Jessica Radke-Snead, RD, MS Bio 241 Anatomy & Physiology Unit 2: Skeletal System Lab 2: Axial Skeleton

Review: Bones of the Adult Skeletal System Axial skeleton (80) – LAB 1 Skull (22) Auditory ossicles (6) Hyoid bone (1) – LAB 2 Vertebral column (26) Thoracic cage (25) Appendicular skeleton (126) – LAB 3 Pectoral girdle (4) Upper limb (60) Pelvic girdle (2) Lower limb (60)

Curves of the Vertebral Column

Cervical Vertebrae Distinctive features – All have transverse foramen—protection for the vertebral arteries—that are NOT present in any other vertebrae – C1 (atlas) and C2 (axis) allow for head movement  Axis is the only vertebrae with a dens; begins to form during the first year of life and fuses with the axis by the age of 3-6 years – C3-C6 have transverse foramina and bifid spinous processes – C7 is different—spinous process is not bifid, but especially long and forms the prominent bump on the lower back of the neck (vertebra prominens) Atlanto-occipital joint: articulation between the atlas and the cranium Atlanto-axial joint: articulation between the atlas and axis

Vertebral Column Bones

Thoracic Vertebrae Distinctive features – Lack transverse foramina and bifid processes – Spinous processes pointed and angle sharply downward – Include costal facets  No other vertebrae have ribs articulating with them – T1-T10 have transverse costal facets at the end of each transverse process  provides a second point of articulation for ribs 1-10 – T11 and T12 have NO transverse costal facets  ribs 11 and 12 attach only to the bodies of vertebrae (“floating ribs”) Inferior and superior costal facet: position on the vertebrae, not articulating rib Superior and inferior articular facets: position on a vertebrae – T12 inferior articular facets face laterally instead of anteriorly  positions them to articulate with the medially facing superior articular facets of the first lumbar vertebrae

Thoracic vertebrae: include: Rib facets: round fossa where ribs connect to the vertebrae or Demifacets: rib facet divided between 2 vertebraes

Lumbar Vertebrae Distinctive features – Thick, stout body – Blunt, square-like spinous processes – Articular processes oriented differently: Superior processes face medially Inferior processes face laterally (toward the superior processes of the next vertebrae)  resistant to twisting

Lumbar vertebrae lack: Rib facets and Transverse foramina

Sacrum Consists of 5 vertebrae  Fuses age Forms the posterior wall of the pelvic cavity

Coccyx Consists of 4-5 small vertebrae  Fuses age Serves as attachment points for muscles of the pelvic floor Cornua: hornlike projections that serve at attachment points for ligaments that bind the coccyx to the sacrum

Thoracic Cage: Sternum

Thoracic Cage: Ribs 12 pairs, no differences between genders Attached at posterior (proximal) end to the vertebral column Costal cartilage – Hyaline cartilage extends from the anterior (distal) ends of ribs 1-7 to the sternum  “true ribs” – Ribs 8-10 attach to the costal cartilage of rib 7 – “false ribs” – Ribs do not attach to anything at the distal end, but are embedded in muscle  “false ribs”, “floating ribs”

Thoracic Cage: Ribs

Lab 2 Objectives Identify and describe the bones and features of the vertebral column and thoracic bones designated in your lab – Observe these structures from multiple viewpoints to develop a 3D comprehension Review the bones and features of the skull (adult and fetal) designated in lab 1 Put together a comprehensive understanding of the axial skeleton Please be careful with the bones—ask for assistance if needed! Enjoy!