Anatomy and pattern recognition of the skull, facial bones and teeth

Question 1

Bony anatomy of the skull and associated joints

Answer 1

• Bone classification of the skull
• Cranial bones - mainly flat for cranium
- parietal bones, temporal bones, frontal bone, occipital bone, ethmoidal bone and Sphenoid bone
• Facial bone - irregular
- mandible, maxillary bones, zygomatic bones and orbit

Question 2

Bones of the skull

Answer 2

• Most complex bony structure,
• the skull can be divide into 2 sets of bones, those of the cranium (cranial bones) and Facial bones.
• Most of the skull bones are flat.
• Skull bones in the adult are firmly locked by sutures. Main sutures are Sagittal, Coronal and Lambdoid sutures
• The interior of the skull is divided into 3 fossae, anterior, middle and posterior.
• Provide points of entry and exit to the skull through foramina and fossae

Question 3

Cranial bones

Answer 3

Cranial bones provide:
• muscle attachment
• protection for the brain, and organs of hearing and
balance
Cranium formed by 8 cranial bones:
• Paired
- parietal bones (2)
- temporal bones (2)
• Unpaired
- Frontal bone (1)
- Occipital bone (1)
- Ethmoidal bone (1)
- Sphenoid bone (1)

Question 4

Parietal bones

Answer 4

Form large part of the roof of the cranium (superior and lateral aspect of the skull). Curved and rectangular in shape. The 4 largest sutures occur where the parietal bones articulate.
Articulation
• Frontal bone – Coronal suture
• Parietal bone – Sagittal suture
• Occipital bone – Lambdoid suture
• Temporal bone and Greater wing of sphenoid –
Squamous suture
Features
• Internally contains grooves for middle meningeal
arteries.
• Temporal ridges (superior and inferior)
• Sagittal sulcus

Question 5

Temporal bones

Answer 5

Form the infero–lateral aspects of the skull.
Contains three main regions
• Squamous,
• Tympanic,
• Petromastoid
mastoid,
petrous.

Question 6

Temporal bone squamous region

Answer 6

• Thin portion of bone.
• Articulates with
the parietal bone.
The sphenoid
the mandible
Features
• Zygomatic process, with the zygomatic
bone forms the zygomatic arch.
• Articular fossa
• Articular tubercule

Question 7

Temporal bones tympanic region

Answer 7

Feature
. Externally auditory meatus
. Styloid process

Question 8

Temporal bones mastoid part

Answer 8

Features
• Mastoid process
• Mastoid notch
• Mastoid foramen
• Sigmoid sulcus

Question 9

Sphenoid bone

Answer 9

Butterfly-shaped bone. Spans the with of the middle cranial fossa. Forms the central wedge and as such considered key stone of the cranium.
• Articulates with all the other cranial bones

Question 10

Ethmoid bone

Answer 10

Delicate bone. Contains ethmoid sinuses

Question 11

Facial bones

Answer 11

Form the framework of the face
• Contain cavities for the sense organs (sight, taste, smell)
• Provide opening for food; and air entry and exit
• Secure teeth
• Act as an attachment for muscle

Question 12

Bones of the face

Answer 12

. Inferior nasal concha (Paired) – forms part of nasal cavity
• The vomer (Single) – forms part of nasal septum
• The Nasal bone (Paired) – forms the bridge of the nose
• The Lacrimal bone (Paired) – form part of orbit
• Palatine bone (Paired) – forms part of nasal cavity and a small part of the orbit. Posterior part of hard palate
• Mandible (Paired)
• Maxillary bones (Paired)
• Zygomatic bones (Paired)

Question 13

Maxiallary bones

Answer 13

• All facial bones with the exception of the mandible
articulate with it.
• Form the upper jaw and the central portion of the facial skeleton

Question 14

Zygomatic bones

Answer 14

Irregular shape. Form the cheek commonly referred to as the “cheek bone”

Question 15

Orbit

Answer 15

Formed by
• Frontal bone
• Maxillary bone
• Ethmoid bone
• Lacrimal bone
• Palatine bone
• Lesser wing of sphenoid
• Greater wing of sphenoid
• Zygomatic bone

Question 16

Mandilble

Answer 16

U shaped bone. Largest strongest bone of the face

Question 17

Temporomandibular joint (TMJ)

Answer 17

Type
• Synovial condylar joint
Articular surfaces
• Temporal bone: - anterior part of the mandibular fossa
• Head of the mandible.
Special feature
• Articular disc
Ligaments
• Fibrous capsule
• Temperomandibular ligament
• Sphenomandibular ligament
• Stylomandibular ligament
• Blood supply
• Nerve supply

Question 18

Teeth

Answer 18

• Primary and permanent dentitions have formed by
age 21
• Primary – 20 deciduous teeth that erupt at intervals between 6 and 24 months
• Permanent – enlarge and develop causing the root
of deciduous teeth to be resorbed and fall out
between the ages of 6 and 12 years

Question 19

What are the function of your teeth

Answer 19

. Cut - incisors
• Tear - canines
• Grind food – molar and premolar

Question 20

Depressed skull fracture

Answer 20

Description
• Nearly always the result of trauma
• Part of the skull is pressed into the brain
Causes
• trauma
Symptoms
• Recent trauma and head wound
Treatment
. Surgical management

Question 21

Osteomas

Answer 21

Description
• Benign primary bone tumour
Causes
• Can be associated with some syndromes but aetiology is unknown
Symptoms
• May present as a slow growing mass
Treatment
. They are benign and are only removed if there are causing complications

Question 22

Osteomas diagnosis

Answer 22

Plain film
• Appear as round lesions.
CT
• Appear as round hyper dense lesions.
MRI
• Appearances depend on the amount of bone marrow within the Osteomas but on T1 normally give low signal

Question 23

Skull fractures

Answer 23

Description
• Fracture of a skull vault bone. They are a marker of
the severity of the injury. They can be classified as a
base of skull fracture or skull vault fracture
Causes
• Trauma
Symptoms
• Depends on mechanism of injury
Treatment
. Conservative or surgical depending on severity

Question 24

Pagets disease

Answer 24

Description
• Common metabolic bone disorder which results in extensive bone remodelling
Causes
• Unknown. More common as you age
Symptoms
• Localised pain
• Increased bone size
• Decreased range of motion
Treatment
. Medication to reduce bone growth and improve pain
. Painkillers

Question 25

Skull metastases

Answer 25

Description
• Secondary cancer deposits in the bony skull
Causes
• Common in patients with skeletal metastatic disease
• Cancers that most frequently metastasize are
• Breast, lung, prostate, renal cell, multiple myeloma
Symptoms
• Can cause pressure on the brain leading to seizures
• In 90% of cases there will be bony metastases elsewhere
Treatment
. Many patients are at end of life so palliative care is given. Radiotherapy chemotherapy and surgery can be used

Question 26

Multiple myeloma

Answer 26

Description
• Is a malignant bone neoplasm and the most common in adults
Causes
• Unknown but more common in older age
Symptoms
• Bone pain, anaemia, renal failure
Treatment
. Incurable

Question 27

Facial bone le fort fractures

Answer 27

Description
• Fractures of the midface – which separate the midface from the skull base.
This includes fractures of the pterygoid plates and:
• Nasal fossa
• Inferior orbital rim
• Zygomatic arch
Causes
• trauma
Symptoms
• Pain and visible facial injury

Question 28

Orbital blow out fractures

Answer 28

Description
• Describes a fracture of one of the walls of the orbit.
Causes
• Typically, a fist or ball direct hit
Symptoms
• Air around the eye (orbital emphysema)
• Numbness in the area
• The eye may be slightly displaced
Treatment
• Generally now conservative management
• Surgery if it’s a significant injury with risk of long term vision
problems

Question 29

Mandible fractures

Answer 29

Description
•One of the most common facial fractures (60-70%).
Causes
•Trauma, commonly road traffic collisions
Symptoms
•Patient may be unable to close or open their mouth.
•Pain
Treatment
•Conservative
•If the mandible is displaced the patient may need surgery with / without fixation

Question 30

Dental abscess

Answer 30

Description
. Acute infection of the periodical tissue around the tooth root
Causes
•Damaged tooth enamel allowing bacteria into the tooth
Symptoms
•Pain and swelling.
•Infection symptoms
Treatment
. Antibiotics