Musculoskeletal Physiology Flashcards
Bones contain organic components such as
collagen and various mineral elements, including 98% of calcium storage in the body
Bone has vascular structures, can heal itself and is dynamic and changing
Low bone mass density can lead to osteopenia (pre disease state) and if untreated, can progress to osteoporosis
Osteoporosis
bone disease which causes skeletal structures to become brittle and fragile, often leading to fractures and disability
Skeleton consists of two segments:
Axial skeleton - skull, hyoid bone, vertebral column, and rib cage
Appendicular skeleton - the limbs and their respective girdles
Epiphyseal plate:
transverse cartilage plates located near the end of long bones are responsible for increases in vertical growth during childhood/adolescence
Bone length increases until the cartilage is ossified in the epiphyseal plates of long bones; peak bone mass is usually attained by about age 18
Bone types
Long bones (arms/legs)
Short bones (hands/feet)
Irregular bones (vertebrae)
Flat bones (scapula)
Body mass density (BMD) can be improved until what age?
30
genetics, behaviors and lifestyle factors dictate the rate of decline – muscle strength is a key indicator
the intersection of two bones; major types include fibrous, cartilaginous and synovial
Joint
Synovial joint:
uses synovial fluid to reduce frictional stresses and allow for considerable movement between the associated articulating bones
Joints of the appendicular skeleton are mostly synovial to support locomotion and activity needs
Synovial joints include: plane, pivot, hinge, condyloid, saddle, ball & socket.
Synovial joints
PLANE JOINT
A plane joint allows bones to slide past each other.
Midcarpal and midtarsal joints are plane joints.
PIVOT JOINT
A pivot joint allows
rotator arouna am axis,
Pivot joints are found in the neck and forearm.
HINGE JOINT
A hinge joint allows extension and retraction of an appendage. Hinge joints are found in the knees, elbows, fingers, and toes.
CONDYLOID JOINT
A condyloid joint is similar to a ball and socket but with less movement. Ex. Wrist
A saddle joint allows
to ball and socket but with movement back and forth less movement. The wrist and up and down. The is a condyloid joint.
SADDLE JOINT
A saddle joint allows
to ball and socket but with movement back and forth less movement. The wrist and up and down. The is a condyloid joint.
only saddle joint in the human body is the thumb.
BALL-AND-SOCKET JOINT
A ball and socket joint allows for radical movement in almost any direction. Ball-and-socket joints are found in the shoulders and hips.
Ligament
: fibrous bands of connective tissue that support internal organs and hold bones together at joints
Tendons
: fibrous band of connective tissue that connects muscles to bones
Ligaments and tendons assist in providing structural support to strengthen joints
Three types of muscles
Skeletal, cardiac, smooth
Muscle Fascia
: fibrous connective tissue that encapsulates full muscles as well as bundles of fibers; provides the muscle’s shape and regulates tension/transfer of force across joints
How muscles contract
Nerve information is carried via action potentials
Action potential: wave-like electrical change in a cell membrane that signals the cascade of events leading to a muscular contraction
Action potential current travels to motor neurons which connect to specific fibers (motor unit)
Motor unit: motor neuron and all the muscle fibers it innervates
Sliding Filament Theory:
An action potential travels down T-tubules to stimulate the sarcoplasmic reticulum to release calcium ions which unlock the bond between actin filaments and troponin
When troponin is moved due to calcium activity, myosin can attach to actin forming a cross bridge via its myosin head
ATP is split at the myosin-actin attachment site which releases energy and allows the myosin head to pull or “slide” the actin to shorten/contract the muscle fiber
Force production
A muscle fiber is either in a state of producing maximum tension or not producing any tension at all - known as the “all or none” principle
Force production is dictated by motor unit firing rate, recruitment and synchronicity
Two types of motor unit firing patterns:
Synchronized firing - employed during high-output demands involving fast-twitch fibers and warranting significant fiber recruitment
Asynchronous firing - employed during endurance activities involving slow-twitch fibers which conserve motor unit potential, allowing prolonged work
Agonist
muscle that contracts/shortens during a given exercise (e.g., biceps during a curl)
Antagonist
muscle that relaxes and lengthens during a given exercise to accommodate contraction of the agonist (e.g., triceps during a biceps curl)
Isotonic
tension remains constant while joint angles change; seen during most exercises that include an acceleration and deceleration component
Concentric
occurs during the acceleration phase of a lift as the muscle shortens
Eccentric
occurs during the deceleration phase of a lift as the muscle lengthens
Isometric
tension is created but no joint angle changes; common in stabilizers
Isometric
involves a constant speed of movement; requires specialized rehab equipment
Muscle Fiber Types
Type I: slow-twitch oxidative fibers possess the lowest power output, smallest diameter, and highest resistance to fatigue; they are well suited for prolonged aerobic work and possess the highest capillary and mitochondrial densities, fire first in anticipation of joint stability needs
Type IIA: fast-twitch, oxidative-glycolytic fibers that possess intermediate power output capabilities and diameter with moderate resistance to fatigue; provide support during both intense strength/power work and prolonged exercise (most versatile from a metabolic standpoint)
Type IIX: fast-twitch glycolytic fibers that possess the highest power output capabilities, largest diameter, and lowest resistance to fatigue; provide significant support during intense strength/power activities
Size principle
muscle fiber types are recruited sequentially based on their size and force output capacities; type I → type IIA → type IIX
Fiber Type Distribution
Distribution is genetically predetermined; training will not change concentrations of fibers within specific muscles from fast to slow or slow to fast
Postural muscles maintain higher concentrations of type I fibers (e.g., soleus)
Movers tend to have a greater type II fiber concentration (e.g., biceps)
Muscles with greater quantities of type II fibers experience greater changes in response to hypertrophy training
Proprioceptors
are special sensory receptors found inside the joints and connective tissues that signal the body about position and movement, thus managing muscle and tendon tension.
Homeostasis
is the body’s desire to stay in a constant, desirable range of conditions so that equilibrium in the physiological systems is present.
