Set 7: Lecture 7 - The Axial Skeleton

Axial skeleton components

Skull, vertebral column, ribcage (80 bones total)

Appendicular skeleton components

Limbs and girdles (126 bones total)

Facial bones count

14 bones total

Maxillae bones

Form upper jaw, contain maxillary sinus

Mandible

Only movable skull bone (except ossicles)

Hyoid bone

Only bone not articulating with another bone

Auditory ossicles

Malleus, Incus, Stapes (smallest bones in body)

Paranasal sinuses

Frontal, Ethmoid, Sphenoid, Maxillary (all open into nasal cavity)

Fontanels

"Soft spots" on baby's head allowing skull growth

Four major fontanels

Frontal (anterior), Posterior (occipital), Anterolateral (sphenoid), Posterolateral (mastoid)

Cervical vertebrae count

7 (C1-C7)

Thoracic vertebrae count

12 (T1-T12) with rib attachments

Lumbar vertebrae count

5 (L1-L5) for weight-bearing

Sacrum

5 fused vertebrae (S1-S5)

Coccyx

1-5 partially fused sections ("tailbone")

C1 (Atlas)

Vertebra with no centrum, articulates with occipital for "yes" gesture

C2 (Axis)

Vertebra with dens (odontoid process) for rotation

Kyphosis

Exaggerated thoracic curvature ("hunchback")

Lordosis

Exaggerated lumbar curvature ("swayback")

Scoliosis

Lateral curvature mainly in thoracic region

True ribs (7 pairs)

Attach directly to sternum via own costal cartilage

False ribs (5 pairs)

Do not attach directly to sternum

Floating ribs (2 pairs)

Have no sternal attachment at all

Sternum parts

Manubrium, Body, Xiphoid process

Xiphoid process importance

Landmark for CPR hand placement (two finger-widths above)