CSD LAB 8: Cranium part 1

Question 1

six major bones of the cranium

Answer 1

• frontal
• parietal
• occipital
• temporal
• ethmoid
• sphenoid

Question 2

frontal bone

Answer 2

• unpaired
• anterior portion of the cranium (forehead region)
• inferior surface is the orbital margin (eye socket)
• posteriorly bound by the coronal suture
• calvariam - skull cap

Question 3

parietal bone

Answer 3

• paired
• forms the bulk of the brain case
• sagittal suture: superior midline, separates the two parietal bones
• fontanelle: anterior and posterior soft spots on the infant skull which close as the bones of the skull fuse together

Question 4

occipital bone

Answer 4

• unpaired
• forms the base of the brain case
• foramen magnum: hole in occipital bone where the spinal cord passes through into the brain
• occipital condyles: lateral to the foramen magnum, where the skull attaches to C1 (atlas)
• lamboidal suture: posterior, horizontal suture at the superior margin of the occipital lobe, separates the occipital and parietal lobes

Question 5

temporal bone

Answer 5

• paired
• forms the lateral portions of the brain case
• contains the structures for the auditory and vestibular systems
  5 portions:
• squamous: includes an anterior projection called the zygomatic process which articulates with the zygomatic bone to form the zygomatic arch
• petrous: hardest portion, forms the base of the temporal bone, houses the organs for hearing and balance
• mastoid process: prominence behind the ear, behind the EAM
• tympanic: forms the external auditory meatus
• styoid process: long, slender, inferior portion

Question 6

ethmoid bone

Answer 6

• unpaired
  parts:
• cribiform plate: horizontal part, divides the cranium above from the nasal cavities below
• perpendicular plate: middle portion, forms the upper portion of the nasal septum
• crista galli: superior projection from the midline of the cribifom plate
• superior and medial nasal concha: forms the lateral walls of the nasal cavities

Question 7

sphenoid

Answer 7

• unpaired
• very complicated bone that communicates with (touches) all other bones of the cranium and several face bones
• resembles a bat with its wings spread
  parts:
• body: central portion, main mass of bone
• -sella turcica, turkish saddle: depression in the superior surface of the body
• greater wings: paired, hold temporal lobes of the brain
• lesser wings: paired, superior to the greater wings, contribute to the orbital cavity
• medial and lateral pterygoid plates: paired, vertical plates on the inferior portion of the bone
• -pterygoid fossa: posterior space between the medial and lateral pterygoid plates
• hamulus: small prominence attached to the medial pterygoid plate, paried, tensor veli palatine and medial pterygoid muscles wind around the hamulus