Skeletal System

Cheryl Krivitsky, RN

Objectives

• List the five functions of bones
• Label the parts of a bone on a diagram of a long bone
• Name two divisions of the skeletal system and the main groups of bones in each division
• Identify the main bones of the skeleton
• Give one example of each joint classification
• Describe at least four diseases of the skeletal system

​

​

Related Health Careers

• Athletic Trainer
• Chiropractor
• Orthopedist
• Orthoptist
• Osteopathic Physician
• Physiatrist
• Physical Therapist
• Podiatrist
• Prosthetist

​

• Radiologic Technologist
• Sports Medicine Physician

​

​

Skeletal System

• Made up of organs called bones, a network of tendons, ligaments, and cartilage that connects them
• Adult = 206 bones
• Children = 300-350 bones that fuse together
• Vary in shape and size depending on their locations within the body

​

​

​

​

Functions of Skeletal system

1. Framework – bones form a framework to support the body’s muscles, fat, and skin.
2. Protection – bones surround vital organs to protect them

Examples - ribs protect heart and lungs, skull that protects the brain

• Levers – muscles attach to bones to help provide movement
• Production of blood cells – bones help produce red and white blood cells and platelets, a process called hemopoiesis or hematopoiesis
• Storage – bones store most of the calcium supply of the body in addition to phosphorus and fats.

​

Bones

• Long Bones – bones of the extremities (arms & legs)
• Diaphysis – Shaft of the bone
• Epiphysis – ends of the bone
• Medullary Canal – cavity in the diaphysis
• Yellow Marrow – contained in medullary canal – storage area for fat cells

Bones

• Endosteum – membrane that lines the medullary canal and keeps the yellow marrow intact, produces some bone growth
• Red Marrow – found in certain bones.
• Vertebrae, ribs, sternum, and cranium, proximal ends of the humerus and femur
• Produces RBC’s, platelets, and some WBC’s
• Used to diagnose blood diseases
• Transplanted in people with defective immune systems

Bones

• Periosteum – tough membrane covering outside of the bone
• Contains blood vessels, lymph vessels, and osteoblasts (special cells that form new bone tissue)
• Necessary for bone growth, repair, and nutrition
• Thin layer of articular cartilage overs the epiphysis and acts as a shock absorber when two bones meet to form a joint

​

Axial skeleton

• Forms the main trunk of the body
• Made up of skull, spinal column, ribs, and breastbone
• Skull
• Cranial and facial bones
• Cranium
• Surrounds and protects the brain
• Made up of 8 bones – frontal, 2 parietal, 2 temporal, one occipital, one ethmoid, and one sphenoid

​

Axial skeleton

• Fontanels – “soft spot” – allows for the enlargement of the skull as brain growth occurs
• Made up of membrane and cartilage – turn into solid bone by approximately 18 months of age
• Sutures – areas where the cranial bones have jointed together
• Sinuses – air spaces in the bones of the skull that act as resonating chambers for the voice.
• Foramina – openings in bones that allow nerves and blood vessels to enter or leave the bone.

Axial Skeleton

• 14 Facial Bone
• Mandible – lower jaw
• Maxilla (2) – upper jaw
• Zygomatic (2) – cheek
• Lacrimal (2) – inner aspect of the eyes
• Nasal (5)
• Palatine (2) – hard palate of the roof of the mouth

Spinal Column

• Composed of 26 bones
• Vertebrae – name of bones of the spinal column
• Protect the spinal cord and provide support for the head and trunk
• 7 cervical (neck)
• 12 thoracic (chest)
• 5 lumbar (waist)
• 1 sacrum (back of pelvic girdle)
• 1 coccyx (tailbone)

Spinal Column

• Intervertebral disks – pads of cartilage tissue that separate the vertebrae.
• Act as shock absorbers
• Permit bending and twisting movements of the vertebral column

​

​

​

Ribs (Costae)

• 12 pairs
• Attach to the thoracic vertebrae on the dorsal side of the body
• True Ribs – first 7 pairs – attach directly to the sternum (breastbone) on the front of the body
• False Ribs – next 5 pairs –
• first three pairs attach to the cartilage of the rib above
• Last two pairs are called floating ribs because they have not attachment on the front of the body.

​

Sternum (Breastbone)

• Consists of three parts
1. Manubrium – upper region
2. Gladiolus – body
3. Xiphoid process – small piece of cartilage at bottom
• Manubrium attached to clavicles (collarbones) by ligaments
• Ribs attached to the sternum with costal cartilages to form a “cage” to protect the heart and lungs

Appendicular Skeleton Pectoral (shoulder)

• Made up of 2 clavicles (collarbones) and 2 scapulas (shoulder bones
• Scapulas provide for attachment of the upper arm bones

​

Arm

• Humerus – upper arm
• Radius – lower arm on thumb side
• Rotates around ulna to allow the hand to turn freely
• Ulna – larger bone of the lower arm
• Olecranon process – projection on proximal end of bone – forming the elbow
• Carpals – 8 wrist bones
• Phalanges – 14 – three on each finger and two on the thumb

​

Pelvis

• Made up of 2 os coxae (hip bones) which join with the sacrum on the dorsal part of the body.
• Symphysis pubis – where the os coxae join together on the ventral part of the body
• Os Coxae – three parts
1. Ilium
2. Ischium
3. Pubis

​

Pelvis

• Acetabula – two recessed areas, or sockets that provide for the attachment of the femur
• Obturator foramen – opening between the ischium and pubis
• Allows for the passage of nerves and blood vessels to and from the legs

Leg

• Femur – thigh
• Patella – kneecap
• Tibia – larger weight bearing bone of lower leg (shin bone)
• Fibula – slender smaller bone of the lower leg that attaches to the proximal end of the tibia
• Tarsals – (ankle) – 7
• Metatarsals - (instep of foot)
• Phalanges – 14 – two on the great toe and three on each of the other four toes
• Calcaneous – (heel) – formed by the large tarsal bone

Joints

• Areas where two or more bones join together
• Ligaments – connective tissue bands that help hold long bones together at joints.

Ligaments

• Three types of ligaments
1. Synovial or diarthrosis – Free moving
• Ball and socket – shoulder/hip
• Hinge – elbow and knee
2. Amphiarthrosis – slightly movable
• Attachment of ribs to vertebrae and symphysis pubis, or the joint between two pelvic bones
3. Synarthrosis – immovable; sutures of the cranium

​

Resources

• "Skeletal System Rap." YouTube. YouTube, 29 May 2013. Web. 05 Feb. 2014.
• "The Skeletal System." YouTube. YouTube, 31 Mar. 2012. Web. 05 Feb. 2014.
• Simmers, Louise, Karen Simmers-Nartker, and Sharon Simmers-Kobelak. Diversified Health Occupations. Clifton Park, NY: Delmar Cengage Learning, 2009. Print.

​

​