2. Skull
•The skull is the body’s most complex bony
structure. It is formed by cranial and facial bones
•The cranial bones, or cranium, enclose and protect
the brain and provide attachment sites for some
head and neck muscles.
•The facial bones
• form the framework of the face
• form cavities for the sense organs of sight, taste
and smell
• provide openings for the passage of air and food
• hold the teeth
• anchor the muscles of the face.
3. Skull
•The skull bones are flat bones firmly
united by interlocking, immovable joints
called sutures.
•The suture lines have an irregular,
saw-toothed appearance.
•The longest sutures—the coronal,
sagittal, squamous and lambdoid
sutures—connect the cranial bones.
•Most other skull sutures connect facial
bones and are named according to the
specific bones they connect.
4.
5.
6. Skull
•The skull is made up of the cranium and facial
bones
•The cranium is divided into the cranial vault and
base
• Cranium: forms the superior, lateral, and
posterior aspects of the skull, as well as the
forehead region.
• Base: forms the floor and inferior part of the
skull. On the inside, prominent bony ridges divide
the cranial base into three distinct or fossae—the
anterior, middle and posterior cranial fossae
•The brain sits snugly in these cranial fossae and is
completely enclosed by the cranial vault
•Has about 85 openings (foramen, canals and
fissures) for the passage of blood vessels and the
12 cranial nerves
7. Cranial Bones
•There are eight large bones
of the cranium, 2 paired
bones and 4 unpaired bones
•Parietal bones (paired)
•Temporal bones (paired)
•Frontal (unpaired)
•Occipital (unpaired)
•Sphenoid (unpaired)
•Ethmoid bones (unpaired)
8. Parietal Bone
• Shaped like curved rectangles
• make up the bulk of the cranial vault and form
most of the superior and lateral walls of the
skull
• They articulate with the other bones of the
skulls at the 4 sutures
• Coronal suture – runs the coronal plane, anteriorly
where the parietal bones meet the frontal bone.
• Squamous suture – occurs where each parietal
bone meets the temporal bone inferior to the
lateral aspect of the skull.
• Sagittal suture – occurs where the right and left
parietal bones meet superiorly in the midline of
the cranium
• Lambdoid suture – occurs where the parietal
bones meet the occipital bone posteriorly
9. Temporal Bone
•They lie inferior to the parietal bones and
form the inferolateral
•region of the skull and parts of the cranial
floor.
•Each temporal bone has four major
regions: the squamous, tympanic,
mastoid, and petrous regions
•The plate-shaped squamous region has a
projection called the zygomatic process
that projects anteriorly to meet the
zygomatic bone of the face.
•Together, these two bony structures form
the zygomatic arch, commonly called the
cheek bone.
10. Temporal Bone
•The oval mandibular fossa on the inferior
surface of the zygomatic process articulates
with the mandible (lower jawbone),
forming the freely movable
temporomandibular joint ( jaw joint).
•The tympanic region surrounds the
external acoustic meatus (external ear
canal) through which sound enters the ear.
•The external acoustic meatus and the
tympanic membrane (eardrum) at its deep
end are parts of the external ear.
•Projecting inferiorly from the tympanic
region is the needle-like styloid process.
11. Temporal Bone
•The mastoid region has a prominent mastoid
process, an anchoring site for some neck
muscles. This process can be felt as a lump
just posterior to the ear.
•The stylomastoid foramen is located
between the styloid and mastoid processes.
A branch of cranial nerve VII, the facial
nerve, leaves the skull through this foramen.
•The mastoid process is full of air sinuses
(mastoid sinuses) which lie just posterior to
the middle ear cavity.
•Infections can spread from the throat to
the middle ear (mastoiditis) to the
mastoid cells and even spread to the
brain
12. Temporal Bone
•The petrous region of the temporal
bone projects medially and contributes
to the cranial base, it is bony wedge
between the occipital bone posteriorly
and the sphenoid bone anteriorly
•It posterior slope of ridge of the petrous
bones lies in the posterior cranial fossa,
whereas the anterior slope is in the
middle cranial fossa
•The middle cranial fossa holds the
temporal lobes of the brain.
•It also houses the cavities of the middle
and inner ear, which contain the sensory
apparatus for hearing and balance
13. Temporal Bone
•Several foramina penetrate the bone of the petrous region.
•The large jugular foramen is located where the petrous region joins
the occipital bone. The following structures pass through this foramen
• Internal jugular vein
• Cranial nerves IX, X, and XI.
•The internal acoustic meatus lies in the cranial cavity on the posterior
face of the petrous region. It transmits cranial nerves VII and VIII, the
facial and vestibulocochlear nerves.
15. Frontal Bone
•The frontal bone forms the forehead and the roofs of the
orbits (eyes). Just superior to the orbits, it protrudes slightly to
form superciliary arches, deep to our eyebrows.
•The supraorbital margin, or superior margin of each orbit, is
pierced by a hole or by a notch, respectively called the
supraorbital foramen or supraorbital notch.
•This opening transmits the supraorbital nerve (a branch of
cranial nerve V) and artery, which supply the forehead.
•The smooth part of the frontal bone between the superciliary
arches in the midline is the glabella.
•The regions of the frontal bone lateral to the glabella contain
the air-filled frontal sinuses
16.
17. Occipital Bone
•The occipital bone makes up the posterior part of the cranium and cranial
base
•Articulates with the parietal bones at the lambdoid suture and with the
temporal bones at the occipitomastoid sutures.
•Interiorly it forms the walls of the posterior cranial fossa, which holds a
part of the brain called the cerebellum.
•On the inside of the base of the occipital bone is the foramen magnum
through which the brain connects with the spinal cord.
•Hidden medial and superior to the occipital condyle is a canal through
which the cranial nerve XII (hypoglossal nerve) runs.
•Anterior to the foramen magnum, the occipital bone joins the sphenoid
bone via the basilar part (base) of the occipital bone.
19. Sphenoid Bone
•The sphenoid bone spans the width of the cranial floor and resembles a
bat with its wings spread.
•Articulates with every other cranial bone and consists of a central body
and three pairs of processes: the greater wings, lesser wings, and
pterygoid processes.
•The superior surface of the body bears a saddle-shaped prominence, the
sella turcica which houses the pituitary gland
•Within the sphenoid body are the paired sphenoid sinuses.
•The greater wings project laterally from the sphenoid body, forming
parts of the middle cranial fossa and the orbit (eye sockets).
20. Sphenoid Bones
The sphenoid bone has five important openings on each side.
• Optic canal: lies just anterior to the sella turcica. Cranial nerve II (optic
nerve), passes through this opening from the orbit into the cranial cavity.
• Superior orbital fissure : a long slit between the greater and lesser wings.
cranial III, IV, and VI nerves that control eye movements pass through this
opening.
• Foramen rotundum and Ovale: Foramen rotundum lies in the medial part of
the greater wing and are passageways through which two large branches of
cranial nerve V (the maxillary and mandibular branches) exit the cranium.
• Foramen spinosum: has short spine that projects from its margin on the
inferior aspect of the skull. The middle meningeal artery which supplies blood
to the broad inner surfaces of the parietal and the squamous temporal bones
passes through this foramen.
23. Ethmoid Bone
• The most deeply situated bone of the skull. It lies anterior to the sphenoid bone and
posterior to the nasal bones.
• It is thin walled, hence delicate
• Its superior surface is formed by paired, horizontal cribriform plates that form the roof
of the nasal cavities and the floor of the anterior cranial fossa
• The cribriform plates has the olfactory foramina. Through which filaments of cranial
nerve I (olfactory nerve), pass through
• these holes as they run from the nasal cavity to the brain.
• The 2 cribriform plates come together to form a projection called crista galli to which
the falx cerebri (fibrous material) attaches to secure the brain within the cranial cavity
• The perpendicular plate of the ethmoid bone projects inferiorly in the median plane
forming the superior part of the nasal septum.
• Flanking the perpendicular plate of the ethmoid bone are the ethmoidal sinuses.
• Extending medially from the lateral masses are the thin superior and middle nasal
conchae which protrude into the nasal cavity.
30. High Yield
Cranial Nerve Passageways
• Cribriform plate: I
• Optic canal: II
• Superior orbital fissure: III, IV, V¹, VI
• Foramen rotundum: V²
• Foramen ovale: V³
• Internal auditory meatus: VII, VIII
• Jugular foramen: IX, X, XI
• Hypoglossal canal: XII
36. Facial Bone
•The skeleton of the face
consists of 14 bones
•Unpaired bones
• mandible
• Vomer
•Paired bones
• Maxillae
• Zygomatics
• Nasal bones
• Lacrimal bones
• Palatine bones
• Inferior nasal conchae
37. Unpaired Bones - Mandible
• The U-shaped mandible or lower jawbone is the largest, strongest bone in the
face
• The mandible has a horizontal body that forms the inferior jawline, and two
upright rami each meeting the body posteriorly at a mandibular angle.
• The anterior coronoid process forms a flat, triangular projection, where the
temporalis muscle(for chewing) inserts. The posterior condylar process enlarges
superiorly to form the mandibular condyle or head of the mandible which
articulates with the temporal bone to form the temporomandibular joint. The
coronoid and condylar processes are separated by the mandibular notch
• The body of the mandible anchors the lower teeth and forms the chin.
• The superior border of the mandible is the alveolar margin. The tooth sockets,
called alveoli, open onto this margin.
• Anteriorly, the two halves of the mandible fuse to form the mental protuberance
38.
39. Unpaired Bones - Mandible
• Several openings pierce the mandible.
• Mandibular foramen: located on the
medial surface of each ramus, through
which the inferior alveolar nerve, a
branch of cranial nerve V (a nerve
responsible for tooth sensation) enters
the mandibular body and supplies the
roots of the lower teeth.
• Dentists inject anesthetic into this
foramen before working on the lower
teeth.
• Mental foramen: opens on the
anterolateral side of the mandibular
body, transmits blood vessels and nerves
to the lower lip and the skin of the chin.
40. Unpaired Bones - Vomer
•It is a slender, plow-shaped vomer lies in the
nasal cavity.
•It forms the inferior part of the nasal septum
Pathology Integration
• A markedly off center septum is referred to as a
deviated septum
• Mostly results from trauma to the nose
• Results in nasal congestion, frequent nose-bleeds and
frequent sinus infections
• Can be corrected surgically via septoplasty
41. Paired bones - Maxillae
• The maxillary bones form the upper jaw and the central part of the facial
skeleton and articulates with other facial bones.
• The maxilla has an alveolar margin that contains teeth. The palatine processes
project medially from the alveolar margins to form the anterior region of the
hard palate (bony roof of the mouth).
• The maxillae lie just lateral to the nasal cavity and contain the maxillary sinuses
which extend from the orbit down to the roots of the upper teeth.
• The maxillae articulate with the zygomatic bones at the zygomatic processes.
The maxilla, along with several other bones, forms the borders of the inferior
orbital fissure .
• The inferior orbital fissure transmits several vessels and nerves including the
maxillary nerve (branch of cranial nerve V) or its continuation - infraorbital
nerve which goes through the infraorbital foramen.
42.
43. Paired Bones – Zygomatic Bones
•Also called Cheek bones
•Each zygomatic bone joins the
zygomatic process of a temporal
bone posteriorly, the zygomatic
process of the frontal bone
superiorly, and the zygomatic
process of the maxilla) anteriorly.
•The zygomatic bones form the
prominences of the cheeks and
define part of the margin of each
orbit.
44. Paired Bones – Nasal Bones
•Paired rectangular shaped bones that
join medially to form the bridge of the
nose.
•They articulate with the frontal bone
superiorly, the maxillae laterally, the
perpendicular plate of the ethmoid
bone posteriorly and inferiorly, they
attach to the cartilages that form most
of the skeleton of the external nose
45. Paired Bones – Lacrimal Bones
•A pair of delicate, fingernail-shaped lacrimal
bones are located in the medial orbital walls.
•They articulate with the frontal bone
superiorly, the ethmoid bone posteriorly, and
the maxilla anteriorly.
•Each lacrimal bone contains a deep groove
that contributes to a lacrimal fossa which
contains a lacrimal sac that stores tears,
allowing the fluid to drain from the eye
surface into the nasal cavity (lacrima tear).
46. Paired Bones – Palatine Bones
•The palatine bones are paired
L-shaped bones that lie posterior to
the maxillae
•They articulate with each other at
their inferior horizontal plates, which
complete the posterior part of the
hard palate.
•The perpendicular plates form the
posterior part of the lateral walls of
the nasal cavity and a small part of
the orbits
47. Paired Bones – Inferior Nasal Conchae
•A pair of thin curved bones in the
nasal cavity
•They project medially from the
lateral walls of the nasal cavity, just
inferior to the middle nasal
conchae of the ethmoid bone.
•They are the largest of the three
pairs of conchae.
48.
49. Facial Cavities and Sinuses
Nasal Cavity
• The nasal cavity is made up of bone and cartilage.
• The ethmoid bone’s cribriform plates forms the roof of the nasal cavity and floor
is formed by the palatine processes of the maxillae and horizontal plates of the
palatine bones.
• These nasal-floor structures also form the roof of the mouth (the hard palate).
• The lateral walls are formed by the nasal bones, the superior and middle conchae
of the ethmoid, the inferior nasal conchae, a part of the maxilla, and the
perpendicular plates of the palatine bones
• On these lateral walls, each of the three conchae forms a roof over a
groove-shaped air passageway called a meatus - superior, middle, and inferior
meatuses.
• Remember the nasal cavity is divided into right and left halves by the nasal
septum.
50. Orbital Cavity
(Eye Cavity)
•Cone-shaped bony cavities that
hold the eyes, the muscles that
move the eyes, fatty tissues and
the tear-producing glands.
•The walls of each orbit are formed
by parts of seven bones—the
frontal, sphenoid, zygomatic,
maxillary, palatine, lacrimal and
ethmoid bones.
•The superior and inferior orbital
fissures, optic canal, and lacrimal
fossa are also in the orbital cavity.
51. Paranasal Sinuses
•The bones surrounding the nasal cavity—the
frontal, ethmoid, sphenoid, and both maxillary
bones contain air-filled sinuses called
paranasal sinuses ( “para” because they cluster
around the nasal cavity).
•They are also lined by mucosa and function in
warming, moistening, and filtering inhaled air.
•The paranasal sinuses also lighten the skull,
giving the bones they occupy a moth-eaten
appearance in an X-ray image (air is black on
x-ray)
52.
53. FYI Joint Classification
Joints can be classified either by function or structure.
The functional classification focuses on the amount of movement
allowed. We have
Synarthroses (“syn” together; “arthro” joint) are immovable joints.
amphiarthroses (“amphi” of both kinds) are slightly movable joints.
diarthroses (“di” two) are freely movable joints.
NB: Diarthroses predominate in the limbs, whereas synarthroses and
amphiarthroses are largely restricted to the axial skeleton.
54. Joint Classification
The structural classification is based on the material that
binds the bones together and on the presence or absence of a
joint cavity. Structurally, joints are classified as;
Fibrous
Cartilaginous
Synovial joints
55.
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57.
58.
59. FACE AND SCALP
•The face is the anterior aspect of the head from the forehead to the
chin and from one ear to the other. The face provides our identity as
an individual human.
•The scalp consists of skin (normally hair bearing) and subcutaneous
tissue that cover the neurocranium from the superior nuchal lines on
the occipital bone to the supra-orbital margins of the frontal bone.
•The scalp is composed of five layers, the first three of which are
connected intimately and move as a unit (e.g., when wrinkling the
forehead and moving the scalp).
60. SCALP
1. Skin: thin, except in the occipital region, containing many sweat and sebaceous glands and hair
follicles. It has an abundant arterial supply and good venous and lymphatic drainage.
2. Connective tissue: forms the thick, dense, richly vascularized subcutaneous layer that is well
supplied with cutaneous nerves.
3. Aponeurosis (epicranial aponeurosis): the broad, strong, tendinous sheet that covers the calvaria
and serves as the attachment for muscle bellies converging from the forehead and occiput (the
occipitofrontalis muscle).
4. Loose areolar tissue: a sponge-like layer including potential spaces that may distend with fluid as
a result of injury or infection. This layer allows free movement of the scalp proper (the first three
layers—skin, connective tissue, and epicranial aponeurosis) over the underlying calvaria.
5. Pericranium: a dense layer of connective tissue that forms the external periosteum of the
neurocranium.
61.
62. Muscles of the Head – Facial Expression
• The muscles that promote facial expression lie in the face and scalp, just deep to
the skin.
• They are thin and vary in shape, and adjacent muscles in this group tend to be
fused.
• Unlike other skeletal muscles, facial muscles insert on the skin, not on the bones.
• In the scalp, the main muscle is the epicranius, which has distinct anterior and
posterior parts.
• In the face, the muscles covering the facial bones lift the eyebrows and flare the
nostrils, close the eyes and lips, and helps us smile.
66. Muscles of the Head – Mastication & Tongue
Movement
• 4 main pair of muscles are involved in mastication and are innervated by the
mandibular branch of cranial nerve V (trigeminal nerve).
• Main muscles of jaw closure and biting are masseter and temporalis muscles.
Side to side grinding movements by the pterygoid muscles. The buccinator
muscles in the cheeks also play a role in chewing. Jaw lowering or opening by
the mylohyoid and digastric muscles.
• All the tongue muscles are innervated by cranial nerve XII, the hypoglossal
nerve.
