PSIO 201 Required Handout Department of Physiology Axial Skeleton Bones and bone features of the skull TABLE 1 Bones of the cranium Bone Frontal bone 1 Parietal bones 2 Occipital bone 1 Temporal bones 2 Ethmoid bone 1 Sphenoid bone 1 Description Unpaired bone of the cranium that makes up the forehead and forms the superior portion of the eye orbit Paired bones that lie posterior to the frontal bone and form the lateral walls of the cranium Unpaired bone that forms the posterior and inferior portion of the cranium Features of interest foramen magnum and occipital condyles Paired bones that lie inferior to the parietal bones and contribute to forming the lateral wall of the cranium The interior of the temporal bone houses the auditory ossicles small bones that contribute to the sense of hearing Features of interest external auditory meatus zygomatic process styloid process mastoid process and mandibular fossa Unpaired bone that forms a portion of the posterior eye orbit part of the cranial floor the roof of the nasal cavity and the superior nasal septum Features of interest crista galli cribriform plate olfactory foramina perpendicular plate superior nasal conchae not visible on articulated skull and middle nasal conchae Unpaired bat shaped cranial bone that serves to unite the cranial and facial bones acting as a keystone to strengthen the lateral walls of the cranium Features of interest sella turcica and optic canals TABLE 2 Facial bones Bone Maxilla 2 Mandible 1 Zygomatic 2 Nasal 2 Lacrimal 2 Palatines 2 Vomer 1 Inferior nasal conchae 2 Description The two maxillae together form the upper jaw bone Each maxilla has alveoli sockets for articulation with the teeth The maxillae also form the inferior and medial portions of the eye orbit and part of the bony roof of the mouth Features of interest alveoli and palatine processes The mandible is the lower jaw bone that articulates with the temporal bone forming the only moveable joint of the skull The mandible also has alveoli for articulation with the teeth Features of interest body ramus mandibular condyle condylar process of mandible coronoid process and alveoli The two zygomatic bones form the cheekbones and the lateral portion of the eye orbits Feature of interest temporal process The nasal bones form the superior portion of the bridge of the nose Together with the maxillae the lacrimal bones contribute to the medial portion of each eye orbit The palatine bones are L shaped bones that form with the maxillae part of the bony roof of the mouth the hard palate and a small portion of the eye orbit The vomer forms the inferior portion of the nasal septum The conchae lie inside the nasal cavity and serve to increase the turbulence of air flowing through en route to the lungs PSIO 201 Required Handout Department of Physiology Activity Palpate your own bone markings to review the axial skeleton ZYGOMATIC BONE Find the most prominent part of your cheek This is the zygomatic bone Follow the posterior course of the temporal process of this bone to the junction with your temporal bone via the zygomatic process MASTOID PROCESS The large rounded area behind your ear is the mastoid process TEMPOROMANDIBULAR JOINTS Open and close your jaw to find these joints where the mandibular condyles articulate with the mandibular fossas of the temporal bone SPHENOID Place your fingers on your zygomatic arches and then move your fingers superiorly until you find the indentations on the lateral skull that are often called your temples EXTERNAL AUDITORY MEATUS Stick your finger in your ear The opening through which your finger passes is the external auditory meatus NASAL BONES Run your index finger and thumb along opposite sides of the bridge of your nose until they slip medially at the inferior end of the nasal bones VOMER Place your finger in the small ridge above your upper lip Move your finger superiorly toward the base of the nose and apply a gentle pressure there The bony structure that you feel underneath the skin is the vomer HYOID BONE Place a thumb and forefinger under the mandible and gently squeeze medially VERTEBRAL PROMINENS The spinous process of C7 is usually visible through the skin and protrudes far enough to palpate easily It is often used as a landmark for counting the vertebrae MEDIAN SACRAL CREST Palpate this one in private The median sacral crest is essentially a remnant of the spinous processes of the fused vertebrae that compose the sacrum XIPHOID PROCESS The juncture between the xiphoid process and the manubrium can be found by moving your fingers along the sternum until they slip into a small depression this marks the end of the manubrium and the beginning of the xiphoid process This is the point from which you move two fingers widths superiorly before you would begin chest compressions during CPR Fracturing the sternum at the xiphoid process is dangerous because damage to the liver may result JUGULAR NOTCH The depression formed at the upper border of the manubrium is where you will find the jugular notch