Lecture 4 - The Skull Flashcards
What is the Cranium?
- also known as the skull
- the skeletal structure of the head that supports the face & protects the brain
How can the cranium be broken down?
- broken down into the neurocranium & the viscerocranium
What is the neurocranium?
- broken down into 7 total bones
What are the 7 bones of the neurocranium?
- frontal bone
- parietal bone (2)
- temporal bone (2)
- sphenoid bone
- occipital bone
What is the frontal bone?
- the single bone that forms the forehead
What is the parietal bone?
- forms most of the upper lateral side of the skull
- paired bones that join together at the top of the skull
What is the temporal bone?
- forms the lower lateral side of the skull
What are the bony landmarks of the temporal bone?
- external auditory meatus
- mastoid process
- styloid process
- zygomatic arch
- half temporal bone, half zygomatic bone
What is the sphenoid bone?
- a single, complex bone of the central skull but also extends laterally to contribute to the sides of the skull
- serves as a “keystone” because it joins with almost every other bone of the skull
What is the occipital bone?
- forms the posterior skull & posterior base of the cranial cavity
What are the bony landmarks of the occipital bone?
- External Occipital Protuberance
- Important for muscle attachment - Occipital Condyles
- Attaches the skull to the vertebral bone
What is the viscerocranium?
- the facial bones
- broken down into 15 bones
What are the 15 bones of the viscerocranium?
- mandible
- ethmoid bone
- vomer
- maxilla (2)
- inferior nasal concha (2)
- zygomatic bone (2)
- palatine bone (2)
- nasal bone (2)
- lacrimal bone (2)
What is the mandible?
- forms the lower jaw & is the only moveable bone of the skull
- at birth the mandible is paired but they fuse during the first year to a single bone
What are the bony landmarks of the mandible?
- Mandibular condyle & fossa
- the fossa is part of the temporal bone which forms the temporomandibular joint (TMJ)
What is the ethmoid bone?
- forms the roof & lateral walls of the upper nasal cavity, the upper portion of the nasal septum, & contributes to the medial wall of the orbit
- also forms the floor of the anterior cranial cavity
What is the vomer bone?
- an unpaired bone which forms the posterior-inferior part of the nasal septum
What is the maxilla bone?
- a pair of bones that form the upper jaw, much of the hard palate, the medial floor of the orbit, & the lateral base of the nose
What is the inferior nasal concha?
- a right & left bone that project into the nasal cavity space from the lower lateral wall
- it is the largest of the nasal conchae
What is the zygomatic bone?
- also known as the cheekbone
- paired bones that form much of the lateral wall of the orbit & the lateral-inferior margins of the anterior orbital opening
What is the palatine bone?
- paired bones that contribute to the small areas to the lateral walls of the nasal cavity & the medial wall of each orbit
- the largest region is the horizontal plate which join together at the midline to form the posterior quarter of the hard palate
What is the nasal bone?
- paired bones that join together to form the bony base of the nose
- they also support the cartilages that form the lateral walls of the nose
What is the lacrimal bone?
- a small bone that that forms the anterior, medial wall of the orbit
- the anterior portion of the lacrimal bone forms a shallow depression called the lacrimal fossa
What are sutures?
- how the cranial bones are united
What are the 4 main sutures?
- sagittal
- coronal
- lambdoidal
- squamosal
What is the sagittal suture?
- joins the right & left parietal bones
What is the coronal suture?
- joins the frontal bone to the parietal bones
What is the lambdoidal suture?
- joins the occipital bone & the parietal bones
What is the squamosal suture?
- joins the temporal bone to the parietal bone
What are the 3 cranial fossae ?
- anterior cranial fossa
- middle cranial fossa
- posterior cranial fossa
What is the anterior cranial fossa?
- the most interior & shallowest
- overlies the orbits & contains the frontal lobes of the brain
- bounded by the frontal bone, which forms the majority of the floor
What is the middle cranial fossa?
- deeper & situated posterior to the anterior fossa
- has several openings for the passage of blood vessels & cranial nerves
What is the posterior cranial fossa?
- the most posterior & deepest portion
- contains the cerebellum of the brain
