1. AXIAL SKELETON. SKULL. Objectives. 1. On a skull or diagram, identify and
name the bones of the skull. 2. Identify the structure and function of the bones of ...
Objectives
AXIAL SKELETON SKULL
CRANIAL BONES (8 total flat bones w/ 2 paired)
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.
1. Frontal Bone • forms forehead & upper portion of eyesocket (orbital)
2. Parietal Bones • paired bones; form superior & lateral walls of cranium
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
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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 1st cervical vertebrae
5. Sphenoid Bone • butterfly shaped; spans entire width of skull
SPHENOID
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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
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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
FONTANELS 1. Frontal (anterior) – between parietal & frontal bones; diamond shaped; largest; closes within 18 – 24 months 2. Occipital (posterior) – between parietal & occipital bones; closes within 2 months
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
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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
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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
8. Mandible – lower jaw; only free moving joint of skull Nasal bones
A. Body – horizontal;
chin conchae
vomer
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
