SKELETAL SYSTEM

Google Slides | Student Handout

FUNCTIONS - support and protection
- body movement - muscles "pull" on bones
- blood cell formation - occurs in red bone marrow
- storage of inorganic materials - calcium, magnesium, sodium, potassium...

Organization of the Skeleton

- normally 206 bones with 2 Main Divisions: axial and appendicular

1. Axial: head, neck, trunk, vertebrae, ribs, and sternum
2. Appendicular: limbs and bones connecting the limbs to the:
- pectoral girdle - (scapula & clavicle), upper limbs (arms)
- pelvic girdle - (coxal bones), lower limbs (legs)

Long Bone Structure:

Epiphysis - ends of bone, forms a joint with another bone.(1)
Spongy bone - red marrow (3)
Diaphysis - shaft of bone (6)

Articular cartilage- padding covering the ends of bones (2)
Epiphyseal line - growth plate (4)

Periosteum - tough membrane covering over entire bone. (8)
Endosteum - lines interior (3)

Medulla- within diaphysis, contains yellow bone marrow (7)

Color the Long Bone

Label the Bone Structures (Long Bone)

Endosteum- lining of the medullary cavity

- Red Marrow = produces blood cells | Yellow Marrow =fat storage

Two Types of Bone Tissue

1. Compact bone - wall of the diaphysis, solid, strong
2. Spongy(cancellous) bone - epiphysis.

Microscopic Structure

*Bone tissue is called osseous tissue. - The matrix is composed of collagen and inorganic salts

- Osteocytes (mature bone cells)
- enclosed in tiny chambers called lacunae
- lacuna form concentric rings called lamella

- Canaliculi (canaliculus) connect the osteocytes
- Haversian and Volkmann canals provide passageways for blood vessels

bone matrix

Bone Matrix Coloring (assignment)

Bone Development and Growth:

Bones first form as hyaline cartilage. The cartilage then gradually changes into bone tissue - a process called ossification.

primary ossification center - diaphysis, increase diameter
secondary ossification center - epiphysis, increase length

epiphyseal disk ( growth plate) between the diaphysis and the epiphysis.

Osteoblasts - produce bone cells called OSTEOCYTES
Osteoclasts - dissolve bone tissue - a process called RESORPTION.

Basic Types of Joints (articulations):

1. Synarthrotic - immoveable joint, these junctions are called sututes
2. Amphiarthrotic- slightly moveable joint, vertebrae
3. Diarthrotic - freely moveable joint

Ball & Socket (shoulder, hip)
Hinge (elbow, knee)
Pivot (lower arm)
Saddle (thumb)

Bones of the Skull

skull bones

1. Frontal - anterior portion (forehead)
2. Parietal - one on each side of the top part of skull
3. Temporal - side, above ear
4. Occipital- forms the back of the skull
5. Sphenoid - within the cranium, partly visible in eye socket
6. Ethmoid - nasal cavity, visible in eye socket
7. Maxilla - forms upper jaws
8. Mandible - lower jaws, only moveable bone of the skull
9. Zygomatic - cheek bones
10. Vomer bone - divides nasal cavity
11. Palatine bone - roof of the mouth
12. Ethmoid bone - roof of nasal cavity

Sutures - connection points between skull bones

1. Coronal - between frontal and parietal bones
2. Lambdoidal - between occipital and parietal bones
3. Squamosal - between temporal and parietal bones
4. Sagittal - between parietal bones

Fontanels - "soft spots" of an infant's skull, these form sutures as you age, top spot is the anterior fontanel

Foramen Magnum - Large opening through bottom of skull, where the spinal cord enters skull

Label the Bones of the Skull

The Rest of the Bones

Vertebrae - Cervical (C1-C7) = neck | Thoracic (T1-T12) = middle back | Lumbar (L1-L5) = lower back
Sacrum and Coccyx (tailbone)

Ribs - Thoracic Cage, 12 pairs

Pectoral Girdle: Shoulder. Two clavicles (collar bones) and two scapulae (shoulder blades)

Upper arm - humerus.
Lower arm - radius and ulna
Wrist - 8 small bones called carpals
Hand: Metacarpals | Fingers: phalanges

Pelvic Girdle: Hips. Two large bones called coxae (coxal bones)

Upper leg - femus
Kneecap: patella
Lower leg - tiba and fibula
Ankle and Upper foot - 7 bones called tarsals
Largest is the heel bone called the calcaneus
Foot: metatarsals | Toes: phalanges

Label the Bones of the Skeleton

Carpals and Tarsals

carpals tarsal