Osteology of the Skull and TMJ Flashcards
2 components of the skull
- Cranium
- Mandible
How many bones form the skull?
22
What type of joint joins most of the bones of the skull?
Sutures
What is the bilateral moveable joint in the skull?
Temporomandibular joint
What is the cranium?
Skull with the mandible removed
2 gross compartments of the cranium
- Neurocranium
- Viscerocranium
What is the neurocranium?
Part of cranium that houses the brain and attendant anatomical structures
What is the viscerocranium?
All parts of cranium that aren’t neurocranium (facial skeleton)
What are the calvaria and skull base?
- Calvaria = upper, box-like bony structure housing brain
- Skull base = base of calvaria articulating with vertebral column
Basic functions of the skull
- Enclose and protect brain and special sense organs
- Create specialised environment for brain to thrive
- Site of attachment for muscles and meninges
What type of bones are the bones of the skull?
Flat bones
3 layers of flat bones of the skull
- Compact bone (outer plate)
- Spongy bone (diploe)
- Compact bone (inner plate)
Which parts of the cranium are very thick?
- Occipital bone
- Frontal bone
Which part of the cranium is very thin?
Pterion
Gross divisions of the calvaria
- Base
- Cap
Main bones of the cranial cap
- Frontal
- Parietal
- Occipital
- Temporal
Suture lines of the cranial cap
- Coronal
- Longitudinal
- Lambdoid
- Bregma (point)
- Lambda (point)
3 fossae of cranial floor
- Anterior
- Middle
- Posterior
Functions of foramina of cranial floor
- Allow passage between intra- and extra-cranial compartments
- Lessen weight of skull
What joint joins the left and right mandibles?
Mental symphysis (midline fibrous joint)
What does the articular disc/meniscus do in the TMJ capsule?
- Separates bony surfaces from making direct contact
- Creates 2 cavities
2 cavities of the TMJ capsule
- Upper cavity
- Lower cavity
What type of movements do the 2 TMJ cavities allow?
- Upper = translational movements (gliding joint)
- Lower = rotational movements (modified hinge joint)
Where do the muscles of mastication receive motor innervation from?
Mandibular division of CNV
4 primary muscles of mastication
- Masseter
- Temporalis
- Lateral pterygoid
- Medial pterygoid
Which muscles of mastication are jaw-depressors?
Lateral pterygoid
Which muscles of mastication are jaw-elevators?
- Masseter
- Temporalis
- Medial pterygoid
Where do muscles of facial expression receive motor innervation from?
Motor division of CNVII
2 categories of muscles of facial expression
- Sphincter muscles
- Muscles of facial expression proper
What do sphincter muscles of facial expression do?
Attend orifices of cavities (eyes, mouth)
What do muscles of facial expression proper do?
Alter facial expression
