Skull

Objectives Identify the different bones forming the skull with important foramina. Differentiate between the bony features of the skull of an adult and infant.

The Skull It consists of flat and irregular bones Divides into: Cranial bones which encase the brain Facial bones which form the bones of the face The following must be identified: Nasion Inion Bregma Lambda External occipital protuberance Parietal eminence Zygomatic arch

Nasion Inion Bregma Lambda

5. External occipital protuberance (EOP) 6.Zygomatic arch ( temporal + zygomatic bones) 7. Parietal eminence

The Skull Cranial bones include: Facial bones include: (Neurocranium) Frontal Ethmoid Sphenoidal Occipital Parietal Temporal Facial bones include: (Viscerocranium) Maxilla Zygomatic Nazal Palatine Lacrimal Inferior concha Vomer Mandible

Cranial bones include: (Neurocranium) Frontal Ethmoid Sphenoidal= eagle Occipital Parietal Temporal

Temporal bone Landmarks: Squamaus: flat portion Mastoid process ( behind the ear) --External auditory meatus: opening to the ear canal Styloid process Zygomatic process : process forming part of the cheek ( one part is inside the skull ) Petrous portion (Petrous=pyramid) Like horizontal pyramid It's internal, between the sphenoid and occipital

Sphenoid bone Landmarks -Body Greater wings Lesser wings Pterygoid processes sella turcica ( pituitary fossa) inside the body of sphenoid

Ethmoid Bone Occipital bone Landmarks: Crista galli: upward extension of bone above the cribriform plate Cribriform plate( on both sides of crista): Cribriform= sieve ( a lot of openings) forms the roof of the nasal cavity Occipital bone External occipital protuberance (EOP) Internal occipital protuberance (at the same point of external) GIF pic

Foramina of the Skull Foramina are found within the skull bones They vary in size and shape They transmit nerves, blood vessels and dura matter

Foramina of the Skull 5 1 R O S Present in the sphenoid bone 3 2 4

Nasal Foramina Lacrimal Bones Smallest and most fragile bone of the face +It’s behind the nasal bone

Foramina of the Skull Supraorbital Infraorbital Mental

Foramina of the Skull 7 12 9,10,11 Carotid artery + beginning of jugular vein

The Skull Parietal Temporal Squamous Mastoid Styloid Tympanic Petrous Sphenoid Greater wing Lesser wing Pterygoid process Body Occipital

The Skull Petrous part of temporal Lesser wing of sphenoid Body of sphenoid Pterygoid process Ethmoid bone Crista galli Cribriform plate Perpendicular plate Vomer Palatine bone

Cranial Fossa It is the cavity of the skull Divides into: Anterior cranial fossa Middle cranial fossa Posterior cranial fossa

Anterior Cranial Fossa Formed of: Orbital plate of frontal bone Cribriform plate of ethmoid Crista galli Lesser wing of sphenoid Occupies: Frontal lobe of the cerebrum Optic nerves Olfactory bulb and tract

Middle Cranial Fossa Formed of: Greater wing of sphenoid Body of sphenoid Squamous part of temporal bone Anterior part of petrous bone It occupies: Temporal lobe of the cerebrum

Posterior Cranial Fossa Formed of: Sphenoid part of clivus Posterior part of petrous bone Occipital bone It shows the following land marks: Groove for transverse sinus Groove for segmoid sinus Internal occipital protuberance It occupies: Cerebellum Brain stem

Base of The Skull Most of the bones are seen in other views Fracture base of the skull why?

Sutures of the Skull Sutures are fibrous joints articulating the skull bones They include: Coronal Sagittal Lambdoid Pterion

Pterion= H-like suture made by Frontal temporal partial + greater wing of sphenoid It’s the place of meningeal artery ( above pterion)

Skull Fontanelles Fontanelles are spaces between some of the skull bones of infants. They permit easy growth of the brain. They permit overlapping of skull bones during labor. They include: 1. Anterior Fontanelle ( bregma) Lies between Frontal and Parietal Bones Closed by 18 months of age 2. Posterior Fontanelle (lambda) Lies between Parietal and Occipital Bones Closed by end of 1st year 3. Anterolateral Fontanelle 4. Posterolateral Fontanelle

The Mandible It is a flat bone Identify the following: Head(condylar process) Mandibular notch Coronoid process Ramus Angle Body Mylohyoid line Submandibular fossa Digastric fossa Mandibular foramen Mental foramen