Skeletal System

HST I

2010 -2011

The skeletal system:

• Is made up of organs called bones• Provides a framework that supports the

body’s muscles, fat, and skin• Provides protection by surrounding

vital organs• Forms levers where muscles attach to

provide movement• Produces red and white blood cells and

platelets (hemopoiesis or hematopoiesis)

• Stores most of the calcium supply of the body in addition to phosphorus and fats

Long Bones

• Refers to the bones of the arms and legs, or extremities

Parts of Long Bones

• Diaphysis – long shaft• Epiphysis – the extremity or

end• Medullary canal – cavity

within the diaphysis, • Yellow marrow – fills the

medullary cavity; storage area for fat cells; contains cells that form leukocytes or white blood cells

Parts of Long Bones• Endosteum – membrane that

lines the medullary canal and keeps the yellow marrow intact; produces some bone growth

• Red marrow – found in certain bones, such as the vertebrae, ribs, sternum, cranium, and the proximal ends of the humerus and femur; produces erythrocytes (red blood cells), thrombocytes (platelets), and some leukocytes (white blood cells).

Red Marrow

• Because it is important in the manufacturing of blood cells, and is involved with the body’s immune response, it is used to diagnose blood diseases (ex. leukemia), and is sometimes transplanted in people with defective immune systems.

Parts of Long Bones

• Periosteum – tough membrane that covers the outside of bone; contains blood vessels, lymph vessels, and osteoblasts (special cells that form new bone tissue); necessary for bone growth, repair and nutrition

• Articular cartilage – covers the epiphysis and acts as a shock absorber when two bones meet to form a joint

The Skeletal System is divided into two sections:

1. Axial skeleton – forms the main trunk of the body and is composed of the skull, spinal column, ribs, and breastbone

2. Appendicular skeleton – forms the extremities and is composed of the shoulder girdle, arm bones, pelvic girdle, and leg bones

The Skull:

• Composed of the cranial and facial bones

• Spherical structure that surrounds and protects the brain

The Skull:• Made of eight bones

1. Frontal (1)

2. Parietal (2)

3. Temporal (2)

4. Occipital (1)

5. Ethmoid (1)

6. Sphenoid (1)

Fontanels

• Soft spaces (soft spots), present at birth, that allow for the enlargement of the skull as brain growth occurs

• Made up of membrane and cartilage, and turn into solid bone by approximately 18 months of age.

There are 14 Facial Bones

• Mandible (lower jaw); (1)• Maxilla (upper jaw); (2)• Zygomatic (cheek); (2)• Lacrimal (inner aspect of eyes); (2)• Nasal (5)• Palantine (hard palate or roof of mouth); (2)

Sutures

• Are areas where the cranial bones have joined together

Sinuses

• Air spaces in bones of the skull that act as resonating chambers for the voice; lined with mucous membranes

Foramina

• Openings in bones that allow nerves and blood vessels to enter or leave the bone

Vertebrae

• Compose the spinal column (26-vertebrae)

• Protects the spinal cord and provides support for the head and trunk

• Divided into 5 sections: 1) cervical, 2) thoracic, 3) lumbar, 4) sacral, and 5) coccyx

Vertebrae• Cervical (neck);

(7)• Thoracic

(chest); (12)• Lumbar (waist);

(5)• Sacrum (back

of pelvic girdle); (1)

• Coccyx (tailbone); (1)

Intervertebral Disks

• Pads of cartilage tissue that separate the vertebrae

• Act as shock absorbers and permit bending and twisting movements of the vertebral column

Ribs (Costae)• 12 pairs of ribs• Attach to the thoracic vertebrae on the

dorsal surface of the body• The first 7 pairs are called true ribs

because they attach directly to the sternum, or breastbone, on the front of the body

• The next 5 pair are called false ribs, and attach to cartilage extending from the rib above

• The last 2 pairs of ribs are called floating ribs because they have no attachment on the front of the body

Sternum

• Breastbone• Consist of 3 parts: 1) Manubrium

( upper region), 2) Gladiolus (body), and the Xiphoid process (a small piece of cartilage at the bottom)

Two collarbones, or clavicles are attached to the manubrium by ligaments. The ribs are attached to the sternum with costal cartilages to form a “cage” that protects the heart an lungs.

The Pectoral (Shoulder) Girdle

Is made up of:• 2 clavicles (collarbones) and 2

scapulas (shoulder bones)• The scapula is utilized in the

attachment of the upper arm bones

Bones of each arm include:

• 1 humerus (upper arm)• 1 radius (lower arm on thumb side) that

rotates around the ulna to allow the hand to turn freely

• 1 ulna (larger bone of lower arm)with a projection called the olecranon process at its upper end, forming the elbow

Bones of each arm include:

• 8 carpals (wrist)• 5 metacarpals (palm of hand)• 14 phalanges (three on each

finger, and two on the thumb)

The Pelvic Girdle is:

• Made up of 2 os coxae (coxal, or hip bones)

• Join the sacrum on the dorsal part of the body

• Fuse together a joint called the symphysis pubis on the ventral part of the body

Pelvic Girdle

• Each coxae is made up of 3 fused sections: 1) ilium, 2) ischium, and 3) the pubis

• Contains 2 recessed areas or sockets called acetabula, which provide for the attachment of the smooth rounded head of the femur (upper leg bone)

Pelvic Girdle

• An opening between the ischium and pubis, called the obturator foramen, allows for the passage of nerves and blood vessels to and from the legs

Each leg consists of:

• 1 femur (thigh bone)• 1 patella (kneecap)• 1 tibia (larger weight bearing bone of

the lower leg; shin bone)• 1 fibula (slender, smaller bone of the

lower leg that attaches to the proximal end of the tibia

Each leg consists of:

• 7 tarsals (ankle bones)• 5 metatarsals (instep of foot)• 14 phalanges (2 on the great toe and 3

on each of the other 4 toes)• The heel is formed by the large tarsal

bone called the calcaneous

Joints

• Areas where two or more bones join together

• Connective tissue bands, called ligaments, help hold long bones together at joints

• There are 3 main types of joints: 1) Diarthrosis or synovial, 2) Amphiarthrosis, and 3) Synarthrosis

Diarthrosis or Synovial Joints

• Freely movable• Examples include the ball

and socket joints of the shoulder, hip, or the hinge joints of the elbow and knee

Amphiarthrosis Joints

• Slightly movable• Examples include the

attachment of the ribs to the thoracic vertebrae and the symphysis pubis

Synarthrosis Joints

• Immovable• Examples include the suture

joints in the cranium

Related Health Careers

Related Health Careers

• Athletic trainer• Chiropractor• Orthopedist• Orthoptist• Osteopathic

Physician• Radiologist

• Physical Therapist

• Podiatrist• Prosthetist• Radiologic

Technologist• Sports Medicine

Physician

Questions?