Cranium RTEC 233 Fall 2008 Fall 2008 Week 1 & 2

Cranial Anatomy Calvaria Calvaria Frontal Frontal Occipital Occipital Left Parietal Left Parietal Right Parietal Right Parietal Floor Floor Ethmoid Sphenoid Left Temporal Right Temporal

The regions of the Cranial Floor Anterior: extends form anterior frontal bone to the lesser wings of the sphenoid Anterior: extends form anterior frontal bone to the lesser wings of the sphenoid It is associated with frontal lobes of cerebellum It is associated with frontal lobes of cerebellum Middle: Extends from lesser wings to the apices of petrous ridges of temporal bone Middle: Extends from lesser wings to the apices of petrous ridges of temporal bone Accommodates temporal lobes and associated neurovascular structures Accommodates temporal lobes and associated neurovascular structures Posterior: deep depression posterior to petrous ridge Posterior: deep depression posterior to petrous ridge which protects cerebellum, pons and medulla oblongata which protects cerebellum, pons and medulla oblongata

Frontal Bone Has a vertical and horizontal portion Has a vertical and horizontal portion Vertical portion- forms the forehead and anterior part of the vault Vertical portion- forms the forehead and anterior part of the vault Horizontal portion- forms roof of orbits, part of the roof of nasal cavity, and greater part of anterior cranial fossa. Horizontal portion- forms roof of orbits, part of the roof of nasal cavity, and greater part of anterior cranial fossa.

Parietal Bone Forms large part of sides of the cranium Forms large part of sides of the cranium Forms posterior portion of the cranial floor Forms posterior portion of the cranial floor Parietal eminence is used to measure width of head Parietal eminence is used to measure width of head

Occipital Bone Inferosuperior portion of calvaria Inferosuperior portion of calvaria Squamous portion is superior to inion Squamous portion is superior to inion Ext. occipital protuberance – prominent bulge Ext. occipital protuberance – prominent bulge Contains foramen magnum and articulates with atlas (C1) Contains foramen magnum and articulates with atlas (C1)

Ethmoid Bone Horizontal portion is called cribiform plate Horizontal portion is called cribiform plate Vertical portion is called perpendicular plate Vertical portion is called perpendicular plate 2 light spongy labyrinths 2 light spongy labyrinths

Sphenoid Bone Resembles shape of a bat Resembles shape of a bat Consists of a body, 2 lesser wings, 2 greater wings, 2 pterygoid processes Consists of a body, 2 lesser wings, 2 greater wings, 2 pterygoid processes Contains Sella turcica- important for positioning errors Contains Sella turcica- important for positioning errors

Sella Turcica Lies in the MSP Lies in the MSP ¾” anterior & superior to EAM ¾” anterior & superior to EAM Deformity of the sella is often the only clue that a lesion exists intracranially Deformity of the sella is often the only clue that a lesion exists intracranially

Temporal Bone Divided in 3 parts Divided in 3 parts Squamous: upper portion forming part of the wall of skull Squamous: upper portion forming part of the wall of skull Mastoid: Posterior to EAM contains mastoid tip (process) Mastoid: Posterior to EAM contains mastoid tip (process) Petrous: dense & houses organs of hearing and balance Petrous: dense & houses organs of hearing and balance Thickest most dense bone in cranium Thickest most dense bone in cranium Level of TEA Level of TEA

Superior Cranium Visualized more clearly: Visualized more clearly: Sphenoid Sphenoid Temporals Temporals Occipital Occipital Frontal Frontal Not well visualized: Not well visualized: Ethmoid Ethmoid Parietals Parietals Copyright © 2003, Mosby, Inc.

Lateral Cranium From this view you can visualize all the cranial bones Copyright © 2003, Mosby, Inc.

Infant Sutures & Fontanels Anterior Anterior Close approx 2 years Close approx 2 years 2 Mastoids 2 Mastoids Close approx 2 years Close approx 2 years 2 Sphenoidal 2 Sphenoidal 1-3 months old 1-3 months old Posterior Posterior 1-3 months 1-3 months Copyright © 2003, Mosby, Inc.

Adult Sutures and Junctions Sutures: Sutures: Coronal Coronal Sagittal Sagittal Squamosal Squamosal Lamboidal Lamboidal Junctions Junctions Bregma Bregma Lambda Lambda Pterion Pterion Asterion Asterion Copyright © 2003, Mosby, Inc.

Lets compare Infant Infant Anterior fontanel Anterior fontanel Posterior fontanel Posterior fontanel Sphenoidal fontanels Sphenoidal fontanels Mastoidal fontanels Mastoidal fontanels Adult Adult Bregma Lambda Pterions Asterions

Anterior Cranium Not able to visualize: Not able to visualize: Occipital Occipital Ethmoid Ethmoid Able to visualize: Able to visualize: Parietals Parietals Frontal Frontal Sphenoid Sphenoid Temporals Temporals Copyright © 2003, Mosby, Inc.

Cranial Topography

Surface Landmarks

Skull morphology Mesocephalic: average Mesocephalic: average 47 degrees 47 degrees Brachycephalic: Short and broad Brachycephalic: Short and broad Width 80% or greater than length Width 80% or greater than length 54 degrees 54 degrees Dolichocephalic: long and narrow Dolichocephalic: long and narrow Width is less than 75% than the length Width is less than 75% than the length 40 degrees 40 degrees

Skull Positioning Lines

Skull Topography Glabella Glabella Inner canthus Inner canthus Outer canthus Outer canthus Nasion Nasion Infraorbital margin Infraorbital margin Acanthion Acanthion Gonion Gonion Mental point Mental point External auditory meatus (EAM) External auditory meatus (EAM) Auricular point Auricular point Top of ear attachment (TEA) Top of ear attachment (TEA) Be able to locate the following landmarks:

Radiographic Landmarks Interpupillary line (IPL) Interpupillary line (IPL) Perpendicular line between pupils of eyes Perpendicular line between pupils of eyes Acanthiomeatal line (AML) Acanthiomeatal line (AML) From acanthion to EAM From acanthion to EAM Mentomeatal line (MML) Mentomeatal line (MML) From mental point (center of chin) to EAM From mental point (center of chin) to EAM

Radiographic Landmarks Orbitomeatal line (OML) Orbitomeatal line (OML) From outer canthus to EAM From outer canthus to EAM Infraorbitomeatal line (IOML) Infraorbitomeatal line (IOML) From infraorbital margin to EAM From infraorbital margin to EAM Glabellomeatal line (GML) Glabellomeatal line (GML) From glabella to EAM From glabella to EAM

Positioning Aids Use any straightedge: Straw Pen/pencil

Most Common Positioning Errors Rotation Rotation Tilt Tilt Excessive Flexion Excessive Flexion Excessive Extension Excessive Extension Incorrect CR angle Incorrect CR angle Rotation Tilt Copyright © 2005, Mosby, Inc.

Indications for Cranial Radiography Skull fractures Skull fractures Linear Linear Depressed Depressed Basal skull Basal skull Gunshot wounds Gunshot wounds Pituitary Adenomas Pituitary Adenomas Subdural hematoma Subdural hematoma Neoplasms Neoplasms Metastases Osteolytic Osteoblastic Combo of both Multiple myeloma Multiple myeloma Paget’s Disease Paget’s Disease Acoustic neuroma Acoustic neuroma

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Disinfect the Table or Bucky!!

Cleanliness Hair and skin of face are naturally oily; illness often increases oiliness Hair and skin of face are naturally oily; illness often increases oiliness Cranial procedures require direct contact of patient’s face with VBS Cranial procedures require direct contact of patient’s face with VBS Clean device after each patient Clean device after each patient Wash your hands!!! Wash your hands!!!

Radiation Protection Collimate to anatomy of interest Collimate to anatomy of interest Shield gonads/abdomen of pediatric patients and those of reproductive age Shield gonads/abdomen of pediatric patients and those of reproductive age Shield thyroid and thymus of pediatric patient when doing so will not interfere with demonstration of anatomy of interest Shield thyroid and thymus of pediatric patient when doing so will not interfere with demonstration of anatomy of interest Good communication and positioning skills reduce chance of need for repeat radiographs Good communication and positioning skills reduce chance of need for repeat radiographs

General Body Position Hyposthenic/asthenic patients usually need support at chest to elevate C-spine Hyposthenic/asthenic patients usually need support at chest to elevate C-spine Helps prevent downward tilt of MSP Helps prevent downward tilt of MSP Hypersthenic patients require radiolucent support at head Hypersthenic patients require radiolucent support at head Helps prevent upward tilt of MSP Helps prevent upward tilt of MSP

Hyposthenic/Asthenic Patients

Hypersthenic Patients