Skull Flashcards
What two divisions can the skull be divided into?
- cranial skeleton and facial skeleton
- facial skeleton includes the mandible
What three layers make up the cranial skeletal bones?
- external table of compact bone
- diploe (middle spongy layer)
- internal table of compact bone
What is the a covering AND lining of the skull called?
- periostium
What is the outer later (the covering) of the Periosteum called? What about the inner layer (the lining)?
- outer layer = pericranium
- inner layer = endocranium
Which 8 bones make up the cranial cavity?
- frontal, ethmoid, sphenoid, occipital, temporal (2x), and parietal (2x)
Sutures
- immovable joints between most of the bones of the skull
Fontanelles
- the gaps between the bones of the skull in a newborn
- these will eventually form sutures
What is a persistent frontal suture called?
- metopic suture
- normally, when the frontal bones fuse during childhood, they leave no trace of a suture
In the anatomical position, what horizontal plane lines up the lower margins of the orbits and the upper margins of the external acoustic meatus?
- the orbitomeatal plane
What is the flattish part of the temporal bone called?
- squamous temporal
- it is on the external part of the skull
What is located at the start of the zygomatic arch, just in front of the mandibular fossa?
- the tubercle of the root of the zygoma
Which joint is associated with the tubercle of the root of the zygoma?
- the temporomandibular joint (TMJ)
Which part of the temporal bone makes up the external acoustic meatus?
- the tympanic part
What is the top part of the skull called? (The part that is often removable in many models)
- the calvaria or the calvarium
Which bones make up the anterior cranial fossa?
- frontal, ethmoid, and sphenoid bones
What passes through the cribriform plates of the ethmoid bone?
- the olfactory nerves (cranial nerve 1)
Which bones make up the middle cranial fossa?
- the sphenoid and temporal bones
What lies in the sella turcica?
- the pituitary gland
What four projections surround the sella turcica?
- the clinoid processes (2 anterior and 2 posterior)
What lies between the two anterior clinoid processes?
- the chiasmatic groove (for the optic chiasma)
The sella turcica actually encompasses the recess AND the four clinoid processes; what is the name of the actual recess itself?
- the hypophysial fossa
- (because the pituitary gland is also known as the hypophysis)
Which bones make up the posterior cranial fossa?
- the sphenoid, temporal, parietal, and occipital bones
Which parts of the brain are housed in the posterior cranial fossa?
- the hindbrain (cerebellum, pons, medulla oblongata)
The inferior orbital fissure opens into what area?
- the infratemporal fossa
How many processes does the zygomatic bone have? What are they?
- three processes
- frontal, temporal, and maxillary
Palatine Process; What does it form?
- the portion of the maxilla that joins two maxilla bones
- it helps form the hard palate
What is the rim of the maxilla that carries the teeth of the upper jaw?
- the alveolar process
What passes through the infraorbital foramen?
- the infraorbital nerve and artery
T or F: the nasal conchae are separate bones from the ethmoid bone.
- true and false!
- the superior and middle conchae are part of the ethmoid bone, but the inferior conchae is separate
What lies beneath the superior conchae/turbinate? The middle conchae/turbinate? The inferior conchae/turbinate?
- the superior meatus
- the middle meatus
- the inferior meatus
Which bones makes up the hard palate?
- the maxilla’s palatine processes
- the palatine bones
Lingula
- a small tongue of bone of the mandible that “guards” the mandibular foramen
The mylohyoid (the main muscle of the floor of the mouth) attaches to what part of the mandible?
- the mylohyoid line/groove
Alveolar Margin
- the part of the mandible that holds the teeth of the lower jaw
- (don’t get confused with the maxilla’s alveolar process which holds the teeth of the upper jaw)
What passes through the hypoglossal foramen/canals?
- the hypoglossal nerves (cranial nerve XII)
What passes through the jugular foramen?
- the jugular vein and cranial nerves IX (glossopharyngeal nerve), X (vagus nerve), and XI (accessory nerve)
What passes through the stylomastoid foramen?
- facial nerve (cranial nerve VII)
What passes through the carotid canal?
- the internal carotid artery
What passes through the foramen lacerum?
- no major structures actually pass through the foramen lacerum
- the internal carotid artery passes across the top of the foramen
What passes through the foramen spinosum?
- the middle meningeal artery passes through INTO the skull
What passes through the optic canals?
- the optic nerves (cranial nerve II)
What passes through the internal acoustic meatus?
- the vestibulocochlear nerve (cranial nerve VIII) and the facial nerve (cranial nerve VII)
List all the Cranial Nerves and the foramina they pass through.
- cribriform plate: olfactory nerve (I)
- optic canal: optic nerve (II)
- superior orbital fissure: oculomotor nerve (III), trochlear nerve (IV), abducans nerve (VI)
- trigeminal nerve (V) (a branch of the trigeminal ganglion; does not pass through a foramen; other branches of the ganglion pass through the foramen rotundum and foramen ovale)
- internal acoustic meatus: facial nerve (VII), auditory/vestibulocochlear nerve (VIII)
- jugular foramen: glossopharyngeal nerve (IX), vagus nerve (X), spinal accessory nerve (XI)
- hypoglossal canal: hypoglossal nerve (XII)
