Lecture 5- Skull, facial bones Flashcards
what is the bone classification of the skull?
cranial bones- mainly flat or cranium
facial bones- irregular
give examples of cranial and facial bones
cranial- parietal bones, temporal bones, frontal bone, occipital bone, ethmoidal bone and Sphenoid bone
facial- mandible, maxillary bones, zygomatic bones and orbit
what are some features of bones of the skull
-most complex bone structure
-divided into cranial and facial
-most of the skull bones are flat
-skull bones in adults are locked by sutures, main ones are coronal, sagittal and lambdoid.
-interior of skull divided into 3 fossae- ant, middle, post.
- this provides points of entry and exit through foramina and fossae
what do cranial bones proivde
-muscle attachment
-protection for the brain and organs of hearing and blalance
the cranium is formed by 8 cranial bones, paired and unpaired.
what are these?
Paired
parietal bones (2)
temporal bones (2)
Unpaired
Frontal bone (1)
Occipital bone (1)
Ethmoidal bone (1)
Sphenoid bone (1)
what are parietal bones
Form large part of the roof of the cranium (superior and lateral aspect of the skull). Curved and rectangular in shape. The 4 largest sutures occur where the parietal bones articulate.
parietal bone articulation
Articulation
Frontal bone – Coronal suture
Parietal bone – Sagittal suture
Occipital bone – Lambdoid suture
Temporal bone and Greater wing of sphenoid – Squamous suture
what are 3 features of parietal bones
Features
Internally contains grooves for middle meningeal arteries.
Temporal ridges (superior and inferior)
Sagittal sulcus
what is the occipital bone
Forms posterior wall of the skull
Internally forms the posterior cranial fossa
Divided into 3 parts - Squamous, lateral and basilar
what are some external features of the occipital bone?
- External occipital protruberence
- External occipital crest
- Occipital condyle
- Superior nuchal line
- Median nuchal line
- Inferior nuchal line
what are some internal features of the occipital bone?
- Internal occipital protruberence
- Internal occipital crest
- Transverse sulcus - groove for transverse sinus.
- Groove for sigmoid sinus
- Jugular process
what does the occipital bone articulate with?
Parietal bone
Temporal bone
Sphenoid bone
1st cervical vertebra
what is the frontal bone?
-dome shaped
-forms anterior part of cranium and roof of orbits
-forms most of anterior cranial fossa
what are soem ext. features of the frontal bone?
- superior orbital foramina
- supercilliary arches
- glabella- smooth area between orbits
- contains frontal sinus
- zygomatic process
- nasal spine
- temporal line
what are some int. features of the frontal bone?
- ethmoid notch
- sagittal sulcus
- frontal crest
what does the frontal bone articulate with?
- parietal bone at conoral suture
- nasal bones
- zygomatic bone
- greater & lesser wings of sphenoid
- ethmoid bone
- maxillary bone
- lacriomal bone
what is the temporal bone and what 3 main regions does it contain?
- froms infero-lateral aspects of skull
- regions:
- squamous
- tympanic
- petromastoid: mastoid and petrous
what is the sqamous region of the temporal bone and name some features
Thin portion of bone.
Articulates with
the parietal bone.
The sphenoid
the mandible
Features
Zygomatic process, with the zygomatic bone forms the zygomatic arch.
Articular fossa
Articular tubercule
what are some features of the tympanic region of the temporal bones
extenral auditory meatus
styloid process
what are some features od the mastoid part of the temporal bones
Mastoid part
Features
* Mastoid process
* Mastoid notch
* Mastoid foramen
* Sigmoid sulcus
what is the petrous part of the temporal bone and what does it articulate with?
Petrous
Looks like a miniature mountain ridge.
Posterior slope lies in the posterior cranial fossa. Anterior slope is in the middle cranial fossa
Articulates with the
Occipital bone posteriorly
Sphenoid bone anteriorly
what are some features of the petrous part of the temporal bone?
Features
Contains middle and inner ear cavities. Housing organs of hearing and balance.
Arcuate eminence
Internal auditory meatus
Stylomastoid foramina
Carotid canal
Jugular fossa
Foramen lacerum
what is the sphenoid bone and what does it consist of?
Butterfly-shaped bone. Spans the with of the middle cranial fossa. Forms the central wedge and as such considered key stone of the cranium.
Articulates with all the other cranial bones
The sphenoid bone consists of
* Body centrally (contains sphenoid sinus) Posterior aspect forms the dorsum sellea that culminate to the posterior cliniod processes
* Greater wing of sphenoid
* Lesser wing of sphenoid project posteriorly to form the anterior clinoid processes
* Pterygoid processes – project inferiorly from body, anchor muscle for chewing
what are some features of the sphenoid bone?
- Sella turcica (Pituitary fossa) Hollowed out forming a deep depression.
- Anterior clinoid processes
- Posterior clinoid processes
- Optic foramina
- Optic groove
- Foramen ovale
- Foramen spinosum
- Foramen rotundum
- Superior orbital fissure
- Pterygoid canal
what is the ethmoid bone?
and name some features
Delicate bone. Contains ethmoid sinuses
Features
Cribiform plate – forms roof of nasal cavity. Punctured by tiny holes called olfactory foramina allow the passage of olfactory nerves to the smell receptors in the nasal cavity in the brain.
* Perpendicular plate* – forms superior part of nasal septum.
*Lateral mass *– either side of the perpendicular plate containing ethmoid sinuses
Crista gali – projects superiorly from the cribiform plate is a process. Dura mater outer covering of the brain is attached to this area, helps secure the brain.
what does the ehtmoid bone articulate with?
Articulates with
Sphenoid bone
Frontal bone
Lacrimal bone
Palatine bone
Vomer
Nasal bone
Maxilla
what are facial bones?
Form the framework of the face
Contain cavities for the sense organs (sight, taste, smell)
Provide opening for food; and air entry and exit
Secure teeth
Act as an attachment for muscle.
provide some examples of facial bones
Inferior nasal concha (Paired) – forms part of nasal cavity
The vomer (Single) – forms part of nasal septum
The Nasal bone (Paired) – forms the bridge of the nose
The Lacrimal bone (Paired) – form part of orbit
Palatine bone (Paired) – forms part of nasal cavity and a small part of the orbit. Posterior part of hard palate
Mandible (Paired)
Maxillary bones (Paired)
Zygomatic bones (Paired)
what are maxillary bones?
All facial bones with the exception of the mandible articulate with it.
Form the upper jaw and the central portion of the facial skeleton
what are some features of maxillary bones?
Features
Alveolar margin - contains sockets in which the upper teeth are embedded.
Palatine process – forms anterior part of the hard palate
Frontal process – articulates with the frontal bone
Maxillary sinus – air filled cavity within the maxillary bone. Largest of the paranasal sinuses
Zygomatic process – articulates with the zygomatic bone
Infra orbital foramina – permits nerves (zygomatic and maxillary to pass) and blood vessels to the face.
Anterior nasal spine – located immediately below the nasal aperture.
what are zygomatic bones and its features?
Irregular shape. Form the cheek commonly referred to as the “cheek bone”.
Features
Frontal process - articulates with frontal bone
Temporal process – zygomatic process of the temporal bone
Also articulates with the maxillary bone inferiorly.
what are the orbits formed by?
- Frontal bone
- Maxillary bone
- Ethmoid bone
- Lacrimal bone
- Palatine bone
- Lesser wing of sphenoid
- Greater wing of sphenoid
- Zygomatic bone
what are some features of the orbits?
Features
Superior orbital fissure
Inferior orbital fissure –
Optic foramina – passage of optic nerve
what is the mandible?
- U shaped bone, largest and strongest bone of the face
what are some features of the mandible?
Features
Body
Ramus
Mandibular angle
Mandibular notch
Coronoid process
Mandibular condyle
Alveolar margin - contains sockets in which the lower teeth are embedded.
Symphysis Menti or Mandibular symphysis – Line of fusion of the two mandibular bones
Mental foramina
Mandibular foramina – located on medial surface of each ramus
Oblique (ridge) line
Mylohyoid line
Mylohyoid groove
Submandibular fossa
Sublingual fossa
temporomandibular joint (TMJ)
state type, articular surfaces and special feature
type: synovial codylar joint
articular surfaces: temporal bone - anterior part of the mandibular fossa
head of the mandible
special feature: articular disc
what are the ligaments of the face, and what si their purpose
Fibrous capsule
Temperomandibular ligament
Sphenomandibular ligament
Stylomandibular ligament
purpose:
blood supply- brances of the superficial temporal and maxillary arteries
nerve supply- branches of the mandibular part of the trigeminal nerve
what muscles are responsible for the movements of the TMJ, and what movements occur
- Temporalis muscle
- Masseter muscle
- Medial pterygoid muscle
- Lateral pterygoid muscle
- Platysma muscle
- Suprahyoid muscles:
Geniohyoid muscle
Mylohyoid muscle
Stylohyoid muscle
Digastric muscle - Infrahyoid muscle
movements:
depression
elevation
protrusion
retraction
lateral movement
teeth- primary and permenant
Primary and permanent dentitions have formed by
age 21
Primary – 20 deciduous teeth that erupt at intervals
between 6 and 24 months
Permanent – enlarge and develop causing the root
of deciduous teeth to be resorbed and fall out
between the ages of 6 and 12 years
All but the third molars have erupted by the end of adolescence There are usually 32 permanent teeth
the tooh structure consist of 3 divisoons and 3 components, what are these?
Tooth structure consists of 3 divisions
Crown
Root
neck
And consists of 3 componants
Enamel
Dentin
Pulp cavity
what are the function of the teeth?
Cut - incisors
Tear - canines
Grind food – molar and premolar
