Osteology of H&N

Question 1

What is the cranium divided into and how many bones are in each part

Answer 1

Neurocranium - 8 bones

Viscerocranium - 14 bones

Question 2

What does the neurocranium consist of

Answer 2

Calvaria

Cranial floor

Cranial cavity

Question 3

What are the bones of the calvaria

Answer 3

Parietal

Occipital

Frontal

Sphenoid

Temporal

Question 4

What structures are found between calvaria bones - what do they do and what are their names

Answer 4

Sutures join calvaria bones together

Coronal, sagittal and lambdoid sutures

Sutures are serrated, immobile fibrous joints that interlock to make it hard for the bones to dislocate

Question 5

What are found at the joining of suture lines - name and describe them

Answer 5

Fontanelles

Anterior fontanelle - between coronal and sagittal. Fuses to form bregma

Posterior fontanelle - between sagittal and lambdoid. Fuses to form lambda

Question 6

What is the importance of the fontanelles

Answer 6

Allow for alteration of the skull during childbirth so it can fit through the birth canal

Allows for growth of infant brain

Question 7

Describe the structure of the calvaria bones

Answer 7

Inner and outer table layers of compact bone separated by the diploe (spongy bone)

Question 8

What happens if an artery between the inner table and periostium is damaged and haemorrhage occurs

Answer 8

Blood from the artery causes the periostium to strip away from the inner table as far as the margins of the bone sutures

This results in extra-dural haemorrhage

Question 9

What is the pterion and why is it significant

Answer 9

Pterion is the thinnest part of the calvaria where many suture lines join - on lateral sides

It is significant as a # at this site may injure the anterior branch of the middle meningeal artery

Question 10

How is the cranial floor divided

Answer 10

Floor is divided into anterior, middle and posterior cranial fossae

Question 11

What are the bones of the cranial floor - what structures are found on the bones

Answer 11

Frontal bone - orbital plates, gap for ethmoid, supraorbital ridge

Ethmoid bone - cribriform foramina and cribriform plate

Sphenoid bone - lesser and greater wings, body, sella turcica

Temporal bones - petrous

Occipital bone - foramen magnum

Question 12

What bones form the viscerocranium

Answer 12

Nasal bones

Zygomatic bones

Maxilla bones

Mandible

Lacrimal bones

Vomer

Palatine bones

Inferior nasal conchae

Question 13

What is the supraciliary arch

Answer 13

Sharp bony ridge lying just above the orbital margin

Question 14

What are the types of intracranial haematomas

Answer 14

Epidural

Extradural

Subdural

Question 15

Describe the types of skull fractures

Answer 15

Linear # - single line away from point of injury. No bone displacement

Comminuted # - multiple # lines with fragments. Fragments may or may not displace inwards towards brain - depressed vs non-depressed

Question 16

What is a basilar skull fracture

Answer 16

of the cranial floor

Occurs when significant force is transmitted through the vertebral column to the skull base, fracturing the cranial floor

Question 17

What are the signs of a basilar skull fracture

Answer 17

Battle’s sign

Raccoon eyes

Haemotympanum

CSF rhinorrhoea

CSF otorrhoea

Epistaxis

Question 18

What are the common facial bones to fracture

Answer 18

Nasal bones

Zygomatic bones

Mandible

Question 19

What should you do when looking at an x-ray of a fractured mandible

Answer 19

Look for more than one fracture line - there will normally be more than one # line if mandible #ed

Question 20

If trauma occurs to supraorbital ridge or supraciliary arch, what will be seen

Answer 20

Splitting of the skin as these areas are very tough so are unlikely to fracture

Question 21

What osteological features are found on the fronal bone

Answer 21

Supraorbital ridge

Supraorbital notch/foramen

Orbital plate

Question 22

What osteological features are found on the ethmoid bone

Answer 22

Crista galli

Cribriform plate

Perpendicular plate

Superior and middle conchae

Cribriform foramina

Question 23

What osteological features are found on the sphenoid bone - name structure which pass through

Answer 23

Body

Lesser and greater wings

Clinoid processes

Sella turcica

Hypophyseal/pituitary fossa

Pterygoid processes

Superior orbital fissure - occulomotor nerves and muscles run through

Optic canal - optic nerves pass through

Foramen rotundum - maxillary branch of trigeminal

Foramen ovale - mandibular branch of trigeminal

Foramen spinosum - middle meningeal artery

Question 24

What osteological features are found on the temporal bone

Answer 24

Squamous part

Zygomatic process

Petrous part

Mastoid process

Styloid process

Articular fossa for mandible

External and internal auditory meatus

Foramen lacerum

Carotid canal

Stylomastoid foramen

Question 25

What osteological features are found on the occipital bone

Answer 25

External occipital protuberance

Superior nuchal line

Articular condyles for atlas (Occipital condyles)

Clivus

Foramen magnum

Hypoglossal canal

Jugular foramen

Question 26

What osteological features are found on the mandible

Answer 26

Body

Ramus

Angle

Coronoid process

Condylar process

Mental protuberance

Mental foramen

Mandibular foramen

Question 27

What three fossa are found on the lateral sides of the skull

Answer 27

Temporal fossa

Infra-temporal fossa

Pterygopalatine fossa

Question 28

What bones make up the skull

Answer 28

Spenoid bone

Zygomatic bones

Lacrimal bones

Temporal bones

Occipital bone

Frontal bone

Nasal bones

Mandible

Maxillae

Ethmoid bone

Vomer

Parietal bones

Palatine bones

Inferior nasal conchae