The Skeletal System

Unit-Anatomy and Physiology Part I

What you will Learn!• The functions of the skeleton

• Describe the general structure of a bone and list the functions of its parts

• List and define the major kinds of bones in the human skeleton

• Name and describe the general types of fractures

• Distinguish between the axial and appendicular skeletons and name the major parts of each

• Locate and identify the bones and the major features of the bones that comprise the skull, arms, legs, pectoral and pelvic girdles

What Does Your Skeleton Do?

Five Functions:

• Protects your internal organs

• Supports-provides a framework so that we can stand up and move

• Movement-many of the body muscles attach to the skeleton and joints and produce movement

• Stores minerals such as calcium, potassium, phosphorus, and sodium so that our body can function properly

• Produces blood cells

The Skeletal System

•The Skeletal System is made up of 206 different bones.

•There are 4 basic shapes of bones.

4 Basic Shapes1. Long bones-Are longer than they are wide and are found in the upper limbs such as the humerus (arm) and lower limbs such as the femur (thigh).

4 Basic Shapes

2. Short bones-

Such as those found in the wrist and ankle bones.

4 Basic Shapes

3. Flat bones- Such as the scapula, ribs and sternum, and the thin bones that form the roof of the skull.

4 Basic Shapes4. Irregular bones- Such as the vertebrae, pelvic girdle (hip bones), and parts of the skull bones such as your ear bones.

2 Types of Bone Tissue

Compact Bone-

• Dense

• Smooth

• Strong

• Both Compact and Cancellous bone tissue contain living cells which help make repairs if a bone is injured or broken.

Cancellous Bone-

• Spongy

• Lightweight

Structure of the Bone

1.Diaphysis-the bone shaft

• Composed of compact bone tissue-tightly packed together tissue that is solid, strong and will not bend.

• Inside the bone shaft is a cavity called the Medullary Cavity (also called yellow marrow) that stores fat, produces blood cells and plays an important part in our immune system.

Structure of the Bone

2. Epiphysis-the two ends of the shaft

• Spongy bone-contains the red marrow that functions in the formation of red blood cells, certain white blood cells and platelets. It is red because of the red, oxygen-carrying pigment called hemoglobin.

3. Periosteum-a tough, vascular covering of fibrous tissue that covers the bone.

The Skeletal SystemPart II

The Axial and Appendicular Skeleton

Unit-Anatomy and Physiology Part II

2 Divisions of the Skeletal System

Axial Skeleton

Appendicular Skeleton

The Appendicular Skeleton

Appendicular Skeleton

• Has 126 bones

• Contains upper extremities

• Shoulders

• Lower extremities

• Hips (Pelvic Girdle)

Upper Extremities and Shoulder

Upper Extremities (Arms):

• humerus-the bone that extends from the scapula to the elbow

• radius—the bone that extends from the elbow to the wrist

• ulna-the bone that overlaps the end of the humerus posteriorly

Shoulder girdle:

• Scapula-shoulder blade

• Clavicles-collar bone

The Hands• 27 bones

• carpal bones-8 on each arm make up the wrist

• metacarpal bones-5 on each hand make of the palm

• phalanges-3 in each finger, 2 in the thumb, a total of 14 in each hand

Lower Extremities and HipsLower Extremities-(Legs)

• femur- thigh bone

• patella- kneecap

• tibia-shinbone

• fibula-lateral side of the tibia

Hips (Pelvic Girdle)-protect the bladder, the reproductive organs, lower colon and rectum.

• os coxa--2 bones that make up the hip

• ilium--largest and uppermost portion

• ischium-lowest portion and is L-shaped; supports ones weight when seated

• pubis--the anterior portion

The Foot• 26 bones and 33 joints

• tarsals--7 bones in each foot; make up the ankle that includes the calcaneus (heel bone) which is the largest of the ankle bones

• metatarsals--5 bones on each foot

• phalanges—3 bones in each toe, except the big toe which has only 2

• 7+5+12+2=26

The Axial Skeleton

•Has 80 bones

Consist of:

•Bones of the Skull

•Hyoid Bone (neck bone)

•The vertebral column

•The thorax (cage)

Bones of the Skull-Cranial BonesCranial Bones:

A. Frontal Bone--forms the anterior portion of the skull above the eyes

B. Parietal Bone--2 bones on each side of the skull just posterior to the frontal bone

C. Occipital Bone--back of the skull and base of the cranium

D. Temporal Bone—2 bones on each side of the skull

E. Sphenoid Bone--anterior to temporal

F. Ethmoid Bone--located in front of the sphenoid

Cranial Sutures-lines that join two bones

Skull-Ear Bones

• 3 Middle ear bones-ossicles•malleus-hammer• stapes-stirrup (smallest bone in the body)• incus-anvil

Skull –Facial Bones13 immovable ones and 1 immovable lower jawbones

• maxilla--2 bones of upper jaw

• palatine--2 bones behind the maxilla; make up posterior portion of the hard palate

• zygomatic--2 bones that make up the cheeks

• lacrimal--2 bones in the medial wall of each orbit

• nasal--2 bones that fuse to form the bridge of the nose

• vomer--a single bone in the middle of the nasal cavity

• inferior nasal concha--2 fragile, scroll-shaped bones attached to the nasal cavity

• mandible--1 lower jawbone (only part that moves when you eat and talk)

Hyoid Bone•Hyoid bone--located in the neck between the lower jaw and the larynx

• serves as an attachment for muscles that help move the tongue and for swallowing

The Vertebral Column•Supports the body's frame, keeping it standing upright. • It connects the head to the rest of the body•Serves as protection for the spinal cordBones:• cervical--7 bones• thoracic--12 bones• lumbar--5 bones• sacrum--1 bone; composed of 5 fused bones• coccyx--1 bone; tailbone composed of 4 fused vertebrae

The Thorax

Thoracic Cage-protects the heart and lungs1. ribs--12 pair (24 ribs)• a. true ribs--first 7 pair; directly join the sternum

• b. false ribs--remaining 5 pair because their cartilage does not reach the sternum directly

• c. floating ribs--last 2 pair of the 5 pair of false ribs; called floating because they have no attachments

2. sternum--1 breastbone

The End!