Download Organization of the Skeleton

Organization of the
Skeleton
Chapter 7B Notes
The Skeleton
• The axial skeleton consists of
the bony and cartilaginous parts
that support and protect the
organs of the head, neck, and
trunk.
The Skeleton
• The skull- has a total of 22
bones.
–8 cranial bones
–13 facial bones
–1 mandible (jaw)
The Skeleton
• The cranium of the skull– Encloses and protects the brain
– Some contain air- filled paranasal
sinuses, which are lined with mucous
membranes and connected by
passageways to the nasal cavity.
– Sinuses reduce the weight of the skull
and increase the intensity of the voice by
serving as resonant sound chambers.
The Skeleton
• The 8 Cranium bones includes:
– The Frontal bones- forms the anterior
portion of the skull above the eyes.
• Is marked by a supraorbital foramen
through which blood vessels and
nerves pass to the tissues of the
forehead.
• There are also two frontal sinuses,
one above each eye near the midline.
The 8 Cranium bones
• The Parietal bones:
–Located on each side of the skull,
just behind the frontal bone.
–Forms the bulging sides and roof
–They are fused at the midline along
the sagittal suture, and they meet
the frontal bone along the coronal
suture.
The 8 Cranium bones
• The Occipital bone:
–Forms the back of the skull and the
base of the cranium.
–Joins the parietal bones along the
lambdoidal suture.
–Large openings on its lower surface
called the foramen magnum allow
nerve fibers from the brain pass and
enter the vertebral canal.
The 8 Cranium bones
• The Temporal bones:
– Joins the parietal bone along a
squamosal suture.
– The temporal bones form parts of the
sides and the base of the cranium.
– A zygomatic process projects
anteriorly from the temporal bone,
joins the zygomatic bone, and helps
form the prominence of the cheek.
The 8 Cranium bones
–There are two projections:
• A mastoid process provides an
attachment for certain muscles of
the neck.
• A styloid process serves as an
anchorage for muscles associated
with the tongue and pharynx.
The 8 Cranium bones
• The Sphenoid bone:
– Wedged between several other bones in the
anterior portion of the cranium.
– Helps form the base of the cranium, sides of
the skull, and floors and sides of the orbits.
– Along the midline, a portion of the sphenoid
bone rises up and forms a saddle shaped
mass called the sella turcica.
• This depression is occupied by the
pituitary gland.
The 8 Cranium bones
• The Ethmoid bone:
–Located in front of the sphenoid
bone, one on each side of the nasal
cavity.
–These are joined horizontally by
thin cribriform plates, that form
part of the roof of the nasal cavity.
The Skeleton
• Facial bones also help compose the
skull.
–Provides the basic shape of the
face, and attachments for muscles.
–Consist of thirteen immovable
bones and a movable lower
jawbone.
The Facial Skeleton
• The maxillae:
– Forms the upper jaw.
– Portions of these bones comprise the
anterior roof of the mouth (hard
palate).
– Contains sockets for the upper teeth.
– Inside the maxillae, lateral to the nasal
cavity, are maxillary sinuses, which
are the largest of the paranasal
sinuses.
The Facial Skeleton
• The maxillae:
–The inferior border of each
maxillary bone projects downward
forming an alveolar process.
–Together these processes form a
horseshoe- shaped alveolar arch
which is occupied by the teeth.
The Facial Skeleton
• The Palatine bones:
–Located behind the maxillae.
–Serves as both the posterior section
of the hard palate and the floor of
the nasal cavity.
–Also helps form the lateral walls of
the nasal cavity.
The Facial Skeleton
• The Zygomatic bones:
–Responsible for the prominences of
the cheeks.
–Help form the lateral walls and
floors of the orbits (eyes).
The Facial Skeleton
• The Lacrimal bones:
–Thin, scale like structure located
between the ethmoid bone and
maxilla.
The Facial Skeleton
• The Nasal bones:
–Long, thin, and nearly
rectangular.
–Lie side by side to form the
bridge of the nose.
The Facial Skeleton
• The Vomer:
–Thin, flat bone located along the
midline within the nasal cavity.
–Joins with the ethmoid bone to
form the nasal septum.
The Facial Skeleton
• The Inferior nasal conchae:
–Fragile, scroll shaped bone
attached to the lateral walls of
the nasal cavity.
–Provides support for mucous
membranes within the nasal
cavity.
The Facial Skeleton
• The Mandible:
– The movable facial bone.
– Divided into two sections:
• The mandibular condyles
• The coronoid processes that serve
as attachments for muscles used in
chewing.
• Also has an alveolar arch the
contains the lower teeth.
The Skeleton
• Another part of the axial skeleton is
the Hyoid bone.
–Located at the neck between the
lower jaw and larynx.
–Supports the tongue and serves as
an attachment for muscles that help
move the tongue and function in
swallowing.
The Skeleton
• The Vertebral column:
–The backbone consist of many
vertebrae.
–Near its end, several vertebrae
fused together to form the sacrum.
–Attached to the end of the sacrum
is a small, rudimentary tailbone
called the coccyx.
The Skeleton
• The Thoracic Cage:
–Protects the organs of the
thorax and upper abdomen.
–Composed of 12 pairs of ribs
that are attached anteriorly to
the sternum.
The Skeleton
• The Appendicular skeleton
(limbs):
• The Pectoral Girdle:
–Formed by a scapula and a
clavicle.
–Connects the bones of the arms
to the axial skeleton and aids in
arm movements.
The Skeleton
• The Upper Limb:
–Each consists of a humerus,
and two lower arm bones- the
radius and ulna.
–Each has carpals, metacarpals,
and phalanges.
The Skeleton
• The Pelvic Girdle:
–Formed by two coxal bones
(hipbone)
–Connect the bones of the legs
to the axial skeleton
–Helps form the pelvis.
The Skeleton
• The Lower Limb:
–Each consists of a femur and two
lower leg bones- the fibula and
tibia.
–Also consists of a patella or knee
cap.
–Each has tarsals, metatarsals,
and phalanges.
Infantile Skull
• At birth, cranial bones are separated
by fibrous membranes called
fontanels (soft spot).
–Permit some movement, so the
developing skull is partially
compressible and an change shape
slightly (easier to give birth).
–Eventually close as cranial bones
grow together.