• Bone is the hard part of the body providing
framework to it
• Bone acts as levers for muscles and therefore
help in the movements of the body
• Bone provides protection to the visceral
organs like brain, lungs and heart
• Bone is the site of blood formation
• Plays an important role in the immune
responses of body
• Store house of calcium and phosphorus
• Study of bones-osteology
• There are 206 bones in our body
• Skull has 22 bones
• Skull is the skeleton of head
• Cranium- skull minus mandible
• Calvaria is upper part of cranium also called
• Facial skeleton is skull minus calvarium
22 bones join to form the skull
8 pairs and 6 individuals
Divided into neurocranium and viscerocranium
Sometimes sutural bones present
According to shape
Long bones ( eg: humerus, radius)
Short bones (eg: carpal and tarsal bones)
Flat bones (eg: vault of the skull, ribs )
Irregular bones (eg: Vertebra, hip bone )
Pneumatic bones (eg: maxilla, sphenoid )
Sesamoid bones (eg: patella)
Intramembranous or mesenchymal ossification.
eg: bones of the vault of skull and facial bones
Intracartilaginous or endochondral ossification.
eg: bones of limbs, vertebral column and thoracic
eg: clavicle, mandible.
covers the brain
comprises the facial
• The bones which constitute the calvaria or brain
• Unpaired bones
• Paired bones-
• Oval in shape
• Wider posteriorly than anteriorly.
• Bones seen in norma verticalis:
1) upper part of frontal bone anteriorly.
2) uppermost part of occipital bone posteriorly.
3) A parietal bone on each side.
Sutures seen are:
• Coronal suture: placed between the frontal bone
and the 2 parietal bone.
• Sagittal suture: placed in the median place
between the 2 parietal bone.
• Lambdoid suture: posteriorly between the
occipital and the 2 parietal bone.
• Metopic (latin forehead) suture: occasionally
present in about 3-8% individuals. Lies in the
median plane. Separates 2 half of frontal bone
and fuses at the 6 yrs of age.
• Other features are:
Vertex- highest point on saggital suture
Bregma- meeting point between the coronal
and sagittal sutures.
Lambda- meeting point between sagittal and
Obelion- point on sagittal suture between two
• The main bone on the side
of the skull.
• It articulates (joins) with
the other parietal bone in
the midline (top of the
head), with the frontal
bone in front of it, with
the occipital bone behind
it, and with the sphenoid
and temporal bones lower
down on the side of the
Frontanelles are sites of
growth of skull, permitting
growth of brain and pulps to
If frontanelles fuse early-
brain growth stunted, and
child will be less intelligent.
• Convex upward and on each side , flattened
• Bones seen:
• 1) posterior part of parietal bones, above.
• 2)Upper part of squamous part of the occipital
• 3)mastoid part of the temporal bone on each
• Sutures seen are:
4)Posterior part of saggital suture.
• From the Latin, meaning the part of the head
opposite the front.
• It occupies the posterior and inferior part of the
• The occipital bone articulates (joins) with the
parietal and temporal bones of the skull, the
sphenoid bone in front of it, and the first cervical
vertebra (the atlas) beneath it
– Foramen magnum: large hole, allowing
passage of the spinal cord
– External occipital protuberance (EOP):
prominent projection on back of occiput
– Nuchal lines: a superior and inferior line
running laterally from the midline, serve as a
point of muscle attachment
Wider posterior a. Lowest part of medulla oblongata
b. Three meninges
Subarachanoid space a. Spinal accessory nerves
b. Vertebral arteries
c. Sympathetic plexus
d. Post spinal arteries
e. Ant spinal arteries
Narrow anterior part a. Apical ligament of dens
b. Vertical band of cruciate ligament
c. Membrana tectoria
• Roughly oval in outline, being wider above
• Bones seen are:
2)right and left maxillae form the upper jaw.
3)right and left nasal bones.
• Sutures seen are
• The large bone that makes up the forehead and
supplies the upper edge and roof of the orbit (eye
• The frontal bone articulates (comes together)
with a number of other bones including the
parietal, nasal, ethmoid, maxillary, and zygomatic
– Squama: flat portion that forms the forehead
– Supraorbital margin: ridge under the eyebrow,
forming the upper part of the orbit (eye
– Supraorbital foramen: small hole within
supraorbital margin for blood vessels and
– Frontal sinuses: hollow spaces behind the
squama, act as sound chambers to give the
Nasal bone is the most commonly fractured
bone of the face.
Mandible and parietal eminence are next
bone to be fractured.
• A large irregular bone situated at the base and
side of the skull.
• The temporal bone is connected with the
mandible (the jaw bone) via the
temporomandibular (TM) joint.
• The temporal bone is formed of three parts
(squamous, tympanic and petrous) that are
distinct at birth but then fuse. The petrous
portion of the temporal bone contains the
structures of the inner ear.
– Squama: flat portion of the temporal bone
forming the anterior and superior part of the
– Zygomatic process: process forming part of the
– Petrous portion: internal, forming part of the floor
of the cranium. Contains the ear canal and
internal ear structures.
– Mandibular fossa: socket between squama and
petrous portion, articulates with the condyle of
the mandible (TMJ)
– External auditory meatus: opening to the ear
– Mastoid process: bony prominence behind the
external auditory meatus
– Styloid process: looks like an elephant’s tusk
located between the mastoid process and the
jaw. Acts as a point of attachment for muscles
Pterion is the thin part of the skull.
In roadside accidents, the anterior division of
middle meningeal artery may be ruptured,
leading to clot formation between the skull bone
and durameter or extradural haemorrhage. The
clot compresses the motor area of the brain
leading to paralysis of the opposite site.
The clot must be sucked out at the earliest by
The head must be protected by a helmet.
• Divided arbitrarily into-
o and posterior parts.
• A prominent, irregular, wedge-shaped bone at the
base of the skull. The sphenoid bone has been called
the "keystone" of the cranial floor since it is in
contact with all of the other cranial bones.
• Sphenoid bone resemble a bat with outstretched
• Comprises: a body in the centre
two lesser wings from the anterior part
two greater wings from the lateral part
two pterygoid processes.
– Greater wings: large lateral projections of bone
that help to form the lateral border of the skull
– Lesser wings: smaller lateral projections of
bone above the greater wings
– Pterygoid processes: two long downward
projections from the greater wings that act as
a point of muscle attachment.
– Sella turcica: known as the Turkish Saddle
which cradles the pituitary gland.
• An irregularly shaped, bone that provides the floor of
the front part of the skull and the roof of the nasal
• The ethmoid consists of two masses of thin plates
enclosing air cells and looks like a sieve.
– Lateral masses: form most of the wall between
the nasal cavity and the orbits
– Perpendicular plate: forms the superior portion of
the nasal septum
– Cribiform plate: forms the roof of the nasal cavity
– Olfactory foramina: small holes within the
cribiform plate for passage of the first cranial
nerve (for smell)
– Crista galli: upward extension of bone above
the cribiform plate, acts as an anchoring point
for one of the coverings of the brain.
– Nasal concha (turbinates): two scroll-shaped
projections with a mucus membrane on either
side of the nasal septum. Function to cause air
turbulence and trap inhaled particles.
• Fracture of cribriform plate of ethmoid with
tearing off of the meninges may tear the
olfactory nerve rootlets. In such cases, CSF
may drip from the nasal cavity. It is called CSF
Pyramidal bony cavities, situated one on each
side of the root of the nose.
They provide sockets for rotatory movements of
Protection of eye
Bony recess that holds the eye
medial wall: frontal
process, lacrimal bone and
part of ethmoid
lateral wall: sphenoid,
floor: maxillary, zygomatic
pos: sphenoid + superior
top: frontal bone
• Weakness and paralysis of a muscle causes squint
or strabismus, which may be concomitant or
• Nystagmus is characterized by involuntary,
rhythmical oscillatory movement of the eyes.
• Optic neuritis is characterized by pain in and
behind the eyes on ocular movements and on
• Hypertension causes atheromatous changes in
the arteries of the eyes.
• Facial skeleton is composed of following bones
B. Unpaired bones
• The largest bones of the face, except for the
mandible and formed by their union, the whole of
the upper jaw.
• They hold the upper teeth, and connect on the left
and right to the zygomatic bones (cheek bones).
• Each assists in forming of face, nose, mouth, orbit,
infratemporal and pterygopalatine fossae.
• Each maxilla has a body and 4 processes:
• Maxilla ossifies in membrane from 3 centers-
one for the maxillary proper and 2 for incisivum
• Center for maxillary proper appears above the
canine fossa during 6th week of IUL and 2
premaxilla – main above the incisive fossa
during the 7th week of IUL and 2nd one appears
at ventral margin of nasal septum during 10th
– Infra Orbital foramen: hole below the orbit,
for blood vessels and nerves
– Alveolar process: arch of the maxilla
containing the upper teeth
– Palatine process: horizontal projection of the
maxilla forming the anterior ¾ of the hard
• At birth:
Transverse and anterioposterior diameter > vertical diameter
Frontal process- well marked
Body consists of a little more than the alveolar process.
Tooth sockets reaching to the floor of the orbit
Maxillary sinus is rudimentary.
• In the adult:
Vertical diameter due to development of alveolar process
and increase in size of the sinus.
• In the old:
The bone reverts to infantile condition. Height reduced
due to absorption of the alveolar process.
• Also called antrum of highmore
• It is pyramidal in shape with base towards the
nasal cavity and apex towards the zygomatic
• It is the largest paranasal sinus and commonly
involved in inflammation process (maxillary
• Infection of a sinus is known as sinusitis.
• The maxillary sinus is most commonly
• Carcinoma of maxillary sinus arises from the
• Caldwell-luc operation is done as treatment.
• Unilateral fracture of maxilla usually involves
its alveolar process
• Bilateral maxillary fractures can be classified
into Lefort I, Lefort II, Lefort III fractures
• Lefort I (Guerins fracture)-it is a horizontal
fracture along the floor of the nose and below
the zygomatic bone
• Lefort II (in this the fracture line passes through orbits then
runs medial to and below the zygomatic bones towards the
• Lefort III (In this fracture the fracture line runs through the
nasal bones and orbits above the zygomatic bone. This is
also called craniofacial dysjunction)
Smallest and most fragile
bone of the face, is
situated at the front part of
the Medial of the orbit.
Contains: a)lacrimal sac and
Anterior- frontal process
Posterior- orbital plate of
Superior- frontal bone
• Commonly referred to as
• It is situated at the upper
and lateral part of the Face.
• It forms the prominence of
FORMS: a) floor and lateral
wall of the orbit b) walls of
temporal and infraorbital
PROCESSES: 1) FRONTAL AND
• 2 small oblong bones
• Forms bridge of the
• Superior- frontal bone
• Inferior- lateral nasal
• Medial- opposite nasal
• Lateral- frontal process
• Common cold or rhinitis is the most common
infection of the nose
• Paranasal air sinuses may get infected from
• Little’s area on the septum is a common site of
bleeding from the nose or epistaxis.
One of the unpaired
facial bones of the skull.
Located in the
midsagittal line, and
touches the sphenoid,
the ethmoid, the left
and right palatine bones,
and the left and right
• Nasal conchae are curved bony projections directed
downward and medially.
• 3 conchae are found:
Inferior concha – independent bone.
Middle concha- projection from middle surface of
Superior concha- projection from middle surface of
ethmoidal labyrinth and the smallest one.
• 2 L-shaped bones
• Posterior part of nasal cavity.
1) the lateral wall and floor of
the nasal cavity,
2) the roof of the mouth
3)floor of the orbit
4)Parts of pterygopalatine fossa
• Largest and strongest bone of the face.
• Develops from 1st pharyngeal arch.
• Forms the lower jaw and holds the lower teeth in
– Body: curved horizontal portion of the mandible
– Rami: two upward projections of bone that are
perpendicular to the body of the mandible.
– Angle of the mandible: angle formed where the
body meets the ramus
– Condylar process: a condyle on the posterior
portion of the ramus that articulates with the
mandibular fossa of the temporal bone.
– Coronoid process: a sharp projection of bone on
the anterior portion of the ramus that acts as a
point of muscle attachment.
– Alveolar process: arch of bone containing the
– Mental foramen: small hole on the side of the
body for blood vessels and nerves.
BODY OF MANDIBLE
• External surface
• Internal surface
• The mandible is mostly
fractured at the canine
socket where it is weak.
Involvement of the IAN
in the callus may cause
neuralgic pain, which
may be referred to the
areas of distribution of
the buccal and
• Next common fracture
areas are- angle and
neck of the mandible.
• The body of the bone is a mere shell,
• The mandibular canal is of large size, and runs near the lower
border of the bone;
• The mental foramen opens beneath the socket of the
deciduous molar tooth.
• The angle is obtuse (140°), condyloid portion is nearly in line
with the body.
• The coronoid process is of comparatively large size, and
projects above the level of the condyle.
Two segments of the bone become joined at the
Increased growth of the body & the alveolar part
behind the mental foramen
The mandibular canal, is situated just above the level
of the mylohyoid line.
The mental foramen occupies the position usual to it
in the adult.
The angle becomes less obtuse, 110°.
Bone reduced in size. The alveolar process is resorbed.
The chief part of the bone is below the oblique line.
The mandibular canal & mental foramen is close to the
The ramus is oblique in direction, the angle measures
Neck of the condyle is more or less bent backward.
Cunningham’s Manual Of Practical Anatomy: G.J.Romanes
Text book of Human Osteology: Inderbir Singh 1st Edition
Human Anatomy Regional and Applied: B.D.CHAURASIA
Kumar GS, Orban’s oral histology & embryology, 12th ed
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