Module 5

• Cranium and Facial Bones

• Structures of the ear• Sinuses• Orbit

ANATOMIC OVERVIEW

8 Cranial Bones

• 1 x Ethmoid Bone• 1 x Frontal Bone• 1 x Occipital Bone• 2 x Parietal Bones• 1 x Sphenoid Bone • 2 x Temporal Bones

44

• Occipital bone forms the posterior part of the cranium and contains the largest opening of the skull, the foramen magnum

14 Facial Bones

• 2 x Inferior Nasal Conchae

• 2 x Lacrimal Bones• 1 x Mandible• 2 x Maxillae (pl.); Maxilla

(sing.)• 2 x Nasal Bones • 2 x Palatine Bones• 1 x Vomer• 2 x Zygomatic Bones

Facial bones

• Maxilla

- Anterior nasal spine

- Infraorbital foramen

- Maxillary sinuses

- Frontal process

- Zygomatic process

- Alveolar process

- Palatine process– a. Hard palate

• This is an axial CT image obtained at the inferior aspect of the maxillae.

Mandible

-Body

- Gonion

- Ramus

a. Coronoid process

b. Condyloid process

c. Mandibular notch

• Nasal bones– visible in the

midline just inferior to the frontal sinuses

• The middle vomer bone form the bony nasal septum.

The screen image demonstrates a comminuted fracture of the left zygoma on axial CT (left image) and 3-D reconstruction images. These images are essential to the proper treatment of this complex fracture. Note the effect of this facial trauma on the adjacent sinuses and orbit

Facial bones

• This is a coronal section of the face obtained at about the midline of the orbits.

• The facial bones visible are?

http://knol.google.com/k/-/-/pi3gI5WQ/l3TZAw/Ct%20scan-grayscale.gif

Superior View - Base of the Skull

Inferior View – Base of the Skull

1616

• The posterior skull base consists of three bones:– Occipital– temporal – sphenoid

http://waukesha.uwc.edu/lib/reserves/pdf/zillgitt/zoo234/diagrams/unit2/skeletal/ZOO%20234%20Unit%202%20The%20Sphenoid%20Bone.jpg

Sphenoid bone

Temporal Bone

• Squamous portion• Mastoid Portion• Petrous Portion• Temporal styloid

process

Petrous portion of the Temporal bone

• External auditory meatus or auditory canal

• Middle ear or auditory ossicles

• Internal ear contains the– Semicircular canals– Cochela

Structures of the Ear • Protection of the dense

petrous pyramids of the temporal bones.

• Auricle and the external auditory meatus (EAM).

• The tympanic membrane divides the external and middle portions of the ear.

http://images.google.com/imgres?imgurl=http://waukesha.uwc.edu/lib/reserves/pdf/zillgitt/zoo234/diagrams/unit2/skeletal/ZOO%2520234%2520Unit%25202%2520The%2520Sphenoid%2520Bone.jpg&imgrefurl=http://www.waukesha.uwc.edu/lib/reserves/zoo234diagrams.html&usg=__Gp4lfdvLxsIqNsuGB8odU7H_Wzg=&h=561&w=800&sz=97&hl=en&start=4&um=1&tbnid=N0NRMj1rjvbU7M:&tbnh=100&tbnw=143&prev=/images%3Fq%3Dsphenoid%2Bbone%26hl%3Den%26um%3D1

• auditory ossicles are located in the middle ear:– malleus– incus– stapes

• The auditory (Eustachian) tube allows communication between the middle ear and the nasopharynx and mastoid antrum.

• Which cranial bone is the most posterior?

• Which cranial bones are located on the lateral and inferior aspects of the cranium

Paranasal sinuses

Frontal Sinuses • The frontal sinuses are

located in the body portion of the frontal bone.

• The frontal sinuses are particularly susceptible to traumatic injury due to their location.

• The frontal sinuses vary greatly in shape, size, and number from one individual to the next

Maxillary Sinuses

http://www.google.com/imgres?q=maxillary+sinus&hl=en&sa=X&biw=1280&bih=737&tbm=isch&prmd=ivns&tbnid=AYUq0L9VmIoNiM:&imgrefurl=http://www.sinuses.com/ctscan.htm&docid=EemPlZh7ShlNHM&w=640&h=480&ei=WFdaTqSrFdPF0AGKvpSUCQ&zoom=1&iact=hc&vpx=174&vpy=120&dur=1437&hovh=194&hovw=259&tx=145&ty=111&page=1&tbnh=120&tbnw=166&start=0&ndsp=27&ved=1t:429,r:0,s:0

• Found in the body of the maxilla, this sinus has three recesses: – alveolar recess– zygomatic recess – infraorbital recess

Sphenoid Sinuses

The size and shape of the sphenoid varies greatly, but it is consistently located within the body of the sphenoid, just below the sella turcica.

Oftentimes, septa are present that divide the sinus into chambers

Ethmoid Sinuses

• The ethmoid air cells are commonly divided into three groups: – anterior – middle– posterior

Paranasal sinuses The screen

image demonstrates a tumor in the ethmoid sinus.

Coronal Section of Nasal CavityCoronal Section of Nasal Cavity

Sagittal View of Nasal Cavity

Osteomeatal Complex

• The osteomeatal complex is the region where the drainage channels of the paranasal sinuses come together.

• The coronal view is the best to assess the osteomeatal complex

http://www.nyee.edu/images/ent_rss_sts_001.jpg

• Which cranial bone is located in the midline, posterior and inferior to the frontal bone

• Which cranial bones

contain air cells or sinuses?

Sutures

• The sutures of the cranium are actually the articulations, though immovable, between the cranial bones.

• Coronal • Sagittal • Squamous• Lambdoidal

Sutures

Temporomandibular joint

• TMJ, is the only moveable joint of the skull, and its proper function plays an essential role in speech and chewing.

• This is a sagittal CT image of TMJ

Orbit• Composed of portions

of seven bones.– three cranial – four facial,– soft tissue structures

of the eye, i.e., the globe, ocular muscles, and nerves.

The bones of the orbit

• Frontal bone • Maxilla • Palatine • Zygoma • Lacrimal • Ethmoid • Sphenoid

Orbit• Sectional imaging

of the orbit is performed – examine trauma to

the face – demonstrate the

extent and characteristics of masses

– or to aid in the diagnosis of vision problems and eye diseases

• A. The orbit is a paramidal cavity

• B. medial rectus muscle attached to the nasal aspect of the eye ball.

• C. eye ball-orbit • D. optic nerve • E. visible extending to

the posterior and medial towards the optic canal or foramen.

http://www.liv.ac.uk/HumanAnatomy/phd/mbchb/stroke/images/ct2.jpg

• The bony orbit also contains three openings that transmit key nerves and vessels of the eye. These openings are:– Optic canal

(foramen) – Superior orbital

fissure – Inferior orbital fissure

MRI Orbithttp://www.netanatomy.com/RA/ra_frame.htm

http://www.netanatomy.com/RA/ra_frame.htm

Fundamentals of Sectional Anatomy-Chapter 2-pages 81 & 82

Anterior skull

Lateral skull

Sagittal view

Inferior view

http://faculty.washington.edu/chudler/skull3.gif

http://library.thinkquest.org/J0111100/graphics/skull1.JPG