4. Introduction: Skull, TM joint Flashcards
For the skull there is only restricted movement at which relations?
Restricted movement only in relation to the mandible at:
- the temporomandibular joint (TMJ)
- the atlanto-occipital joint
Function of the skull?
- Protects the brain, brainstem, cranial nerves & vasculature • Provides attachment for muscles
- Provides a framework for the head
- Gives us our identity as individuals…
Made up of which 2 types of bone?
Flat and irregular bones
Pneumatised bones
What are pneumatised bones?
Bones with air spaces (air cells or sinuses) such as the frontal, temporal, sphenoid and ethmoid
Why are there pneumatised bones in the skull?
to reduce weight & add resonance to our voice
What are the divisions of the skull?
Mandible
Neurocranium
Viscerocranium
What is the neurocranium?
Bony case of the brain including cranial meninges with a dome-like roof (calvaria/skullcap) & a floor (cranial base/basicranium)
What is the viscerocranium (facial skeleton)?
Anterior part of cranium that consists of bones surrounding the oral cavity, nasal cavity & most of the orbit
What bones make up the neurocranium?
8 bones in total….
4 single midline bones: Frontal, ethmoid, sphenoid, occipital
4 bilateral paired bones: Temporal x 2, parietal x 2
What bones make up the viscerocranium?
15 irregular bones..
3 x single midline bones L Ethmoid, vomer and mandible
6 bilateral paired bones: nasal x 2, lacrimal x 2, zygomatic x 2, palatine x 2, maxillae x 2 & inferior nasal conchae x 2
Main lateral structural features of the viscerocranium?
Zygomatic arch
Mandible fossa
Infratemporal fossa
What are the main lateral features of the neurocranium?
External acoustic meatus
Styloid process
Mastoid process
Temporal fossa
Borders of the temporal fossa?
Superior & posterior borders: Superior & inferior temporal lines
Anterior border: Frontal process of zygomatic bone & zygomatic process of frontal bone
Inferior border: Infratemporal crest deep to zygomatic arch
Floor: Includes pterion
Pterion:
- Appearance?
- Made up of which bones?
- Strong or weak?
- Major vascular relation?
- Risk?
- Main result of trauma?
- Location?
• H-shaped junction of sutures
• Frontal, parietal, temporal, & greater wing of sphenoid bone
• Structurally weak (thin) area of the skull
• Overlies anterior branch of
middle meningeal artery
• Vulnerable to injury
• Trauma can lead to extradural (epidural) haematoma
Location: 4cm superior to midpoint of zygomatic arch & 3cm posterior to frontal process of zygomatic bone
What makes up the calvaria?
4 x flat bones (parietal x 2, single frontal and occiptal)
FUSED by the coronal, sagittal and lambdoid sutures
What is contained in the granular foveolae?
Arachnoid granulations which return CSF to the venous circulation
What are frontanelles?
Allows moulding of cranial shape during birth and post natal growth of the brain
By 18 months the corners of frontal and parietal bones fuse (ant frontanelle no longer palpable).
Flat bones are seperated by fibrous membranes that fuse in post-natal life (sutures)
What type of joint are sutures? Do they allow movement?
- Structurally, type of fibrous joint
* Functionally, limited or no movement (synarthrosis)
Which foramen in the anterior head form divisions of the trigeminal nerve (CN V)
Supra-orbital notch (foramen)
Infra-orbital foramen
Mental foramen