Anatomy, Pathology, and Radiography The Skull Welcome to Anatomy, Pathology, and Radiography of the Skull. Anatomy, Pathology, and Radiography All images copyright Mosby Inc., an affiliate of Elsevier Inc.

Anatomy Cranium The ***skull consists of two parts – the cranium and the facial bones. The cranium is divided into two sections, the floor and the calvaria. The floor of the cranium is made up of the ethmoid, sphenoid, and 2 temporal bones. The calvaria is made of the frontal, occipital, and 2 parietals. ***Orbits are commonly referred to as eye sockets. Each orbit is composed of 7 bones--3 cranial and 4 facial.

Words that end in s have two bones Anatomy Cranium From Parents Encouragement A mnemonic to help you remember the cranium is: From Parents, One Takes Some Encouragement. Each word in this phrase should help you remember one area of the cranium. ***From – Frontal ***Parents – Parietals ***One – Occipital ***Takes – Temporals ***Some – Sphenoid ***Encouragement – Ethmoid Notice that the words that end in “s” have two bones. Some Words that end in s have two bones One Takes

Occipital Bones Anatomy The ***occipital bone is at the back of the cranium. It also wraps under and becomes part of the floor. It contains a large hole, called the ***foramen magnum. This is where the medulla oblongata passes as it exits the cranial cavity and joins the spinal cord. Notice the little ***grey condyles on either side of the foramen magnum. The occipital condyles allow an articulation point for the atlas of the spine.

Anatomy Sphenoid ***Here’s another point to remember: The ***Sphenoid has a Saddle called a Sella turcica (Turkish Saddle) that holds the Super important master gland –the pituitary. The sella turcica lies in the midsagittal plane about ¾ inch superior and ¾ inch anterior to the EAM (external acoustic meatus), so it is close to the center point of the head.

Temporal Bones Anatomy Dolichocephalic Brachycephalic Mesocephalic The ***two temporal bones are quite oddly shaped. If you place your hands over your ears, you will cover most of these bones. Notice the zygomatic process, the mastoid process, the styloid process, and the external acoustic meatus, a.k.a. EAM. These are important landmarks. In the second image, notice the petrous portion of the temporal bone. This will be significant in radiographic images of the skull. It will be referred to as the petrous pyramid, petrous ridges, and petrous portion. The petrous pyramids help to determine skull shape. In ***average or “mesocephalic” skulls, the petrous pyramids will be at 47 degrees from the midsagittal plane. In ***brachycephalic skulls, which are shorter front to back and wider side to side, the ridges are wider too. The pyramids can be found about 54 degrees. Finally, in the longer front to back and narrower side to side ***dolichocephalic skull, the petrous portion will be found at 40 degrees.

Sutures C L a S S Anatomy Coronal (wear a crown on top) Lamdoidal (pat the lamb on the back of the head) L a The fibrous joints connecting most of the cranial bones are called sutures. Remember that sutures have CLaSS. Sagittal (midline) S Squamosal: Push on the head to squish the parietals into the temporals S

Anatomy Fontanels Infants’ cranial bones are not fully developed. These incomplete ossification areas are called ***fontanels. The fontanels primarily align with sutures. There is a special fontanel that resides at the junction of the two parietals and one frontal bone. Perhaps you have noticed the baby’s “soft spot”. This is called the bregma.

Facial Bones Anatomy Virgil Vomer Can Conchae Not Nasal Make Maxilla Mandible Pet Palatine Zebra Zygomatic Laugh Lacrimal What do facial bones and zebras have in common? Here is a fun mnemonic: “Virgil Can Not Make My Pet Zebra Laugh!” Now, every time you see a zebra’s face, you will think of your facial bones! The palatines cannot be seen from this angle. Together with the maxillae, they form the roof of the mouth. Tear ducts pass through the lacrimal foramina in the lacrimal bone. The mandible is the largest and densest bone of the face. The hyoid bone, while not part of the skull, is often discussed in this section because of the location. It is a small, U-shaped structure situated at the base of the tongue.

Anatomy Sinuses The frontal, ethmoidal, sphenoidal, and maxillary bones all have cavities in the bone called paranasal sinuses. Another phrase you might encounter for sinuses is “air cells”.

Click on the correct answer. Anatomy Knowledge Check Parietals Which is the only bone in the skull that doesn’t connect with sutures? Occiput Mandible Maxilla Click to select an answer. Click on the correct answer.

The only bone in the skull that doesn’t connect with sutures is the mandible. Continue

Skull Pathologies Fractures Tumors Mastoiditis Sinusitis Pathology Skull Pathologies Fractures Tumors Mastoiditis Sinusitis TMJ dysfunction From automobile collisions to sports injuries to fist fights, the skull gets radiographed for many types of fractures. The basal fracture occurs at the base of the skull. A blowout fracture is at the base of the orbit. Contre-coup occurs when one side of the head gets hit, but the skull fractures on the opposite side. Think of contre like contrary, or opposite. The tripod fracture involves the zygomatic arch, orbital floor or rim, and dislocation of the frontozygomatic suture. Special kinds of tumors can occur in this area. Acoustic neuroma, for example, is a benign tumor arising from Schwann cells of the 8th cranial nerve. Pituitary adenoma is a tumor arising from the pituitary gland, usually in the anterior lobe. Mastoiditis, which is inflammation of the mastoid antrum and air cells, sinusitis, and temporomandibular joint (TMJ) dysfunction are pathologies exclusive to this area.

Click on the correct answer. Anatomy Knowledge Check Top of skull A blowout fracture occurs at: Base of orbit Base of skull Side of skull Click to select an answer. Click on the correct answer.

A blowout fracture occurs at the base of the orbit. Continue

General Exposure Technique Radiography General Exposure Technique Most skull images require a kVP of 80 and all of them require a 40” SID. Positioning lines and landmarks are crucial for proper positioning of the skull. Here are a few you will need to commit to memory.

Lateral Cranium Radiography Either the upright or semiprone position is utilized for the lateral cranium. With the side of interest closest to the IR, adjust the head so the MSP is parallel to the plane of the IR. A support may be needed under the mandible. The IOML should be perpendicular to the front edge of the IR. The IPL should be perpendicular to the IR. The CR is perpendicular, entering 2” superior to the EAM. Suspend breathing for the exam. The evaluation criteria requires a lot of superimposition with this exam. The orbital roofs, greater wings of sphenoid, mastoid regions, EAMs, and TMJs should all be superimposed with the correct positioning.

PA Axial cranium – Caldwell Method Radiography PA Axial cranium – Caldwell Method The PA cranium and PA axial (Caldwell method) are very similar and visualize similar features. To position the part, make sure the OML is perpendicular to the plane of the IR. The Caldwell method uses a 15 degree caudal angle. This moves the petrous ridges into the lower third of the orbit instead of filling the orbit like the PA would do. The other structures seen with these methods are: posterior ethmoidal air cells, crista galli, frontal bone, and frontal sinuses.

AP Axial Cranium – Towne Method Radiography AP Axial Cranium – Towne Method Memory aid: When you are driving through town, you face forward and stay at 30 mph. Or, you can tip your head up a bit to go a little faster, like 37 mph. The Towne angles depend on the degree of flexion in the neck. If the patient can flex enough to get the OML perpendicular to the IR, use a 30 degree caudal angle on the CR. If the patient is less flexible, position the IOML perpendicular and use a 37 degree angle instead. The Towne method shows a symmetric image of the petrous pyraminds, the posterior portion of the foramen magnum, the dorsum sellae, and posterior clinoid processes projected within the foramen magnum.

PA Axial Cranium – Haas Method Radiography PA Axial Cranium – Haas Method Another essential PA axial image of the cranium requires a very different CR angulation. While the Caldwell method had a caudal angle of 15 degrees, the Haas has a cephalad angle of 25 degrees. With so many similar images, we need to ask the questions: Which? How? Why?

Click on the correct answer. Anatomy Knowledge Check 5 How many bones are in the hand? 8 14 27 Click to select an answer. Click on the correct answer.

There are 27 bones in the hand-- 14 phalanges (in the fingers), 5 metacarpals (in the palm), and 8 carpals (wrist bones) Continue

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