoid air cells form ethmoid sinus• Perpendicular plate forms part of

nasal septum• Concha or turbinates on lateral wall

Ethmoid Bone

• Superior & middle concha• Perpendicular plate of nasal

septum

Maxillary Bones• Forms upper jaw

– alveolar processes are bony pointsbetween teeth

– alveolar sockets hold teeth

• Forms inferomedial wall of orbit– infraorbital foramen

• Forms anterior 2/3’sof hard palate– incisive foramen– cleft palate

Locations of Paranasal Sinuses

• Maxillary sinus fills maxillae bone• Other bones containing sinuses are frontal, ethmoid &

sphenoid.

EthmoidMaxillarySphenoid

Frontal

Palatine Bones

• L-shaped bone• Posterior 1/3 of the hard

palate • Part of lateral nasal wall• Part of the orbital floor

Zygomatic Bones

• Forms angles of the cheekbones and part of lateral orbital wall

• Zygomatic arch is formed from zygomatic bone and zygomatic process of temporal bone

Lacrimal Bones

• Form part of medial wall of each orbit

• Lacrimal fossa houses lacrimal sac in life

Nasal Bones

• Forms bridge of nose and supports cartilages of nose

• Often fractured by blow to the nose

Inferior Nasal Conchae

• A separate bone

Vomer

• Inferior half of the nasal septum

• Supports cartilage of nasal septum

Mandible• Only bone of the skull that can move

– jaw joint formed between mandibular fossaof temporal bone & condyloid process

• Holds the lower teeth• Attachment of muscles of mastication

– temporalis muscle onto coronoid process

– masseter muscle onto angle of mandible

• Mandibular foramen• Mental foramen

• Auditory ossicles– malleus– incus– stapes

• Hyoid bone– suspended from styloid

process of skull by stylohyoid muscle and ligament

– greater & lesser cornua

Bones Associated With the Skull

Major Skull Cavities

• Cranial cavity holds brain• Orbit contains eyeball &

extraocular muscles• Ethmoid sinus• Nasal cavity• Maxillary sinus• Oral cavity

Cranial Fossa

• 3 basins that comprise the cranial floor or base– Anterior cranial fossa

– Middle cranial fossa

– Posterior cranial fossa

The Skull in Infancy & Childhood

• Spaces between unfused skull bones called fontanelles– filled with fibrous membrane

– allow shifting of bones during birth & growth of brain in infancy

• 2 frontalle bones fuse by age six– metopic suture

Norma Verticalis

Norma Frontalis

Norma Occipitalis

Norma Lateralis

Norma Basalis