Myology

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Myology

• Bony Anatomy of the Skull

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Bone Surface Markings

• Depressions and openings
• Fissure narrow opening between 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

• Processes for tendon and ligament attachment
• 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
• (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)
• (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 elephants 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 pituitary gland.

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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

• 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.
• Contains the lacrimal
• sac and the naso-
• lacrimal duct.

Lacrimal bone
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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 partners 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.