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2. Head
Human Head
• In anatomy, the head of an animal is the rostral part (from
anatomical position) that usually comprises the brain, eyes, ears,
nose, and mouth (all of which aid in various sensory functions,
such as sight, hearing, smell, and taste). Some very simple
animals may not have a head, but many bilaterally symmetric
forms do.

3. Bones of the head
Human skull
• The skull is divided
into the cranium (all
the skull bones except
the mandible) and the
mandible (or jawbone).
One feature that
distinguishes mammals
and non-mammals is
that there are also
three ear bones (called
ossicles):
• malleus (hammer)
• incus (anvil)
• stapes (stirrup)

4. Ossicles
(Malleus,Incus,Stapes)
Ossicles (also called auditory ossicles) are the three smallest bones in
the human body. They are contained within the middle ear space and
serve to transmit sounds from the air to the fluid filled labyrinth
(cochlea). The absence of the auditory ossicles would constitute a
moderate to severe hearing loss.
Malleu
s
Incu
s
Stape
s

5. Mandible
Jaw
 is either of the two opposable structures forming, or near
the entrance to, the mouth.
Jaws
 is also broadly applied to the whole of the structures
constituting the vault of the mouth and serving to open and
close it.
In vertebrates, the lower jaw, dentary or mandible is the
mobile component that articulates at its posterior processes,
or rami (singular ramus), with the temporal bones of the skull

6. Mandible
A.) Body
a.) Symphysis menti
b.) Mental protuberance
c.) Mental foramen
d.) Mylohyoid line
B.) Ramus
a.) Mandibular foramen
b.) Mylohyoid groove
c.) Mandibular canal
d.) Angle
e.) Coronoid process
f.) Condyloid process
g.) Mandibular notch

7. Body of the Mandible
Mandible (from Latin mandibŭla, "jawbone") or inferior maxillary bone is,
together with the maxilla, the largest and strongest bone of the
face[citation needed]. It forms the lower jaw and holds the lower teeth in
place.
Body of the
mandible
Symphysis menti
Mental
protuberance
Mental foramen
Mylohyoid line

8. Symphysis Menti
• The external surface of the mandible is marked in the median line by a faint ridge,
indicating the symphysis menti or line of junction of the two pieces of which the bone
is composed at an early period of life.
• This ridge divides below and encloses a triangular eminence, the mental
protuberance, the base of which is depressed in the center but raised on either side to
form the mental tubercle.
• It serves as the origin for the Geniohyoid and the Genioglossus.

9. Mental protuberance
Symphysis of the external surface of the mandible divides below and
encloses a triangular eminence, the Mental protuberance, the base of
which is depressed in the center but raised on either side to form the
mental tubercle.

10. Mental foramen
Mental foramen
 is one of two holes ("foramina") located on the anterior surface of the mandible.
It permits passage of the mental nerve and vessels. The mental foramen descends
slightly in edentulous individuals

11. Mylohyoid line
• Extending upward and backward on either side from the lower part of
the symphysis of the Mandible is the mylohyoid line, which is the origin
of the mylohyoid muscle; the posterior part of this line, near the alveolar
margin, gives attachment to a small part of the Constrictor pharyngis
superior, and to the pterygomandibular raphé.

12. Ramus of the Mandible
• The ramus of the mandible (perpendicular portion) is
quadrilateral in shape, and has two surfaces, four borders, and two
processes.

13. Mandibular foramen
• The Mandibular foramen is an opening on the internal surface of
the ramus (posterior and perpendicularly oriented part of the
mandible) for divisions of the mandibular vessels and nerve to
pass.

14. Mylohyoid groove
• Behind this groove is a rough
surface, for the insertion of the
Pterygoideus internus.
• The margin of the mandibular
foramen is irregular; it presents in
front a prominent ridge, surmounted
by a sharp spine, the lingula
mandibulæ, which gives attachment
to the sphenomandibular ligament;
at its lower and back part is a notch
from which the mylohyoid groove
runs obliquely downward and
forward, and lodges the mylohyoid
vessels and nerve.

15. Mandibular
Canal
Mandibular canal
 runs obliquely downward and
forward in the ramus, and then
horizontally forward in the body,
where it is placed under the alveoli
and communicates with them by
small openings.
• On arriving at the incisor teeth, it
turns back to communicate with the
mental foramen, giving off two
small canals which run to the
cavities containing the incisor teeth.
• Carries branches of inferior alveolar
nerve and artery. Is continuous with
the mental foramen (opents onto
front of mandible) and mandibular
foramen (on medial aspect of
ramus).

16. Angle of the Mandible
At the junction of the lower border of the ramus of the mandible with the
posterior border is the angle of the mandible, which may be either inverted
or everted and is marked by rough, oblique ridges on each side, for the
attachment of the Masseter laterally, and the Pterygoideus internus medially;
the stylomandibular ligament is attached to the angle between these muscles.

17. Coronoid Process
Coronoid process
 is a thin, triangular eminence, which is flattened from side to side and varies in
shape and size.
• Its anterior border is convex and is continuous below with the anterior border of the
ramus.
• Its posterior border is concave and forms the anterior boundary of the mandibular
notch.
• Its lateral surface is smooth, and affords insertion to the Temporalis and Masseter.
• Its medial surface gives insertion to the Temporalis, and presents a ridge which
begins near the apex of the process and runs downward and forward to the inner side
of the last molar tooth.
• Between this ridge and the anterior border is a grooved triangular area, the upper part
of which gives attachment to the Temporalis, the lower part to some fibers of the

18. Condyloid
Process
The condyle presents an articular surface for articulation with the articular
disk of the temporomandibular joint; it is convex from before backward
and from side to side, and extends farther on the posterior than on the
anterior surface.
• Its long axis is directed medialward and slightly backward, and if
prolonged to the middle line will meet that of the opposite condyle near
the anterior margin of the foramen magnum.
• At the lateral extremity of the condyle is a small tubercle for the
attachment of the temporomandibular ligament.
 is thicker than the
coronoid, and consists of
two portions: the condyle,
and the constricted portion
which supports it, the neck.

19. Mandibular Notch
The upper border of the ramus of mandible is thin, and is surmounted by
two processes, the coronoid process in front and the condyloid process
behind, separated by a deep concavity, the mandibular notch.

20. Cranium
• The cranium can be divided into a skull cap (or calvarium) and base.
The cranium consists of several bones which fuse together at junctions
called sutures. Several sutures join to form a pterion.
• This process of bone fusion occurs in utero to protect the most
important organ in the body, the brain. Although most fusing is
complete before birth, there are large areas of fibrous tissue (called
fontanelles) where fusion is incomplete until puberty.
• Facial and skull bones formed:
• two maxillae (one on each side of the head) that cover the inferior and
medial to the eye socket (or orbit)
• two zygomatic bones, inferior and lateral to the orbit
• two temporal bones, covering an area where the ears are located
• a single frontal bone, superior to the orbit
• two parietal bones, posterior to the frontal bone and superior to the
temporal bone
• an occipital bone at the back of the head
• several more internal bones which are not easily seen which are
a sphenoid bone, ethmoid bone, two lacrimal bones, two nasal

21. Pterion
• The point corresponding with the
posterior end of the sphenoparietal
suture is named the pterion.
Location
• It is situated about 3 cm. behind,
and a little above the level of the
zygomatic process of the frontal
bone.
• It marks the junction between four
bones:
• the parietal bone
• the temporal bone
• the sphenoid bone
• the frontal bone

22. Fontanels
• In human anatomy, a fontanelle (or
fontanel) is one of two "soft spots"
on a newborn human's skull. There
are, however, two more fontanelles
of interest, the mastoid fontanelle,
and the sphenoidal fontanelle.
• Fontanelles are soft spots on a
baby's head which, during birth,
enable the soft bony plates of the
skull to flex, allowing the head to
pass through the birth canal.
Fontanelles are usually completely
hardened by a child's second
birthday, and will eventually form
the sutures of the neurocranium.

23. Maxilla
I.) Body of maxilla
II.) Maxillary sinus
A.) Surfaces of body
1.) Anterior
a.) Incisive fossa
b.) Canine fossa
c.) Infraorbital foramen
d.) Anterior nasal spine
2.) Infratemporal
a.) Alveolar canals
b.) Maxillary tuberosity
3.) Orbital
a.) Infraorbital groove
b.) Infraorbital canal
4.) Nasal
a.) Pterygopalatine canal
Processes
1.) Zygomatic process
2.) Frontal process
a.) Agger nasi
b.) Anterior lacrimal
crest
3.) Alveolar process
4.) Palatine process
a.) Incisive foramen
b.) Incisive canals
c.) Foramina of
Scarpa
d.) Premaxilla e.)
Anterior nasal spine

24. Maxilla
Maxilla
 is a fusion of two bones along the
palatal fissure that form the upper jaw.
This is similar to the mandible, which is
also a fusion of two halves at the mental
symphysis.
Function
• The alveolar process of the maxilla holds
the upper teeth, and is referred to as the
maxillary arch. The maxilla attaches
laterally to the zygomatic bones (cheek
bones).
• The maxilla assists in forming the
boundaries of three cavities:
• the roof of the mouth
• the floor and lateral wall of the nasal
antrum
• the floor of the orbit
• The maxilla also enters into the formation
of two fossae: the infratemporal and
pterygopalatine, and two fissures, the
inferior orbital and pterygomaxillary.

25. Body of the Maxilla
Body of the Maxilla
 is somewhat
pyramidal in shape, and
contains a large cavity, the
maxillary sinus (antrum of
Highmore).
• It has four surfaces - an
anterior, a posterior or
infratemporal, a superior
or orbital, and a medial or
nasal.

26. Maxillary Sinus
Maxillary sinus (or
Antrum of Highmore)
 is the largest of
the paranasal
sinuses, and is
pyramidal in shape.

27. Surfaces of body
1.) Anterior
a.) Incisive fossa
b.) Canine fossa
c.) Infraorbital foramen
d.) Anterior nasal spine
2.) Infratemporal
a.) Alveolar canals
b.) Maxillary tuberosity
3.) Orbital
a.) Infraorbital groove
b.) Infraorbital canal
4.) Nasal
a.) Pterygopalatine canal

28. Anterior surface of the
body of the maxillaAnterior surface
 is directed forward and
lateral ward. It presents at its
lower part a series of eminences
corresponding to the positions
of the roots of the teeth. Just
above those of the incisor teeth
is a depression, the incisive
fossa, which gives origin to the
Depressor alae nasi; to the
alveolar border below the fossa
is attached a slip of the
Orbicularis oris; above and a
little lateral to it, the Nasalis
arises.

29. Incisive fossa
On the anterior surface of the
maxilla, just above the
eminences corresponding to the
incisor teeth is a depression, the
incisive fossa, which gives origin
to the Depressor alæ nasi; to the
alveolar border below the fossa
is attached a slip of the
Orbicularis oris; above and a
little lateral to it, the Nasalis
arises.

30. Canine fossa
Lateral to the incisive fossa is
another depression, the
canine fossa; it is larger and
deeper than the incisive fossa,
and is separated from it by a
vertical ridge, the canine
eminence, corresponding to
the socket of the canine tooth;
the canine fossa gives origin
to the Caninus.

31. Infraorbital Foramen
Above the canine
fossa is the
infraorbital
foramen, the end
of the infraorbital
canal; it
transmits the
infraorbital
artery, vein, and
infraorbital
nerve.

32. Anterior Nasal Spine
• Medially, the anterior surface
of the maxilla is limited by a
deep concavity, the nasal
notch, the margin of which
gives attachment to the
Dilatator naris posterior and
ends below in a pointed
process, which with its fellow
of the opposite side forms the
anterior nasal spine.

33. Infratemporal surface of
the body of the maxilla
Infratemporal surface
 is convex, directed
backward and lateralward, and
forms part of the infratemporal
fossa.
• It is separated from the anterior
surface by the zygomatic
process and by a strong ridge,
extending upward from the
socket of the first molar tooth. It
is pierced about its center by the
apertures of the alveolar canals,
which transmit the posterior
superior alveolar vessels and
nerves.

34. Alveolar canals
The infratemporal
surface of the
maxilla is
pierced about its
center by the
apertures of the
alveolar canals,
which transmit
the posterior
superior alveolar
vessels and
nerves.

35. Maxillary Tuberosity
• At the lower part of the
infratemporal surface of the maxilla
is a rounded eminence, the
maxillary tuberosity, especially
prominent after the growth of the
wisdom tooth; it is rough on its
lateral side for articulation with the
pyramidal process of the palatine
bone and in some cases articulates
with the lateral pterygoid plate of
the sphenoid.
• It gives origin to a few fibers of the
Pterygoideus internus.

36. Orbital surface of the body
of the maxilla
Orbital surface
 is smooth and
triangular, and
forms the greater
part of the floor
of the orbit.

37. Infraorbital Groove
• Near the middle of the posterior
part of the orbital surface of the
maxilla is the infraorbital groove
(or sulcus), for the passage of the
infraorbital vessels and nerve.
• The groove begins at the middle of
the posterior border, where it is
continuous with that near the upper
edge of the infratemporal surface,
and, passing forward, ends in a
canal, which subdivides into two
branches.

38. Infraorbital canal
• One of the canals of the orbital
surface of the maxilla, the
infraorbital canal, opens just
below the margin of the orbit.

39. Nasal surface of the
body of the maxilla
• The nasal surface presents a
large, irregular opening
leading into the maxillary
sinus. At the upper border of
this aperture are some broken
air cells, which, in the
articulated skull, are closed in
by the ethmoid and lacrimal
bones.

40. Greater Palatine
Canal
Greater palatine canal
(or pterygopalatine
canal)
 is a passage in the
skull that transmits
the greater palatine
artery, vein, and
nerve between the
pterygopalatine fossa
and the oral cavity.

41. Maxilla
A.) Four processes
1.) The zygomatic process
2.) The frontal process
a.) Agger nasi
b.) Anterior lacrimal crest
3.) The alveolar process
4.) The palatine process
a.) Incisive foramen
b.) Incisive canals
c.) Foramina of Scarpa
d.) Premaxilla
e.) Anterior nasal spine

42. Zygomatic Process
The zygomatic process of the maxilla (malar
process) is a rough triangular eminence,
situated at the angle of separation of the
anterior, zygomatic, and orbital surfaces.

43. Frontal Process
Frontal process of the maxilla (nasal
process) is a strong plate, which projects
upward, medialward, and backward, by
the side of the nose, forming part of its
lateral boundary.
• Its lateral surface is smooth, continuous
with the anterior surface of the body, and
gives attachment to the Quadratus labii
superioris, the Orbicularis oculi, and the
medial palpebral ligament.

44. Agger nasi
• The agger nasi (from agger meaning "mound or heap")
is a small ridge on the lateral side of the nasal cavity. It
is located midway at the anterior edge of the middle
nasal concha, directly above the atrium of the middle
meatus. It is formed by a mucous membrane that is
covering the ethmoidal crest of the maxilla.
• It is also called the nasoturbinal concha and the nasal
ridge.

45. Anterior lacrimal crest
• The lateral margin of the lacrimal fossa is named
the anterior lacrimal crest, and is continuous
below with the orbital margin; at its junction with
the orbital surface is a small tubercle, the
lacrimal tubercle, which serves as a guide to the
position of the lacrimal sac.

46. Alveolar Process
The alveolar process is the thickened ridge of bone that contains the tooth sockets on
bones that bear teeth. It is also referred to as the alveolar bone. In humans, the tooth-
bearing bones are the maxilla and the mandible.

47. Palatine Process
• The palatine process of the maxilla (palatal process), thick and strong, is horizontal
and projects medialward from the nasal surface of the bone.
• It forms a considerable part of the floor of the nose and the roof of the mouth and is
much thicker in front than behind.

48. Incisive Foramen
• When the two maxillæ are articulated, a funnel-shaped
opening, the incisive foramen, is seen in the middle line,
immediately behind the incisor teeth.

49. Incisive Canal
• In the opening of the incisive foramen, the orifices of two lateral
canals are visible; they are named the incisive canals or
foramina of Stenson.

50. Foramina of Scarpa
• In the maxilla, occasionally two additional canals are present in the
middle line of the palatine process; they are termed the foramina of
Scarpa, and when present transmit the nasopalatine nerves, the left
passing through the anterior, and the right through the posterior canal.

51. Premaxilla
• The premaxilla is a pair of small cranial bones at the very tip
of the jaws of many animals, usually bearing teeth, but not
always. They are connected to the maxilla and the
nasals.

52. Anterior Nasal Spine
• Medially, the anterior surface
of the maxilla is limited by a
deep concavity, the nasal
notch, the margin of which
gives attachment to the
Dilatator naris posterior and
ends below in a pointed
process, which with its fellow
of the opposite side forms the
anterior nasal spine.

53. Palatine Bone
• The palatine bone is a bone in the
palate (Latin palatum; unrelated to
palatium 'palace', from which other
senses of palatine derive).

54. Palatine Bone
1.) Pterygopalatine fossa
2.) Pterygoid fossa
3.) Horizontal plate
a.) Posterior nasal spine
4.) Perpendicular plate
a.) Pterygopalatine canal
b.) Sphenopalatine foramen
c.) Pyramidal process
5.) Processes
a.) Orbital
b.) Sphenoidal

55. Pterygopalatine Fossa
• The pterygopalatine fossa
 is a fossa in the skull.

56. Pterygoid fossa
• The pterygoid fossa
 is an anatomical term for the fossa formed by the divergence
of the lateral pterygoid plate and the medial pterygoid plate of the
sphenoid bone.

57. Horizontal plate of palatine
bone
• The horizontal part of the palatine bone
(horizontal plate) is quadrilateral, and has
two surfaces and four borders.

58. Posterior nasal spine
• Its medial end of the posterior
border of the horizontal plate
of palatine bone is sharp and
pointed, and, when united with
that of the opposite bone,
forms a projecting process,
the posterior nasal spine for
the attachment of the
Musculus uvulæ.

59. Perpendicular plate of
palatine bone
• The vertical part (perpendicular plate)
of the palatine bone is thin, of an oblong
form, and presents two surfaces and four

60. Greater palatine canal
• The greater palatine canal (or
pterygopalatine canal) is a passage in the skull
that transmits the greater palatine artery, vein, and
nerve between the pterygopalatine fossa and the

61. Sphenopalatine
foramen
• The sphenopalatine foramen is a
foramen in the skull that connects the nasal
cavity with the pterygopalatine fossa.

62. Pyramidal process of
palatine bone
• The pyramidal process of the palatine bone
projects backward and lateralward from the
junction of the horizontal and vertical parts, and is
received into the angular interval between the

63. Orbital process of palatine
bone
• The orbital process of the palatine bone is placed on a
higher level than the sphenoidal, and is directed upward and
lateralward from the front of the vertical part, to which it is
connected by a constricted neck. It presents five surfaces,
which enclose an air cell. Of these surfaces, three are

64. Sphenoidal process of
palatine bone
• The vertical part (perpendicular plate)
of the palatine bone is thin, of an oblong
form, and presents two surfaces and four

65. Zygomatic Bone
Zygomatic bone
(malar bone)
 is a paired bone of the human
skull. It articulates with the maxilla,
the temporal bone, the sphenoid
bone and the frontal bone. It forms
part of the orbit and is commonly
referred to as the cheekbone. It is
situated at the upper and lateral part
of the face: it forms the prominence
of the cheek, part of the lateral wall
and floor of the orbit, and parts of the
temporal and infratemporal fossae. It
presents a malar and a temporal
surface; four processes, the
frontosphenoidal, orbital, maxillary,
and temporal; and four borders.

66. Zygomatic Bone
Orbital process
Zygomaticofacial foramen
Zygomaticotemporal foramen
Zygomaticoörbital foramina

67. Orbital Process of the
Zygomatic bone
Orbital process
of the
zygomatic
bone
 is a thick,
strong plate,
projecting
backward and
medialward
from the
orbital

68. Zygomaticofacial
foramen The malar surface of the
zygomatic bone is convex
and perforated near its center
by a small aperture, the
zygomaticofacial foramen,
for the passage of the
zygomaticofacial nerve and
vessels; below this foramen is
a slight elevation, which gives
origin to the Zygomaticus.

69. Zygomaticotemporal
foramen
• Near the center of
the temporal
surface of the
zygomatic bone is
the
zygomaticotempor
al foramen for the
transmission of
the
zygomaticotempor
al nerve.

70. Zygomaticoörbital foramina
On the orbital process of the
zygomatic bone are seen the
orifices of two canals, the
zygomaticoörbital foramina;
one of these canals opens
into the temporal fossa, the
other on the malar surface of
the bone; the former transmits
the zygomaticotemporal, the
latter the zygomaticofacial
nerve.

71. Temporal Bone
Temporal bones
 are situated at the sides and
base of the skull.
• The temporal bone supports that
part of the face known as the
temple.
Parts
• Each consists of five parts:
• Squama temporalis
• Mastoid portion
• Petrous portion
• Tympanic part
• Styloid process (temporal)

72. Squama Temporalis
Squama of the
temporal bone
 forms the
anterior and
upper part of the
bone, and is
scale-like, thin,
and translucent.

73. Mastoid portion of the
temporal bone
Mastoid portion of
the temporal
bone
 forms the
posterior part of
the temporal
bone.

74. Petrous portion of the
temporal bone
Petrous portion of the temporal
bone or pyramid
 is pyramidal and is wedged in
at the base of the skull between the
sphenoid and occipital. Directed
medialward, forward, and a little
upward, it presents for examination
a base, an apex, three surfaces,
and three angles, and contains, in
its interior, the essential parts of
the organ of hearing.

75. Tympanic part of the
temporal bone
Tympanic part of
the temporal
bone
 is a curved
plate of bone
lying below the
squama and in
front of the
mastoid process.

76. Temporal styloid
process
Styloid process
 is pointed
piece of bone
that extends
down from the
human skull, just
below the ear.

77. Frontal bone
Frontal bone
 is a bone in the
human skull that
resembles a cockle-
shell in form, and
consists of two
portions:
• A vertical portion, the
squama frontalis,
corresponding with
the region of the
forehead.
• An orbital or
horizontal portion,
the pars orbitalis,

78. Frontal bone
I.) Squama frontalis
a.) Frontal suture
b.) Frontal eminence
c.) Superciliary arches
d.) Glabella
e.) Supraorbital foramen
f.) Zygomatic process
g.) Sagittal sulcus
h.) Frontal crest
i.) Foramen cecum
II.) Pars orbitalis
a.) Ethmoidal notch
b.) Lacrimal fossa
c.) Trochlear fovea
d.) Posterior ethmoidal foramen
e.) Anterior ethmoidal foramen
f.) Frontal sinus
g.) Frontonasal duct

79. Squama frontalis
• There are two surfaces of the squama of the
frontal bone: the external surface, and the
internal surface.

80. Frontal suture
Frontal suture is a dense connective
tissue structure that divides the two
halves of the frontal bone of the
skull in infants and children. It
usually disappears by the age of
six, with the two halves of the
frontal bone being fused together. If
it does not disappear it may be
called a "metopic suture" or "sutura
frontalis persistens." If the suture is
not present at birth
(craniosynostosis) it will cause a
keel-shaped deformity of the skull
called "trigonocephaly."

81. Frontal Eminence
• On the frontal bone, on either side
of the frontal suture, about 3 cm.
above the supraorbital margin, is a
rounded elevation, the frontal
eminence (tuber frontale).
• These eminences vary in size in
different individuals, are
occasionally unsymmetrical, and
are especially prominent in young
skulls; the surface of the bone
above them is smooth, and covered
by the galea aponeurotica.

82. Superciliary Arches
• On the squama frontalis of the
frontal bone, below the frontal
eminences, and separated
from them by a shallow
groove, are two arched
elevations, the superciliary
arches; these are prominent
medially, and are joined to one
another by a smooth elevation
named the glabella. The
superciliary arches are more
prominent in men

83. Glabella
Glabella
 is the space
between the
eyebrows and
above the nose.
It is slightly
elevated, and
joins the two
superciliary
ridges.

84. Supraorbital foramen
Supraorbital foramen
 is a bony elongated path located
above the eye socket and under the
forehead. The supraorbital foramen lies
directly under the eyebrow.
The supraorbital foramen arches
transversely below the superciliary
arches and is the upper part of the
margin of the orbit, thin and prominent
in its lateral two-thirds, rounded in its
medial third, and presenting, at the
junction of these two portions, the
supraorbital notch or foramen for the
supraorbital nerve and vessels
(supraorbital artery and supraorbital
vein.)

85. Zygomatic process of
frontal bone
• The
supraorbital
margin of the
frontal bone
ends laterally
in the
zygomatic
process,
which is
strong and
prominent,
and
articulates

86. Sagittal Sulcus
• The internal surface of the
squama frontalis of the frontal
bone is concave and presents
in the upper part of the middle
line a vertical groove, the
sagittal sulcus, the edges of
which unite below to form a
ridge, the frontal crest; the
sulcus lodges the superior
sagittal sinus, while its
margins and the crest afford
attachment to the falx cerebri.
• It also is part of the parietal,
and occipital bones.

87. Frontal Crest
• The internal surface of the
squama frontalis of the frontal
bone is concave and presents in
the upper part of the middle line
a vertical groove, the sagittal
sulcus, the edges of which unite
below to form a ridge, the frontal
crest; the sulcus lodges the
superior sagittal sinus, while its
margins and the crest afford
attachment to the falx cerebri.

88. Foramen cecum (frontal
bone)
• The frontal crest of the frontal bone ends
below in a small notch which is converted
into a foramen, the foramen cecum, by
articulation with the ethmoid.
• This foramen varies in size in different
subjects, and is frequently impervious;
when open, it transmits a vein from the
nose to the superior sagittal sinus. This
has clinical importance in that infections
of the nose and nearby areas can be
transmitted to the meninges and brain
from what is known as the danger triangle
of the face.

89. Pars Orbitalis
• The orbital or horizontal part of the
frontal bone (pars orbitalis) consists of two
thin triangular plates, the orbital plates,
which form the vaults of the orbits, and are
separated from one another by a median
gap, the ethmoidal notch.

90. Ethmoidal notch
Ethmoidal notch
 separates the two orbital
plates; it is quadrilateral, and
filled, in the articulated skull, by
the cribriform plate of the
ethmoid.
• The margins of the notch present
several half-cells which, when
united with corresponding half-
cells on the upper surface of the
ethmoid, complete the ethmoidal
air cells.

91. Lacrimal fossa
The inferior surface of each
orbital plate of the frontal
bone is smooth and
concave, and presents,
laterally, under cover of the
zygomatic process, a
shallow depression, the
lacrimal fossa (or fossa for
lacrimal gland), for the
lacrimal gland.

92. Trochlear fovea
Near the nasal part
of the interior
surface of the
frontal bone is a
depression, the
trochlear fovea,
or occasionally a
small trochlear
spine, for the
attachment of
the cartilaginous
pulley of the
Obliquus oculi

93. Posterior ethmoidal
foramen
• Lateral to either olfactory
groove are the internal
openings of the anterior and
posterior ethmoidal foramina
(or canals).
Posterior ethmoidal foramen
opens at the back part of this
margin under cover of the
projecting lamina of the
sphenoid, and transmits the
posterior ethmoidal vessels
and nerve.

94. Anterior ethmoidal foramen
• Lateral to either olfactory groove
are the internal openings of the
anterior and posterior ethmoidal
foramina (or canals).
Anterior ethmoidal foramen, situated
about the middle of the lateral
margin of the olfactory groove,
transmits the anterior ethmoidal
vessels and the nasociliary nerve;
the nerve runs in a groove along
the lateral edge of the cribriform
plate to the slit-like opening above
mentioned.

95. Frontal sinus
Frontal sinuses, situated behind the superciliary arches, are rarely symmetrical,
and the septum between them frequently deviates to one or other side of the
middle line.
• Their average measurements are as follows: height, 3 cm.; breadth, 2.5 cm.;
depth from before backward, 2.5 cm.

96. Frontonasal duct
• The frontal air sinuses are lined by mucous
membrane, and each communicates with the
corresponding nasal cavity by means of a
passage called the frontonasal duct.

97. Parietal bone
Parietal bones
are bones in the human
skull and form, by their
union, the sides and roof of
the cranium. Each bone is
irregularly quadrilateral in
form, and has two surfaces,
four borders, and four
angles.
Oute
r
Inne
r

98. Borders
Sagittal border, the longest and thickest, is dentated and
articulates with its fellow of the opposite side, forming the
sagittal suture.
Frontal border is deeply serrated, and bevelled at the expense
of the outer surface above and of the inner below; it
articulates with the frontal bone, forming half of the coronal
suture. The point where the coronal suture intersects with the
sagittal suture forms a T-shape and is called the bregma.
Occipital border, deeply denticulated, articulates with the
occipital, forming half of the lambdoid suture. That point
where the sagittal suture intersects the lambdoid suture is
called the lambda, because of its resemblance to the Greek
letter.
Squamous border is divided into three parts: of these:
• the anterior is thin and pointed, bevelled at the
expense of the outer surface, and overlapped by the
tip of the great wing of the sphenoid;
• the middle portion is arched, bevelled at the
expense of the outer surface, and overlapped by the
squama of the temporal;
• the posterior part is thick and serrated for
articulation with the mastoid portion of the temporal.

99. Angles
• Frontal angle is practically a right angle, and corresponds
with the point of meeting of the sagittal and coronal
sutures; this point is named the bregma; in the fetal skull
and for about a year and a half after birth this region is
membranous, and is called the anterior fontanelle.
• Occipital angle is rounded and corresponds with the point
of meeting of the sagittal and lambdoidal sutures—a point
which is termed the lambda; in the fetus this part of the
skull is membranous, and is called the posterior fontanelle.
• Mastoid angle is truncated; it articulates with the occipital
bone and with the mastoid portion of the temporal, and
presents on its inner surface a broad, shallow groove
which lodges part of the transverse sinus. The point of
meeting of this angle with the occipital and the mastoid
part of the temporal is named the asterion.
• Sphenoidal angle, thin and acute, is received into the
interval between the frontal bone and the great wing of the
sphenoid. Its inner surface is marked by a deep groove,
sometimes a canal, for the anterior divisions of the middle
meningeal artery.

100. Occipital
bone
Occipital bone,
 a saucer-shaped membrane
bone situated at the back and lower
part of the cranium, is trapezoid in
shape and curved on itself. It is
pierced by a large oval aperture,
the foramen magnum, through
which the cranial cavity
communicates with the vertebral
canal.
• The curved, expanded plate behind
the foramen magnum is named the
squama occipitalis.
• The thick, somewhat quadrilateral
piece in front of the foramen is
called the basilar part of occipital
bone.
• On either side of the foramen are
the lateral parts of occipital bone.

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