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Left maxilla

Superior view, anterior at top

Left maxilla

Medial view, anterior to right

Left maxilla

Lateral view, anterior to left

Left maxilla

Inferior view, anterior at top

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arched body with a tooth-bearing alveolar process. Posteriorly each side of the arched body joins the vertically directed rami at the mandibular angle. The superior aspects of the two rami articulate with the

temporal bones at the base of the cranium. The mandible is a strong bone composed predominantly of

compact bone. It houses the lower tooth row in its alveolar arch. The strong masticatory muscles act on

this bone to move it in the temporomandibular joint. Its shape can vary exceedingly with age. If the teeth

are lost, bone gets resorbed on the alveolar surface leading to the thinning of the dental arch. The mandible articulates with two bones.

The mandible, the largest of

the facial bones, forms the

lower jaw. The bone has an

Cranial Bones – Mandible

 1 Body of mandible

 2 Mental protuberance

 3 Mental foramen

 4 Mental tubercle

 5 Oblique line

 6 Digastric fossa

 7 Mental spines

 8 Mylohyoid line

 9 Submandibular fossa

10 Alveolar part

 11 Retromolar triangle

12 Ramus of mandible

13 Angle of mandible

14 Mandibular foramen

15 Coronoid process

16 Mandibular notch

17 Condylar process

18 Head of mandible

19 Pterygoid fovea

20 Masseteric tuberosity

21 Pterygoid tuberosity

Mandible

Anterior view

Mandible

Posterior view

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Mandible

Superior view, anterior at bottom

Mandible

Lateral view, anterior to right

Mandible

Inferior view, anterior at bottom

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sieve-like bone because of the many small foramina that transmit the olfactory nerves to the nasal cavity.

This unpaired bone is both complex and delicate and is the central bone of the nasal cavity. Wedged between the two orbits, the bone consists of a median vertical plate, a horizontal plate perforated by many

small foramina, and bilateral pneumatic, labyrinthine regions. The labyrinthine regions form most of the

medial walls of the orbit and the superior and middle nasal conchae. This bone consists of thin laminae of

compact bone surrounding many small air sinuses, which communicate with the nasal cavity. The ethmoid

bone articulates with thirteen bones, more articulations than any other cranial bone.

Cranial Bones – Ethmoid

 1 Cribriform plate

 2 Cribriform foramina

 3 Crista galli

 4 Perpendicular plate

 5 Ethmoidal air cells

 6 Orbital plate

 7 Superior nasal concha

 8 Middle nasal concha

 9 Ethmoidal bulla

10 Uncinate process

 11 Ethmoidal infundibulum

Ethmoid bone

Anterior view

Ethmoid bone

Posterior view

Ethmoid bone

Lateral view, anterior at right

Ethmoid bone

Superior view, anterior at top

Ethmoid bone

Inferior view, anterior at top

The term ethmoid comes from the

Greek term ethmos meaning

sieve. Galen called the bone the

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the Greek word zygon meaning yoke, after its resemblance to a yoke placed on oxen. This yoke-shaped

bone has three distinct surfaces, fi ve borders, and two processes. It is situated anterolateral on the face

as the “cheekbone”, and contributes to the lateral and inferior walls of the orbit. It consists of external and

internal laminae of compact bone with an inner core of spongy bone. The zygomatic bone articulates with

four bones.

Cranial Bones – Zygomatic

 1 Orbital surface

 2 Temporal surface

 3 Lateral surface

 4 Temporal process

 5 Frontal process

 6 Zygomatico-orbital foramen

 7 Zygomaticofacial foramen

 8 Zygomaticotemporal foramen

Right zygomatic bone

Superior view, anterior to top Right zygomatic bone

Inferior view, anterior to top

Right zygomatic bone

Anterior view Right zygomatic bone

Posterior view

Right zygomatic bone

Lateral view, anterior to right

Right zygomatic bone

Medial view, anterior to left

The zygomatic bone, originally named by Galen the

os zygoma, comes from

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in the posterior facial region where it contributes to the roof of the mouth, fl oor of the orbit, fl oor and

lateral walls of the nasal cavity, and to the pterygopalatine fossa. It has a strong horizontal plate with a

delicate vertical lamina that projects superiorly. The palatine bone articulates with six bones.

The palatine bone is a delicate

and intricate bone that forms the

shape of the letter L. It sits deep

Cranial Bones – Palatine

 1 Perpendicular plate

 2 Sphenopalatine notch

 3 Greater palatine groove

 4 Pyramidal process

 5 Orbital process

 6 Lesser palatine foramina

 7 Posterior nasal spine

 8 Conchal crest

 9 Horizontal plate

Left palatine bone

Anterior view, lateral at right Left palatine bone

Posterior view, lateral at left

Left palatine bone

Superior view, anterior at top Left palatine bone

Inferior view, anterior at bottom

Left palatine bone

Lateral view, anterior at left

Left palatine bone

Medial view, anterior at right

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with transverse posterosuperior projections resembling the handles of the plow. This is a small, thin,

unpaired bone that sits in the median plane. It is wider at its superoposterior base and it tapers toward its

antero-inferior apex. It forms the inferior portion of the bony nasal septum. Its surfaces face laterally and

form the lower, medial wall of the nasal cavities. The vomer articulates with six bones and one cartilage.

The vomer is a fl at, triangular bone

that resembles a plow. It has a fl at,

median, vertical blade-like process

Cranial Bones – Vomer

 1 Ala of vomer

 2 Vomerine groove

 3 Vomerine crest of choana

 4 Cuneiform part

Vomer

Inferior view, anterior at bottom

Vomer

Superior view, anterior at bottom

Vomer

Lateral view, anterior at left

Vomer

Anterior view

Vomer

Posterior view

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upon which a pair of eye glasses rest. The external surface of the bones provides attachment for the

procerus and nasalis muscles, two thin muscles of facial expression. Each nasal bone articulates with

four bones.

The paired nasal bones are small, rectangular bones with a subtle bow-like

shape. They form the bridge of the nose

Cranial Bones – Nasal

 1 Ethmoidal groove

 2 Nasal foramina

 3 Superior border

 4 Inferior border

 5 Lateral border

 6 Medial border

Left nasal bone

Posterior view, lateral at right

Left nasal bone

Anterior view, lateral at left

Left nasal bone

Lateral view, anterior at right

Left nasal bone

Medial view, anterior at left

Left nasal bone

Superior view, anterior at bottom

Left nasal bone

Inferior view, anterior at bottom

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This is a small, delicate bone that projects from the lateral wall of the nasal cavity. It is scroll-like in appearance as it arches inferiorly and laterally from the nasal cavity’s lateral wall. The medial surface of the bone

is convex and furrowed by many longitudinal grooves that transport blood vessels beneath the thick nasal

mucosa that covers this surface. The lateral surface of the bone is concave and forms most of the superior and medial boundary of the inferior nasal meatus. The inferior border of the bone has a rough, spongy

appearance. Superiorly the bone forms an articular border with four bones.

Cranial Bones – Inferior Nasal Concha

 1 Lacrimal process

 2 Maxillary process

 3 Ethmoidal process

 4 Lateral surface

 5 Medial surface

Left inferior nasal concha

Posterior view, lateral at right

Left inferior nasal concha

Anterior view, lateral at left

Left inferior nasal concha

Lateral view, anterior at right

Left inferior nasal concha

Medial view, anterior at left

Left inferior nasal concha

Superior view, anterior at right

Left inferior nasal concha

Inferior view, anterior at right

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the “tear duct.” This small, delicate, quadrate-shaped bone has a vertical axis that is slightly longer than

its horizontal axis. It is extremely thin. When it is held up to a light source, the light easily penetrates the

bone. The bone sits in the anterior part of the medial wall of the orbit. The orbital surface is smooth and

fl at in its posterior half where it contributes to the medial wall of the orbit. Anteriorly this surface has a

longitudinal groove that ends posteriorly in a longitudinal crest that is hook-shaped inferiorly. This groove

supports the nasolacrimal duct. Covered with mucous membrane, the slightly rough, medial surface of the

bone contributes to the nasal cavity. The lacrimal bone articulates with four bones.

The lacrimal bone derives its name

from the Latin word meaning

tear because the bone houses

Cranial Bones – Lacrimal

 1 Posterior lacrimal crest

 2 Lacrimal groove

 3 Lacrimal hamulus

Left lacrimal bone

Anterior view, lateral at right

Left lacrimal bone

Lateral view, anterior at left

Left lacrimal bone

Posterior view, lateral at left

Left lacrimal bone

Medial view, anterior at right

Left lacrimal bone

Superior view, lateral at right

Left lacrimal bone

Inferior view, lateral at left

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three small bones occupy the middle ear cavity, where they transmit and amplify the sound waves from the tympanic membrane to the inner ear. From lateral to medial the bones are the malleus, the incus, and the stapes, or in layman’s terms the

hammer, the anvil, and the stirrup, because of their striking resemblance to these structures.

The auditory ossicles are

the smallest bones of the

human skeleton. These

Cranial Bones – Auditory Ossicles

 1 Malleus

 2 Incus

 3 Stapes

 4 Handle of malleus

 5 Head of malleus

 6 Neck of malleus

 7 Lateral process

 8 Anterior process

 9 Body of incus

10 Long limb

 11 Lenticular process

12 Short limb

13 Head of stapes

14 Anterior limb

15 Posterior limb

16 Footplate

Auditory ossicles in situ within temporal bone

Anterior view, left temporal bone

Left auditory ossicles

Anterior view, lateral at left

Left malleus

Anterior view, lateral at left

Left incus

Lateral view, anterior at left

Left stapes

Superior view, lateral at left

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occupies the ventrosuperior neck just inferior to the mandible. It serves as a skeletal attachment site for

muscles associated with the tongue, larynx, and pharynx. It consists of fi ve elements — a body and bilateral lesser and greater cornua. The body is the rectangular ventral element that sits in the transverse

plane. Projecting posterolaterally from the body are the paired, long, slender greater cornua. At the junction of the greater cornua and the body are smaller superior projections, the lesser cornua.

Suspended from the styloid processes

of the temporal bones by the stylohyoid

ligaments, the U-shaped hyoid bone

Cranial Bones – Hyoid

 1 Body

 2 Lesser horn

 3 Greater horn

Hyoid bone

Anterior view

Hyoid bone

Lateral view, anterior at right

Hyoid bone

Superior view, anterior at bottom

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of the vertebrae has a similar structure. The bones of the vertebral column are grouped into seven cervical vertebrae, twelve thoracic vertebrae, fi ve lumbar vertebrae, the sacrum consisting of fi ve fused segments, and the

coccyx comprised of three to fi ve fused segments, most typically four. The column is the central axis of the body

that supports the limbs and the cranium, protects the spinal cord, and provides attachment for muscles that

move this fl exible column of bones.

The vertebral column consists of 26 bones that develop

from a series of 33 identical embryonic body segments. Because they develop from similar repeating segments, each

Vertebral Column

 1 Cervical vertebrae

 2 Thoracic vertebrae

 3 Lumbar vertebrae

 4 Sacrum

 5 Coccyx

 6 Thoracic kyphosis

 7 Sacral kyphosis

 8 Cervical lordosis

 9 Lumbar lordosis

10 Intervertebral foramen

Vertebral column

Anterior view

Vertebral column

Lateral view, anterior at right

Vertebral column

Posterior view

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Frontal bone

Superior view, anterior to bottom

Frontal bone

Lateral view, anterior to left

Frontal bone

Inferior view, anterior to top

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nium. The external surface of each parietal bone is slightly convex while the internal surface is concave

and marked with impressions from meningeal vessels. The inferior border forms a beveled articular surface, while the superior, anterior, and posterior borders form deeply denticulate articular surfaces. The

bone consists of inner and outer laminae of compact bone sandwiching a layer of trabecular bone, the

diploë. Each parietal bone articulates with fi ve bones.

The parietal bones are large quadrilateral bones forming the greater

part of the roof and sides of the craCranial Bones – Parietal

 1 Groove for sigmoid sinus

 2 Groove for superior sagittal sinus

 3 Grooves for middle meningeal artery

 4 Superior temporal line

 5 Inferior temporal line

 6 Parietal tuber

 7 Squamosal border

 8 Occipital border

 9 Frontal border

10 Sagittal border

 11 Frontal angle

12 Occipital angle

13 Sphenoid angle

14 Mastoid angle

15 Parietal foramen

Left parietal bone

Medial view, anterior to right

Left parietal bone

Lateral view, anterior to right

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Left parietal bone

Anterior view

Left parietal bone

Posterior view

Left parietal bone

Inferior view, anterior to right

Left parietal bone

Superior view, anterior to left

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behind it has an oval to round shape. The bone has four distinct regions. The squamous portion is the internally concave posterosuperior plate and forms the greater part of the bone. The thick quadrilateral basioccipital, or basilar part, contributes to the base of the cranium anterior to the foramen magnum. Lateral

to this and converging with the squama are the two condylar parts or exoccipitals. Together the four regions of the bone form the borders to the large circular opening, the foramen magnum, which provides

passage for the spinal cord between the cranial vault and the spinal canal. The occipital bone articulates

with six bones.

The occipital bone forms the

greater part of the posterior and

inferior cranium. Viewed from

Cranial Bones – Occipital

 1 Foramen magnum

 2 Clivus

 3 Pharyngeal tubercle

 4 Squamous part

 5 Mastoid border

 6 Lambdoid border

 7 Occipital condyle

 8 Condylar canal

 9 Hypoglossal canal

10 Condylar fossa

 11 Jugular tubercle

12 Jugular notch

13 Jugular process

14 External occipital protuberance

15 Superior nuchal line

16 Inferior nuchal line

17 Internal occipital protuberance

18 Groove for transverse sinus

19 Groove for occipital sinus

20 Groove for superior sagittal sinus

21 Cerebral fossa

22 Cerebellar fossa

Occipital bone

Posterior view

Occipital bone

Anterior view

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Occipital bone

Inferior view, anterior to bottom

Occipital bone

Lateral view, anterior to right

Occipital bone

Superior view, anterior to bottom

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the bone is the thin lateral plate that contributes to the lateral wall of the cranium. It projects anteriorly

as the zygomatic process and forms the mandibular fossa for the temporomandibular joint. The styloid

part is represented by the styloid process. This projection of bone arises from the upper elements of the

second pharyngeal arch. The petrous part forms the thick pyramidal base of the bone. It begins posterior to the external acoustic meatus as the mastoid process and ends where it forms a junction with the

basi-occipital and greater wing of the sphenoid. The name petrous describes its rock-like appearance.

This is the thickest part of the temporal bone. It arises from the otic capsules that stabilize the delicate

internal ear structures. The mastoid is the posterolateral protuberance of the petrous portion that is easily

palpable just posterior to the ear. The tympanic part of the temporal bone is the ring-like plate that forms

the walls of the external acoustic meatus. Each temporal bone articulates with fi ve bones.

The temporal bone is a complex bone with fi ve distinct

parts. The squamous part of

Cranial Bones – Temporal

Left temporal bone

Medial view, anterior to right

Left temporal bone

Lateral view, anterior to left

 1 Petrous part

 2 Mastoid process

 3 Mastoid notch

 4 Groove for sigmoid sinus

 5 Carotid canal

 6 Apex of petrous part

 7 Musculotubal canal

 8 Tegmen tympani

 9 Hiatus for greater petrosal nerve

10 Hiatus for lesser petrosal nerve

 11 Trigeminal impression

12 Internal acoustic meatus

13 Mastoid canaliculus

14 Tympanic canaliculus

15 Styloid process (broken)

16 Stylomastoid foramen

17 Jugular notch

18 Tympanic ring

19 External acoustic meatus

20 Greater tympanic spine

21 Lesser tympanic spine

22 Squamous part

23 Zygomatic process

24 Mandibular fossa

25 Articular tubercle

26 Petrotympanic fissure

27 Tympanomastoid fissure

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Left temporal bone

Superior view, anterior at top

Left temporal bone

Posterior view

Left temporal bone

Anterior view

Left temporal bone

Inferior view, anterior at bottom

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terfl y. Like it name suggests, it is wedged into the center of the cranium where it articulates with twelve

neighboring bones and contributes to much of the cranial base. It is divisible into four principal components — the body, greater wings, lesser wings, and pterygoid processes. With the calvaria removed the

bone is visible from any view. This bone plays a prominent role at the base of the skull. It supports the

brain, serves to protect the optic stalks and capsules, provides passage for many vessels and nerves

entering and leaving the skull, and forms a sinus cavity that communicates with the nasal cavity.

The sphenoid bone is a complex bone that has the spread

-winged appearance of a butCranial Bones – Sphenoid

 1 Jugum

 2 Sella turcica

 3 Tuberculum sellae

 4 Hypophysial fossa

 5 Dorsum sellae

 6 Posterior clinoid process

 7 Middle clinoid process

 8 Carotid sulcus

 9 Sphenoidal crest

10 Sphenoidal rostrum

 11 Sphenoidal sinus

12 Sphenoidal concha

13 Lesser wing

14 Optic canal

15 Anterior clinoid process

16 Superior orbital fissure

17 Greater wing

18 Infratemporal crest

19 Orbital surface

20 Foramen rotundum

21 Foramen ovale

22 Foramen spinosum

23 Spine of sphenoid bone

24 Lateral plate of pterygoid process

25 Medial plate of pterygoid process

26 Pterygoid notch

27 Pterygoid fossa

28 Scaphoid fossa

29 Vaginal process

30 Pterygoid hamulus

31 Pterygoid canal

Sphenoid bone

Anterior view

Sphenoid bone

Posterior view

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Sphenoid bone

Inferior view, anterior at top

Sphenoid bone

Superior view, anterior at top

Sphenoid bone

Lateral view, anterior to left

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walls of the nasal cavity, orbit, oral cavity, and maxillary sinus. The maxillary sinus is the hollow central

cavity within the large body of the maxilla. Four variable-shaped processes project from the maxillary

body. The processes are the posterolateral zygomatic process, the medial projecting palatine process,

the arched inferior process called the alveolar, and the superiorly projecting frontal process. Each

maxilla articulates with nine bones.

Cranial Bones – Maxilla

 1 Orbital surface

 2 Infra-orbital groove

 3 Infra-orbital foramen

 4 Anterior nasal spine

 5 Canine fossa

 6 Maxillary tuberosity

 7 Lacrimal groove

 8 Maxillary sinus

 9 Greater palatine groove

10 Frontal process

 11 Zygomatic process

12 Palatine process

13 Incisive canal

14 Alveolar process

15 Interalveolar septum

Left maxilla

Anterior view

Left maxilla

Posterior view

The maxillae are large, paired

bones that unite to form the upper

jaw. They also contribute to the

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