Dominican_University_A_P_1_-_Lesson_7_-_Skeletal_System_-_Axial_Skeleton

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• Dominican University, New York• Course: Anatomy & Physiology I• Instructor: Spendy Pierre-Louis, PT, DPT, GCS

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• Principles of Anatomy & Physiology• Focus: The Skeletal System: The Axial Skeleton

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• The average human body contains enough bones to make an entire human skeleton.

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• The Axial Skeleton and Homeostasis• Protects many of the body's organs.

  • Cranium surrounds the brain.

  • Vertebrae surround the spinal cord.

  • Ribs surround the heart and lungs.• Supports calcium storage and release, an essential ion for various physiological functions.

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• Divisions of the Skeletal System• Human skeleton consists of 206 named bones grouped into:

  • Axial Skeleton (80 bones)

    • Skull bones, auditory ossicles, hyoid bone, ribs, sternum, vertebrae, and sacrum.

  • Appendicular Skeleton (126 bones)

    • Bones of the upper and lower extremities and the bones forming the girdles that connect limbs to the axial skeleton.

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• Bones of the Axial Skeleton• Total of 80 bones:

  • Skull

  • Vertebral column (including the sacrum)

  • Ribs

  • Sternum

  • Includes hyoid bone and ear ossicles (3 small bones in each middle ear).

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• Table 7.1 The Bones of the Adult Skeletal System• Axial Skeleton (80 bones)

  • Skull: 8 cranial cavity bones, 14 facial bones, 1 hyoid bone, 6 auditory ossicles.

  • Vertebral Column.

  • Thorax: 1 sternum, 24 ribs.• Appendicular Skeleton (126 bones)

  • Pectoral girdles (2), Upper limbs (60 bones), Pelvic girdle (2), Lower limbs (60 bones).

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• Types of Bones by Shape• Classified into five main types:

  • Long bones: greater length than width (e.g., femur).

  • Short bones: cube-shaped (e.g., carpals).

  • Flat bones: thin layers of parallel plates (e.g., ribs).

  • Irregular bones: complex shapes (e.g., vertebrae).

  • Sesamoid bones: shaped like sesame seeds (e.g., patella).

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• Bone Surface Markings• Characteristic surface markings adapted for specific functions:

  • Depressions and open: allow passage of soft tissues and form joints.

  • Processes: projections or outgrowths that form joints or serve as attachment points for ligaments and tendons.

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• Processes on Bone Surface Markings• Condyle: large, round protuberance with smooth articular surface (example: lateral condyle of femur).• Facet: smooth, flat articular surface (e.g., superior articular facet of vertebra).

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• Skull Overview• Contains 22 bones, excluding middle ear bones.• Associated structures: processes, ridges, lines, depressions, and foramina.

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• Facial Bones: Mandible• Largest and strongest facial bone.• Only moveable skull bone (excluding middle ear bones).

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• Hyoid Bone• Unique as it does not articulate with any other bone.• Supports tongue and serves as an attachment site for neck and pharynx muscles.

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• The Vertebral Column• Also called spinal column or backbone.• Composed of 26 vertebrae divided into 5 regions to protect the spinal cord.

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• Disorders Related to Spinal Curvature• Scoliosis: increased lateral curvature.• Kyphosis: exaggerated thoracic curve (hunched forward).• Lordosis: increased lumbar curve (bent backwards).

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• Spina Bifida• Congenital defect of the vertebral column due to improper lamina development.• Severity varies from minor to severe (meningomyelocele).