Cranial Bones

Axial skeleton

  • Forms central supporting axis of body

  • Skull, vertebras, sternum, ribs, sacrum

Apendicular skeleton

  • pectoral girdle, scapula, clavicle

The Skull

  • most complex of skeleton

  • 22 bones

  • several cavities

    • cranial cavity

    • nasal cavity

    • oral cavity

    • inner and middle cavities

    • paranasal

Faromina

  • holes that allow passage of nerves and blood vessels

Paranasal (sinuses)

  • frontal, sphenoid, ethmoid and maxillary - air filled holes lined by mucosa membrane.

  • act as chamber that add resonance to voice.

8 Cranial Bones

  • frontal

  • parietal

  • temporal

  • occipital

  • sphenoid

  • ethmoid

Frontal Bone

  • forms forehead and part of cranium

  • Coronal suture - posterior boundary of frontal bone

  • supraorbital margin - ridge of eyebrows.

Parietal Bones

Forms most of cranial rood and part of lateral walls

  • Border of 4 sutures

    • Sagital - between parietal bones

    • Coronal - at anterior margin

    • Lamboid

    • Squamous

Two temporal lines for attachement of temporal muscles.

Temporal Bones

  • Form lateral walls and part of cranial cavity

Four parts: squamous, mastoid, tympanic and petrous

  • Squamous part

    • zygomatic process

    • mandibular process

  • mastoid part

    • mastoid process

    • mastoid foramen

  • tympanic part

    • external auditory meatus

    • styloid process

  • petrous part

    • houses middle and inner ear cavity

    • receptors for hearing and balance

    • Internal auditory meatus

      • opening for CN 8 (vestibulocochlear nerve)

    • caratid canal - provides blood for brain

    • Jugular foramen - carries deoxygenated brain away from brain.

The Occipital Bone

  • Forms rear and base of skull

  • Foramen magnum - opening for spinal chord

  • occipital condyles - knob resting in spinal chord

  • hypoglosal canal - transmits nerve for tongue

  • Externbal occipital proturbarence - attachement nor nuchal lines

  • inferior and superior nuchal lines - for neck muscle attachments

Sphenoid Bones

  • Optical canal - passage of the optic nerve and opthalmic artery

  • superior orbital fissure - passage for three nerves that supply muscles for eye movement.

  • Sella Turcia - houses the pituitary gland.

Ethmoid bones

  • Located between eyes

  • contributes medial wall of orbits, roof of nasal cavity and nasal septum

  • perpendicular plate - superior two thirds of nasal septum

  • crista galli - blade like attachement for dura

  • cribiform plate - depressed area perforated with holes

    • cribiform formina (olfactory) - passages for olfactory nerves traveling from nasal cavity to olfactory bulbs inside cranium.