Dr. Sami Zaqout, IUG Medical School

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2 The skull The skull is composed of several separate bones united at immobile joints called sutures. Exceptions?

3 Frontal bone Occipital bone Vault Cranium Sphenoid bone Zygomatic bones Base Ethmoid bone Maxillae Temporal bones Nasal bones Bones of the Skull Parietal bones Face Lacrimal bones Palatine bones External tables Inferior conchae Diploë Vomer Internal tables Mandible

4 Frontal bone Nasal bones Vomer Anterior View Ethmoid Inferior conchae Maxillae Zygomatic bone Mandible

5 Frontal bone Superciliary arches Supraorbital notch Frontal air sinuses

6 Nasal bones

7 Nasal Fractures Fractures of the nasal bones, because of the prominence of the nose, are the most common facial fractures. Because the bones are lined with mucoperiosteum, the fracture is considered open.

8 Ethmoid

9 Inferior conchae

10 Maxillae Upper jaw Anterior part of the hard palate Part of the lateral walls of the nasal cavities Part of the floors of the orbital cavities.

11 Paranasal sinuses

12 Maxillofacial Fractures Maxillofacial fractures usually occur as the result of massive facial trauma. There is extensive facial swelling, midface mobility of the underlying bone on palpation. Malocclusion of the teeth with anterior open bite.

13 Fracture of the cribriform plate Cerebrospinal rhinorrhea Maxillofacial Fractures Orbital wall damage Involvement of the infraorbital nerve Diplopia Anesthesia or paresthesia of the skin of the cheek and upper gum Blood enters the maxillary air sinus Nose bleeding

14 Blowout Fractures of the Maxilla A severe blow to the orbit may cause the contents of the orbital cavity to explode downward through the floor of the orbit into the maxillary sinus. Damage to the infraorbital nerve, resulting in altered sensation to the skin of the cheek, upper lip, and gum, may occur.

15 Zygomatic bone

16 Fractures of the Zygomatic Arch Zygomatic arch can be fractured by a blow to the side of the face. Although it can occur as an isolated fracture it may be associated with multiple other fractures of the face.

17 Frontal bone Lateral View Parietal bones Occipital bone Temporal bone Sphenoid bone

18 The Pterion The pterion is the thinnest part of the lateral wall of the skull The pterion is an important area because it overlies the anterior division of the middle meningeal artery and vein.

19 Squamous Tympanic Temporal Bone Mastoid process Styloid process Zygomatic process

20 Temporal fossa & infratemporal fossa

21 Pterygomaxillary fissure laterally Infratemporal fossa Pterygopalatine fossa Sphenopalatine foramen medially Nasal cavity Foramen rotundum superiorly The skull Inferior orbital fissure anteriorly The orbit

22 Posterior View Parietal bones Occipital bone Temporal bone

23 Superior View Frontal bone Parietal bones

24 Maxillae Palatine bones Inferior View Vomer Sphenoid bone Temporal bones Occipital bone

25 Hard Palate Palatal processes of the maxillae Horizontal plates of the palatine bones

26 Body Lesser Wings Sphenoid Bone Greater Wing lateral pterygoid plate Medial pterygoid plate

27 Foramen ovale Foramen spinosum Foramen lacerum Carotid foramen Stylomastoid foramen Jugular foramen

28 The Cranial Cavity Vault of the Skull Base of the Skull Anterior Cranial Fossa Middle Cranial Fossa Posterior Cranial Fossa

29 Anterior Cranial Fossa Boundaries: Anteriorly by the inner surface of the frontal bone. In the midline is a crest for the attachment of the falx cerebri. Posteriorly by the sharp lesser wing of the sphenoid. The median part of the anterior cranial fossa is limited by the groove for the optic chiasma. Lodges the frontal lobes of the cerebral hemispheres.

30 Anterior Cranial Fossa The floor of the fossa is formed by: The ridged orbital plates of the frontal bone laterally The cribriform plate of the ethmoid medially. The upper surface of the cribriform plate supports the olfactory bulbs, and the small perforations in the cribriform plate are for the olfactory nerves.

31 Fractures of the Anterior Cranial Fossa Epistaxis Cerebrospinal rhinorrhea Exophthalmos. Raccoon's sign The frontal air sinus may be involved, with hemorrhage into the nose.

32 Lodges the temporal lobes of the cerebral hemispheres. Middle Cranial Fossa Median part Lateral parts Body of the sphenoid Lesser wings of the sphenoid Superior borders of the petrous parts of the temporal bones Squamous parts of the temporal bones The greater wings of the sphenoid The parietal bones.

33 Lesser Wings Optic canal Optic nerve Superior orbital fissure (Lacrimal, frontal, trochlear) nerves, superior ophthalmic vein (Abducent, oculomotor, nasociliary) nerves Ophthalmic artery Sphenoid Bone Foramen rotundum Maxillary division of the trigeminal nerve Mandibular division of the trigeminal nerve Greater Wings Foramen ovale Lesser petrosal nerve Temporal Bone Foramen lacerum Foramen spinosum Middle meningeal artery Internal carotid artery

34 Right temporal bone, superior view Impression for the trigeminal ganglion. The largest medial groove is for the greater petrosal nerve, a branch of the facial nerve The smaller lateral groove is for the lesser petrosal nerve, a branch of the tympanic plexus. The arcuate eminence: superior semicircular canal. Tegmen tympani

35 Tegmen tympani From behind forward, it forms the roof of the: Mastoid antrum Tympanic cavity Auditory tube. This thin plate of bone is the only major barrier that separates infection in the tympanic cavity from the temporal lobe of the cerebral hemisphere

36 Internal carotid artery The internal carotid artery enters the foramen lacerum through the carotid canal and immediately turns upward to reach the side of the body of the sphenoid bone. Here, the artery turns forward in the cavernous sinus to reach the region of the anterior clinoid process. At this point, the internal carotid artery turns vertically upward, medial to the anterior clinoid process, and emerges from the cavernous sinus.

37 Oculomotor nerve Trochlear nerve Cavernous sinus Structures in the wall Structures within the sinus Ophthalmic division of trigeminal nerve Maxillary division of trigeminal nerve Abducens nerve Internal carotid artery Carotid sympathetic plexus

38 The median part of the middle cranial fossa Sulcus chiasmatis Tuberculum sellae Sella turcica Dorsum sellae Posterior clinoid processes

39 Fractures of the Middle Cranial Fossa Fractures of the middle cranial fossa are common, why? The leakage of cerebrospinal fluid and blood from the external auditory meatus is common. Blood and cerebrospinal fluid may leak into the sphenoidal air sinuses and then into the nose. The seventh and eighth cranial nerves may be involved. The third, fourth, and sixth cranial nerves may be damaged.

40 Posterior Cranial Fossa Anteriorly the fossa is bounded by the superior border of the petrous part of the temporal bone Posteriorly it is bounded by the internal surface of the squamous part of the occipital bone The floor of is formed by the basilar, condylar, and squamous parts of the occipital bone and the mastoid part of the temporal bone. The roof of the fossa is formed by the tentorium cerebelli Lodges parts of the hindbrain

41 Medulla oblongata Foramen magnum Spinal parts of the accessory nerves Two vertebral arteries Hypoglossal canal Hypoglossal nerve Posterior Cranial Fossa Jugular foramen Inferior petrosal sinus 9th, 10th, and 11th cranial nerves Sigmoid sinus Internal acoustic meatus Vestibulocochlear nerve Roots of the facial nerve

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43 Fractures of the Posterior Cranial Fossa Blood may escape into the nape of the neck deep to the postvertebral muscles. The mucous membrane of the roof of the nasopharynx may be torn, and blood may escape there. In fractures involving the jugular foramen, the 9 th, 10 th, and 11 th cranial nerves may be damaged. It does not damage the 12 th cranial nerve, why?

44 Neonatal Skull Has a disproportionately large cranium relative to the face. The bones of the vault are ossified in membrane The bones of the base are ossified in cartilage. Anterior and posterior fontanelles are most important and are easily examined in the midline of the vault.

45 Neonatal Skull The external auditory meatus is almost entirely cartilaginous in the newborn. The tympanic membrane is nearer the surface and faces more inferiorly. The mastoid process is not present at birth. The mandible has right and left halves at birth, united in the midline with fibrous tissue.

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