Functional structure of the skull and Fractures of the skull Thickened and thinner parts of the skull = important base for understanding of the functional structure of the skull → - the transmission of masticatory forces - fracture predilection zesílená_místa Thickned parts: § sagittal line § ventral lateral line § dorsal lateral line zesílená_místa Thinner parts: § articular fossa § cribriform plate § foramines, canals and fissures § anterior, medial and posterior cranial fossa § Thickned parts: § tuber parietalis § mastoid process § protuberantia occipitalis ext. et int. § linea temporalis § margin of sulcus sinus: - sagitalis sup. - transversus Functional structure of the skull Facial buttresses system § Of thin segments of bone encased and supported by a more rigid framework of "buttresses" § § The midface is anchored to the cranium through this framework § § Is formed by strong frontal, maxillary, zygomatic and sphenoid bones and their attachments to one another rám_lebka Vertical buttress § nasomaxillary § zygomaticomaxillary § pterygomaxillary Horizontal buttress § glabella § orbital rims § zygomatic processes § maxillary palate Tuber maxillae Sinus maxillae Orbita Nasal cavity § The buttress system absorbs and transmits forces applied to the facial skeleton § § Masticatory forces are transmitted to the skull base primarily through the vertical buttresses, which are joined and additionally supported by the horizontal buttresses § When external forces are applied, these components prevent disruption of the facial skeleton until a critical level is reached and then fractures occur Stress that occurs from mastication or trauma is transferred from the inferior of the mandible via various trajectory lines → to the condyles glenoid fossa → temporal bone The main alveolar stress concentration were located interradicularly and interproximally pilíře_maxilla Fractures of the skull II. Craniofacial fractures I. Neurocranial fractures I. Neurocranial fracture § A break in the skull bone are generally occurs as a result of a direct impact § § If the force and deformation is excessive, the skull fractures at or near the site of impact § § Uncomplicated skull fractures themselves rarely produce neurologic deficit, but the associated intracranial injury may have serious neurologic sequelae 1. Linear skull fracture § Most common, comprising 2/3 of all cases § § Involve a break in the bone but no displacement § § Usually the result of low-energy transfer § Due to blunt trauma over a wide surface area of the skull § Are of little clinical significance Figure 2. Depressed skull fractures A fracture is clinically significant and requires elevation when a fragment of bone is depressed deeper than the adjacent inner table Closed or compound (open) Compound fractures may be exposed when they are associated with a skin laceration or when the fracture extends into the paranasal sinuses and the middle-ear structures Inner lamina is more subjected to compression DepressedSkullFracture49 3. Basilar skull fractures § Basilar fractures are the most serious and involve a linear break in the bone at the base of the skull § § Fractures line often occur at predilection sites (no accidental injury) § § Are often associated with dural tears, of which cerebrospinal fluid (CSF) rhinorrhea and otorrhea are known complications frbase4 frbase3 frbase1 fr frbase2 Symptoms and complications of skull fracture § Otorrhea, rhinorrhea § Battle´s sign § Raccoon eyes § Cranial nerve lesion § § Intracranial hemorrhage: extradural subdural subarachnoideal intracerebral Rhinorrhea Otorrhea Battle%27_sign2 Battle´s sign Raccoon eyes – bilateral ecchymosis Cranial nerve lesion I. (Olfactory n.) - loss of smell (anosomia) II. (Optic n.) - loss of vision, abnormal pupillary reflex III. (Oculomotor n.) - loss of accommodation, lateral strabismus VI. (Abducens n.) - medial strabismus VII. (Facial n.) - paralysis VIII. (Auditory n.) - hearing loss subdural+hematoma+visual NOTE! Extradural = epidural Extradural hemorrhage § An arterial bleed from a middle meningeal artery accumulates and forming a hematoma § § Between the inner skull table and dura matter § § The temporal bone is usually the thinnest part of the skull Subdural hemorrhage § Shears and tears of the small veins that bridge the gap between the dura and the cortical surface of the brain § Between the dura matter and arachnoid § § Common in the elderly, children, and individuals with alcoholism Subarachnoid hemorrhage § A result of a ruptured intracranial arterial aneurysm or trauma § § Beneath arachnoid Intracerebral hemorrhage § A result of a ruptured atheromatous intracerebral arteriole, vasculitis, ruptured intracranial arterial aneurysm, or trauma § § Traumatic intracerebral hemorrhage is usually due to extension of hemorrhage from surface contusions deep into the substance of the brain Subdural2 Subdural ANd9GcRapECmyQFbEgPOLzcBkUr8eA0GTPxE5hGaNoPnQLBKWJ5LLS3KmA large-intracerebral-hemorrhage Intracerebral Subarachnoid Extradural II. Craniofacial Fractures 1. Mandible 2. Lower mid-face 3. Upper mid-face 4. Craniobasal-facial 84611-84613-132 1. Fracture of the mandible Body fractures § Between the distal aspect of the canines and a hypothetical line corresponding to the anterior attachment of the masseter, proximal to the third molar § The actions of the masseter, temporalis, and medial pterygoid muscles distract the proximal segment superomedially § The mylohyoid muscle and anterior belly of the digastric muscle may contribute to the displacing the fractured segment posteriorly and inferiorly frmandib Angle fractures § Occur in a triangular region between the anterior border of the masseter and the posterosuperior insertion of the masseter, distal to the third molar § The actions of the masseter, temporalis, and medial pterygoid muscles distract the proximal segment superomedially Symphyseal and parasymph. fractures § In the midline of the mandible are classified as symphyseal § § When teeth are present, the fracture line passes between the mandibular central incisors § § In the area of the mandible from cuspid to cuspid, but not in the midline, are classified as parasymphyseal Condylar process fractures § Classified as extracapsular, intracapsular and subcondylar § § The lateral pterygoid muscle tends to cause anterior and medial displacement of the condylar head Lower mid-face Upper mid-face 2. Lower midfacial fracture Le Fort I or low horizontal fractures: From nasal septum to the lateral pyriform rims → horizontally above the teeth apices → below the zygomaticomaxillary junction, and traverses the pterygomaxillary junction to interrupt the pterygoid plates Elefort1 3. Upper midfacial fracture a) Naso-orbitoethmoid Fractures b) b) Zygomaticomaxillary Complex c) c) Orbital fractures d) d) Le Fort II e) e) Le Fort III a) Naso-orbitoethmoid Fractures § The NOE complex represents a bony onfluence that separates the nasal, orbital, and cranial cavities (the nasal, frontal, maxillary, ethmoid, lacrimal, and sphenoid bones) § § If there is bilateral comminution an displacement, the nasofrontal ducts are disrupted-predisposes the patient to future mucocele formation § If the fracture segments are displaced, nasal bones and frontal process of the maxilla may be telescoped posteriorly beneath the frontal bone § In patients with comminution, the bony segments may spread medially into the nasal cavity, superiorly to the anterior cranial fossa, and laterally into the orbit § For this reason, high-energy impact may lead to cerebrospinal fluid (CSF) leak, cerebral injury, or globe injuries 1271089-1283798-1852 Telecanthus b) Zygomaticomaxillary Complex § Fracture lines usually run through the infraorbital rim, involve the posterolateral orbit, and extend to the inferior orbital fissure § The fracture line then continues to the zygomatic sphenoid suture area and on to the frontozygomatic suture line § § All zygomatic complex fractures involve the orbit, making visual complications a frequent occurrence c) Orbital Fractures The internal orbital skeleton includes blow-out and blow-in patterns, as seen in isolated fractures of the orbital floor, medial wall, and roof the orbital rim Fractures associated with other fractures of the facial skeleton (zygomaticomaxillary, naso-orbito-ethmoid, frontal-sinus, Le Fort II, and Le Fort III fracture) Orbital apex fractures - associated with damage to the neurovascular structures of the superior orbital fissure and optic canal § Periocular ecchymosis and oedema § The position of the globe should be assessed § Enophthalmos is rarely evident in the first days after injury because of edema of the orbital tissues § A degree of proptosis is evident early § Hypoglobus may be seen with severe floor disruption with a subperiosteal hematoma of the roof § Epistaxis, cerebrospinal fluid leakage, lacrimal drainage problems § Diplopia Blow-out orbital fracture d) Le Fort II fractures (pyramidal) below the nasofrontal suture → the frontal processes of the maxilla → the lacrimal bones and inferior orbital floor and rim → the inferior orbital foramen → the anterior wall of the maxillary sinus → under the zygoma → the pterygomaxillary fissure → the pterygoid plates e) Le Fort III fractures (transverse) The nasofrontal and frontomaxillary sutures → along the medial wall of the orbit → through nasolacrimal groove and ethmoid bones → along the floor of the orbit → along the inferior orbital fissure → through the lateral orbital wall, zygomaticofrontal junction and the zygomatic arch Intranasally: through the base of the perpendicular plate of the ethmoid, through the vomer, and through the interface of the pterygoid plates to the base of the sphenoid lefort3 4. Craniobasal-facial Combinations of different fractures Ø