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Flashcards in Ch 8 - Skeletal System Deck (58)
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What are the two major divisions of the skeletal system?

Axial and Appendicular


What does the axial skeleton consist of?

80 bones skull, hyoid bone, auditory, vertebral column, sternum and ribs
Lie along the longitudinal axis of the body


What does the appendicular skeleton consist of?

126 bones AND muscles


What are the functions of the skeletal system?

Skull protects the brain from injury and the ribs and vertebra protect viscera, such as the heart and lungs
Allows us to sit, stand, and move by the attachment of muscles to bones
Bone acts as a reservoir for over 99 percent of the calcium in our body.
White and red blood cells are produced by red bone marrow contained within bone.


What are two types of bone tissue?

Cancellous (spongy) bone -Spaces filled with red bone marrow.
Compact bone


What are osteons?

Osteons (Haversian systems) are the fundamental unit.
Each osteon consists of a long, cylindrical tube of concentric layers of bone called lamellae.
Inside the lamellae are lacunae where osteocytes can be found
Central canal is lined with the endosteum and contains blood vessels and nerves.
Canaliculi are smaller canals which run perpendicular to the central canal. They carry blood vessels and nerves to lamellae and lacunae


What are the three types of bone cells and what do they do?

Osteoblasts: immature bone cells, responsible for mineralizing the bone matrix
Osteocytes: mature bone cells
Osteoclasts: tear down bone for remodeling and cause the release of calcium


What is the bone growth process called?

ossification or osteogenesis.


What are the two types of ossification?



What happens in intramembranous ossification?

Bones begin as tough, fibrous membranes that are replaced by a bone matrix that is produced by osteoblasts.
Matrix is made up of calcium, phosphate, collagen fibers, and water.
Collagen fibers give bone its flexibility and the minerals give bone its strength.
Other factors essential to bone growth
Vitamins A for osteoblast stimulation and C for collagen synthesis , growth hormone, insulin, and thyroid hormone.
All bones of the skull but the lower jaw is formed by intramembraneous ossification.


What happens in endochondral ossification?

Bones start out as models made of hyaline cartilage.
Common in long bones such as femur
Osteoblasts form a bone “collar” around the diaphysis and replace the cartilage model.
Ossification centers is the area where ossification first begins is the primary ossification center
Each end or epiphysis are the secondary ossification centers. Some bones such as the vertebrae have more than two


What is the medullary cavity?

It is in the center of long bones and is initially filled with red bone marrow, involved in hematopoiesis - RBC formation.


What is the epiphyseal plate?

growth plate
Between the epiphysis and diaphysis
Between 18 and 25 years of age, made of hyaline cartilage is replaced by bone, becoming the epiphyseal line and the bone is no longer capable of growing in length


What are osteoclasts?

Cells that tear down bone
Regulated by parathyroid hormone
Bone remodeling is a balance between tearing down and building up bone.
Increased demand for calcium, osteoclastic activity will increase
Decreased demand for calcium, osteoblastic activity will increase


What are flat bones?

Thin and consist of a layer of spongy bone between two layers of compact bone
Sternum, ribs, scapulae, and cranial bones


What are long bones?

Greater in length than width
Mostly compact bone, but their epiphyses are spongy bone
Femur, tibia, fibula, humerus, radius, ulna, and phalanges


What are short bones?

Cuboidal in shape
Spongy bone with just a thin outer layer of compact bone
Carpals and tarsals


What are irregular bones?

Variety of shapes
Vertebrae, coxal, some facial bones, and the calcaneus


What are seasmoid bones?

Resemble sesame seeds
Patella (kneecap) and pisiform


What is diaphysis?

Tubular structure with a thick collar of compact bone surrounding a space called the medullary cavity
In children, this is the location of red bone marrow and is responsible for hematopoiesis
In adults, red bone marrow is replaced by yellow bone marrow
Except for skull, ribs, vertebra, and pelvis


What is epiphysis?

At each end of a long bone
Expanded area consisting of a thin layer of compact bone surrounding more abundant cancellous bone
Covering each epiphysis is articular cartilage of the hyaline cartilage. It is smooth and helps in frictionless movement of joints.


What is periosteum?

Membrane surrounds the diaphysis
Dense fibrous connective tissue
Blood vessels and nerves penetrating it
Responsible for “growing pains” during adolescence


What two main types of bone markings?

Projection- Grow out
Depressions- Indent the bone


What is the rib cage formed of?

Formed by sternum and 12 pairs of ribs


What is the sternum?

Sternum is also called the breastbone
Made up of three bones
From most superior to inferior they are the manubrium, the body, and the xiphoid process
Anteriorly, the clavicles and most of the ribs attach to the sternum
Posteriorly, the ribs articulate with the vertebra


What does the spinal column consist of?

7 cervical vertebrae
12 thoracic
5 lumbar


What are the 4 major curvatures to the spine?

cervical, thoracic, lumbar and pelvic


What is the cervical vertebrae and what does it consist of?

Located in the neck
1st - called atlas/C1 - helps to turn your head, 2nd is axis/c2
Have 3 foramina - 2 transverse and single vertebral foreman .
Vertebral artery , vein, nerves travel through transvers
Spinal cord travels through foramen


What is the lumbar vertebrae and what does it consist of?

Biggest and sturdiest - support body weight


What are clavicles?

Clavicles or collarbones
Slender in shape and each articulates with the sternum and scapula