ODS The Skull

Cranial Bones

• Eight cranial bones include:
  • Parietal bones (2) - forms the sides of the skull
  • Temporal bones (2) - located on the sides and base of the skull
  • Frontal bone (1) - forms the forehead
  • Occipital bone (1) - located at the back of the head; houses the occipital lobe for visual processing
  • Ethmoid bone (1) - light, spongy bone located within the skull
  • Sphenoid bone (1) - butterfly-shaped bone contributing to the base of the skull

Cranial Sutures

• Five key sutures include:
  • Coronal suture - connects the frontal bone to the parietal bones
  • Sagittal suture - unites the two parietal bones along the midline
  • Lambdoid suture - connects occipital bone to the parietal bones at the back of the skull
  • Squamosal suture - links the squamous part of the temporal bone to the parietal bones
  • Metonic suture - connects the two frontal bones when present

Views of the Cranium

• Anterior view - front perspective of the skull
• Lateral view - side perspective of the skull
• Posterior view - back perspective of the skull
• Superior view - looking down at the open skull
• Inferior view - looking up from beneath the skull

Sphenoid Bone Features

• Irregular, butterfly-shaped bone located anteriorly in the cranium
• Key features include:
  • Body - central part of the sphenoid
  • Lesser wing - smaller upper wing structure
  • Greater wing - larger lower wing structure
  • Pterygoid process - extension downward for muscle attachment

Ethmoid Bone Features

• Small, lightweight, unpaired bone with a spongy structure
• Composed of:
  • Ethmoid labyrinths (2) - bulk of bone with ethmoid air cells for warming air
  • Cribriform plate - roof of nasal cavity, perforated by olfactory fibers, associated with sense of smell
  • Perpendicular plate - makes up the superior two-thirds of the nasal septum

Infratemporal Fossa

• Irregular cavity located below and medial to the zygomatic arch
• Contains muscles of mastication:
  • Lateral and medial pterygoid muscles
  • Masseter and temporalis muscles at the borders
• Houses the mandibular branch of the trigeminal nerve passing through foramen ovale

Pterygopalatine Fossa

• Inverted pyramid-shaped space located between the infratemporal fossa and nasopharynx
• Contains:
  • Maxillary branch of the trigeminal nerve entering through foramen rotundum
  • Pterygopalatine ganglion
  • Maxillary artery

Facial Skeleton Bones

• Fourteen facial bones consist of:
  • Single bones:
    • Mandible - largest bone of the face, forming the lower jaw
    • Vomer - thin bone forming lower part of the nasal septum
  • Paired bones:
    • Nasal bones - forming the bridge of the nose
    • Zygomatic bones - cheekbones, involved in mastication
    • Maxilla - upper jaw, comprised of two pieces
    • Lacrimal bones - delicate bones associated with tear ducts
    • Inferior nasal concha - filters and warms air in the nasal cavity
    • Palatine bones - L-shaped bones forming the posterior hard palate

Orbit Bones

• Composed of seven bones:
  • Four facial bones: maxilla, zygomatic, lacrimal, palatine
  • Three cranial bones: frontal, sphenoid, ethmoid
• Provides protection for the eyeball and its associated structures

Intracranial Fossae

• Three anatomical depressions within the skull:
  • Anterior cranial fossa - shallowest, accommodates the frontal lobe, located over nasal and orbital cavities
  • Middle cranial fossa - butterfly-shaped, houses pituitary gland and lateral temporal lobes
  • Posterior cranial fossa - deepest fossa, accommodates brainstem, cerebellum, and foramen magnum for spinal cord connection

Hyoid Bone

• U-shaped bone with two pairs of horns (greater and lesser)
• Serves as an anchor point for the tongue and associated muscles, facilitating speech and swallowing

Local Anesthesia Infiltrations

• Foramen rotundum - transmits the maxillary division of the trigeminal nerve into the pterygopalatine fossa
• Foramen ovale - transmits the mandibular division of the trigeminal nerve into the infratemporal fossa
• Foramen spinosum - carries the middle meningeal vessels related to the mandibular division of the trigeminal nerve

Cranial Bones

• Eight cranial bones include:
  • Parietal bones (2) - forms the sides of the skull
  • Temporal bones (2) - located on the sides and base of the skull
  • Frontal bone (1) - forms the forehead
  • Occipital bone (1) - located at the back of the head; houses the occipital lobe for visual processing
  • Ethmoid bone (1) - light, spongy bone located within the skull
  • Sphenoid bone (1) - butterfly-shaped bone contributing to the base of the skull

Cranial Sutures

• Five key sutures include:
  • Coronal suture - connects the frontal bone to the parietal bones
  • Sagittal suture - unites the two parietal bones along the midline
  • Lambdoid suture - connects occipital bone to the parietal bones at the back of the skull
  • Squamosal suture - links the squamous part of the temporal bone to the parietal bones
  • Metonic suture - connects the two frontal bones when present

Views of the Cranium

• Anterior view - front perspective of the skull
• Lateral view - side perspective of the skull
• Posterior view - back perspective of the skull
• Superior view - looking down at the open skull
• Inferior view - looking up from beneath the skull

Sphenoid Bone Features

• Irregular, butterfly-shaped bone located anteriorly in the cranium
• Key features include:
  • Body - central part of the sphenoid
  • Lesser wing - smaller upper wing structure
  • Greater wing - larger lower wing structure
  • Pterygoid process - extension downward for muscle attachment

Ethmoid Bone Features

• Small, lightweight, unpaired bone with a spongy structure
• Composed of:
  • Ethmoid labyrinths (2) - bulk of bone with ethmoid air cells for warming air
  • Cribriform plate - roof of nasal cavity, perforated by olfactory fibers, associated with sense of smell
  • Perpendicular plate - makes up the superior two-thirds of the nasal septum

Infratemporal Fossa

• Irregular cavity located below and medial to the zygomatic arch
• Contains muscles of mastication:
  • Lateral and medial pterygoid muscles
  • Masseter and temporalis muscles at the borders
• Houses the mandibular branch of the trigeminal nerve passing through foramen ovale

Pterygopalatine Fossa

• Inverted pyramid-shaped space located between the infratemporal fossa and nasopharynx
• Contains:
  • Maxillary branch of the trigeminal nerve entering through foramen rotundum
  • Pterygopalatine ganglion
  • Maxillary artery

Facial Skeleton Bones

• Fourteen facial bones consist of:
  • Single bones:
    • Mandible - largest bone of the face, forming the lower jaw
    • Vomer - thin bone forming lower part of the nasal septum
  • Paired bones:
    • Nasal bones - forming the bridge of the nose
    • Zygomatic bones - cheekbones, involved in mastication
    • Maxilla - upper jaw, comprised of two pieces
    • Lacrimal bones - delicate bones associated with tear ducts
    • Inferior nasal concha - filters and warms air in the nasal cavity
    • Palatine bones - L-shaped bones forming the posterior hard palate

Orbit Bones

• Composed of seven bones:
  • Four facial bones: maxilla, zygomatic, lacrimal, palatine
  • Three cranial bones: frontal, sphenoid, ethmoid
• Provides protection for the eyeball and its associated structures

Intracranial Fossae

• Three anatomical depressions within the skull:
  • Anterior cranial fossa - shallowest, accommodates the frontal lobe, located over nasal and orbital cavities
  • Middle cranial fossa - butterfly-shaped, houses pituitary gland and lateral temporal lobes
  • Posterior cranial fossa - deepest fossa, accommodates brainstem, cerebellum, and foramen magnum for spinal cord connection

Hyoid Bone

• U-shaped bone with two pairs of horns (greater and lesser)
• Serves as an anchor point for the tongue and associated muscles, facilitating speech and swallowing

Local Anesthesia Infiltrations

• Foramen rotundum - transmits the maxillary division of the trigeminal nerve into the pterygopalatine fossa
• Foramen ovale - transmits the mandibular division of the trigeminal nerve into the infratemporal fossa
• Foramen spinosum - carries the middle meningeal vessels related to the mandibular division of the trigeminal nerve