The Skull and Cranial Cavity Flashcards
How many bones is the skull formed from?
22 bones (plus ear ossicles)
How are most bones in the skull joined?
By sutures with the exception of the TMJs and the inner ear ossicle joints
How many pairs of synovial joints in the skull?
3
- temporomandibular
- 2 inner ear
Basic Facts of the Skull: Foramina:
- passageways
- vessels/nerves pass between the
cranial cavity and face/neck
Basic Facts of the Skull: Weight:
Reduced by the unique structure and paranasal sinuses
Bones in the upper dome of the skull are called calvaria and are unique containing
2 dense tables; external and internal which are separated by spongy bone called diploe
Bony Structure of the Skull:
What are the two divisions of the cranium and provide a brief description.
Neurocranium:
- contains brain and further divided
into
- Calvaria (upper domed part)
- Base (floor of cranial cavity)
Viscerocranium:
- contains viscera for sense organs
- lower anterior part; facial skeleton
Division of Cranium:
Neurocranium: What is the Calvaria formed from?
- paired temporal and parietal bones
- parts of unpaired:
- frontal bone
- occipital bone
- sphenoid bones
Neurocranium:
The base of cranium is formed from
parts of the sphenoid, ethmoid, temporal and occipital bones
Base of Cranium:
Skull Inferior View:
note there are medial and lateral pterygoid plates of sphenoid
Bones forming the Facial Skeleton:
- paired nasal bones
- lacrimal bones
- zygomatic bones
- inferior nasal conchae
- single ethmoid bone
- paired palatine bones
- unpaired vomer bone
Facial Skeleton:
not shown are the paired palatine and unpaired vomer
Facial Skeleton:
What skeleton is shown in this diagram? Label the diagram.
- facial skeleton in the inferior view
The hard palate is made from which bones?
Maxilla and palatine bones
Sutures and Junctions of the skull: Bregma:
Anterior junction of the sagittal suture with the coronal suture
Sutures and Junctions of the skull:
Sutures and Junctions of the skull: Lambda:
the posterior junction of the sagittal suture with the lambdoid suture is the lambda
occipital and parietal nerves
The mandible is part of the viscerocranium.
True or False?
True
Sutures and Junctions of the skull: Asterion:
the junction of the occipital, temporal and parietal bones
Sutures and Junctions of the skull: Pterion:
the junction of the temporal, parietal, frontal and sphenoid and is adjacent to the course of the middle meningeal artery
thinnest part of the skull
extradural haematome common here
Neonatal Differences:
- what are the —– gaps found in
foetus and neonate called?
- names
- closures
Landmarks of the Inferior Skull:
Clinical significance of the anterior fontanelle:
in newborn fontanelles allow brain expansion with growth
allow movement during labour
also allows evaluation of hydration status and intracranial pressure
Cranial Nerves:
- Olfactory – I
- Optic – II
- Oculomotor– III
- Trochlear – IV
- Trigeminal – V
- Ophthalmic V1, Maxillary V2 and Mandibular V3
- Abducens – VI
- Facial – VII
- Vestibulocochlear - VIII
- Glossopharyngeal – IX
- Vagus – X
- Accessory – XI
- Hypoglossal – XII
OOTTAFVGVAH
Floor of the Cranial Cavity:
- divisions
- first division with bones
- second division with bones
- third division with bones
- divided into 3 fossae
- anterior fossa: frontal, ethmoid, body and lesser wings of the sphenoid
- middle fossa: sphenoid, temporal
- posterior fossa: temporal and occipital with small contributions from sphenoid and parietal
Levels of fossae of cranial cavity floor:
anterior highest
posterior lowest?
Anterior Cranial Fossa:
- location (1)
- contains (2)
- bones (3)
- dural folds (2)
- nerves (?)
- above the nasal cavity
- contains the frontal lobes
- Orbital part of the front bone (thin)
- ethmoid bone separates from the
nasal cavity - lesser wings of sphenoid are
distinct boundary between anterior
and middle cranial fossa - Tentorium cerebelii attaches to
anterior clinoid processes = dural
folds - Falx cerebri attaches to the front
crest and crista galli (continous with
crest)
*Cribriform Plate of the ethmoid
bone is where the olfactory nerves
exit the skull
Anterior Cranial Fossa:
Middle Cranial Fossa:
- location
- consists of which bones (2)
- contains (3)
- dural folds (1)
- nerves
- below and behind anterior fossa
- sphenoid and temporal bones
- contains temporal lobes
- pituitary lies in sella turcica
- tentorium cerebelli attaches to
posterior clinoid processes - CN 2-6 exit the skull in the middle
cranial fossa
Middle Cranial Fossa:
- optic canal in middle cranial fossa in
lesser wing of sphenoid just posterior
to anterior clinoid process - CN2 = optic nerves exit the skull
Middle Cranial Fossa:
- superior orbital fissure
- CN3,4,5.1&6 and opthalmic veins exit
the skull here - Occhlomotor, Trochlear, Ophthalmic
branch of Trigeminal, Abducens
Middle Cranial Fossa:
- foramen rotundum
- cranial nerve 5.2
- maxillary branch of the
trigeminal nerve - passes to pterygopalatine fossa
Middle Cranial Fossa:
- CN 5.3
- mandibular nerve
- lesser petrosal nerve
- pass to the infratemporal fossa
Middle Cranial Fossa:
NO NERVES
Foramen Spinosum
Middle meningeall artery and veins
enter cranium from infratemporal fossa
Middle Cranial Fossa:
Foramen Lacerum
NO NERVES
- covered with cartilaginous plug
- no structures pass through