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RT 233 Skull Radiography introducing Zygomatic Arches REVIEW: http://wn.com/Cranial_Facial _bones#/videos Zygomatic Arches Anatomy of Zygomatic Arches Essential Projections Pathology of Zygomatic Arches This is just getting more and more fun ! ! ! Anatomy of Zygomatic Arches Bones Involved, anatomical landmarks Anatomy of Zygomatic Arches The squamous portion of the temporal bone is the thin upper portion. It forms a part of the side of the cranium and has a prominent arched process called the zygomatic process. The zygomatic process projects anteriorly articulating with the zygomatic facial bone, this completes the zygomatic arch. On the inferior border of the zygomatic process is the rounded eminence called the articular tubercle. The articular tubercle forms the anterior boundary of the mandibular fossae. The mandibular fossa receives the condyle of the mandible to form . Anatomy of Zygomatic Articulations 1) zygomatic processtemporal bone 2) Mandibular condyle 3) Articular tubercle 4) zygomatico-temporal sutures 5) zygoma Possible Indications for Zygomatic Arch Imaging 1. 2. 3. 4. 5. 6. Car accident Sports injury Domestic violence, child or elder abuse Blunt trauma Fall Gunshot Essential Projections SMV, Tangential, modified Townes Essential Projections: Zygomatic Arches Submentovertical (SMV) Tangential Anteroposterior (AP) axial (modified Towne) Submentovertical Zygomatic Arches • Patient position – Seated upright or supine – If supine, elevate thorax • Part position – Hyperextend neck to place IOML parallel with IR plane (as much as possible) – Rest head on vertex – MSP perpendicular to IR plane Submentovertical Zygomatic Arches • CR – Perpendicular to IOML – Enters MSP of throat at level 1 inch (2.5 cm) posterior to outer canthi – Center IR and CR • Collimated field – 8 x 10 inches (18 x 24 cm) SMV SMV SMV projection Tangential Zygomatic Arches • Patient position – Seated upright with back against vertical Bucky – Supine with trunk elevated Tangential Zygomatic Arches • Part position – Hyperextend neck and rest head on vertex – IOML as parallel with IR plane as possible – Rotate MSP of head 15 degrees toward side being examined – Tilt top of head 15 degrees away from side being examined – Center zygomatic arch to IR Tangential Zygomatic Arches CR Perpendicular to IOML Centered to zygomatic arch at a point 1 inch (2.5 cm) posterior to outer canthus Centered to IR Collimated field 8 x 10 inches (18 x 24 cm) AP Axial (Modified Towne) Zygomatic Arches Patient position Seated upright or supine Part position MSP perpendicular to midline of grid OML perpendicular to IR plane • May use IOML and increase CR angle to ??° AP Axial (Modified Towne) Zygomatic Arches CR Angled 30 degrees caudad to enter glabella approximately 1 inch (2.5 cm) above nasion If IOML used, angle 37 degrees caudad Center IR and CR Collimated field 8 x 10 inches (18 x 24 cm) Exciting new transitions What about the seeing? beautiful images you’ve been It’s up to you. Pathology of Zygomatic Arches LeFort Fractures, Tripod Fractures, FRACTURES SITES TRIPOD FRACTURE The tripod fracture, also called the zygomaticomaxillary complex or malar fracture, is composed of a set of three (actually 4) fractures. The first portion of the tripod fracture involves the maxillary sinus including the anterior and postero-lateral walls and the floor of the orbit. The second portion involves the zygomatic arch. The third portion involves the lateral orbital rim, usually including the lateral orbital wall, or the fronto-zygomatic suture. The term is actually not accurate as there is a fourth suture that can be involved: between the sphenoid and zygomatic bones. LeFort Fractures LeFort Fractures, Type I, Type II Type III LeFort ___________ Fractures _____________ Zygomatic Arches Isolated Zygomatic Arch Fractures Where is the fracture? Waters view What ??? Name this fracture: Name this fracture: Name this fracture: What is the bone just posterior to the lacrimal bone? What’s Your Message? ZYGOMATIC ARCHES