Bones of the Scull

• Composed of 22 bones:
• 8 form the cranium or "braincase"
• 14 are associated with the face

7 additional bones are just associated with the scull

• Unpaired:
• Frontal bone
• Occipital bone
• Sphenoid bone
• Ethmoid bone

• Paired:
• Parietal bones (2)
• Temporal bones (2)

• Calvaria

Anterior, posterior, lateral view of the skull

Superior, internal, and inferior view of the scull

• Fibrous Joint
• Very short fibers connect the interlocking edges of articulating bones
• Joints between bones of the scull

Coronal Suture

• Squamosal (squamous) suture
• Super thin along the squamous portion

• Lambdoidal (lambdoid) suture
• Looks like lambda (λ)

Sagittal Suture

Frontal bone

• Superciliary arch
• Rainbow shaped and projects out
• Eyebrows are here
• More prominent in men (more defined brows bc of this arch)

• Supra-orbital notch (foramen)
• This notch may be a full circle in people (foramen)
• Orbit is where the eyeballs are

• Frontal sinus
• One of the four paranasal sinuses which are the holes near the nose.

The paranatal sinus are holes near the nose that get blocked by mucus causing pressure.

Parietal Bones

Superior temporal line

Inferior Temporal Line

• Temporalis M
• Important for chewing
• Causes the two lines because of where it sits

• Inferior/Superior (external/internal) view of Occipital Bone
• This bone is on the back/bottom of the scull

• Foramen Magnum
• Where the spinal cord is held

• Occipital Condyle
• Flat ear like structure; where the C1 vertebrae articulates with scull

• Hypoglossal Canal
• Inside the magnum there is this opening
• One on each side; CN12 (hypoglossal N) travels through this

• Inferior/Superior Nuchal Line
• One of the traps origins
• Superior is under the inferior

• External Occipital Protuberance
• Trap origin; large bunp on the bottom of the occipital bone
• Usually larger in males

Foramen Magum

• Jugular Notch
• Helps form the foramen
• Half of the circle is here
• Can only see well from the superior view

Entrance to hypoglossal canal

• Temporal Bones
• Right, Lateral view
• Inferior View
• All of the hearing structures are housed in this bone

• Squamous part (squama)
• Very thin; almost see through it

• External acoustic meatus
• Opening to the ear canal

• Mastoid Process
• Where a portion of the mastoid is going to sit

• Styloid Process
• Site for muscle attachment
• Very thin and sharp

• Mandibular Fossa
• Where a portion of the mandible (jaw) articulates in and out of

• Zygomatic Process
• Forms part of your cheekbones

• Carotid canal
• Medial to styloid process
• Where blood supply to brain comes from (internal carotid artery goes through this)

• Mastoid Process
• Big bump

• Stylomastoid Foramen
• Inbetween mastoid and styloid processes
• A portion of CN 7 will travel through this

Medial view of the right temporal bone

• Internal acoustic meatus
• Connection to external acoustic meatus (CN 7/8 travel through this to get out of the scull

Mastoid Process

• Sphenoid bone
• Irregular shape (butterfly)
• Tons of hole

• Sella Turcica
• Looks like a "Turkish saddle"
• Pituitary gland sits in this saddle

• Optic Canal
• Openings on either side of the saddle (CN 2 "optic n" travels through these 2 canals)

• Superior Orbital Fissure
• Inferior and posterior or optic canal; CN 3,4, first division of 5, and 6 all go out of this

• Foramen Rotundum
• Where the second division of CN 5 travels through
• On either side of the sella turcica

• Foramen Ovale
• Third division of CN goes through this

• Foramen Spinosum
• Artery travels through; its small for a small artery

Sphenoidal Sinus

Foramen rotundum

• Lateral plate of the pterygold process
• Bigger than the medial
• Muscles for chewing come here

• Medial plate of the pterygold process
• Small

Superior/Anterior/Posterior view of Ethmoid Bone

• Cribriform plate
• Houses the cribriform foramina
• CN 1 goes through here

• Crista Galli
• Sharkfin pointing straight up from the back view

• Superior Nasal Concha
• Looks like a conch shell when you look from the inside
• On either side of the perpendicular plate

• Middle Nasal Concha
• On either side of the perpendicular plate

Foramina

• Perpendicular Plate
• Forms a lot of the nasal septum
• Divides the sides of the nose

• Yellow: ethmoid bone
• Blue: middle nasal concha
• Purple: perpendicular plate

• Anterior: looks like the top step
• --Made up of : frontal bone, ethmoid, portion of sphenoid bone
• Middle: middle step
• --Made up of: sphenoid bone, temporal bone, parietal bone
• Posterior: last step
• --Made up of: occipital, temporal, sphenoid, partial (cerebellum is here)

• Yellow: maxillary bone
• Purple: infra-orbital foramen
• Green: alveolar processes-- grooves where the teeth are housed

• Maxillary Sinus
• The last of the paranasal sinuses

• Where there is a hole in the hard palate
• One of the bones didn't fuse right which allows you to see through to the nose

• Frontal Sinus
• Ethmoid Sinus
• Sphenoid Sinus
• Maxillary Sinus

• Horizontal Plate on the Palatine Bones
• These meet to help form the posterior of the hard palate

• Nasal Bone
• Bridge of the nose

• Inferior Nasal Concha
• Articulates with the maxilla
• Warms air as you breathe in and out

Zygomatic Bone and the Temporal Process

Zygomatic process of temproal bone + Temporal process of zygomatic bone

• Temporal fossa
• Area superior and deep to the zygomatic arch
• Temporalis is in here

• Infratemporal fossa
• Area inferior and deep to the zygomatic arch
• Arteries and nerves in here

• Lacrimal Bones
• Inner portion of the orbit of eye with the sac which collects tears

Vomer

• Lateral, posterior, medial view of Mandible
• Lower Jaw
• Houses inferior teeth

• Coronoid process
• Sharp

• Condylar process
• Rounded and posterior
• Goes into the mandibular fossa

• Ramus
• Sticks straight up

• Angle
• Where the ramus meets the body

Mental foramen

• Mental protuberance
• Chin
• Butt chin is when this doesn't form all the way

Body

Genoid Tubercle

• Mandibular foramen
• Only on the inside

• Inferior Alveolar N is what they numb at the dentist

• Soft spots
• Soft fibrous areas where several sutures unite allowing for molding and remodeling
• This allow the scull to be pliable during child birth

• Anterior fontanel
• Posterior fontanel
• Mastoid fontanelles
• Sphenoid fontanelles

• Anterior/Anterosuperior View of the Hyloid Bone
• Moves up and down to assist with eating and talking 
• Aka "wish bone"

• Green: Greater Horn
• Purple: Lesser Horn
• Orange: Body