Presentation ,skull,by Dr Iram Iqbal

Osteology Cranium

Dr 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 VERTICALIS • CORONAL SUTURE • SAGITAL SUTURE • LAMBDOID SUTURE • BREGMA • LAMBDA

NORMA FRONTALIS • ORBITAL OPENING • ANTERIOR NASAL APERTURE

ORBITAL OPENING

ORBIT ROOF • Lecrimal fossa • Optic canal

MEDIAL WALL • • • •

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

ORBIT

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

BOUNDRIES CONTENTS • • • • •

Eye boll Muscles Vessels Nerves Lecrimal apparatus

ANTERIOR NASAL APERTURE

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

NORMA LATERALIS TEMPORAL FOSSA • Boundaries • Pterion ZYGOMATIC ARCH • • • •

Formation Roots of arch Tubercle of zygoma Supra mastoid crest

NORMA LATERALIS EXTERNAL ACOUSTIC MEATUS • 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

– Anterior Maxilla

- Medial Lateral Pterygoid plate

ROOF • Greater wing of sphenoid • Squamous temporal of bone Laterally Ramus of mandible Posteriorly Styloid process It has no anatomical floor

INFRATEMPORAL FOSSA COMMUNICATIONS • Temporal fossa • Orbit • Pterygopalatine fossa CONTENTS • Maxillary nerve • Maxillary artery • Pterygopalatine ganglion

PTERYGOPALATINE 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 SUPERIOR ORBITAL FISSURE • Branch of ophthalmic artery • Occulomotor nerve • Trochlear nerve • Abducent nerve • Lecrimal nerve • Frontal nerve • Nasociliary nerve • Ophthalmic veins

CONTENTS OF INFERIOR ORBITAL FISSURE • Infraorbital nerve &Vessels • Zygomatic nerve • Branches from Pterygopalatine ganglion

NORMA BASALIS EXTENT • From incisor teeth back to superior nuchal lines

LATERRALLY • Teeth • Zygomatic arch • Mastoid process

ANTERIOR PART

MIDDLE PART

POSTERIOR PART

POSTERIOR PART Hypoglossal canal Condylar fossa Occipital condayl Condylar canal Stylomastoid foramen • External occipital crest • Inferior nuchal line • • • • •

ANTERIOR CRANIAL FOSSSA

MIDDLE CRANIAL FOSSA

POSTERIOR 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

Ossification

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 • 3 surfaces

. 5 borders . 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

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.

REFERANCES • GRAY’S ANATOMY 40th edition • GOOGLE Chrome

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