Bones Of The Axial Skeleton THE SKULL Skull
Bones Of The Axial Skeleton THE SKULL
Skull Thoracic cage (ribs and sternum) Vertebral column Sacrum Cranium Facial bones Clavicle Scapula Sternum Rib Humerus Vertebra Radius Ulna Carpals Phalanges Metacarpals Femur Patella Tibia Fibula (a) Anterior view Tarsals Metatarsals Phalanges Figure 7. 1 a
Frontal bone Glabella Frontonasal suture Supraorbital foramen (notch) Supraorbital margin Superior orbital fissure Optic canal Inferior orbital fissure Middle nasal concha Ethmoid Perpendicular bone plate Inferior nasal concha Vomer Parietal bone Squamous part of frontal bone Nasal bone Sphenoid bone (greater wing) Temporal bone Ethmoid bone Lacrimal bone Zygomatic bone Infraorbital foramen Maxilla Mandible Mental foramen (a) Anterior view Mandibular symphysis Figure 7. 4 a
The Skull • Two sets of bones 1. Cranial bones • Enclose the brain in the cranial cavity – Cranial vault (calvaria) – Cranial base: anterior, middle, and posterior cranial fossae • Provide sites of attachment for head and neck muscles 2. Facial bones • Framework of face • Cavities for special sense organs for sight, taste, and smell • Openings for air and food passage • Sties of attachment for teeth and muscles of facial expression
Bones of cranium (cranial vault) Coronal suture Squamous suture Lambdoid suture Facial bones (a) Cranial and facial divisions of the skull Figure 7. 2 a
Anterior cranial fossa Middle cranial fossa Posterior cranial fossa (b) Superior view of the cranial fossae Figure 7. 2 b
Cranial Bones • • • Frontal bone Parietal bones (2) Occipital bone Temporal bones (2) Sphenoid bone Ethmoid bone
Frontal bone Sphenoid bone (greater wing) Coronal suture Parietal bone Ethmoid bone Temporal bone Lacrimal fossa Lambdoid suture Squamous suture Occipital bone Zygomatic process Occipitomastoid suture External acoustic meatus Mastoid process Styloid process Nasal bone Zygomatic bone Maxilla Alveolar margins Mandibular condyle Mandibular notch Mandible Mental foramen Mandibular ramus Mandibular angle Coronoid process (a) External anatomy of the right side of the skull Figure 7. 5 a
Notable Features of Cranial Bones Frontal Bone • Anterior portion of cranium • Most of anterior cranial fossa • Superior wall of orbits • Contains air-filled frontal sinuses Parietal Bones • • Superior and lateral aspects of cranial vault Four sutures mark the articulations of parietal bones with frontal, occipital, and temporal bones: 1. 2. 3. 4. Coronal suture—between parietal bones and frontal bone Sagittal suture—between right and left parietal bones Lambdoid suture—between parietal bones and occipital bone Squamous (squamosal) sutures—between parietal and temporal bones on each side of skull
Sagittal suture Parietal bone Sutural bone (tiny irregular bones within sutures) Lambdoid suture Occipital bone Superior nuchal line External occipital protuberance Occipitomastoid suture (b) Posterior view External occipital crest Occipital condyle Mastoid process Inferior nuchal line Figure 7. 4 b
Maxilla (palatine process) Hard Palatine bone palate (horizontal plate) Zygomatic bone Temporal bone (zygomatic process) Vomer Mandibular fossa Styloid process Mastoid process Temporal bone (petrous part) Pharyngeal tubercle of basilar region of the occipital bone Parietal bone External occipital crest External occipital protuberance (a) Inferior view of the skull (mandible removed) Incisive fossa Intermaxillary suture Median palatine suture Infraorbital foramen Maxilla Sphenoid bone (greater wing) Foramen ovale Foramen spinosum Foramen lacerum Carotid canal External acoustic meatus Stylomastoid foramen Jugular foramen Occipital condyle Inferior nuchal line Superior nuchal line Foramen magnum Figure 7. 6 a
External acoustic meatus Mastoid region Squamous region Zygomatic process Mastoid process Mandibular fossa Tympanic region Styloid process Figure 7. 8
Notable Features of Cranial Bones Occipital Bone • Most of skull’s posterior wall and posterior cranial fossa • Articulates with 1 st vertebra • Sites of attachment for the ligamentum nuchae and many neck and back muscles Temporal Bones • Inferolateral aspects of skull and parts of cranial floor • Four major regions – Squamous – Tympanic – Mastoid – Petrous
Optic canal Greater wing Hypophyseal fossa of sella turcica Body of sphenoid Lesser wing Superior orbital fissure Foramen rotundum Foramen ovale Foramen spinosum (a) Superior view of Sphenoid bone Figure 7. 9 a
Body of sphenoid Greater wing (b) Posterior view Lesser wing Superior orbital fissure Pterygoid process Sphenoid Bone • Complex, bat-shaped bone • Keystone bone - Articulates with all other cranial bones • Three pairs of processes Greater wings Lesser wings Pterygoid processes Figure 7. 9 b
Ethmoid Bone • • • Olfactory foramina Orbital plate Deepest skull bone Superior part of nasal septum, roof of nasal cavities Contributes to medial wall of orbits Crista galli Cribriform plate Left lateral mass Ethmoidal air cells Perpendicular plate Middle nasal concha
Ethmoid bone Cribriform plate Crista galli Anterior cranial fossa Sphenoid Lesser wing Greater wing Hypophyseal fossa of sella turcica Middle cranial fossa Temporal bone (petrous part) Frontal bone Olfactory foramina Optic canal Foramen rotundum Foramen ovale Foramen spinosum Foramen lacerum Internal acoustic meatus Jugular foramen Hypoglossal canal Posterior cranial fossa Parietal bone Occipital bone (a) Superior view of the skull, calvaria removed Foramen magnum View
Frontal bone Glabella Frontonasal suture Supraorbital foramen (notch) Supraorbital margin Superior orbital fissure Optic canal Inferior orbital fissure Middle nasal concha Ethmoid Perpendicular bone plate Inferior nasal concha Vomer Parietal bone Squamous part of frontal bone Nasal bone Sphenoid bone (greater wing) Temporal bone Ethmoid bone Lacrimal bone Zygomatic bone Infraorbital foramen Maxilla Mandible Mental foramen (a) Anterior view Mandibular symphysis Figure 7. 4 a
Facial Bones • Mandible • Maxillary bones (maxillae) (2) • Zygomatic bones (2) • Nasal bones (2) • • Lacrimal bones (2) Palatine bones (2) Vomer Inferior nasal conchae (2)
Frontal bone Glabella Frontonasal suture Supraorbital foramen (notch) Supraorbital margin Superior orbital fissure Optic canal Inferior orbital fissure Middle nasal concha Ethmoid Perpendicular bone plate Inferior nasal concha Vomer Parietal bone Squamous part of frontal bone Nasal bone Sphenoid bone (greater wing) Temporal bone Ethmoid bone Lacrimal bone Zygomatic bone Infraorbital foramen Maxilla Mandible Mental foramen (a) Anterior view Mandibular symphysis Figure 7. 4 a
Maxilla (palatine process) Hard Palatine bone palate (horizontal plate) Zygomatic bone Temporal bone (zygomatic process) Vomer Mandibular fossa Styloid process Mastoid process Temporal bone (petrous part) Pharyngeal tubercle of basilar region of the occipital bone Parietal bone External occipital crest External occipital protuberance (a) Inferior view of the skull (mandible removed) Incisive fossa Intermaxillary suture Median palatine suture Infraorbital foramen Maxilla Sphenoid bone (greater wing) Foramen ovale Foramen spinosum Foramen lacerum Carotid canal External acoustic meatus Stylomastoid foramen Jugular foramen Occipital condyle Inferior nuchal line Superior nuchal line Foramen magnum Figure 7. 6 a
Articulates with frontal bone Frontal process Orbital surface Zygomatic process (cut) Infraorbital foramen Anterior nasal spine Alveolar margin (b) Maxilla, right lateral view Maxillary Bones • Medially fused to form upper jaw and central portion of facial skeleton • Keystone bones – Articulate with all other facial bones except mandible
Temporomandibular joint Mandibular notch Mandibular fossa of temporal bone Coronoid process Mandibular condyle Mandibular foramen Alveolar margin Mental foramen Ramus of mandible Mandibular angle Body of mandible (a) Mandible, right lateral view • Lower jaw • Largest, strongest bone of face • Temporomandibular joint: only freely movable joint in skull
Facial Bones Zygomatic Bones • Cheekbones • Inferolateral margins of orbits Nasal Bones And Lacrimal Bones • Nasal bones – Form bridge of nose • Lacrimal bones – In medial walls of orbits – Lacrimal fossa houses lacrimal sac Palatine bones – Posterior one-third of hard palate – Posterolateral walls of the nasal cavity – Small part of the orbits Vomer – Plow shaped – Lower part of nasal septum Inferior Nasal Conchae • Form part of lateral walls of nasal cavity Orbits • Encase eyes and lacrimal glands • Sites of attachment for eye muscles • Formed by parts of seven bones
Paranasal Sinuses • • Mucosa-lined, air-filled spaces Lighten the skull Enhance resonance of voice Found in frontal, sphenoid, ethmoid, and maxillary bones Frontal sinus Ethmoidal air cells (sinus) Sphenoid sinus Maxillary sinus (a) Anterior aspect (b) Medial aspect Frontal sinus Ethmoidal air cells Sphenoid sinus Maxillary sinus
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