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