Bones of Skull

Fontanelles

fuse within 18 months

frontal/anterior fontanelle: junction of coronal and sagittal sutures

occipital fontanelle: junction of lambdoid and sagittal sutures

Sutues

Frontal: closes within 3-9 months

Coronal: frontal and parietal junction

Squamous: parietal and temporal junction

Lambdoid: parietal and occipital junction

Bregma

point on skull where coronal and sagittal sutures intersect

• where frontal/anterior fontanelle is during infancy

Lambda

point on skull where lambdoid and sagittal sutures intersect

• where lambdoid fontanelle is during infancy

Craniosynostosis

premature closing of fontanelles

• scaphocephaly: sagittal suture closing too early,

  • anterior-posterior elongation, cranium too long

• Brachycephaly: coronal and lambdoid sutures

  • superior-inferior elongation, cranium too tall

• Plagiocephaly: one side of coronal and lambdoid sutures

  • asymmetric cranium

Sinuses

develop as diverticula of lateral nasal wall

reduce weight of anterior skull

• frontal, ethmoid, maxilla, sphenoid

Mandible angle

changes with dentition

infancy: greatest angle

angle becomes less obtuse with age until potential edentulous

Principle lines of skull

Principal lines of force: vertical, strong areas of skull

principal lines of fracture: LeFort Lines, weak, horizontal lines where fracture are most common.

• Pterion: where frontal, parietal, temporal, and sphenoid bone join

Orbital bones

frontal

maxillary

palatine

lacrimal

ethmoid

sphenoid

zygomatic

Ethmoid bone

crista galli: falx cerebri of dura mater attaches here

uncinate process: directs sinus drainage

cribriform plate: passage for CN1

superior and middle nasal conchae: directs airflow

Sphenoid Bone

stella turcica: holds pituitary gland

clinoid process: 4 processes surrounding stella turcica, attaches to dura mater

lesser wing: part of anterior cranial fossa

greater wing: part of middle cranial fossa

Nasal Septum

septal cartilage

perpendicular plate of ethmoid bone

vomer bone

Nasal Meatuses

superior meatus: openings to sphenoid sinus, posterior ethmoid sinus, sphenopalatine foramen

middle meatus: openings to anterior and middle ethmoid sinus, maxillary sinus, frontal sinus via semilunar hiatus

inferior meatus: nasolacrimal duct