6The skull has 22 bones, excluding the ossicles of the ear. COMPONENT PARTSThe skull has 22 bones, excluding the ossicles of the ear.Except for the mandible, which forms the lower jaw, the bones of the skull are attached to each other by sutures, are immobile, and form the cranium.
82.Lower anterior part-the facial skeleton (viscerocranium). Subdivisons1.The cranium can be subdivided into: an upper part the calvaria, which surrounds the cranial cavity containing the brain(Neurocranium).2.Lower anterior part-the facial skeleton (viscerocranium).
9The cranium consists of the following bones, two of which are paired Frontal bone: 1Parietal bones: 2Occipital bone: 1Temporal bones: 2Sphenoid bone: 1Ethmoid bone: 1
10The facial bones consist of the following, two of which are single: Zygomatic bones: 2Maxillae: 2Nasal bones: 2Lacrimal bones: 2Vomer: 1Palatine bones: 2Inferior conchae: 2Mandible: 1
11External Views of the Skull Anterior View of the Skull(Norma frontalis)The anterior view of the skull includes the forehead superiorly, and, inferiorly, the orbits, the nasal region, the part of the face between the orbit and the lower jaw
13Metopic sutureSuture that divides the two halves of the frontal bone of the skull in infants and children.It usually disappears by the age of six.In some individuals the suture can persist (totally or partly) into adulthood.
19Anterior fontanelleLargest fontanelle, and is placed at the junction of the sagittal suture, coronal suture, and frontal suture; it is lozenge-shaped, and measures about 4 cm in its antero-posterior and 2.5 cm in its transverse diameter.Not completely closed until about the middle of the second year.
21Clinical significance Examination of an infant includes palpating the anterior fontanelle.A sunken fontanelle indicates dehydration, whereas a very tense or bulging anterior fontanelle indicates raised intracranial pressure.
26Fracture of the Pterion A hard blow to the side of the head may fracture the thin bones forming the pterion, producing a rupture of the anterior branch of the middle meningeal artery crossing the pterion
38Foramen of Anterior cranial fossa 1. Cribriform plate:olfactory nerves (CN-I)2. Foramen cecum: occasional small emissary vein from nasal mucosa to superior sagittal sinus.3. Anterior and posterior ethmoidal foramina: anterior and posterior ethmoidal nerves, arteries, and veins.
47Foramen of posterior cranial fossa Foramen magnum: medulla, the ascending portions of the spinal accessory nerve (XI), and the vertebral arteries.Internal acoustic meatus:facial (VII) and vestibulocochlear (VIII) cranial nervesJugular foramen: internal jugular vein (actually begins here), the glossopharyngeal (IX), the vagus (X) and the accessory (XI) nerves.Anterior condylar (hypoglossal) canal:hypoglossal (XII) nerve.
49Fractures of the Calvaria A depressed skull fracture is a break in a cranial bone (or "crushed" portion of skull) with depression of the bone in toward the brain.A compound fracture involves a break in, or loss of, skin and splintering of the bone.
50Contrecoup (counterblow) fracture No fracture occurs at the point of impact, but one occurs on the opposite side of the cranium.When a moving object impacts the stationary head, coup injuries are typical, while contrecoup injuries are produced when the moving head strikes a stationary object
51Fractures to the Maxilla and associated bones Le Fort I Fracture = Horizontal FractureLe Fort II Fracture = Pyramidal FractureLe Fort III Fractures = Craniofacial Separation
53Raccoon eyes (periorbital ecchymosis ) blood from skull fracture seeps into the soft tissue around the eyesPeriorbital ecchymosis If bilateral, it is highly suggestive of basilar skull fracture They are most often associated with fractures of the anterior cranial fossa