Human Skeleton Overview

Structure of the Human Skeleton

• Comprised of bones, cartilage, joints, and ligaments.
• About 206 bones in an adult.
• Makes up approximately 20% of body mass.

Two Main Sections of the Skeleton

1. Axial Skeleton
   • Skull
   • Vertebral column
   • Thoracic cage
2. Appendicular Skeleton
   • Limbs

Axial Skeleton

Skull

• Made of 22 bones.
• Cranial Bones: Protect the brain
  • 8 bones: Frontal, Parietal (2), Occipital, Temporal (2), Sphenoid, Ethmoid
  • Connected by sutures: Coronal, Sagittal, Lambdoid, Squamous, Occipitomastoid
• Facial Bones: Give structure to the face
  • 14 bones: Mandible, Maxillary (2), Zygomatic (2), Nasal (2), Lacrimal (2), Palatine (2), Vomer, Inferior Nasal Conchae (2)
• Other: Hyoid bone (not part of the skull), located below the mandible.

Vertebral Column (Spine)

• Made of 26 irregular bones forming an S-shape
• Sections:
  • Cervical vertebrae (7)
  • Thoracic vertebrae (12)
  • Lumbar vertebrae (5)
  • Sacrum (5 fused vertebrae)
  • Coccyx (tailbone; fused tiny vertebrae)
• Ligaments:
  • Anterior and posterior longitudinal ligaments
  • Intervertebral discs: Nucleus pulposus and anulus fibrosus
• Vertebrae Structure
  • Body, vertebral arch, vertebral foramen, and various processes

Thoracic Cage

• Sternum: Manubrium, body, xiphoid process
• Ribs:
  • 12 pairs of ribs
  • True ribs (1-7)
  • False ribs (8-12); last two are floating ribs

Appendicular Skeleton

Pectoral Girdle

• Clavicle (collarbone) and scapula (shoulder blade)

Upper Limb

• Arm: Humerus
• Forearm: Radius and ulna, connected by interosseous membrane
• Hand:
  • Carpals (wrist bones): Scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, hamate
  • Metacarpals (palm)
  • Phalanges (fingers)

Pelvic Girdle

• Hip bones: Ilium, ischium, pubis (fuse in adulthood)

Lower Limb

• Thigh: Femur
• Leg: Tibia and fibula, connected by interosseous membrane
• Foot:
  • Tarsals (ankle bones): Talus, calcaneus, cuboid, navicular, cuneiforms
  • Metatarsals
  • Phalanges (toes)

Conclusion

• Overview of bones in the human skeleton.
• Discussion to continue on joints.