1.1 Osteology and Arthrology of the Head

Question 1

Orbitomeatal plane

Answer 1

Inferior margin of orbit and superior margin of ext acoustic meatus in same horizontal plane

Question 2

Parts of the cranium

Answer 2

• Neurocramium

- Viscerocranium

Question 3

Neurocramium

Answer 3

• AKA cranial vault

- Bony base of the brain and meninges

Question 4

What does the neurocranium contain?

Answer 4

Parts of cranial nerves and cranial vasculature

Question 5

Parts of neurocranium

Answer 5

• Calvaria –> skullcap

- Cranial base –> floor (basicranium)

Question 6

Bones of neurocranium

Answer 6

• Frontal
• Ethmoid
• Sphenoid
• Occipital
• Temporal (bilateral)
• Parietal (bilateral)

Question 7

Viscerocranium

Answer 7

Facial skeleton

Question 8

Bones of viscerocranium

Answer 8

Midline
- Mandible
- Ethmoid
- Vomer
Paired
- Maxilla
- Inferior nasal concha
- Zygomatic
- Palatine
- Nasal
- Lacrimal

Question 9

What kind of joint is the temporomandibular joint?

Answer 9

Modified hinge synovial joint

Question 10

Why is the TMJ considered a modified hinge joint?

Answer 10

Articular surfaces are covered by fibrocartilage instead of hyaline cartilage

Question 11

What are the articulating surfaces of the TMJ?

Answer 11

• Head of mandible
• Articular tubercle of temporal bone
• Mandibular fossa

Question 12

What does the articular disc do?

Answer 12

• Divides cavity into 2 separate synovial compartments

- Anterior and posterior bands make the disc biconcave

Question 13

Describe the joint capsule of the TMJ

Answer 13

Loose

Question 14

Where does the fibrous layer of the capsule of the TMJ attach?

Answer 14

• Margins of the articular area on temporal bone

- Around neck of mandible

Question 15

What are the ligaments of the TMJ?

Answer 15

• Lateral ligament
• Stylomandibular ligament
• Sphenomandibular ligament

Question 16

Which TMJ ligaments are instrinsic?

Answer 16

Lateral ligament (AKA temporomandibular l.)

Question 17

Which TMJ ligaments are extrinsic?

Answer 17

• Stylomandibular ligament

- Sphenomandibular ligament

Question 18

What does the lateral ligament do?

Answer 18

• Strengthen TMJ laterally

- Prevent posterior dislocation (along w/ postglenoid tubercle)

Question 19

What is continuous with the lateral ligament?

Answer 19

The thick part of the TMJ joint capsule

Question 20

What does the stylomandibular ligament do?

Answer 20

DOES NOT contribute significantly to strength of TMJ

Question 21

Where does the sylomandibular ligament attach?

Answer 21

• Thickening of parotid gland

- Styloid process to angle of mandible

Question 22

What does the sphenomandibular ligament do?

Answer 22

• Primary passive support

- “Swing rope” of mandible

Question 23

Where does the sphenomandibular ligament attach?

Answer 23

Spine of sphenoid → lingula of mandible

Question 24

Movements of the TMJ

Answer 24

• Elevation/Depression
• Protrusion/Retrusion
• Lateral movements

Question 25

What muscles perform elevation?

Answer 25

Temporalis Massester Medial pterygoid

Question 26

What muscles perform depression?

Answer 26

Lateral pterygoid Suprahyoid Infrahyoid

Question 27

What muscles perform protrusion?

Answer 27

Lateral pterygoid Masseter Medial pterygoid

Question 28

What muscles perform retrusion?

Answer 28

Temporalis | Masseter

Question 29

What muscles perform lateral jaw movements?

Answer 29

Temporalis of same side Pterygoids of opposite side Masseter

Question 30

Describe the arthrokinematics of the TMJ in the superior articular cavity

Answer 30

Depression- mandibular anterior translation | Protrusion- bilateral anterior translation

Question 31

Describe the arthrokinematics of the TMJ in the inferior articular cavity

Answer 31

Depression- mandibular rotation

Question 32

Describe the arthrokinematics of the TMJ during lateral deviation

Answer 32

Contralateral side: anteromedial translation | Ipsilateral side: Posterior translation and rotation

Question 33

What are common fractures of the cranium?

Answer 33

- Depressed fractures - Comminuted fractures - Linear calvarial fractures - Contrecoup (counterblow) fracture - Basilar fracture - Pterion fracture

Question 34

Depressed fractures

Answer 34

- Fragment of bone is depressed inward | - Compresses/injures the brain

Question 35

Comminuted fractures

Answer 35

Bone broken into several pieces

Question 36

Linear calvarial fractures

Answer 36

- Most frequent type - Occurs at point of impact - Fracture lines radiate away in 2+ directions

Question 37

Contrecoup (counterblow) fracture

Answer 37

Fracture occurs on the opposite side of cranium

Question 38

Basilar fracture

Answer 38

- Involves bones forming base of skull - CSF may leak into the nose and ear - CN and blood vessel injury may occur

Question 39

Pterion fracture

Answer 39

- Can be life-threatening - Results from hard blow to side of the head - Vessels may burst, putting pressure on cranium

Question 40

What causes dislocation of the TMJ?

Answer 40

Excessive contraction of lateral pterygoids may cause mandible heads to dislocate anterior to the articular tubercles

Question 41

What is the effect of a dislocation of the TMJ?

Answer 41

Cannot close the mouth

Question 42

What causes arthritis of the TMJ?

Answer 42

Inflammation from degenerative arthritis

Question 43

What is the effect of arthritis of the TMJ?

Answer 43

May result in dental occlusion and joint clicking (from delayed anterior disc movement)