Head And Neck Week 2 Flashcards
How many bones are there in the skull?
22
How many bones in the neurocranium?
8
Which part of the skull houses the brain?
Neurocranium
What is the viscerocranium and how many bones are involved in its structure?
The bones forming the facial skeleton
14
Or 15 if include part of ethmoid
How is the neurocranium divided anatomically?
The calvaria (roof) The cranial base
Which bones make up the calvarium?
Frontal, occipital and two parietal
Which bones make up the cranial base?
Frontal, sphenoid, ethmoid, occipital, parietal and temporal
What do the bones of the cranial base articulate with?
Bones of the facial skeleton and mandible
1st cervical vertebra
Name the bones of the viscerocranium
Zygomatic (2) Lacrimal (2) Nasal (2) Inferior nasal conchae/turbinates (2) Palatine (2) Maxilla (2) Vomer Mandible Part of ethmoid
What type of joints are between the bones of the skull?
Sutures (fibrous joints)
How do the bones of the calvaria form?
Intramembranous ossification
At what age do the joints of the skull fuse and why?
Around age 20
To allow growth of the brain in adolescence
Name the sutures of the skull and which bones they fuse together
Coronal suture - frontal bone with the two parietal bones
Sagittal suture - both parietal bones to each other
Lambdoid suture - the occipital bone to the two parietal bones
Squamous suture - the squamous part of the temporal bone to the inferior border of the parietal bone
Why are sutures of clinical importance?
Can be points of potential weakness in both childhood and adulthood
What is a fontanelle?
The membranous gap between the bones of the skull in neonates due to incompletely fused suture joints
What are the two major fontanelles?
The frontal fontanelle (At the joint of the coronal and sagittal sutures)
The occipital fontanelle (At the joint of the sagittal and lambdoid sutures)
What is the only mobile joint in the skull?
Temporomandibular joint (TMJ)
At what age do fontanelles close?
In the first two years of life
What is the function of fontanelles?
Makes skull more flexible for passage through birth canal
Allows for brain growth
What kind of bones form the calvaria?
Flat bones
What kind of bones form the cranial base?
Primarily irregular bones with substantial flat portions
How are bones of the cranial base formed?
Endochondral ossification or by more than one type of ossification (e.g. Intramembranous and endochondral)
Why is the name flat bone not quite correct to describe the bones of the neurocranium?
They are actually curved - convex external and concave internal surfaces
What are sutures called before they fuse around the age of 20 and what are they made up of?
Synchondroses - hyaline cartilage
Through which structure is the spinal cord continuous with the brain and where is the structure located?
Foramen magnum
Cranial base
From what do the bones of the viscerocranium develop?
Mesenchyme of the embryonic pharyngeal arches
What structures do bones of the viscerocranium form?
Orbits
Nasal cavity
Mouth
What kind of bones are the bones of the viscerocranium?
Irregular
Why do bones of the skull contain air spaces?
To decrease their weight
What is the name of bones with air spaces/large sinuses?
Pneumatised bones
What happens to the volume of air spaces in these bones with age?
Increase
What is the orbitomeatal plane?
The “anatomical” position
Cranium orientated so inferior margin of orbit and superior margin of external acoustic opening of external acoustic meatus of both sides lie in same horizontal plane
Draw and label the frontal bone
Squamous part, glabella, nasion, supraorbital margin, supraorbital foramen or notch, supraciliary arch
Look at picture in workbook
Which bones does the squamous part of the frontal bone articulate with inferiorly ?
Nasal, maxillae and zygomatic bones
What is a metopic suture?
Persistent frontal suture or remnant that is visible in some people in midline of the glabella
What is the glabella?
The smooth, slightly depressed area between superciliary arches of the frontal bone
What is the intersection of the frontal and nasal bones called?
Nasion
What is the nasion also known as?
The bridge of the nose
What other bones does the frontal bone articulate with? (Through horizontal orbital portion)
Lacrimal, ethmoid, sphenoid
What does the orbital part of the frontal bone form?
Roof of the orbit and part of the floor of the anterior cranial cavity
What structures pass through the supraorbital foramen/notch?
Supraorbital nerve and vessels
How does the prominence of the supraciliary arch differ between the sexes?
More prominent in males
Draw and label the zygomatic bone (Zygomatic arch, Zygomaticofacial foramen)
Check workbook or textbook
What is the zygomatic arch made up of?
The temporal process of the zygomatic bone
The zygomatic process of the temporal bone
What do the zygomatic bones form?
Prominence of the cheeks
The anterolateral rims, walls and floor of orbits
Lateral infraorbital margins
Which bones do the zygomatic bones articulate with?
Frontal, temporal, sphenoid and maxillae
What is the name of the anterior nasal opening in the cranium?
Piriform aperture
Draw and label the maxilla (Zygomatic process, Palatine process, Alveolar process, Frontal process, Infraorbital foramen)
Check workbook, textbook
What do the maxillae form?
The upper jaw
Surround most of the piriform aperture
Form the infraorbital margins medially
How are the two maxilla united?
Intermaxillary suture
What is the alveolar process of the maxilla and what does it do?
Includes tooth sockets (alveoli)
Constitutes the supporting bone for maxillary teeth
What structures pass through the infraorbital foramen?
Infraorbital nerve and vessels
Draw and label the mandible (Body, Ramus, Angle, Coronoid process, Condyloid process (head + neck), Mental protuberance, Mental foramen, Mandibular foramen)
Check workbook , textbook
What structures are transmitted through the mental foramena?
The mental nerves and vessels
What passes through the mandibular foramen?
The inferior alveolar nerve and vessels - branch of mandibular division of trigeminal nerve (exit at mental foramen)
What are the boundaries of the temporal fossa?
Superior and posterior - Superior and inferior temporal lines
Anterior - frontal and zygomatic bones
Inferior - zygomatic arch
What does the superior border of the zygomatic arch correspond to?
The inferior limit of the cerebral hemisphere of the brain
What is the pterion?
Junction of greater wing of sphenoid, squamous temporal, frontal and parietal bones
Overlies the course of the anterior division of the middle meningeal artery
Where is the pterion found?
In the anterior part of the temporal fossa, 3-4cm superior to the midpoint of the zygomatic arch
Draw and label the temporal bone (squamous part, zygomatic process, petrous part, mastoid process, styloid process, articular fossa for mandible, external and internal auditory meatus, foramen lacerum, carotid canal, stylomastoid foramen, opening for Eustachian tube)
Look in textbook or workbook
Draw and label the occipital bone (internal and external occipital protuberance, superior nuchal line, inferior nuchal line, foramen magnum, articular condyles for atlas (C1), Clivus, hypoglossal canal, Jugular foramen)
Look in workbook or textbook
What is lambda?
The junction of the sagittal and lambdoid sutures
Lies in the centre of the occiput
What are sutural bones?
Accessory bones that may be found at lambda or near the mastoid process
Draw and label the ethmoid bone (Crista gala, cribriform plate, perpendicular plate, superior concha, cribriform foramina)
Look in workbook or textbook
Draw and label the sphenoid bone (Great and small wings, body, pterygoid processes, anterior and posterior clinoid processes, sella turcica, dorsum sellae, hypophyseal fossa, superior orbital fissure, optic canal, foramen rotundum, foramen ovale, foramen spinous)
Look in workbook or textbook
What is Bregma?
The site where the sagittal and coronal sutures join
What is the vertex?
The most superior point of the calvaria
Near the midpoint of the sagittal suture
What is the infratemporal fossa?
An irregular space inferior and deep to the zygomatic arch and the mandible and posterior to the maxilla
Communicates with inferior orbital fissure and pterygopalatine fossa
Medial and lateral pterygoid muscles here
What is the parietal foramen?
A small, inconsistent aperture located posteriorly in the parietal bone near the sagittal suture - paired foramen may be present
An emissary foramen
What are emissary foramina?
Transmit emissary veins - connecting scalp veins to venous sinuses of the dura mater
What does the free posterior border of the hard palate form?
Projects posteriorly in the median plane as the posterior nasal spine