Chapter 7 & 8: The skeletal system

Components of the axial skeleton

• skull

• Vertebrae

• Sternum

• Ribs

• Hyoid bone

Components of the appendicular skeleton

• pectoral girdle

• Upper limbs

• Lower limb

• Pelvic girdle

Appendicular skeleton - pectoral girdle

• clavicle

• Scapula

Appendicular skeleton - upper limbs

• upper arm

• Forearm

• Wrist

• Hand

• Fingers

Appendicular skeleton - Pelvic girdle

Coxal bones

Appendicular skeleton - Lower limbs

• upper leg

• Lower leg

• Ankle

• Foot

• Toes

Periosteum

The most superficial tissue of the bone

growth, repair, and protection.

provides a source of osteoblasts for bone formation, supports fracture healing, and nourishes the bone tissue through its rich vascular network. 

Diaphysis

The shaft of the long bone

provide structural support, strength, and allow for movement. It is primarily made of compact bone and houses the medullary cavity, which contains bone marrow

Diaphysis - medullary/marrow cavity

Hollow area that has sparse trabeculae and generally is filled with yellow bone marrow in adult bones

houses bone marrow, which plays a crucial role in blood cell formation and fat storage.

Diaphysis - Yellow marrow

composed primarily of adipose tissue

Fat storage

Epiphysis

Contains a shell of compact bone surrounding the inner spongy bone

Ends covered with articular cartilage

primarily functions in joint formation, weight distribution, and bone growth

Epiphysis - proximal epiphysis

Epiphysis - distal epiphysis

Epiphysis - epiphyseal plate/line

Plate - band of hyaline cartilage from which long bones grow in length in children and young adults

Line - thin calcified line that is a remnant of the epiphyseal plate

Spongy bone

Deep to compact bone

provides structural support and lightness to bones while also housing bone marrow, where blood cells are produced.

Compact bone

Hard, dense bone tissue found immediately deep to the periosteum

provides strength, support, and protection to bones.

Articular cartilage

Allows two bones in a joint to move around one another with minimal friction

Endosteum

thin layer of connective tissue that lines the inner surface of bones

contains osteoblasts (bone-forming cells) and osteoclasts (bone-resorbing cells). These cells work together to maintain the balance of bone formation and resorption, ensuring that bones are strong and adaptable. 

Osteon

Repeating, densely packed subunits

the strength of the bone, the influx of nutrients into the bone, and waste removal from the bone

Lamellae

Rings of bone ECM surrounding the central canal

Concentric lamellae

The lamellae in ostensibly

Encircle the osteon

Circumferential lamellae

Lining the outside of the compact bone laid down by the osteoblasts in the periosteum and the endosteum

Interstitial lamellae

Old lamellae located between osteons

Lacunae

Small cavities situated between the lamellae

; contain mature osteocytes

Osteocyte

Maintain and monitor bone ECM; located in lacunae

Canaliculi

Connect neighboring lacunae and osteocytes to each other

Central canal

Running down the center of each osteon

Contains blood vessels and nerves lined with endosteum

Perforating canal

Run perpendicular to lamellae and carry blood vessels deep into the bone from the periosteum

Lined by the endosteum

Depressions

Provide pathways along which blood vessels and nerves travel, or allow two bones to come together to form a joint

Openings

House and protect structures such as blood vessels and special sensory organs

Projections

Provide points of attachment for ligaments and tendons

Long bone

Longer than they are wide

• upper and lower limbs

Flat bones

Flat

• ribs, sternum, hip bones, and certain skull bones

Short bones

About as long as they are wide

• wrist and ankle

Irregular bones

Shape doesn’t fit into any of the other classes

• vertebrae, sacrum, and certain bones of the skulls (sphenoid)

Sesamoid hones

Roughly oval shaped bones within tendons

• patella

Suturas bones

Small bones located between the flat bones of the skull

Depressions - facet

Shallow indented surface where two bones meet to form a joint

Depressions - Fossa

Deeper indented surface in a bone; usually a rounded surface of another bone to fit inside of it

Depressions - Fovea

Shallow pit; often a site for attachment of a ligament

Depressions - groove/sulcus

long, typically shallow depression that usually allows a nerve or blood vessel to travel along the bone’s surface

Openings - canal

Passageway through a bone

Openings - Fissure

Slit within a bone or between bones

Openings - foramen

Hole in a bone through which a structure such as a nerve or blood vessel passes

Opening - Meatus

Another name for canal

Projections - Condyle

Round end of a bone that fits into a fossa or facet of another bone at a joint

Projections - Crest

Ridge along a bone; generally a site of muscle attachment

Projections - Epicondyle

Small projection usually proximal to a condyle; generally the site of a muscle attachment

Projections - Head

Rounded end of the bone that fits into a fossa to form a joint

Projections - Line

Ridge along a bone where a muscle attaches

Projections - Process

Any bony projection; generally the site of muscle attachment

Projections - Protuberance

An outgrowth from a bone due to repetitive pull from a muscle

Projections - Trochanter

Large bony projection to which muscles attach; only examples are in the femur

Projections - Tubercle

Small rounded projection where muscles attach

Projections - Tuberosity

A larger, more prominent tubercle

Costal cartilage

flexible, cartilaginous structures that connect the ribs to the sternum

Laryngeal cartilage

make up the larynx (voice box), primarily protect the lower respiratory tract and enable speech. They provide structural support, prevent food from entering the trachea during swallowing, and, through their connection to muscles and ligaments, allow for vocal cord movement and sound production. 

Tracheal & bronchial cartilage

providing structural support to these airways, preventing them from collapsing during breathing. This support is essential for maintaining airflow to and from the lungs, ensuring efficient gas exchange. 

Nasal cartilage

crucial for maintaining the structure and function of the nose. They provide flexibility and support to the nasal framework, ensuring proper airflow and shape. The cartilages also play a role in regulating airflow, contributing to the nose's ability to warm, humidify, and filter inhaled air. 

Intervertebral discs cartilage

Cartilage of external ear

primarily composed of elastic cartilage covered by skin. This cartilage gives the ear its shape and flexibility.