Axial Skeleton

Lab 2: Axial Skeleton

  • Course: Seeley's Anatomy & Physiology
  • Reference: Chapter 7

Overview of the Skeletal System

  • Total Bone Count: 206 bones
    • Axial Skeleton: 80 bones
    • Appendicular Skeleton: 126 bones
  • Major Functions of the Skeletal System:
    1. Body support
    2. Body movement
    3. Organ protection
    4. Mineral storage
    5. Blood cell production

Classification and Markings of Bones

  • Projections:
    • Processes that grow out from the bone
    • Functions:
    • Muscle attachment
    • Joint formation
  • Depressions:
    • Indentations or openings in the bone
    • Functions:
    • Conduits for nerves and blood vessels

Long Bone Anatomy

  • Key Features of Long Bones:
    • Proximal Epiphysis
    • Spongy Bone: Contains red bone marrow
    • Medullary Cavity: Contains yellow bone marrow
    • Epiphyseal Plate: Growth plate found in long bones
    • Compact Bone: Dense outer layer
    • Periosteum: Dense connective tissue surrounding the bone
    • Diaphysis: Shaft of the bone
    • Distal Epiphysis
  • Vascular Components:
    • Periosteal blood vessels
    • Perforating (Sharpey's) fibers
    • Central canal
    • Perforating (Volkmann's) canal
    • Blood vessels that continue into the medullary cavity

Axial Skeleton Details

  • Total Bones: 80
  • Components of the Axial Skeleton:
    • Skull and Associated Bones: 29 bones
    • Cranium: 8 bones
      • Bones: Occipital, Frontal, 2 Temporal, 2 Parietal, Sphenoid, Ethmoid
    • Face: 14 bones
      • Bones: 2 Palatine, 2 Maxillary, 2 Nasal, 2 Zygomatic, 2 Inferior Nasal Conchae, 2 Lacrimal, Vomer, Mandible
    • Thoracic Cage: 25 bones
    • Associated Bones: 7
      • 6 Auditory Ossicles, Hyoid
    • Vertebral Column: 26 bones
    • Sternum: 1 bone
    • Ribs: 24 bones
      • Vertebrae: 24 bones
      • 7 Cervical, 12 Thoracic, 5 Lumbar
      • Sacrum: 1 bone
      • Coccyx: 1 bone

Cranial Bones

  • Bones included:
    • Frontal
    • Parietal (2)
    • Temporal (2)
    • Occipital
    • Sphenoid
    • Ethmoid

Facial Bones

  • Bones included:
    • Vomer Bone
    • Zygomatic Bones (2)
    • Lacrimal Bones (2)
    • Nasal Bones (2)
    • Inferior Nasal Concha (2)
    • Palatine Bone (2)
    • Maxilla (2)
    • Mandible

Cranial Nerves

  • List of Cranial Nerves (I - XII):
    1. Olfactory nerve (I)
    2. Optic nerve (II)
    3. Oculomotor nerve (III)
    4. Trochlear nerve (IV)
    5. Trigeminal nerve (V)
    6. Abducens nerve (VI)
    7. Facial nerve (VII)
    8. Vestibulocochlear nerve (VIII)
    9. Glossopharyngeal nerve (IX)
    10. Vagus nerve (X)
    11. Spinal accessory nerve (XI)
    12. Hypoglossal nerve (XII)

Thoracic Cage Anatomy

  • Components of the Thoracic Cage:
    • Sternum:
    • Manubrium
    • Sternal Body
    • Xiphoid Process
    • Ribs:
    • True ribs (R1-R7)
    • False ribs (R8-R12)
    • Floating ribs (R11-R12)

Vertebral Column

  • Composition of the Vertebral Column:
    • Cervical: 7 vertebrae
    • Thoracic: 12 vertebrae
    • Lumbar: 5 vertebrae
    • Sacrum: 5 fused bones
    • Coccyx: 4 fused bones
  • Memorable Mnemonic: I eat breakfast at 7, have lunch at 12, and eat dinner at 5.

Cervical Vertebrae

  • Notable Cervical Vertebrae:
    • Atlas (C1)
    • Axis (C2)
    • Other cervical vertebrae (C3)

Comparison of Vertebrae

  • Thoracic vs. Lumbar Vertebrae:
    • Feature: Body size
    • Thoracic: Medium-sized body
    • Lumbar: Large body
    • Feature: Superior articular process
    • Thoracic: Faces posteriorly
    • Lumbar: Faces medially

Sacrum and Coccyx

  • Sacrum:
    • Composed of 5 fused bones
  • Coccyx:
    • Composed of 4 fused bones
  • View: Anterior view of the sacrum and coccyx