anatomy lecture #2 v3 lol

Components of skeletal system

Bones cartilage and joints that support protect and allow movement

Axial skeleton

Central eighty bones of skull vertebral column and thoracic cage that support and protect organs

Appendicular skeleton

Limbs plus pectoral and pelvic girdles that attach to axial skeleton and allow movement

Paranasal sinuses

Air spaces in frontal sphenoid maxilla and ethmoid that open into nasal cavity

Classification of bones

Long short flat irregular and bones with air spaces

Long bones

Bones longer than wide that act as levers in limbs

Short bones

Cube shaped bones found mainly in wrist and ankle

Flat bones

Thin bones providing protection and muscle attachment surfaces

Irregular bones

Bones with complex shapes that do not fit other categories

Pneumatized bones

Bones containing air spaces or sinuses

Tendon

Dense connective tissue that attaches muscle to bone

Ligament

Dense connective tissue that attaches bone to bone

Atrophy

Decrease in muscle size and strength due to lack of use

Hypertrophy

Increase in muscle size and strength due to training or high use

Excitability

Ability of muscle cells to respond to nerve stimulation

Contractility

Ability of muscle cells to shorten and produce force

Extensibility

Ability of muscle cells to be stretched

Elasticity

Ability of muscle cells to return to resting length after stretch

Skeletal muscle

Voluntary striated muscle attached to bones for body movement

Cardiac muscle

Involuntary striated muscle found only in heart with branching fibers

Smooth muscle

Involuntary muscle in walls of organs and blood vessels that is not striated

Origin

Muscle attachment that is more proximal or less movable

Insertion

Muscle attachment that is more distal or more movable

Prime mover agonist

Main muscle responsible for a specific movement

Antagonist

Muscle that opposes the action of the prime mover

Synergist

Muscle that helps the prime mover perform a movement

Fixator

Muscle that stabilizes a joint while other muscles move

Motor neuron

Nerve cell that carries signals from spinal cord or brain to muscle fibers

Motor unit

Single motor neuron and all muscle fibers it controls

Fine motor control

Many small motor units each controlling few fibers for precise movement

Gross motor control

Fewer large motor units each controlling many fibers for powerful movement

Fast twitch fibers

Muscle fibers with large diameter and high glycogen that contract quickly and fatigue rapidly

Slow twitch fibers

Muscle fibers with smaller diameter and high myoglobin that contract slowly and resist fatigue

Myoglobin in slow fibers

Protein that stores oxygen and supports endurance contractions

Glycogen in fast fibers

Stored glucose that supports rapid high power contractions

Muscle shapes

Parallel convergent pennate circular and other patterns of fiber arrangement

Parallel muscle

Fibers run in same direction as muscle length and can shorten greatly

Convergent muscle

Fibers spread out and converge to one tendon

Pennate muscle

Fibers attach to tendon at an angle to increase force

Circular muscle

Fibers arranged in rings around openings

Connective tissue in muscle

Epimysium perimysium endomysium surrounding muscle structures

Epimysium

Connective tissue layer around entire muscle

Perimysium

Connective tissue layer around each fascicle

Endomysium

Connective tissue layer around each muscle fiber

Fascicle

Bundle of muscle fibers within a muscle

Muscle fiber

Single elongated muscle cell containing myofibrils

Myofibrils

Long protein bundles in muscle fiber made of repeating sarcomeres

Sarcomere

Functional unit of contraction from one Z line to the next Z line

Thick filaments

Filaments in sarcomere made mainly of myosin proteins

Thin filaments

Filaments in sarcomere made mainly of actin proteins

Z line

Line at each end of sarcomere where thin filaments attach

M line

Line in center of sarcomere where thick filaments attach

H band

Center region of sarcomere containing only thick filaments

Sliding filament theory

Process where thin filaments slide past thick filaments to shorten sarcomeres during contraction

Cross bridge formation

Myosin heads attach to actin pull release and reattach using ATP

Muscle contraction sequence

Nerve signal reaches terminal neurotransmitter released muscle fiber depolarizes calcium released filaments slide and muscle shortens

Neuromuscular junction

Contact point between motor neuron and muscle fiber where neurotransmitter is released

Joint classification by movement

Synarthrosis amphiarthrosis diarthrosis

Synarthrosis

Immovable joint such as skull sutures

Amphiarthrosis

Slightly movable joint such as some cartilaginous joints

Diarthrosis

Freely movable joint such as synovial joints

Joint structural types

Fibrous cartilaginous synovial

Fibrous joints

Joints joined by dense connective tissue with little or no movement

Cartilaginous joints

Joints joined by cartilage with limited movement

Synovial joints

Joints with cavity fluid capsule and cartilage allowing free movement

Synovial joints components

Joint capsule synovial cavity synovial fluid articular cartilage ligaments possible menisci and bursae

Synovial fluid

Lubricating fluid in joint cavity that reduces friction and nourishes cartilage

Articular cartilage

Smooth hyaline cartilage covering bone ends in joints

Meniscus

Fibrocartilage pad in joint that improves fit and absorbs shock

Bursa

Fluid filled sac that reduces friction at points of rubbing

Hinge joint

Synovial joint that allows flexion and extension in one plane such as elbow or knee

Knee joint

Large hinge joint with femur tibia patella menisci ligaments and bursae

True ribs

First seven pairs of ribs that attach directly to sternum with their costal cartilage

False ribs

Ribs eight to ten that attach to sternum indirectly through cartilage of rib seven

Floating ribs

Ribs eleven and twelve that do not attach to sternum

Costal vertebral joints

Joints between ribs and thoracic vertebrae

Pectoral girdle

Clavicle and scapula that attach upper limb to axial skeleton

Pelvic girdle

Two hip bones that attach lower limb to axial skeleton

Pelvis

Ring formed by pelvic girdle sacrum and coccyx

Primary spinal curves

Thoracic and sacral curves present before birth and bulging posteriorly

Secondary spinal curves

Cervical and lumbar curves forming after birth and curving anteriorly

Kyphosis

Excess thoracic curvature causing humpback appearance

Lordosis

Excess lumbar curvature causing swayback appearance

Angular motion

Movement that changes angle between bones such as flexion or abduction

Rotational motion

Movement that turns bone around its long axis

Flexion

Movement that decreases angle between bones

Extension

Movement that increases angle between bones

Abduction

Movement that moves limb away from midline

Adduction

Movement that brings limb toward midline

External rotation

Rotating limb outward away from midline

Internal rotation

Rotating limb inward toward midline

Protraction

Moving a structure forward such as pushing jaw or shoulders anteriorly

Retraction

Moving a structure backward such as pulling jaw or shoulders posteriorly

Origins and insertions rule

During contraction the insertion moves toward the origin

Smooth muscle VS cardiac muscle VS skeletal muscle

Smooth is involuntary not striated in organs cardiac is involuntary striated in heart skeletal is voluntary striated attached to skeleton