SKULL Cranium, Facial Bones, and Paranasal Sinuses (PART 1)

Calvarium (Skullcap)

1. Frontal

2. Right parietal (pah-ri′-e-tal)

3. Left parietal

4. Occipital (ok-sip′-i-tal)

Floor

5. Right temporal

6. Left temporal

7. Sphenoid (sfe′-noid)

8. Ethmoid (eth′-moid)

CRANIAL BONES

The eight bones of the cranium are divided into the calvarium (skullcap) and the floor. Each of these two areas primarily consists of four bones

14 FACIAL BONES

2 nasal bones,

2 palatine bones,

2 lacrymal bones,

2 zygomatic bones,

2 maxilla bones,

2 inferior nasal conchae,

1 vomer bone and mandible.

GML

glabellomeatal line; from glabella to EAM

OML

ORBITOMEATAL LINE

IOML

INFRAORBITOMEATAL LINE

AML

ACANTHIOMEATAL LINE

LML

LIPSMEATAL LINE

MML

MENTOMEATAL LINE

GLABELA

It is part of the forehead above the bridge of the nose between eyebrows

NASION

It is the junction of the two nasal bones and the frontal bone

OUTER CANTHUS

It is the junction of the eylid where the upper and lower eyelids meet literally

EXTERNAL OCCIPITAL PROTUBERANCE (ONION)

The onion is the most prominent point of the occipital bone at the junction of the head and neck

ANGLE (GONION)

The gonion refers to the angle of the mandible

EXTERNAL AUDITORY ACOUSTIC MEATUS (EAM)

It is opening of the external ear canal

ORBITOMEATAL LINE (OML) RADIOGRAPHIC BASALINE

It is located between the outer canthus of the eye and the EAM of the ear

INFRAORBITOMEATAL LINE

It is an imaginary line that connects the infraorbital margin to the EAM

Skull fractures

Skull fractures are disruptions in the continuity of bones of the skull.

Linear fractures

are fractures of the skull that may appear as jagged or irregular lucent lines that lie at right angles to the axis of the bone

Depressed fractures

are sometimes called ping-pong fractures. A fragment of bone that is separated and depressed into the cranial cavity can occur

Basal skull fractures

are fractures through the dense inner structures of the temporal bone. These fractures are very difficult to visualize because of the complexity of the anatomy in this area

Gunshot wounds

Gunshot wounds can be visualized by plain images that typically are performed to localize bullets in gunshot victims in an antemortem or postmortem examination

Neoplasms

Neoplasms are new and abnormal growths.

• Osteolytic lesions are destructive lesions with irregular margins.

• Osteoblastic lesions are proliferative bony lesions of increased density (brightness).

• Combination osteolytic and osteoblastic lesions have a "motheaten" appearance of bone because of the mix of destructive and blastic lesion

Multiple myeloma

In multiple myeloma, one or more bone tumors originate in the bone marrow. The skull is a commonly affected site

Pituitary adenomas

Plain radiographic images may demonstrate enlargement of the sella turcica and erosion of the dorsum sellae, often as an incidental finding

Paget's disease (osteitis deformans)

is a disease of unknown origin that begins as a stage of bony destruction followed by bony repair. destructive stage, and a "cotton-wool" appearance, increased density (sclerosis) shows reparative stage.

Mastoiditis Acute mastoiditis

is a bacterial infection of the mastoid process that can destroy the inner part of the mastoid process. Mastoid air cells are replaced with a fluid-filled abscess, which can lead to progressive hearing loss.

Neoplasms

are new and abnormal growths (tumors)

Acoustic neuroma

Acoustic neuroma refers to a benign tumor of the auditory nerve sheath that originates in the internal auditory canal. Symptoms include hearing loss, dizziness, and loss of balance.

Cholesteatoma

is a benign, cystlike mass or tumor that is most common in the middle ear or mastoid region secondary to trauma to this region.* It destroys bone, which can lead to serious complications, including hearing loss.

Polyp

is a growth that arises from a mucous membrane and projects into a cavity (sinus). It may cause chronic sinusitis.

Otosclerosis

is a hereditary disease that involves excessive spongy bone formation of the middle and inner ear. It is the most common cause of hearing loss in adults without eardrum damage

Blowout fracture

is a fracture of the floor of the orbit caused by an object striking the eyes straight on. As the floor of the orbit ruptures, the inferior rectus muscle is forced through the fracture into the maxillary sinus, causing entrapment and diplopia (perception of two images).

Tripod fracture

is s caused by a blow to the cheek, resulting in fracture of the zygoma in three places—orbital process, maxillary process, and arch. The result is a "free-floating" zygomatic bone, or a tripod fracture

Le Fort

fractures are severe bilateral horizontal fractures of the maxillae that may result in an unstable detached fragment

Contrecoup

fracture is a fracture to one side of a structure that is caused by an impact on the opposite side. For example, a blow to one side of the mandible results in a fracture on the opposite side.

Sinusitis

is an infection of the sinus mucosa that may be acute or chronic. The patient complains of headache, pain, swelling over the affected sinus, and possibly a low-grade fever.

Secondary osteomyelitis

an infection of the bone and marrow secondary to sinusitis, results in erosion of the bony margins of the sinus.

TMJ

syndrome describes a set of symptoms, which may include pain and clicking, that indicate dysfunction of the TMJ. This condition may be caused by malocclusion, stress, muscle spasm, or inflammation.