The Skull

Skull Structure

22 bones→all but 6 paired

structures between individual bones→immobile fibrous joints

Skull Function

protects

brain

receptor systems associated with special senses

• nasal cavities→smell

• orbits→vision

• ears→hearing+balance

• oral cavity→taste

Mandible

lower jaw

combines with cranium to form skull

articulation→neurocranium at temporomandibular joint

• temporal bone

• mandible

Cranium

top portion of skull

combines with mandible to form skull

divisions

• neurocranium
  -houses brain

• face
  surrounds:
  -orbital
  -nasal
  -oral cavities

Bones of Neurocranium List

frontal

parietal

occipital

temporal

sphenoid

ethmoid

Calvarium

superior portion of neurocranium→roof of skull

upper portions of

• frontal bones

• occipital bones

• parietal bones

Floor of Neurocranium

made up of all bones in the neurocranium

• occipital

• temporal

• sphenoid

• frontal

• ethmoid

houses neural cavity

Frontal Bone

forehead+roof of orbit

paired when born→fused to single bone around age 2

articulation→posteriorly with parietal bones (paired)

Parietal Bones

paired

posterior to frontal bone

anterior to occipital bone

Occipital Bone

single bone

posterior to parietal bones

Temporal Bone

paired

articulation

• parietal

• occipital

• mandible

• sphenoid

• zygomatic

Sphenoid Bone

complex bone

looks small in lateral view→much larger in back wall of orbits

see better extent in inferior view

Face Bones List

maxilla

nasals

lacrimal

zygomatic

ethmoid

inferior nasal concha

vomer

palatine

Maxilla

paired

forms

• upper jaw
  -houses teeth of upper jaw

• portion of hard palate

• floor of orbit

• majority of face inferior to orbit

Nasal Bones

paired

small

form bridge of nose

articulation

• maxilla

• frontal

Lacrimal Bones

paired

articulate with maxilla

inside orbit

Zygomatic Bones

paired

forms portion of zygomatic arch
-with temporal bone

“cheek bone”

forms lateral wall of orbit

Ethmoid

see in nasal cavity→medial wall of orbits

deepest bone of skull

contains

• superior nasal concha

• middle nasal concha

• perpendicular plate
  -bony nasal septum

• crista galli (interior)

• cribiform plate (inferior)

Inferior Nasal Concha

not part of ethmoid

in nasal cavity

paired

Vomer

pink

single bone

in nasal cavity

forms part of nasal septum with ethmoid
-bony septum

Palatine Bone

paired

posterior portion of hard palate

Mandibular Condyle of the Mandible

articulates with temporal bone→temporomandibular joint

insertion point→lateral pterygoid (both heads)

Coronoid Process of the Mandible

insertion point→temporalis

Body of the Mandible

houses roots of teeth

Ramus of the Mandible

vertical process

contains

• condyle

• coronoid process

insertion→masseter

Mental Protuberance of the Mandible

“mental→the thinker”

Mental Foramen of the Mandible

houses mental branch of mandibular N

Mandibular Foramen of the Mandible

on internal surface of ramus

houses inferior alveolar N

Foramen Magnum of Occipital Bone

transmits

• spinal cord

• blood vessels

Occipital Condyles of Occipital Bone

articulate with atlas

Protuberance+Lines of Occipital Bone

protuberance→external occipital protuberance

nuchal lines

• superior

• inferior

Hypoglossal Canal of Occipital Bone

transmits hypoglossal N

Zygomatic Process of Temporal Bone

forms portion of zygomatic arch

• zygomatic process of temporal bone

• temporal process of zygomatic bone

Glenoid Fossa of Temporal Bone

depression

articulation point with mandibular condyle→form temporomandibular joint

Mastoid Process of Temporal Bone

attachment

• SCM

• digastric

• longissimus

• splenius capitis

Styloid Process of Temporal Bone

origin

• styloglossus

• stylohyoid

Stylomastoid Foramen of Temporal Bone

transmits terminal branch of CN VII (facial N)

Carotid Foramen of Temporal Bone

runs through carotid canal

transmits internal carotid A

Foramen Lacerum of Temporal Bone

transmits greater petrosal N

Jugular Foramen of Temporal Bone

transmits

• internal jugular V

• glossopharyngeal N (CN IX)

• vagus N (CN x)

• accessory N (CN XI)

Internal Acoustic Meatus of Temporal Bone

transmits to middle+inner ear cavities

• facial N (CN VII)

• vestibulocochlear N (CN VIII)

External Acoustic Meatus of Temporal Bone

anterior to mastoid process

posterior to temporomandibular joint

Sella Turcica+Hypophyseal Fossa of Sphenoid Bone

sella turcica→ “saddle”

contains depression→hypophysial fossa
-houses pituitary gland

Greater+Lesser Wings of Sphenoid

located on posterior wall of orbit

Optic Canals of Sphenoid

transmit

• optic N (CN II)

• opthalmic A

Superior Orbital Fissure of Sphenoid

separates greater+lesser wings of sphenoid

transmits

• oculomotor N (CN III)

• trochlear N (CN IV)

• abducens N (CN VI)

• opthalmic division of trigeminal N

Foramen Rotundum of Sphenoid

transmits maxillary division of trigeminal N

Foramen Ovale of Sphenoid

transmits mandibular divison of trigeminal N

Foramen Spinosum of Sphenoid

transmits middle meningeal A

Medial Pterygoid Plate of Sphenoid

insertion→medial pterygoid

Lateral Pterygoid Plate of Sphenoid

origin

• medial pterygoid

• both heads of lateral pterygoid

Crista Galli of Ethmoid

raised crest

anchors fold of dura mater

Cribiform Plate of Ethmoid

flanks crista galli

pierced with tiny holes→transmit olfactory N (CN I)

Superior+Middle Nasal Concha of Ethmoid

superior nasal concha→high up in nose→not visible

middle nasal concha

Perpendicular Plate of Ethmoid

articulates with vomer→forms bony nasal septum

Nasolacrimal Canal of Maxilla

transverses maxilla from the orbit→drains into nasal cavity

clinical→why nose runs when crying

Lacrimal Bone

smallest bone of the face

fragile

forms lacrimal groove with the maxilla
-portions of lacrimal apparatus

Sagittal Suture

between L+R parietal bones

Coronal Suture

between frontal and L+R parietal bones

Anterior Fontanelle

aka: bregmatic fontanelle

open area

between L+R frontals and parietal bones
-in fetuses+infants

covered with membrane→area of no bone
-”soft spot”

clinical→allows for flexible head to pass through birth canal

usually gone by age 2

Lambdoid Suture

between L+R parietal bones+occipital bone

Posterior Fontanelle

in fetuses+infants

opening between L+R parietal bones and occipital bones

membrane over opening→area of no ossification

Occipitomastoid Suture

between L+R temporal bones and occipital bone

posterior to mastoid process

Squamous Suture

between parietal+temporal bones

Parietomastoid Suture

between parietal bones+portion of temporal bone

superior to mastoid process

Anterior Temporal Sutures

sphenoparietal

sphenosquamous

zygomaticofrontal

Facial Sutures

frontonasal

zygomaticomaxillary

Bony Orbit

composed of 7 bones

• frontal

• zygomatic

• maxilla

• lacrimal

• ethmoid

• sphenoid

• palatine

Paranasal Sinuses

mucosa-lined air-filled spaces

lighten skull

enhance resonance of voice

warm+humidify air

found in

• frontal

• sphenoid

• ethmoid

• maxillary

Hyoid Bone (General)

bone in neck→level of C3

small+u-shaped

doesn’t articulate with other bones→suspended by ligaments+muscles below mandible

attachment point for 10 muscles

Hyoid Bone Structures

greater horn

lesser horn

body