Mastoid Process

Prone; MSP & IOML parallel, IPL perpendicular

1 ORIGINAL LAW METHOD AXIOLATERAL OBLIQUE Patient Position:

2 in. posterior & 2 in. superior to uppermost EAM

1 ORIGINAL LAW METHOD AXIOLATERAL OBLIQUE Reference point

15° caudad & 15° anterior

1 ORIGINAL LAW METHOD AXIOLATERAL OBLIQUE Central ray

• Auricle

• Mastoid antrum

• Mastoid air cells

• Superimposed internal and external acoustic meatuses

• Mandibular condyle

• Mastoid process

1 ORIGINAL LAW METHOD AXIOLATERAL OBLIQUE Structure shown:

25° caudad & 20° anterior

ORIGINAL LAW METHOD AXIOLATERAL OBLIQUE range Recommendations:

Prone; MSP 15°

LAW METHOD AXIOLATERAL OBLIQUE patient position

2 in. posterior & 2 in. superior to uppermost EAM

LAW METHOD AXIOLATERAL OBLIQUE Reference point

15° caudad

LAW METHOD AXIOLATERAL OBLIQUE Central ray

• Auricle

• Internal and external acoustic meatuses

• Mastoid air cells

• Mastoid process

• Mandibular condyle

LAW METHOD AXIOLATERAL OBLIQUE Structure shown:

Semi-prone; MSP 15°; IPL 15°

2 ORIGINAL LAW METHOD AXIOLATERAL OBLIQUE Patient Position:

2 in. posterior & 2 in. superior to uppermost EAM

2 ORIGINAL LAW METHOD AXIOLATERAL OBLIQUE Reference point

15° caudad & 15° anterior

2 ORIGINAL LAW METHOD AXIOLATERAL OBLIQUE Central ray

• Mastoid cells

• Sigmoid sinus

• Lateral portion of pars petrosa

• Tegmen tympani

• Superimposed internal & external auditory meatuses

• Mastoid emissary vessel

2 ORIGINAL LAW METHOD AXIOLATERAL OBLIQUE Structure shown:

Supine; MSP 55° IR or 35° vertical, IOML perpendicular, IR caudally 15°

MODIFIED HICKEY METHOD AP TANGENTIAL Patient Position:

1 in. superior to tip of mastoid process

MODIFIED HICKEY METHOD AP TANGENTIAL Reference point

15° caudad

MODIFIED HICKEY METHOD AP TANGENTIAL Central ray

• Mastoid process

• occipital bone

MODIFIED HICKEY METHOD AP TANGENTIAL Structure shown:

Prone; IR cranially 15°, MSP 55° IR or 35° vertical, IOML perpendicular

PA TANGENTIAL Patient position

1 in. superior to tip of mastoid process

PA TANGENTIAL Reference point

15 degrees cephalad

PA TANGENTIAL Central ray

• Mastoid process

• occipital bone

PA TANGENTIAL Structure shown

Supine; OML/IOML & MSP perpendicular

TOWNE METHOD AP AXIAL PROJECTION Patient Position:

2 in. above glabella or 2.5 in. above nasion

TOWNE METHOD AP AXIAL PROJECTION Reference point

30° caudad (OML perpendicular; 37° caudad (I0ML perpendicular)

TOWNE METHOD AP AXIAL PROJECTION central ray

• Internal auditory canals

• Petrous portion of temporal bone

• Labyrinths

• Mastoid antrum

• Middle ears

• Dorsum sellae w/in foramen magnum

TOWNE METHOD AP AXIAL PROJECTION Structure shown:

Semiprone; MSP parallel , IPL perpendicular, IOML parallel

HENSCHEN, SCHULLER, & LYSHOLM METHOD AXIOLATERAL PROJECTION Patient Position:

Dependent EAM

HENSCHEN, SCHULLER, & LYSHOLM METHOD AXIOLATERAL PROJECTION Reference point

• 15° caudad (Henschen/Cushing)

• 25° caudad (Schuller)

• 35° caudad (Lysholm/Runstrom II)

HENSCHEN, SCHULLER, & LYSHOLM METHOD AXIOLATERAL PROJECTION Central ray

• Mastoid & petrous portion

• Mastoid cells, mastoid antrum, IAM & EAM & tegmen tympani (Henschen)

• Tumors of the acoustic nerve (Cushing)

• Pneumatic structures of mastoid process, mastoid antrum, tegmen tympani, IAM & EAM, sinus & dural plates & mastoid emissary (Schuller)

• Mastoid cells, mastoid antrum, IAM & EAM, tegmen tympani, labyrinthine area & carotid canal (Lysholm/Runstrom Il)

HENSCHEN, SCHULLER, & LYSHOLM METHOD AXIOLATERAL PROJECTION Structure shown:

Exposure made with open mouth

HENSCHEN, SCHULLER, & LYSHOLM METHOD AXIOLATERAL PROJECTION Runstrom Recommendation: