Download Skull notes

Skull
• Usually consists of 22 bones, all of which
(except the lower jaw) are firmly interlocked
along lines called “sutures”.
– Cranium = 8 bones
– Facial skeleton = 13 bones + lower jaw
– Lower jaw bone is called the mandible, and is the
only movable bone.
Cranium
• Functions:
– Encloses and protects the brain
– Provides attachments for muscles that make
chewing and head movement possible
– Has air-filled, mucous-membrane-lined (??),
sinus cavities
Cranial Bones
1.
2.
3.
4.
5.
6.
Frontal bone
Parietal bones (2)
Occipital bone
Temporal bones (2)
Sphenoid bone
Ethmoid bone
Cranial Bones, continued…..
• Frontal bone
– Anterior portion of skull above the eyes
– Houses 2 frontal sinuses, one above each eye near
the midline
• Parietal bones
– One on each side of the skull just behind the
frontal bone
– Form bulging sides and roof of cranium
– Fused at midline (sagittal suture) and to frontal
bone (coronal suture)
Cranial Bones, continued…..
• Occipital bone
– Joins the parietal bones (lambdoidal suture)
– Forms back of skull and base of cranium
– Foramen magnum – opening at bottom of
occipital bone for nerve processes to connect to
spinal cord
– Occipital condyles – rounded processes on each
side of foramen magnum that articulate with 1st
vertebra
Cranial Bones, continued…..
• Temporal bones
– On each side of the skull
– Joins parietal bone (squamosal suture)
– Form parts of sides and base of cranium
– External auditory meatus (???)
– Mandibular fossae – depressions in the temporal
bone that articulate with condyles (???) of the
mandible
Cranial Bones, continued…..
• Temporal bones, continued….
– Below each external auditory meatus:
• Mastoid process – rounded attachment for certain
neck muscles
• Styloid process – long, pointed anchor for muscles
associated with tongue and pharynx
– Zygomatic process
• Projects anteriorly (???) from temporal bone, joins the
zygomatic bone (“cheek bone”), and helps form
prominence of the cheek
Cranial Bones, continued…..
• Sphenoid bone
– Wedged between several other bones in anterior
portion of cranium
– Has a central portion and 2 wing-like structures
that extend laterally (???)
– Helps form base of cranium, sides of skull, and
sides of orbits (“eye sockets”)
– Midline of sphenoid bone has a depression (sella
turcica) that houses pituitary gland
– Contains 2 sphenoidal sinuses
Cranial Bones, continued…..
• Ethmoid bone
– Located in front of sphenoid bone
– Consists of 2 masses, one on each side of nasal cavity
• Masses joined by thin cribriform plates (???)
• Cribriform plates form part of nasal cavity roof.
– Crista galli – triangular process between cribriform
plates
– Perpendicular plate
• projects downward from cribriform plates
• helps form nasal septum
Cranial Bones, continued…..
• Ethmoid bone, continued…..
– Superior nasal concha and middle nasal concha project inward from lateral portions of ethmoid
bone toward perpendicular plate
– Lateral portions of ethmoid bone contain small
air spaces (ethmoidal sinuses)
Facial Skeleton
• Maxillae (2)
– Form the upper jaw
– Portions comprise the anterior (???) roof of the
mouth (“hard palate”), the floors of the orbits
(???), and the sides and floor of the nasal cavity.
– Contain sockets of the upper teeth
– “Maxillary sinuses”
• Inside the maxillae, lateral (???) to nasal cavity
• The largest of the sinuses
Facial Bones, continued….
• Maxillae, continued….
– “Palatine processes” fuse midline (???) to form
anterior section of hard palate
– Teeth are found in cavities in the “alveolar arch”
(aka “dental arch”) formed by the “alveolar
processes” projecting downward from the
inferior (???) border of the maxillae.
Facial Bones, continued….
• Palatine bones
– Behind the maxillae
– Horizontal portions form posterior (???) section
of hard palate and floor of nasal cavity
– Perpendicular portions help form lateral (???)
walls of nasal cavity
Facial Bones, continued…..
• Zygomatic bones (“???”)
– Also help form lateral walls and floors of the
orbits
– Each bone has a “temporal process” that
connects to the zygomatic process (forming the
zygomatic arch).
• Lacrimal bones
– Thin, scale-like structure in medial wall (??) of
each orbit between ethmoid bone and maxilla
Facial Bones, continued…..
• Nasal bones
– Long, thin, and nearly rectangular
– Lie side by side and fused at midline to form
bridge of nose
• Vomer bone
– Thin and flat
– Along midline in nasal cavity
– Joins perpendicular plate of ethmoid bone
posteriorly (???) to form nasal septum
Facial Bones, continued…..
• Inferior nasal conchae
– Fragile, scroll-shaped bones attached to lateral
walls (???) of nasal cavity
– Support mucous membranes in nasal cavity
• Mandible (“???”)
– Upward projection at ends:
• Posterior “mandibular condyle” articulates with
mandibular fossae on _______ bone
• Anterior “coronoid process” provides attachments for
muscles for chewing
– “Alveolar arch” – curved, superior (???) border
that contains sockets for lower teeth