7 The Skeleton: Part A

Composed of bones, cartilages, joints, ligaments 20% of body mass Skeletal System Composed of bones, cartilages, joints, ligaments 20% of body mass Two major parts Axial Appendicular © 2013 Pearson Education, Inc.

The Axial Skeleton Consists of 80 bones Three major regions Skull Vertebral column Thoracic cage © 2013 Pearson Education, Inc.

Formed by two sets of bones The Skull Formed by two sets of bones Cranial bones (cranium) 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 © 2013 Pearson Education, Inc.

The Skull Facial bones Framework of face Cavities for special sense organs for sight, taste, and smell Openings for air and food passage Sites of attachment for teeth and muscles of facial expression © 2013 Pearson Education, Inc.

Middle and internal ear cavities Nasal cavity Orbits 85 named openings Skull Geography Cranial cavity Middle and internal ear cavities Nasal cavity Orbits 85 named openings Foramina, canals, fissures © 2013 Pearson Education, Inc.

Eight Cranial Bones Frontal bone Parietal bones (2) Occipital bone Temporal bones (2) Sphenoid bone Ethmoid bone © 2013 Pearson Education, Inc.

Anterior portion of cranium Most of anterior cranial fossa Frontal Bone Anterior portion of cranium Most of anterior cranial fossa Superior wall of orbits Contains air-filled frontal sinus © 2013 Pearson Education, Inc.

Parietal Bones and Major Associated Sutures Superior and lateral aspects of cranial vault Four sutures mark articulations of parietal bones with frontal, occipital, and temporal bones: 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 © 2013 Pearson Education, Inc.

Most of skull's posterior wall and posterior cranial fossa Occipital Bone Most of skull's posterior wall and posterior cranial fossa Articulates with 1st vertebra Sites of attachment for ligamentum nuchae and many neck and back muscles © 2013 Pearson Education, Inc.

Inferolateral aspects of skull and parts of cranial base Temporal Bones Inferolateral aspects of skull and parts of cranial base Four major regions Squamous Tympanic Mastoid Petrous © 2013 Pearson Education, Inc.

Complex, bat-shaped bone Keystone bone Three pairs of processes Sphenoid Bone Complex, bat-shaped bone Keystone bone Articulates with all other cranial bones Three pairs of processes Greater wings Lesser wings Pterygoid processes © 2013 Pearson Education, Inc.

Superior part of nasal septum, roof of nasal cavities Ethmoid Bone Deepest skull bone Superior part of nasal septum, roof of nasal cavities Contributes to medial wall of orbits Crista galli for dural attachment © 2013 Pearson Education, Inc.

Tiny irregularly shaped bones that appear within sutures Sutural Bones Tiny irregularly shaped bones that appear within sutures © 2013 Pearson Education, Inc.

Fourteen Facial Bones Mandible Maxillary bones (maxillae) (2) Zygomatic bones (2) Nasal bones (2) Lacrimal bones (2) Palatine bones (2) Vomer Inferior nasal conchae (2) © 2013 Pearson Education, Inc.

Largest, strongest bone of face Temporomandibular joint Mandible Lower jaw Largest, strongest bone of face Temporomandibular joint Only freely movable joint in skull © 2013 Pearson Education, Inc.

Contain maxillary sinuses Maxillary Bones Medially fused to form upper jaw and central portion of facial skeleton Keystone bones Articulate with all other facial bones except mandible Contain maxillary sinuses Largest of paranasal sinuses © 2013 Pearson Education, Inc.

Inferolateral margins of orbits Zygomatic Bones Cheekbones Inferolateral margins of orbits © 2013 Pearson Education, Inc.

Nasal Bones and Lacrimal Bones Form bridge of nose Lacrimal bones In medial walls of orbits Lacrimal fossa houses lacrimal sac © 2013 Pearson Education, Inc.

Palatine Bones and Vomer Posterior one-third of hard palate Posterolateral walls of the nasal cavity Small part of the orbits Vomer Plow shaped Inferior part of nasal septum © 2013 Pearson Education, Inc.

Inferior Nasal Conchae Form part of lateral walls of nasal cavity Largest of three pairs of conchae © 2013 Pearson Education, Inc.

Cavities that encase eyes and lacrimal glands Orbits Cavities that encase eyes and lacrimal glands Sites of attachment for eye muscles Formed by parts of seven bones Frontal, sphenoid, zygomatic, maxilla, palatine, lacrimal, and ethmoid © 2013 Pearson Education, Inc.

Nasal Cavity Roof, lateral walls, and floor formed by parts of four bones Ethmoid Palatine bones Maxillary bones Inferior nasal conchae Nasal septum of bone and hyaline cartilage Perpendicular plate of ethmoid Vomer Anterior septal cartilage © 2013 Pearson Education, Inc.

Mucosa-lined, air-filled spaces Lighten skull Paranasal Sinuses Mucosa-lined, air-filled spaces Lighten skull Enhance resonance of voice Warm and humidify air Found in frontal, sphenoid, ethmoid, and maxillary bones © 2013 Pearson Education, Inc.

Does not articulate directly with another bone Movable base for tongue Hyoid Bone Not bone of skull Does not articulate directly with another bone Movable base for tongue Site of attachment for muscles of swallowing and speech © 2013 Pearson Education, Inc.