Skeletal systemAmanda Dunne

Learning outcomes

By the end of the session you will be able to :

Define the functions of the skeletonDescribe the different types of boneIdentify the organisation of the skeleton & name the bones of the bodyIdentify 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 cageAppendicular skeleton: Shoulder bones, arms, hands, legs and feet bones206 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. vertebraeSesamoid bone: bones within tendons

e.g. kneecap (patella)

The vertebral column (spine)Supports the skull and encloses the spinal cord33 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 tissueSpongy (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 shapeProtection of organs e.g. the skullMovement: Provide attachment for

muscles and to move jointsHaematopoiesis: Formation of blood

cells (in red bone marrow) eg: erythropoiesis

Reservoir: Provides a store of calcium salts and phosphorus