skeletal system

• Skeletal system


  Comprised mainly of bones, around 206 in an adult, but also cartilage, joints, and ligaments, which make up around 20% of a person's body mass
• Sections of the human skeleton

  • Axial skeleton (skull, vertebral column, thoracic cage)
  • Appendicular skeleton (limbs)
• Skull


  • Made of 22 different bones
  • Cranial bones protect the brain
  • Facial bones give structure to the face
  • Most bones are flat and connected by serrated sutures
  • Contains cranial, ear, nasal, and orbital cavities
• Cranial bones


  • Frontal
  • Parietal (2)
  • Occipital
  • Temporal (2)
  • Sphenoid
  • Ethmoid
• Cranial sutures


  • Coronal
  • Sagittal
  • Lambdoid
  • Squamous
  • Occipitomastoid
• Facial bones


  • Mandible
  • Maxillary
  • Zygomatic (2)
  • Nasal
  • Lacrimal
  • Palatine
  • Vomer
  • Inferior nasal conchae
  • Hyoid
• Vertebral column


  • Comprised of 26 irregular bones in a flexible, curvy S-shape
  • Divided into 5 sections: cervical, thoracic, lumbar, sacrum, coccyx
  • Vertebrae get larger to support more weight
  • Ligaments, intervertebral discs, and processes like spinous, transverse, and articular
• Thoracic cage


  • Comprised of sternum and 12 pairs of ribs with costal cartilage
  • First 7 pairs are true ribs, next 3 are false ribs, last 2 are floating ribs
• Pectoral girdle


  • Comprised of clavicle and scapula, attaching upper limbs to axial skeleton
• Upper limb


  • Arm (humerus), forearm (radius and ulna), hand (carpals, metacarpals, phalanges)
• Pelvic girdle


  • Attaches lower limbs to axial skeleton, comprised of two hip bones (ilium, ischium, pubis)
• Lower limb


  • Thigh (femur), leg (tibia and fibula), foot (tarsals, metatarsals, phalanges)
• The human skeleton has other critical structures beyond just bones, including joints and ligaments