Skeletal system Amanda Dunne

Learning outcomes By the end of the session you will be able to : Define the functions of the skeleton Describe the different types of bone Identify the organisation of the skeleton & name the bones of the body Identify common pathologies of the skeletal system.

The human skeleton Structure and composition of the skeleton Function of the skeleton Joints

1. Structure of the Skeleton Axial skeleton: Skull, vertebral column, sternum, and rib cage Appendicular skeleton: Shoulder bones, arms, hands, legs and feet bones 206 individual bones in the body Bones are divided into five different types

Types of bone Long bone: allow movement e.g. limbs (femur) Short bone: compact with little movement e.g. wrist (carpals) Flat bone: protective e.g. occipital (skull) Irregular bone: don’t fit into other categories e.g. vertebrae Sesamoid bone: bones within tendons e.g. kneecap (patella)

The vertebral column (spine) Supports the skull and encloses the spinal cord 33 vertebrae (irregular interlocking bones) Five types of vertebrae Cervical ( seven bones of the neck) Thoracic (twelve central bones supporting the ribs) Lumbar (five bones of lower back) Sacral (five bones of the pelvis fused to form sacrum) Coccygeal (four bones below sacrum that form coccyx – rudimentary tail)

The vertebral column (spine) The spinal cord consists of nervous tissue Spinal nerves connect the spinal cord with various parts of the body via openings called intervertebral foramina

Composition of bone Bone is living tissue continuously involved in making new and breaking down old bone Osteoblasts are bone building cells that secrete collagen fibres and calcium to create a matrix of bone tissue Osteoclasts are involved in the breakdown of bone. Bone consists of Spongy (cancellous, trabecular) and compact tissue. All bones contain both types of tissue

Spongy tissue Spongy (cancellous) : Found at the end of long bones, irregular, flat and sesamoid bones. Spongy tissue contains an irregular lattice of thin columns called trabeculae Some trabeculae are filled with red bone marrow, which produce red blood cells.

Compact tissue Compact tissue is found on the outer layer of most bones and the shaft of long bones The structure is like honeycomb, containing haversian canals Haversian canals contain blood vessels, lymph capillaries and nerves Osteoblasts are arranged in circles around the canals.

Haversian System

Structure of bone

Bones of the Hand : 8 Carpals Scaphoid Capitate Lunate Hamate Triquetrum Pisiform Trapezium Trapezoid

Bones of the Foot : 7 Tarsals Talus Calcaneus Navicular Cuneiforms – medial, intermediate, lateral Cuboid

Function of skeleton Support the body by providing shape Protection of organs e.g. the skull Movement: Provide attachment for muscles and to move joints Haematopoiesis: Formation of blood cells (in red bone marrow) eg: erythropoiesis Reservoir: Provides a store of calcium salts and phosphorus