H&N4 - Osteology & Radiographic Appearance of the Skull Flashcards Preview

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Flashcards in H&N4 - Osteology & Radiographic Appearance of the Skull Deck (14)
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1
Q

4 features of the neurocranium

Contents
Ossification
Bone Arrangement
Periosteum

A
  1. ) Contents - calvaria (skull cap or vault), cranial floor, and cranial cavity
  2. ) Ossification - vault bones is intramembranous whilst cranial floor bones is endochondral
  3. ) Trilaminar Arrangement - present in vault bones.
    - compact:spongy (diploe):compact bone
    - this provides protective strength w/out adding significant weight
  4. ) Periosteum - covers surface of the outer and inner table of skull bones
    - MMA runs underneath the periosteal layer
2
Q

3 features of the viscerocranium

Ossification
Development
Facial Skeleton Bones x5

A
  1. ) Ossification - intramembranous or endochondral ossification
  2. ) Development - from the pharyngeal arches
  3. ) Facial Skeleton Bones - zygomatic, maxilla, nasal, lacrimal, mandible
3
Q

6 Bones and 3 Joints of Calvaria

A
  1. ) Bones - frontal, parietal (x2), sphenoid, temporal, occipital
  2. ) Joints - serrated, immobile joints known as sutures
    - coronal (frontal and parietal), sagittal, (parietals), lamboid (occipital and parietal)
    - interlocking nature makes it difficult to dislocate
4
Q

6 features of fontanelles

Description
Function
Position
Fusion
Examination
Clinical Condition
A
  1. ) Description - large areas of unossified membranous gaps between flat bones of calvaria
    2.) Function - allow for alteration of the skull size and shape during childbirth and permit growth of infant brain
    3.) Position - anterior = bregma (frontal + parietals)
    posterior = lambda (occipital + parietals)
    4.) Fusion - anterior fuses in 18-24 months, posterior fuses in 1-3 months
    5.) Examination - gentle palpation of anterior fontanelle used to assess intracranial pressure and state of hydration in infants
    - bulging suggests increased intracranial pressure
    - sunken suggests dehydration
    6.) Craniosynostosis - early fusion of fontanelles which affects brain development since no room to grow
5
Q

4 features of the cranial floor

Divisions
Bones making up the divisions

A
  1. ) Divisions - consists of anterior, middle and posterior cranial fossa
  2. ) Anterior Floor - frontal, ethmoid, and sphenoid bone
  3. ) Middle Cranial Floor - sphenoid, temporal, parietal
    - sella turcica is where the pituitary gland sits in the sphenoid bone
  4. ) Posterior Cranial Floor - temporal and occipital bone
    - temporal bone houses inner and middle ear structures
    - contains the large foramen magnum
6
Q

4 features of skull fractures affecting the cranial vault or floor

Injury Risk
Type of Fractures
Common Fracture Location
Basilar Skull Fracture

A
  1. ) Injury Risk - to intracranial structures (brain and neurovasculature)
    - you can still have intracranial injury w/out a skull fracture
  2. ) Fracture Types - linear or comminuted
    - comminuted fragments can be depressed or non depressed (displaced inwards towards the brain)
  3. ) Pterion - thinnest area of the skull so easy to fracture
    - fracture can damage the MMA leading to an extradural haematoma
    - bones forming this region are frontal, parietal, temporal

4.) Basilar Skull Fracture - fracture involving bones of the cranial floor.

7
Q

4 features of facial injuries and fractures

Common Fractures x3
Supraorbital Ridge Injuries
Mandibular Fractures
Imaging

A
  1. ) Common Fractures - nasal, zygomatic, mandible
  2. ) Supraoribtal Ridge Injuries - corner of eye is very tough so doesn’t fracture and just splinters the skin
  3. ) Mandibular Fractures - usually fractures in 2 places
  4. ) Imaging - CT scans are used for skull fractures
8
Q

5 features of the temporomandibular joint (TMJ)

Joint Type
Innervation
Movements x4
Disorders
Dislocation
A
  1. ) Joint Type - synovial hinge joint divided into 2 synovial cavities by fibrocartilaginous disc
  2. ) Innervation - auriculotemporal nerve (mandibular division of trigeminal)
  3. ) Movements - hinge (rotational) action (inferior half), gliding forward action (superior half)
    - retraction and protraction of mandible (gliding action at superior half)
  4. ) TMJ Disorders - often refers to pain in ear, jaw and lateral side of head
    - can also get dislocation and arthritis
  5. ) Dislocation - caused by facial trauma or yawning
    - joint fixes in open position due to anterior dislocation of mandibular condyle over the articular tubercle
    - contraction of muscles around joint keeps it locked in anterior displacement
9
Q

What are the 4 Clinical Signs of a Basilar Skull Fracture?

A
  1. ) Battle’s Sign - bruising over mastoid
  2. ) Raccoon Eyes - (bruising around both eyes)
  3. ) Haemotympanum - (blood behind ear drum)
  4. ) CSF Leakage - nose (rhinorrhoea) or ear (otorrhoea)
10
Q

3 features of note on the frontal bone

A
  • Suparorbital ridge and supraorbital notch (foramen)

- Orbital plate

11
Q

6 features of note on the ethmoid bone

A
  • crsita galli - superior spike
  • cribriform plate - forms roof of nasal cavity
  • cribriform foramina - holes in the cribriform plate
  • perpendicular plate - inferior spike
  • superior and middle conchae - protrudes into the passage of the nose
12
Q

6 features of note on the sphenoid bone

Body
Greater Wing
Lesser Wing
Superior Orbital Fissure
Pterygoid Process
Clinoid Processes
A
  1. ) Sphenoid Body - posterior aspect contains the sella turcica which is a just a depression
    - hypophyseal fossa is the deepest part and is where the pituitary gland sits
  2. ) Greater Wing - contains 3 real foramen and 1 other
    - foramen rotundum (maxillary nerve)
    - foramen ovale (mandibular nerve)
    - first 2 communicates with the pterygopalatine fossa
    - foramen spinosum (MMA and vessels)
    - foramen lacerum (empty)
  3. ) Lesser Wing - contains the optic canal
  4. ) Superior Orbital Fissure - gap formed between the greater and lesser wing
  5. ) Pterygoid Process - consists of lateral and medial plate
  6. ) Anterior and Posterior Clinoid Processes - attachment points for the tentorium cerebelli
    - anterior comes from lesser wing, posterior from sella turcica
13
Q

5 features of note on the temporal bone

Squamous Part
Zygomatic Process
Petromastoid
Tympanic Part
Carotid Canal
A
  1. ) Squamous Part - flat and plate-like located superiorly
    - site of origin of temporalis muscle
  2. ) Zygomatic Process - articulates with temporal process of zygomatic bone forming zygomatic arch
    - forms articular tubercle of TMJ
    - attachment of masseter muscle
  3. ) Petromastoid - posterior and made up of petrous part and mastoid part
    - petrous part houses structures of the middle and inner ear
    - petrous part also surrounds part of foramen lacerum
    - mastoid process is site of attachment of SCM
  4. ) Tympanic Part - leads into external auditory meatus
    - styloid process projects outwards

5.) Carotid Canal - where ICA enters the middle cranial fossa

14
Q

3 features of note on the mandible

A

1.) Body –> Ramus –> Neck and Head (posterior) or Coronoid Process (anterior)

  1. ) Mandibular Foramen - internal surface of the ramus
    - contains inferior alveolar nerve and artery
    - mandibular foramen –> mandibular canal –> mental foramen
  2. ) Mental Foramen - external surface of the body
    - contains mental nerve (continuation of inferior alveloar nerve)