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.