Osteology and radiographic appearance

Question 1

What are fossae?

Answer 1

shallow depressions or hollows

Question 2

What are canals?

Answer 2

bony tunnels that allow blood vessels and cranial nerves through

Question 3

What are foramina?

Answer 3

round holes

Question 4

What are fissures?

Answer 4

narrow slit like holes

Question 5

What is the neurocranium made of?

Answer 5

8 bones that encase and protect the brain

Question 6

What is the base of the neurocranium?

Answer 6

the cranial floor

Question 7

What is the viscerocranium?

Answer 7

14 bones making up the facial skeleton and jaw

Question 8

Where do the viscerocranium bones develop from?

Answer 8

pharyngeal arches and begin as membranes and cartilages that ossify

Question 9

What are the 3 sutures in the brain?

Answer 9

Coronal, sagital and lambdoid

Question 10

What are fontanelles?

Answer 10

• found in the infant skull

- large areas of unossified membranous gaps between flat bones of skull cap(calvaria)

Question 11

What is the role of fontanelles?

Answer 11

Allows for alteration of the skull size and shape during childbirth and allows for growth of the infant brain

Question 12

What are the fontanelles and what do they become?

Answer 12

Anterior fontanelle - bregma

Posterior fontanelle - lambda

Question 13

When do the fontanelle fuse?

Answer 13

Anterior - 18months to 2 yrs

Posterior 3 months

Question 14

What happens if the sutures and fontanelles prematurely fuse?

Answer 14

doesn’t allow head or brain to grow - craniosynostosis (rare)

Question 15

What Fontanelle is clinically useful and why?

Answer 15

anterior because it is normally slightly convex in a healthy baby but if you inspect it and there is bulging, it can be used to a ssess intracranial pressure and state of hydration to see how well the baby is

Question 16

What is the arrangement of bones of the calvaria?

Answer 16

Tri-laminar

• outer table (compact bone)
• Diploe (spongy bone)
• inner table (compact bone)

Question 17

What does the periosteum cover and attached to?

Answer 17

the outer and inner table of skull bones - it is strongly adhered to bone edges at suture line and CONTINUOUS THROUGH SUTURE AND OTO INNER TABLE OF THE SAME BONE

Question 18

What is the cranial floor made from?

Answer 18

3 fosse - anterior, middle and posterior

Question 19

What bones form the anterior cranial floor?

Answer 19

Frontal bone, ethmoid bone, sphenoid bone

Question 20

What bones form the middle cranial floor?

Answer 20

Sphenoid, temporal, parietal

Question 21

What bones form the posterior cranial floor?

Answer 21

occipital and temporal

Question 22

What is significant about the petrous part of the temporal bone?

Answer 22

houses the middle and inner ear structures

Question 23

Why does it take different amounts of force to break different bones in the skull?

Answer 23

Significant trauma and force is required to fracture the skull but due to varying thickness and resistance to force of the bones, varying force is required

Question 24

What intracranial structures are at risk of injury in a skull fractures?

Answer 24

Brain, blood vessels, cranial nerves - can get intracranial pathology, neurological deficits and poorer outcomes with damage to these BUT can still have intracranial injury after a head injury without a skull fracture

Question 25

What is a linear fracture?

Answer 25

straight lined fractures involving no bone displacement

Question 26

What is a comminuted fracture/

Answer 26

multiple fracture lines - fragments may or may not displace inwards towards the brain -they can be depressed (pressing on brain) or non-depressed

Question 27

What is the pterion?

Answer 27

weakest part of the skull where lots of sutures are

Question 28

What bones form the pterion?

Answer 28

parietal, frontal, temporal and sphenoid

Question 29

What is significant about the pterion?

Answer 29

(anterior branch of the) Middle meningeal artery

Question 30

What can happen with blows to the side of the head?

Answer 30

can fracture the bone in the area of the pterion and injure MMA causing intracranial haemorrhage (extra dural)

Question 31

What is a basilar fracture?

Answer 31

Rarer type of fracture to the skull floor but shouldn't be missed

Question 32

What would you see in a patient presenting with a basilar fracture?

Answer 32

Clinical signs will indicate which area of the cranial floor has been damaged "Panda eyes" - Anterior Bleeding from the ear (Hemotympanum) - Middle Bleeding behind ear (battles sign) - posterior

Question 33

What is significant about the maxilla bone?

Answer 33

Starts as 2 parts but fuses to form one

Question 34

What fractures of the face are most common?

Answer 34

Nasal bone, zygomatic bone and arch and mandible are most common - supraorbital ridge on the frontal bone is very tough, won't fracture just skin will split

Question 35

What is significant about a mandibular fracture?

Answer 35

will always fracture in 2 places

Question 36

What is the TMJ?

Answer 36

Temporomandibular joint - articulation between the temporal bone and mandible

Question 37

What type of joint is the TMJ?

Answer 37

Synovial hinge-type joint

Question 38

What conditions of the TMJ can you get?

Answer 38

- TMJ disorder (pain referring to ear, jaw, lateral side of head, clicking, locking) - dislocation (secondary to trauma/yawning) - arthritis

Question 39

What is the TMJ innervated by?

Answer 39

Auriculotemporal nerve (branch of the mandibular division of the trigeminal nerve (CNVc)

Question 40

What are the articular surfaces of the TMJ and what are they lined with?

Answer 40

Articular tubercle and mandibular fossa of the temporal bone - lined with fibrocartilage

Question 41

Why don't the 2 surfaces come in direct contact?

Answer 41

They are separated by a fibrocartilaginous disk

Question 42

What is the TMJ stabilised by?

Answer 42

a joint capsule and 3 extra capsular ligaments

Question 43

What movements does the TMJ do in wide depression and how does it carry them out?

Answer 43

Hinge and gliding 1. hinge - rotation (inferior half of joint cavity) 2. gliding - condyle slides onto the articular tubercle - condyle shouldn't pass in front of the articular process (superior half of joint cavity)

Question 44

How can dislocation of the TMJ occur?

Answer 44

- facial trauma | - yawning

Question 45

How does it present?

Answer 45

jaw locks as joint fixes in open position due to anterior dislocation of condyle over the articular tubercle - contraction of muscles around the joint (muscles of mastication) keep joint locked in anterior displacement

Question 46

What name is given to the space with which the foramen rotunda and foramen oval communicate with?

Answer 46

rotundum - pterygopalatine | ovale - infratemporal

Question 47

Why are CT's more beneficial for patients with head injury than X-rays?

Answer 47

CT's show brain tissue as should be eliminating intracranial haemorrhages or suspected neurological damage after a head injury