OsteologyCraniumDr Iram Iqbal

sequence• Skull,• Cranium• Anatomical position of skull • Norma verticalis• Norma Frontalis• Norma occipitalis• Norma Lateralis• Temporal, infra temporal, &Pterygopalatine fosses• Norma basali• Cranial fossae• Individual bones of skull• Muscle attachments

• Clinical note• conclusion

skull The skull is the bony skeletal of the

head. It shield the brain ,the organ of special sense and the cranial part of the respiratory and digestive system and providing attachments for many of the muscles of the head and neck.

Composed of 28 bones

Skull is divided in to 2 main parts– Calvaria (brain box)

– Fascial skeleton (rest of skull including mandible)

Cranium• Skull without mandible is called cranium it is divided into

– Neurocranium or cranial vault

• Enclosing brain ,meninges, csf

– Viscerocranium or fascial skeleton

• Houses the organs of special sense

Anatomical position of skull

Reid's base line• Reid's base line . It

is defined as a line drawn from the inferior margin of the orbit to the auricular point (center of the orifice of the external acoustic meatus) and extending backward to the center of the occipital bone

• skull is the Frankfurt plane , where the lower margins of the orbits and the upper borders of the ear canal s are all in a horizontal plane. ...also called  eye-ear plane, Frankfort horizontal, Frankfort plane

NORMA VERTICALISNORMA VERTICALIS

• CORONAL SUTURE

• SAGITAL SUTURE

• LAMBDOID SUTURE

• BREGMA

• LAMBDA

NORMA FRONTALISNORMA FRONTALIS

• ORBITAL OPENING

• ANTERIOR NASAL APERTURE

ORBITORBIT

ROOF• Lecrimal fossa• Optic canal

MEDIAL WALL• Lecrimal groove• Forms the lateral wall of ethmoidal sinus• Lecrimal crest• Orbital plate of ethmoid

ORBITORBIT

FLOOR• Inferior orbital fissure• Infra orbital groove• Infra orbital foramen

LATERAL WALL•Formed by greater wing of sphenoid • frontal process of zeugmatic bone•Superior orbital fissure

ANTERIOR NASAL APERTUREANTERIOR NASAL APERTURE

NORMA OCCIPITALISNORMA OCCIPITALIS• External occipital protuberance• Inion • Superior nuchal line

NORMA LATERALISNORMA LATERALIS

TEMPORAL FOSSA• Boundaries• PterionZYGOMATIC ARCH• Formation • Roots of arch• Tubercle of zygoma• Supra mastoid crest

NORMA LATERALISNORMA LATERALISEXTERNALACOUSTICMEATUS• Upper margin

formed by squamous part of temporal bone

• Tympanic part• Supra meatal

triangle

MASTOID PART• Parietomastoid suture• Occipitomastoid suture• Asterion

• STYLOID PROCESS

• INFRATEMPORAL FOSSA

– AnteriorMaxilla

- MedialLateral Pterygoid

plate

INFRATEMPORAL FOSSAINFRATEMPORAL FOSSA

COMMUNICATIONS• Temporal fossa• Orbit • Pterygopalatine

fossaCONTENTS• Maxillary nerve• Maxillary artery• Pterygopalatine

ganglion

PTERYGOPALATINE FOSSAPTERYGOPALATINE FOSSA

COMMUNICATIONS– (laterally) Infratemporal

fossa– (Medial wall) Nasal cavity by

sphenopalatine foramen– (Above) Orbit by infraorbital

fissure

• Posterior wall has 3 openings

• (Upper) Foramen rotundum• (Below) Pterygoid cannal• (posterior wall) Sphenopalatine foramen

CONTENTS OF CONTENTS OF SUPERIOR SUPERIOR ORBITAL ORBITAL FISSUREFISSURE

• Branch of ophthalmic artery

• Occulomotor nerve• Trochlear nerve• Abducent nerve• Lecrimal nerve• Frontal nerve• Nasociliary nerve• Ophthalmic veins

• Infraorbital nerve &Vessels

• Zygomatic nerve• Branches from

Pterygopalatine ganglion

CONTENTS OF CONTENTS OF INFERIOR INFERIOR ORBITAL ORBITAL FISSUREFISSURE

NORMA BASALISNORMA BASALIS

EXTENT• From incisor teeth

back to superior nuchal lines

LATERRALLY• Teeth • Zygomatic arch• Mastoid process

ANTERIOR PART

MIDDLE PARTMIDDLE PART

POSTERIOR PARTPOSTERIOR PART

ANTERIOR CRANIAL FOSSSAANTERIOR CRANIAL FOSSSA

MIDDLE CRANIAL FOSSAMIDDLE CRANIAL FOSSA

POSTERIOR CRANIAL FOSSAPOSTERIOR CRANIAL FOSSA

Frontal bone• Half a shallow

irregular cap forming forehead

• It has– 3 parts

• Squamous (Main part)

• Nasal • Orbital • Zygomatic process

– 2 cavities• Frontal sinus

Ossification• It ossified in fibrous mesenchyme from 2

primary centers• Appear in 8th wk in utero near each frontal

tuber• Secondary center for nasal spine appear

about 10th year• At birth it has 2 halves• Median suture disappears at about 8th year• May persist as Metopic suture

Parietal bone

• 2 bones form most of cranial roof and side of the skull

• Irregular quadrilateral • & it has • 2 surfaces• 4 borders• 4 angles

Ossification• Each parietal bone ossified from 2

centres which appear in dense mesenchyme near the tuberosity,one above the other at about the 7th wk in utero.

• Angles are the last part to ossified & fontanelles occur at these sites

• At birth temporal lines are low down• Reach at their final position after the

eruption of molar teeth.

Occipital bone• Unpaired lies in

posterior part of skull• Pierced by foramen

magnum• It has 3 parts

– Squamous part– Basilar part– Condylar part

• Occipital condyles• Hypoglossal &post

Condylar canal. jugular process ,fossa &foramen, mastoid canaliculus ,canaliculus for tympanic n.

Occipital bone

Maxilla• 2nd Largest of facial bone• It has

– Body (4 surfaces)– Maxillary air sinus

• Ant surface• Infratemporal ( Jugal crest ,alveolar canals, pos sup

alveolar n&v)• Orbital (canalis sinuosus ,ant sup alveolar n)• Nasal

– 4 processes • frontal• zyomatic• Alveolar• palatine

Maxilla

Ossification• From a single center in a sheet of

mesenchyme.• Appear above the canine fossa at about

the 6th wk in utero and spread to rest of maxilla and its processes.

• The maxillary sinus appear as a shallow groove on the nasal aspect at about the 4th month in utero. (though small at birth)

• After birth it enlarge with growing maxilla• Fully developed following the eruption of

the permanent teeth.

Zygomatic bone• 2 processes . 5 borders• 3 surfaces . Whitnall,s

tubercle

OSSIFICATION• From one center• Appears in fibrous tissues about the

8th wk in utero

• Sphenoid• Unpaired ,it forms

middle part of base of skull

• Extend into Lateral wall of the vault & into orbit

• It has– Body(5 surfaces)– Rt & Lt greater

wings(3 surfaces)– Rt &Lt lesser wings– Rt & Lt Pterygoid

processes

sphenoid

Ossification• Until the 7th to 8th month in utero the

sphenoidal body has a presphenoidal part, ant to the tuberculum sellae with which the lesser wing was continuous .

• Postsphenoidal part consisting of sella turcica ,dorsum sallae, greater wing and Pterygoid process.

• Much of the bone preformed in cartilage.

• 6 ossification centres for presphenoidal

• 8 for postsphenoidal

Temporal bone

Temporal bone

Ethmoid bone

Inferior nasal concha &VOMER

Ossification• Ethmoidal bone ossifies in the

cartilaginous nasal capsule from 3 centres .1 for perpendicular plate,1 in each labyrinth. later 2 appear In the orbital plates b/e 4th and 5th month in utero.

• Inferior nasal concha ossifies from 1 centre which appear at about the 5th month in utero.

Palatine bone

ossification• Palatine bone ossifies in the

mesenchyme from 1 centre in the perpendicular plate that appear during 8th wk in utero

Clinical note• SCAPHOCEPHALY

• PLAGIOCEPHALY

• OXYCEPHALY

• TRIGONOCEPHALY

• PAN SYNOSTISIS

SCAPHOCEPHALY

Premature closure of sagittal suture.

PLAGIOCEPHALY

Premature closure of coronal suture on one side.

REFERANCESREFERANCES• GRAY’S ANATOMY 40th edition

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