Axial Skeleton

Skull Cranial Bones Facial Bones

Cranial Bones Frontal Bone – Forms the forehead, the roofs of the orbits, and most of the anterior part of the cranial floor

Cranial Bones Parietal Bones – form the greater portion of the sides and roof of the cranial cavity

Cranial Bones Temporal Bones – Form the inferior lateral aspects of the cranium and part of the cranial floor

Cranial Bones Occipital Bone – Forms the posterior part and most of the base of the cranium

Cranial Bones Sphenoid Bone – Lies at the middle part of the base of the skull

Cranial Bones Ethmoid Bone – a light, sponge-like bone located on the midline in the anterior part of the cranial floor medial to the orbits.

Facial Bones Nasal Bones – meet at the midline and form part of the bridge of the nose

Facial Bones Maxillae – unit to form the upper jaw.

Cleft Palate If the maxillary bones do not unite during the weeks 10 to 12 of embryonic development, cleft palate occurs.

Facial Bones Zygomatic Bones – (cheekbones) form the prominence of the cheeks and part of the lateral wall and floor of each orbit.

Facial Bones Lacrimal Bones – They are posterior and lateral to the nasal bones and form part of the medial wall of each orbit.

Facial Bones Palatine Bones – They form the posterior part of the hard palate, part of the floor and lateral wall of the nasal cavity, and a small part of the floor of the orbits.

Facial Bones Inferior Nasal Concha – form a portion of the inferior lateral wall of the nasal cavity and project into the nasal cavity

Facial Bones Vomer – A rough triangular bone on the floor of the nasal cavity

Facial Bones Mandible – lower jawbone

Nasal Septum Divides the nasal cavity into R. and L. sides Consists of vomer, septal cartilage (hyaline cartilage), and perpendicular plate of the ethmoid bone

Deviated nasal septum This occurs when the nasal septum is deflected laterally from the midline of the nose

Orbits Made up of seven bones; Frontal Sphenoid Ethmoid Palatine Zygomatic Lacrimal Maxilla

Paranasal Sinus Paired cavities found in the frontal, sphenoid, ethmoid, and maxillary

Paranasal Sinus Lined with mucous membranes that are continuous with the lining of the nasal cavity

Fontanels Soft spots – membrane filled spaces

Fontanels Allow rapid growth of brain during infancy

Fontanels Allow skull to change shape as it passes through the birth canal

Fontanels Bone ossification occurs via intramembranous

Hyoid Bone Between mandible and larynx

Hyoid Bone Not adam’s apple

Hyoid Bone Suspended from the styloid processes of the temporal bones by ligaments and muscles.

Hyoid Bone Some tongue muscles attach here

Vertebral Column 7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae Sacrum – five fused vertebrae Coccyx – four fused vertebrae

Normal Curves Cervical and lumbar are convex (bulging out)

Normal Curves Thoracic and sacral are concave (cupping in)

Sternum Breastbone Superior part – manubrium Middle part – body Inferior part – xiphoid process

Ribs 12 pairs

Ribs 1 – 7 pairs increase in size 8 – 12 pairs decrease in size

Ribs 1 – 7 true ribs (costal cartilage directly attaches to sternum) 8 – 12 false ribs (indirect attachment or not at all)

Ribs 11 – 12 floating ribs (no attachment to sternum)