1 Flashcards
What is the skeletal system?
A system of bony levers that provide support and protection.
How many bones are in the body?
Approximately 206.
What are the two divisions of the skeleton?
Axial and appendicular.
What bones are part of the axial skeleton?
Vertebral column, coccyx, ribs, and sternum.
What bones are part of the appendicular skeleton?
Shoulder/pectoral girdle, arms, wrists and hands, pelvic girdle, legs and ankles, and feet.
What bones make up the vertebral column?
Cervical, thoracic, lumbar, and sacral vertebrae.
What is the function of the vertebral column?
Provides support and allows movement.
How many cervical vertebrae are there?
Seven (C1-C7).
How many thoracic vertebrae are there?
Twelve (T1-T12).
How many lumbar vertebrae are there?
Five (L1-L5).
What are the five sacral vertebrae?
Fused together and make up the rear of the pelvis.
What factors affect skeletal growth in adults?
Muscle use
How can skeletal bone density be increased?
Heavy loading, explosive movements, frequency of loading axial skeleton
What is required for effective long-term skeletal adaptations?
Varied frequency, intensity, and type of stimulus
Do bones adapt faster than muscles?
No, bones take more time to adapt than muscles
What are joints?
Junctions of bones in the skeleton.
What are the three types of joints?
Fibrous, cartilaginous, and synovial.
What covers the articulating ends of bones?
Smooth hyaline cartilage.
What is the joint capsule filled with?
Synovial fluid.
What are the additional supporting structures of joints?
Ligaments and cartilage.
What type of movement do fibrous joints allow?
Virtually no movement.
What type of movement do cartilaginous joints allow?
Limited movement.
What type of movement do synovial joints allow?
Considerable movement.
What is an example of a fibrous joint?
Sutures of the skull.
What is an example of a cartilaginous joint?
Intervertebral discs.
What is an example of a synovial joint?
Elbow and knee.
What are the characteristics of synovial joints?
Low friction, large range of motion, most movements occur about them.
What are the three categories of articulating joints?
Uniaxial, biaxial, multiaxial
What is an example of a uniaxial joint?
Elbows and knees
What is an example of a multiaxial joint?
Shoulder and hip ball-and-socket joints
What are the categories for muscle attachments?
Location-based
How are limb muscle attachments categorized?
Relative to midline
How are trunk muscle attachments categorized?
Relative to head position
What is a proximal attachment?
Limb muscle closer to midline
What is a distal attachment?
Limb muscle further from midline
What is a superior attachment?
Trunk muscle closer to head
What is an inferior attachment?
Trunk muscle closer to feet
What are skeletal muscles composed of?
Muscle tissue, connective tissue, nerves, and blood vessels.
What are tendons?
Fibrous connective tissue that attaches muscles to bone periosteum.
What is epimysium?
Outer connective tissue layer surrounding the muscle.
What are fasciculi?
Bundles of muscle fibers.
What is perimysium?
Middle connective tissue surrounding fasciculi.
What is endomysium?
Inner connective tissue that surrounds each muscle fiber.
What is sarcolemma?
Muscle fiber membrane contiguous with endomysium.
What is the diameter of muscle fibers?
About 50-100 micrometers.
What is the function of tendons?
To transmit tension developed in the muscle to the tendons and bone attachments.
What is the function of epimysium?
To cover every muscle in the human body.
What is the function of perimysium?
To surround fasciculi.
What is the function of endomysium?
To surround each muscle fiber.
What is the function of muscle fibers?
To group into bundles known as fasciculi.
What are muscles composed of?
Muscle fibers
What is the diameter of muscle fibers?
50-100 micrometers
What are the contractile components in muscle fibers?
Floating proteins
What are muscle fibers grouped into?
Fasciculi
What is the sarcolemma?
Muscle fiber membrane
What are myofibrils composed of?
Actin and myosin
What is the smallest contractile unit in a muscle?
Sarcomere
What forms crossbridges in myofibrils?
Pairs of myosin filaments
What regulates muscle contraction?
Calcium ions in sarcoplasmic reticulum
What are T-tubules?
Intricate system of tubules
Where do T-tubules terminate?
Near the Z-line between two sarcomeres
What delivers the signal from the motor neuron to all depths of the muscle fiber?
T-tubules
What is a sarcomere?
The smallest contractile unit in a muscle.
How are sarcomeres organized?
Based on areas containing myosin or actin.
What does the A-band correspond to?
Alignment of myosin filaments.
What does the I-band correspond to?
Area between two adjacent sarcomeres containing only actin.
What does the Z-line do?
Runs perpendicular to the I-band, separating each sarcomere.