Myology
Bony Anatomy of
the Skull
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Bone Surface Markings
• Depressions and openings:
• Processes for tendon and
ligament attachment:
– Fissure: narrow opening between
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adjacent parts of bones for nerves
and vessels
Foramen: hole, opening
Fossa: shallow depression
Sulcus: groove
Meatus: tubelike passageway
• Processes that form joints
– Condyle: large rounded
prominence
– Facet: smooth flat surface
– Head: rounded articular
projection
– Crest: prominent border or ridge
– Epicondyle: prominence above a
condyle
– Linea: line, less prominent than a
crest
– Trochanter: large projection of
bone found only on the femur
– Tubercle: small rounded process
– Tuberosity: large, rounded, usually
roughened process
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Gross Anatomy
Osteology of the Skull: Cranium
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Skull
• Cranium: Consists of 8 bones
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(1) Frontal Bone
(2) Temporal Bones
(2) Parietal Bones
(1) Occipital Bone
(1) Sphenoid Bone
(1) Ethmoid Bone
• Face: Consists of 14 bones (Studied in lecture 2)
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(2) Maxilla
(2) Zygomatic bones
(2) Lacrimal bones
(2) Palatine bones
(2) Nasal bones
(2) Inferior nasal conchae
(1) Vomer
(1) Mandible
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Bones of the Cranium
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Frontal Bone
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Frontal Bone
• The large bone that makes up the forehead and supplies the upper
edge and roof of the orbit (eye socket).
• The frontal bone articulates (comes together) with a number of
other bones including the parietal, nasal, ethmoid, maxillary, and
zygomatic bones.
• Landmarks:
– Squama: flat portion that forms the forehead
– Supraorbital margin: ridge under the eyebrow, forming the
upper part of the orbit (eye socket)
– Supraorbital foramen: small hole within supraorbital margin
for blood vessels and nerves
– Frontal sinuses: hollow spaces behind the squama, act as
sound chambers to give the voice resonance.
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Frontal Bone (Anterior View) (Blue Colored Bone)
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Frontal Bone (Lateral View) (Blue Colored Bone)
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Temporal Bones
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Temporal Bones
• 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.
• Landmarks:
– Squama: flat portion of the temporal bone forming the anterior and superior part
of the temple
– Zygomatic process: process forming part of the cheek
– 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 canal
– 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 and ligaments.
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Temporal Bone (Lateral View) (Purple Colored Bone)
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Parietal Bones
• The main bone on the side of
the skull.
• The word "parietal" comes
from the Latin "parietalis"
meaning "belonging to the
wall."
• 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 skull.
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Parietal Bone (Lateral View) (Red Colored Bone)
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Occiput
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Occiput
• From the Latin, meaning the part of the head opposite the front.
• The bone that forms the rear and the rear bottom of the skull.
• 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
• Landmarks:
– 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
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Occipital Bone (Posterior View) (Orange Colored Bone)
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Occipital Bone (Lateral View) (Orange Bone)
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Sphenoid Bone
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Sphenoid Bone
• 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.
• The Greek physician Galan wrote that the sphenoid bone was "like
a wedge thrust between the skull and the superior maxilla."
• Landmarks
– 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
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pituitary gland.
Sphenoid Bone (Lateral View) (Green Colored Bone)
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Sphenoid Bone (Floor of Cranium) (Green Colored Bone)
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Ethmoid Bone
• An irregularly shaped, spongy bone that provides the floor of the front part of the
skull and the roof of the nasal cavity.
• The ethmoid consists of two masses of thin plates enclosing air cells and looks
like a sieve.
• Landmarks:
– 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.
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Bones of the Face
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Maxilla
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Maxilla
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The largest bones of the face, except for the mandible and form,
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 the boundaries of three cavities, namely,
the roof of the mouth, the floor and lateral wall of the nose, and
the floor of the orbit.
Landmarks:
– 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 palate.
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Maxilla (Anterior View) (Yellow Colored Bones)
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Zygomatic Bones
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
and part of the lateral wall
and floor of the orbit.
It articulates with the
zygomatic arch of the
temporal bone.
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Zygomatic Bones (Anterior View) (Pink Colored Bones)
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Lacrimal Bones
Smallest and most
fragile bone of the
face, is situated at
the front part of the
Medial of the
orbit.
Lacrimal bone
Contains the lacrimal
sac and the nasolacrimal duct.
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Lacrimal Bones (Anterior View) (Blue Colored Bones below frontal bone)
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Palatine bones
It contributes to the
walls of three
cavities: the floor
and lateral wall of
the nasal cavity,
the roof of the
mouth, and the
floor of the orbit
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Nasal Bones
Varying in size and
form in different
individuals
They are placed side by
side at the middle and
upper part of the face
and form, by their
junction, "the bridge" of
the nose
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Nasal Bones (Anterior View) (Bridge of the nose, below frontal bone)
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Inferior Nasal Conchae
Extends horizontally
along the lateral wall
of the nasal cavity
and consists of a
lamina of spongy
bone, curled upon
itself like a scroll.
Inferior Nasal Conchae
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Inferior Nasal Conchae (Anterior View) (Inside nasal cavity on lateral walls)
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Vomer
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
maxillary bones.
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Vomer (Anterior View) (Center wall in nasal cavity)
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Mandible
Largest and strongest
bone of the face.
Forms the lower jaw and
holds the lower teeth in
place.
The mandible consists of
a curved, horizontal
portion, the body, and two
perpendicular portions,
the rami, which unite with
the ends of the body nearly
at right angles.
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Mandible
• Largest and strongest bone of the face.
• Forms the lower jaw and holds the lower teeth in place.
• Landmarks:
– 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 lower teeth
– Mental foramen: small hole on the side of the body for blood vessels
and nerves.
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Mandible (Anterior View) (Lower Jaw)
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Mandible (Lateral View) (Lower Jaw)
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Palpation of the Cranium
Occiput: Prone; place hands on the back of the head between partner’s ears. Slide your
fingers superiorly to the External Occipital Protuberance (EOP) two to three inches.
Then slide fingers laterally to the mastoid process behind the ears.
Superior Nuchal Lines: Prone or supine; locate the EOP and then slide your fingers
laterally moving your fingerpads up and down feeling for the edge of the superior
nuchal line.
Parietal Bone: Prone or supine; place both hands on the top of the cranium. Palpate the
sagittal suture between the parietals. From the suture, palpate the parietal bones down
towards the ears
Temporal Bone: Supine; locate the mastoid process by placing your fingers behind the ear
lobe. The zygomatic arch can be palpated by placing your fingers anterior to the
external auditory meatus. Palpate anteriorly along the arch with your finger and
thumb. The flat squamous portion can be palpated superior to the mastoids and
external auditory meatus. The styloid process can be palpated between the mandible
and the mastoid process (palpate very gently)
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Frontal bone: Supine; palpate the region of the forehead from the eyebrows up toward the
coronal sutures
Mandible: Supine: place your fingers inferior to the bottom teeth and palpate the body of
the mandible. Move inferiorly and palpate the base of the mandible from the chin to
the angle of the mandible. Then curl your fingertips underneath the edge to palpate the
submandibular fossa. To palpate the angle of the mandible slide posterior alone the
base of the mandible. The angle is located between the body and the ramus. To palpate
the mandibular condyle place your finger anterior to the ear canal and below the
zygomatic arch. Ask your partner to open his/her mouth fully, the condyle will protrude
laterally and become more palpable.
Nasal bones: Supine; locate the bridge of the nose
Zygomatic bone: Supine, return to the zygomatic arch of the temporal bone and continue
to move anteriorly until you reach the zygomatic (cheek) bone.
Maxilla: Supine; palpate inferior to the zygomatic bone down to the mouth. The maxilla
forms the center of the face. The alveolar processes can also be palpated where the
teeth insert into the maxilla.
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02 – Bony Anatomy of the Skull