4. Introduction: Skull, TM joint Flashcards by Alix Wrighton

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

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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…

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Made up of which 2 types of bone?

Flat and irregular bones

Pneumatised bones

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What are pneumatised bones?

Bones with air spaces (air cells or sinuses) such as the frontal, temporal, sphenoid and ethmoid

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Why are there pneumatised bones in the skull?

to reduce weight & add resonance to our voice

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What are the divisions of the skull?

Mandible
Neurocranium
Viscerocranium

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What is the neurocranium?

Bony case of the brain including cranial meninges with a dome-like roof (calvaria/skullcap) & a floor (cranial base/basicranium)

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What is the viscerocranium (facial skeleton)?

Anterior part of cranium that consists of bones surrounding the oral cavity, nasal cavity & most of the orbit

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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

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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

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Main lateral structural features of the viscerocranium?

Zygomatic arch
Mandible fossa
Infratemporal fossa

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What are the main lateral features of the neurocranium?

External acoustic meatus
Styloid process
Mastoid process
Temporal fossa

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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

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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

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What makes up the calvaria?

4 x flat bones (parietal x 2, single frontal and occiptal)

FUSED by the coronal, sagittal and lambdoid sutures

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What is contained in the granular foveolae?

Arachnoid granulations which return CSF to the venous circulation

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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)

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What type of joint are sutures? Do they allow movement?

Structurally, type of fibrous joint

* Functionally, limited or no movement (synarthrosis)

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Which foramen in the anterior head form divisions of the trigeminal nerve (CN V)

Supra-orbital notch (foramen)
Infra-orbital foramen
Mental foramen

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What are the 4 sinuses?

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Maxillary
Frontal
Ethmoidal
Spenoidal

Clinical importance of the infratemporal fosaa?

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Various muscles & neurovascular structures are found in this space that communicates with the temporal fossa through the interval between (deep to) the zygomatic arch & (superficial to) the cranial bones

Boundaries of the infratemporal fossa?

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Laterally: Ramus of the mandible
Medially: Lateral pterygoid plate of sphenoid bone Anteriorly: Posterior aspect of maxilla
Posteriorly: Tympanic plate, mastoid & styloid processes
Superiorly: Infratemporal crest of sphenoid bone
Inferiorly: Angle of the mandible

Where are the following structures found?
Anterior cranial fossa
Superior border of petrous temporal bone
Posterior cranial fossa
Middle cranial fossa
Sphenoid crest

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Cranial base (from internal base)

Anterior cranial fossa:
Made up of which bones?
Where?
Occupied by?

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Anterior cranial fossa
• Frontal, ethmoid & sphenoid bones
• Shallowest part of cranial base
• Occupied by frontal lobes

 Olfactory bulbs (CN I) receive nerve fibres from the nasal cavity via the foramina of the _______ plate (olfaction) Cribriform plate fractures can present with CSF _______

 Olfactory bulbs (CN I) receive nerve fibres from the nasal cavity via the foramina of the cribriform plate (olfaction)  Cribriform plate fractures can present with CSF rhinorrhoea IN ANT CRANIAL FOSSA

Middle cranial fossa: Made up of which bones? Occupied by?

Middle cranial fossa • Sphenoid & temporal bones • Occupied by temporal lobes

The pituitary gland lies in the ________ (pituitary) fossa (deepest part of sella turcica) The pituitary gland is surrounded by 4 ______ processes & 2 superior projections (____ sellae posteriorly & tuberculum _____ anteriorly)

The pituitary gland lies in the hypophyseal (pituitary) fossa (deepest part of sella turcica) The pituitary gland is surrounded by 4 clinoid processes & 2 superior projections (dorsum sellae posteriorly & tuberculum sellae anteriorly)

Structural features of the sphenoid bone?

``` Supra-orbital fissure Greater wing Lesser wing Sphenoid sinus Dorsum sellae Tuberculum sellae Lateral and medial pterygoid plate (on pterygoid process) ```

Posterior cranial fossa: Made up of which bones? Occupied by?

* Sphenoid, occipital & temporal bones | * Occupied by the cerebellum & brainstem

What makes up the TMJ? Type of joint Interior main feature of joint? Most common dislocation?

Glenoid (mandibular) fossa of temporal bone & condylar process of mandible Modified hinge (atypical) synovial joint Articular surfaces of bone covered with fibrocartilage (not hyaline cartilage) Fibrocartilaginous articular disc separating the joint into superior &inferior articular cavities Anterior dislocation

Ligaments of the TMJ?

2 x extrinsic 1 x intrinsic 1. Sphenomandibular ligament: • Primary passive support of the mandible 2. Lateral ligament: • Strengthens TMJ laterally • With postglenoid tubercle prevent posterior dislocation 3. Stylomandibular ligament

What muscle is involved in protrusion of the mandible?

Lateral pterygoid assisted by medial pterygoid

What muscle is involved in retraction of the mandible?

Posterior fibers of temporalis Deep part of masseter Geniohyoid Digastric

What muscle is involved in elevation of the mandible?

Temporalis Masseter Medial pterygoid

What muscle is involved in despression of the mandible?

Gravity Digastric Mylohyoid muscles

Why is the TMJ most unstable during depression?

As the condylar processes move anteriorly & lie underneath the articular eminences with the mandibular head being vulnerable to anterior dislocation into the infratemporal fossa

Which movements happen in the sup and inf cavity of the TMJ?

Sup: Gliding movements between the temporal bone and articular disc Inf: Hinge and rotational movements between the head of mandible and articular disc

What are the lateral movements of the TMJ>

Grinding and chewing

Name the main foramina of the anterior cranial fossa?

Cribiform foramina in cribriform plate: Axons of olfactory cells in olfactory epithelium that form olfactory

What are the 6 main foramina of the middle cranial fossa?

``` Optic canal Sup orbital fissure Foramen rotundum Foramen ovale Foramen spinosum Foramen lacerum ```

What is contained in the Optic canal

Optic nerves (CNII) and ophthalmic arteries MIDDLE CRANIAL FOSSA

What is contained in the Sup orbital fissure

Ophthalmic veins, ophthalmic nerve (CN V1), CN III, IV and VI and sympathetic fibers MIDDLE CRANIAL FOSSA

What is contained in the Foramen rotundum

Maxillary nerve (CN V2) MIDDLE CRANIAL FOSSA

What is contained in the Foramen ovale

Mandibular nerve (CN V3) and accessory meningeal artery MIDDLE CRANIAL FOSSA

What is contained in the | Foramen lacerum

Deep petrosal nerve and some meningeal arterial branches and small veins MIDDLE CRANIAL FOSSA

What is contained in the Foramen spinosum

Middle meningeal artery and vein and meningeal branch of CN V3 MIDDLE CRANIAL FOSSA

What are the main foramina of the posterior cranial fossa?

Foramen magnum Jugular foramen Hypoglossal canal

What is contained in the foramen magnum?

Medulla and meninges, vertebral arteries, CN XI, dural veins, anterior and posterior spinal arteries

Contents of the hypoglossal canal?

Hypoglossal nerve (CNXII)

4. Introduction: Skull, TM joint Flashcards

(49 cards)