23_Axial Skeleton_Vertebral Column and Thoracic Cage.pptx

Axial Skeleton Part 2 Chapter 6, Human Anatomy (LibreTexts) "Skeleton Sitting Smiling " by Clker-Free-Vector-Images is in the Public Domain, CC0 Vertebral Column • Also called spinal column or spine • Sequence of 26 vertebrae separated by intervertebral discs • Functions • supports the head, neck...

Axial Skeleton Part 2 Chapter 6, Human Anatomy (LibreTexts) "Skeleton Sitting Smiling " by Clker-Free-Vector-Images is in the Public Domain, CC0 Vertebral Column • Also called spinal column or spine • Sequence of 26 vertebrae separated by intervertebral discs • Functions • supports the head, neck, and body and allows for their movements • protects the spinal cord Vertebrae • 24 individual vertebrae grouped in regions: • Cervical vertebrae: 7 bones of the neck (C1-C7) • Thoracic vertebrae: 12 bones that help form the superior region of the back and articulate with the ribs (T1-T12) • Lumbar vertebrae: 5 bones that help form the inferior, concave region of the back (L1-L5) • Two inferior bones are fusions of several vertebrae • Sacrum: 5 fused vertebrae (S1-S5) • Coccyx: 4 fused vertebrae forming the “tailbone” (Co1-Co4) Vertebral Column (Image) "Vertebral Column" by OpenStax is licensed under CC BY 3.0 Spinal Curvatures • Primary curvatures form during fetal development: • Thoracic curve retains the curve of the fetus • Sacral curve retains the curve of the fetus • Secondary curves appear after birth: • Cervical curve forms at 3-4 months when baby can hold head up • Lumbar curve forms at 1 year when baby learns to stand and walk General Anatomy of a Vertebra • Every vertebra has: • Body: region that stacks each vertebra upon another one, where intervertebral discs are located. • Spinous process: posterior elevation • Transverse process: lateral elevation • Vertebral arch formed by laminae (region between a transverse process and spinous process) and pedicles (region between transverse process and body) • Vertebral foramen: opening between body and vertebral arch that houses spinal cord • Intervertebral foramen: opening between a pedicle of one vertebra and the subsequent one. General Structure of a Vertebra – Superior View "Vertebra" by Whitney Menefee is licensed under CC BY 3.0 / A derivative from the original work Articulation between Vertebrae • Every vertebra has: • Intervertebral foramen: opening between a pedicle of one vertebra and the subsequent one. Place of exit of spinal nerves. • Superior articular facet: articulating surface superior to pedicle • Inferior articular facet: articulating surface inferior to pedicle • The inferior articular facets of a vertebra articulate with the superior articular facets of the inferior vertebra. General Structure of a Vertebra – Posterolateral View "Vertebra" by Whitney Menefee is licensed under CC BY 3.0 / A derivative from the original work Intervertebral Discs • Each disc absorbs the stress and shock the body incurs during movement and prevents the vertebrae from grinding against one another. • Two parts: • Anulus fibrosus: outer layer made of fibrocartilage • Nucleus pulposus: jelly-like substance of mainly water and collagen • All together discs make ¼ of vertebral column • Compressed while standing/walking • Stretch back while sleeping or doing yoga Intervertebral Disk "Intervertebral Disk" by OpenStax is licensed under CC BY 3.0 Cervical Vertebrae • Atlas (C1): superior articular facets of Atlas articulate with occipital condyles of occipital bone. Does not have a body or spinous process. • Axis (C2) makes articulation with atlas to enable movements of head. Has an elevation called dens that allows Atlas to pivot around it. • All other cervical vertebrae look like a fish face or Sid of Ice Age. • Spinous process is bifurcated (bifid) • Small transverse process houses opening called transverse foramen through which blood vessels pass. Atlas and Axis "Cervical Vertebrae" by Whitney Menefee is licensed under CC BY 3.0 / A derivative from the original work Cervical Vertebrae "Cervical Vertebrae" by Whitney Menefee is licensed under CC BY 3.0 / A derivative from the original work Thoracic Vertebrae • Thoracic vertebrae look like the head of a giraffe. • Have articulation with ribs at costal facets on transverse process and costal demifacets on body. Thoracic Vertebrae Costal facet Costal demifacet Costal demifacet "Thoracic Vertebra" by OpenStax is licensed under CC BY 3.0 Lumbar Vertebrae • Lumbar vertebrae look like the head of a moose. • Large and blunt transverse process • Short and blunt spinous process Lumbar Vertebrae "Lumbar Vertebra" by OpenStax is licensed under CC BY 3.0 Sacrum • Base: superior border • Promontory: body of the first sacral vertebra • Superior articular facets: articulating surfaces for last lumbar vertebra • Auricular surface: articulating surface for os coxae • Transverse ridges: anterior elevations between sacral vertebrae • Median sacral crest: posterior elevation made of the fusion of spinous processes • Sacral canal: opening that represents fusion of sacral vertebral foramina • Sacral hiatus: opening at the end of sacral canal • Sacral foramina: lateral openings of sacral intervertebral foramina • Apex: pointy end of sacrum that articulates with coccyx Sacrum and Coccyx "Sacrum and Coccyx" by OpenStax is licensed under CC BY 3.0 Thoracic Cage • Protects the heart and lungs • Consists of ribs, sternum and thoracic vertebrae • 12 pairs of ribs are anchored posteriorly to the 12 thoracic vertebrae (T1–T12) and anteriorly to the sternum. Sternum • Manubrium: superior region • Body: middle region • Xiphoid process: inferior region • Clavicular notches: depressions for articulation with clavicle • Jugular notch (or suprasternal notch): depression between clavicular notches • Sternal angle: region between manubrium and body • Costal notches: depression for articulations with ribs Sternum (Image) Costal notches "Rib Cage" by OpenStax is licensed under CC BY 3.0 Ribs • Most ribs are attached, either directly or indirectly, to the sternum via their costal cartilage • Ribs are classified into three groups based on their relationship to the sternum • True Ribs 1 – 7: attached directly to the sternum • False Ribs 8 – 12: • 8–10 costal cartilages are attached to the cartilage of the next higher rib • 11-12 do not attached to sternum; also called floating ribs • Head contains articular facets for articulation with body of thoracic vertebrae • Tubercle contains articular facet for articulation with transverse process of thoracic vertebrae A Typical Rib "A Typical Rib" by Whitney Menefee is a derivative from the original work of Daniel Donnelly and is licensed under CC BY 4.0 Articulation between Thoracic Vertebrae and Ribs • Head of rib articulates with costal demifacets of the vertebral body of thoracic vertebrae • Tubercle of rib articulates with costal facet on transverse process of thoracic vertebrae Rib Articulation in Thoracic Vertebrae Costal demifacet Costal facet Costal demifacet "Thoracic Vertebra and Rib" by Whitney Menefee is licensed under CC BY 3.0 / A derivative from the original work