Objectives AXIAL SKELETON. 1. Frontal Bone. 2. Parietal Bones. 3. Temporal Bones. CRANIAL BONES (8 total flat bones w/ 2 paired)

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1 Objectives AXIAL SKELETON SKULL 1. On a skull or diagram, identify and name the bones of the skull 2. Identify the structure and function of the bones of the skull 3. Describe how a fetal skull differs from the adult skull 4. Explain the function of the fontanels. CRANIAL BONES (8 total flat bones w/ 2 paired) forms forehead & upper portion of eyesocket (orbital) 1. Frontal Bone paired bones; form superior & lateral walls of cranium 2. Parietal Bones 3. Temporal Bones paired bones; inferior to parietal bones A. External auditory meatus canal leading to eardrum & middle ear B. Styloid process sharp projection below meatus; attachment of neck & tongue muscles 1

2 C. Zygomatic process bridge of bone that joins with cheekbone D. Mastoid process rough projection inferior & posterior to meatus (feel behind ears); attachment of neck muscles E. Jugular foramen found at junction of occipital & temporal bones; opening for jugular vein F. Carotid canal superior to jugular foramen; passage for carotid artery 4. Occipital Bone most posterior bone; forms base of skull A. Foramen magnum large opening for passage of spinal cord B. Occipital condyles lateral to foramen magnum; projections that rest on 1 st cervical vertebrae butterfly shaped; spans entire width of skull 5. Sphenoid Bone SPHENOID 2

3 A. Sella turcica Turk s saddle ; depression that holds the pituitary gland B. Foramen ovale large oval opening at posterior end of sella turcica; passage of cranial nerves that control chewing Sella turcica Foramen ovale 6. Ethmoid Bone irregular bone anterior to sphenoid Forms roof of nasal cavity & part of medial walls of orbitals A. Cristi galli cock s comb ; projection on superior surface to which outermost brain attaches B. Cribiform plates holey areas on each side of cristi galli; passage of olfactory nerves Bone of the Orbit 1. Frontal bone 2. Ethmoid bone 3. Sphenoid bone 4. Zygomatic bone 5. Lacrimal bone 6. Maxillary bone 3

4 SUTURES OF SKULL (immovable joints of skull bones) 1. Coronal between frontal & parietal bones 2. Sagittal between paired parietal bones 3. Lamboidal between parietal & occipital bones 4. Squamosal between parietal & temporal bones 1 Coronal 5 Squamosal 9 lamboidal 15 - sagittal FETAL SKULL Contains cartilage filled spaces called fontanels that allow for brain growth & compression during birth Face is smaller in comparison to cranium Adult s cranium 1/8 of total body length Infant s cranium ¼ of total body length Frontal bones split Temporal bone is a ring of bone Conical projections present growth areas 1. Frontal (anterior) between parietal & frontal bones; diamond shaped; largest; closes within months 2. Occipital (posterior) between parietal & occipital bones; closes within 2 months FONTANELS 3. Sphenoidal (anterolateral) paired; at the junction of the frontal, parietal, temporal & sphenoid bones ; closes within 3 months 4. Mastoid - (posterolateral); at the junction of parietal, occipital & temporal bones 4

5 FACIAL BONES (14 bones w/ 2 being paired) 1. Maxillae 2 bones that fuse to form the upper jaw All facial bones except mandible join to maxillae A. Alveolar margin (process) holds teeth B. Palantine process anterior hard palate 2. Palatine Bones posterior to palatine processes of maxillae If not fused cleft palate results 3. Zygomatic Bones cheekbones 4. Lacrimal Bones smallest facial bone; forms most of the medial walls of the orbits 5

6 1. Frontal bone 2. Ethmoid bone 3. sphenoid bone 4. Zygomatic bone 5. Nasal Bones form the bridge of the nose 6. Vomer Bone plow shaped ; single bone in the median of nasal cavity 7. Conchae scroll shaped ; form lateral walls of nasal cavity 5. Lacrimal bone 6. Maxillary bone Nasal bones conchae vomer 8. Mandible lower jaw; only free moving joint of skull A. Body horizontal; chin B. Rami perpendicular uprights C. Angle where body meets rami D. Coronoid process spine like process; anterior E. Condylar process knob like process; posterior; forms temporal mandibular joint F. Mandibular notch depression between processes G. Mandibular foramen opening on inner surface of rami H. Mental foramen opening on body HYOID BONE U shaped Only bone that doesn t directly articulate with any other bone in body Located above the larynx ; suspended from styloid process 3 parts: Greater cornua superior Lesser cornua inferior Body anterior 6

7 Greater cornua OSSICLES Lesser cornua Bones of inner ear Incus anvil Malleus hammer Stapes - stirrup 7