Lecture on the Human Skeleton

Introduction to the Human Skeleton

• Comprised of approximately 206 bones in adults.
• Includes bones, cartilage, joints, and ligaments, comprising about 20% of body mass.
• The skeleton divided into:
  • Axial Skeleton: Skull, vertebral column, thoracic cage.
  • Appendicular Skeleton: Limbs and girdles.

Axial Skeleton

Skull

• Structure: 22 bones.
  • Cranial bones: Protect brain.
  • Facial bones: Give structure to the face.
• Cranial bones (8): Frontal, parietal (2), occipital, temporal (2), sphenoid, ethmoid.
• Sutures: Coronal, sagittal, lambdoid, squamous, occipitomastoid.
• Foramina: Openings for nerves and vessels, e.g., foramen magnum.
• Facial bones (14): Mandible, maxillary, zygomatic, nasal, lacrimal, palatine, vomer, inferior nasal conchae.
• Hyoid bone: Not part of skull, supports tongue.

Vertebral Column (Spine)

• Structure: 26 bones, S-shaped.
• Sections:
  • Cervical (7), Thoracic (12), Lumbar (5), Sacrum (5 fused), Coccyx (fused).
• Ligaments: Anterior, posterior longitudinal, shorter ligaments.
• Intervertebral discs: Nucleus pulposus and anulus fibrosus.
• Vertebrae Components: Body, vertebral arch, foramen.
  • Processes: Spinous, transverse, superior and inferior articular.
  • Variations: Size and structure vary by location.

Thoracic Cage

• Components: Sternum, ribs, costal cartilage.
• Sternum: Manubrium, body, xiphoid process.
• Ribs:
  • True ribs (1-7): Directly attach to sternum.
  • False ribs (8-12): Attach indirectly or not at all.
  • Floating ribs (11-12): Do not attach to sternum.

Appendicular Skeleton

Pectoral Girdle

• Components: Clavicle and scapula.
  • Clavicle: Sternal (manubrium) and acromial (scapula) ends.
  • Scapula: Superior, medial, lateral borders.

Upper Limb

• Arm: Humerus with tubercles, grooves, fossae, epicondyles.
• Forearm: Radius and ulna with interosseous membrane.
  • Radius: Radial tuberosity, styloid process.
  • Ulna: Olecranon, coronoid process.
• Hand:
  • Carpus (Wrist): 8 carpals.
  • Metacarpals: Numbered 1-5.
  • Phalanges: Distal, middle, proximal; thumb has 2.

Pelvic Girdle

• Structure: Sacrum, hip bones (ilium, ischium, pubis).

Lower Limb

• Thigh: Femur with head, trochanters, tuberosity, condyles.
• Leg: Tibia and fibula with interosseous membrane.
  • Tibia: Condyles, tuberosity, malleolus.
  • Fibula: Head, malleolus.
• Foot:
  • Tarsus: 7 tarsals; talus, calcaneus.
  • Metatarsals: Numbered 1-5.
  • Phalanges: Similar to hand; big toe (hallux) has 2.

Conclusion

• Overview of human skeleton structure focusing primarily on bones.
• Introduction to joints as a segue to next topic.