Skull Baselines PDF

Radiographic Procedures II Skull Part 1 – Baselines Jena Heflin, MBA, RT(R), CMOM Skull  Located superior to the vertebral column  22 separate skull bones  Divided into 2 distinct groups  Cranial Bones  Facial Bones 1 Cranial Bones (8)  Calvaria (4) Frontal  Occipital  Right Parietal  Left...

Radiographic Procedures II Skull Part 1 – Baselines Jena Heflin, MBA, RT(R), CMOM Skull  Located superior to the vertebral column  22 separate skull bones  Divided into 2 distinct groups  Cranial Bones  Facial Bones 1 Cranial Bones (8)  Calvaria (4) Frontal  Occipital  Right Parietal  Left Parietal   Floor (4) Ethmoid  Sphenoid  Right Temporal  Left Temporal  ***Calvaria is also known as the Skull Cap Facial Bones (14)         Nasal (2) Lacrimal (2) Maxillary (2) Zygomatic (2) Palatine (2) Inferior Nasal Conchae (2) Vomer (1) Mandible (1) 2 Function  Cranial Bones   Form a protective housing for the brain Facial Bones Provide structure, shape, and support for the face  Form a protective housing for upper respiratory and digestive tracts  Skull Sutures  Coronal Suture   Sagittal Suture   Found between the two parietal bones Squamosal Suture   Found between the frontal and parietal bones Found between the temporal bones and the parietal bones Lambdoidal Suture  Found between the occipital bone and the parietal bones 3 Skull Sutures Junction of the coronal and sagittal sutures: Bregma  Junction of the lambdoidal and sagittal sutures: Lambda  Skull Sutures 4 Skull Sutures Newborn Skull Thin, underdeveloped bones  Six areas of incomplete ossification called fontanels  5 Fontanels (6)  Anterior Fontanel (1)   Posterior Fontanel (1)   Closes in the 1st month after birth Sphenoidal Fontanel (2)   Closes during the 2nd year of life Closes in the 3rd month after birth Mastoid Fontanel (2)  Closes during the 2nd year of life Fontanels 6 Skull Development Rapidly during first 5 – 6 years  Gradually until adult size and density achieved   Usually by 12 years old Oval in shape  Wider in back than in front  Approx. 6 in. or 15 cm. at its widest point  Approx. 7 in. or 19 cm. at its longest point  Approx. 9 in. or 23 cm. at its deepest point  Skull Morphology Describes size and shape of skull  Width - Average measurement between the two parietal eminences  Length - Average measurement from the frontal eminence to the external occipital protuberance  Depth - Average measurement from the vertex to beneath the chin  7 Skull Morphology 6 in 9 in Skull Morphology  Mesocephalic Average size and shape  Petrous pyramids form a 47º angle with the MSP  Width is between 75% - 80% of length  8 Skull Morphology  Brachycephalic Short from front to back, broad sides, shallow from vertex to base  Petrous pyramids form a 54º angle with the MSP  Width is 80% or greater than length  Skull Morphology  Dolichocephalic Long from front to back, narrow sides, deep from vertex to base  Petrous pyramids form a 40º angle with the MSP  Width less than 75% of length  9 Skull Topography Collection of points or planes that can be seen or palpated  Used for accurate positioning of the skull  Include:  Body Planes  Surface Landmarks  Skull Positioning Baselines  Skull – Body Planes  Midsagittal Plane (MSP) a.k.a. Median Plane  Divides body into left and right halves   Interpupillary Line (IPL) a.k.a. Interorbital Line  Line connecting the pupils or the outer canthi of the eyes  10 Skull – Surface Landmarks        Superciliary Ridge Supraorbital Groove Glabella Nasion Acanthion Gonion (Angle) Mental Point Skull – Surface Landmarks  Ear Auricle or Pinna  Tragus  Top of ear attachment (TEA)   Corresponds to level of petrous ridge on each side 11 Skull – Surface Landmarks  Eye Inner Canthus  Outer Canthus  Supraorbital Margin (SOM)  Infraorbital Margin (IOM)  Midlateral Orbital Margin  Skull - Baselines  Lines formed with the External Auditory Meatus (EAM) as the base Glabellomeatal Line (GML)  Orbitomeatal Line (OML)  Infraorbitomeatal Line (IOML)  Acanthiomeatal Line (AML)  Mentomeatal Line (MML)  12 Skull - Baselines  Glabellomeatal Line (GML)    Line between the Glabella and EAM Glabella – smooth area between and slightly superior to the eyebrows; above the bridge of the nose Not as precise as other baselines (area vs. point) Skull - Baselines  Orbitomeatal Line (OML)   Line between outer canthus and EAM Outer Canthus – lateral junction of the upper and lower eyelids   a.k.a Midlateral Orbital Margin 8º angle difference between OML and GML 13 Skull - Baselines  Infraorbitomeatal Line (IOML)     Line between infraorbital margin and EAM a.k.a. Reid’s baseline & Anthropologic baseline Infraorbital margin – inferior rim of the orbit 7º angle difference between OML and IOML Skull - Baselines  Acanthiomeatal Line (AML)   Line between acanthion and EAM Acanthion – midline point at junction of upper lip and nasal septum   Literally means “little thorn” Used in radiography of facial bones 14 Skull - Baselines  Mentomeatal Line (MML)   Line between mental point and EAM Mental Point – midpoint of chin   Mentum = Chin Used in radiography of facial bones Skull - Baselines  Inion Most prominent point of the external occipital protuberance  Extension of IOML posteriorly  Inion 15 Skull - Baselines  Glabelloalveolar Line (GAL) Connects glabella to anterior aspect of alveolar process  Used in imaging nasal bones  Review A C B D H E F K I J G 16 Review M L O P N T Q R S U Review B E A F C D 17 Assignment See course schedule for reading assignment  Skull Worksheet  Section 1: Exercise 5, 7  Section 2: Exercise 1   Start reviewing positioning notes 18