Bones - Skeleton

Early Life

• During development of the embryo, the human skeleton is made up of cartilage and fibrous membranes, but most of these early supports are soon replaced by bone.

• Think about the body position in utero during development, and the first few years of child’s life.

• Most bones stop growing during adolescence.

• Some facial bones, especially those of the nose and lower jaw, continue to grow almost to no end throughout life.

(example of change of facial structure in elderly)

Skeleton

• divided into the axial and appendicular• Together comprise 206 bones in the human

body

axial skeleton

• These bones form the vertical axis of the body. They function in protection and support of the body and body parts.

• skull bones• vertebral column• rib cage

Axial Skeleton

Appendicular Skeleton

• These bones comprise the upper and lower limbs of the body, and the bones that connect limbs to the axial skeleton. They function in movement.

• clavicles• pelvis• Arms and hands• Legs and feet

Appendicular Skeleton

Function of Bones

• -Protection of vital organs• -Support & maintenance of posture• -Providing attachment points for muscles• -Storage & release of minerals (calcium &

phosphorus)• -Blood cell production (haemopoiesis)• -Storage of energy (lipids in yellow bone

marrow)

bone classifications (types)

Long bones: longer than they are wide; have a shaft with 2 ends. Movement bones: including femur, metatarsals & clavicleShort bones: small & cube-shaped. Include carpals & tarsalsFlat bones: thin, flat and often curved. Including the sternum, scapula, ribs and skull bonesIrregular bones: have specialized & complicated shapes, including sacrum, coccyx & vertebrae

Bone classifications

Bone Textures

• Bones are made up of 2 layers that differ in texture and function:

• - Compact bone: external layer of the bone that is very dense, filled with passageways for nerves, blood vessels, and lymphatic vessels.

• - Cancellous bone: internal layer of the bone that looks spongy; has an irregular latticework structure.

Long Bone: structure

• Long bones are mainly comprised of a shaft, 2 ends and membranes.

Diaphysis: the shaft; constructed of compact bone and envelopes a marrow cavity. In adults, this cavity stores yellow marrow (fat)

Epiphyses: the bone ends of a long bone; constructed of compact bone externally and spongy bone internally. Blood cell production occurs here

Con’t

• Articular Cartilage: thin layer of cartilage covering the ends of the bone where joints are formed. They reduce friction & absorb shock

• - Periosteum; thin shiny white membrane; important for bone growth, repair, nutrition and attachment of ligaments/tendons.

• - Medullary Cavity: space within the diaphysis where yellow bone marrow is stored.

• -Nutrient Foramen: where blood vessels pass into the bone.

Diagram of Long Bone

Vertebral column

• 33 Vertebrae in the body• Strong and flexible• Cervical: 7 vertebrae; the smallest & have the most

movement• Thoracic: 12 vertebrae; less mobile due to the ribs

attached to them• Lumbar: 5 vertebrae; biggest & strongest; weight

bearing• Sacral: 5 vertebrae (fused); transmit weight to the

legs/pelvis• Coccygeal: 4 vertebrae (fused)

Vertebrae

Vertebrae• The vertebral foramen; (hole) in each

vertebrae line up to house the spinal cord.• -Intervertebral discs: located between the

body of each vertebrae; fibrocartilage on the outside & gel like in the middle; give the vertebral column flexibility; shock absorbers

Spinal column4 curves of the spine increase strength, help maintain upright balance & absorb shock

Sources

“Human Anatomy & Physiology, Pearson International Edition, Eighth Edition.” Marieb and Hoehn. 2010

McGraw-Hill Companies. www.mcgraw-hill.com/

National Library of Medicine and International Osteoporosis Foundation.

www.nlm.nih.gov/ Nucleus Communications, Inc. 2003.

www.nucleusinc.com

Visual Dictionary Online. www.visualdictionaryonline.com

http://tw.aisj-jhb.com/dslattery/files/2013/05/bones.pdf