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Lecture 6Skeletal System:Axial Skeleton

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The Complete Skeleton•Axial skeleton

–Skull–Hyoid bone–Vertebral column–Thoracic (rib) cage

•Appendicular skeleton–Limbs–Girdles

Fig. 7.1

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Superior and Posterior Views of Skull or Cranium

Fig. 7.5• External occipital protuberance

– Ligamentum nuchae: Helps keep head erect

• Nuchal lines: Neck muscle attachment

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Lateral View of Skull

• Temporal lines (temporalis muscle)

• Mandible– Condyle

– Coronoid process for temporalis muscle

Fig. 7.6

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Frontal View of Skull

• Optic foramen (optic nerve)• Lacrimal groove (tears from eye to nasal capsule)

Frontal bone

Parietal bone

Temporal bone Sphenoid bone

Lacrimal bone

Nasal bone

Maxilla

Zygomatic bone

Perpendicular plate of ethmoid bone

VomerInferior nasal concha

Mandible

Ethmoid bone

Fig. 7.4

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Inferior View of Skull

• Foramen magnum• Occipital condyles• Jugular foramen, carotid canal• Hard palate - maxilla and palatine

Fig. 7.8

MaxillaPalatine bone

Vomer

Sphenoid bone

Jugular foramen

Carotid canal

Inferior nuchal line

Superior nuchal line

Occipital bone

External occipital protuberance

External occipital crest

Foramen magnum

Occipital condyleMastoid process

Temporal bone

Mandibular fossaStyloid process

Zygomatic process of temporal bone

Temporal process of zygomatic bone

Hard palate

Zygomatic arch

Fig. 7.8

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Hyoid Bone and Auditory Ossicles

• Hyoid bone– Unpaired– No direct bony attachment

to skull – Attachment point for some

tongue muscles– Attachment point for neck

muscles that elevate larynx during speech and swallowing

• Auditory ossicles– Malleus, incus and stapes

Fig. 7.26

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Vertebra

• Parts– Body– Vertebral foramen– Vertebral arch– Superior and inferior articular processes– Transverse process– Articular facets for rib– Spinous process

Fig. 7.29

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Vertebral Column

• Regions– Cervical (7 vertebrae)

– Thoracic (12 vertebrae)

– Lumbar (5 vertebrae)

– Sacral bone (1)

– Coccygeal bone (1)

Fig. 7.28

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Cervical Vertebrae

• Atlas– First vertebra– ‘yes’ motion

• Axis– Second vertebra– Dens or odontoid process– ‘no’ motion

Fig. 7.30

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Thoracic and Lumbar Vertebrae

Table 7.5 Table 7.5

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Sacrum and Coccyx

Fig. 7.31

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Review Question

The spinal cord passes along the vertebral column through the _______ and enters the skull through the __________.

(a) Spinous process, mandibular fossa(b) Body, occipital condyles(c) Superior and inferior articular processes, jugular foramen(d) Vertebral arch, carotid canal(e) None of the above is correct

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Thoracic Cage and Sternum• Parts

– Thoracic vertebrae– Ribs (12 pair)

• True• False

– Sternum (manubrium, body)

Fig. 7.32

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Points to RememberPoints to Remember• Two major components of the human skeleton:

– Axial skeleton arranged along the medial axis

– Appendicular skeleton connects to the axial skeleton

• Skull consists of:– 22 bones (single and paired)

– 6 auditory ossicles (3 each side) and 1 hyoid

• Vertebral column consists of:– Cervicals (7)

– Thoracics (12)

– Lumbars (5)

– Sacrum (5, fused)

– Coccyx (3-5, fused)

• Rib cage has true (bone) ribs and false (cartilage) ribs

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Questions?