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Anatomy Chapter 6

excitability capacity of skeletal muscle to respond to a stimulus
extensibility ability to be stretched
elasticity ability to recoil to original shape after being strected
epimysium each skeletal muscle surrounded by a connective tissue sheath called the
contractility ability of skeletal muscle to shorten with force
fascia connective tissue located outside the epimysium
perimysium loose connective tissue surrounding the facicle
fibers fasciculi are composed of single muscle cells
endomysium each fiber is surrounded by connective tissue sheath called
myofibrils a threadlike structure that extends from one end of the fiber to the other
actin myofilaments thin myofilaments
actin myofilaments resemble 2 minute strands of pearls twisted togetherr
myosin myofilaments thick myofilaments
myosin myofilaments resemble bundles of minute golf clubs
motor neurons nerve cells that carry action potentials to skeletal muscles
motor unit single motor neuron and all the skeletal muscle fibers it innervates
presynaptic terminal enlarged nerve terminal
synaptic cleft the space between the presynaptic terminal and the muscle cell
postsynaptic terminal muscle fiber
sliding filaments mechanism the sliding of actin myofilaments past myosin myofilaments during contraction
muscle twitch contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers
threshold muscle fiber will not respond to stimulus until that stimulus reaches this level called
all or none response muscle fiber will not respond to stimulus until that stimulus reaches this level called threshold, at which point the muscle fiber will contract maximally
lag phase time between application of a stimulus to a motor neuron and the beginning of a contraction
contraction phase time of contraction
relaxation phase time during which the muscle relaxes
tetany where the muscle remains contracted without relax
recruitment the increase in number of motor units being activated
ATP this is needed for energy muscle for muscle contraction
anaerobic respiration without oxygen
aerobic oxygen with oxygen
muscle fatigue when ATP is used during muscle contraction faster that it can be produced in the muscle cells
isomeric length of muscle does not change, but the amount of tension increases during the contraction process
isotonic the amount of tension produced by the muscle is constant during contraction but the length of the muscle changes
muscle tension muscle tone refers to constant tension produced by the muscles of the body for long periods of time
fast twitch contract quickly and fatigue quickly
slow twitch contract more slowly and are more resistant to fatigue
occipitofrontalis raises the eyebrows
orbicularis oculi closes the eyelids and causes “crows feet” wrinkles in the skin at the lateral corners of the eye.
orbicularis oris puckers the lips
buccinator flattens the cheeks
orbicularis oris, buccinator kissing muscles
zygomaticus smiling muscle
levator labii superioris sneering
depressor anguli oris frowning
mastication chewing
4 pairs of mastication muscles 2 pair of pterygoids, temporalis, and masseter.
intrinsic changes the shape of the tongue
extrinsic moves the tongue
sternocleidomastoid lateral neck muscle and prime mover
Erector spinae group of muscles on each side of the back.
Erector spinae Responsible for keeping the back straight and the body erect.
most involved in breathing Internal intercostals, External intercostals
External intercostals elevate the ribs during inspiration.
Internal intercostals contract during forced expiration.
Diaphragm accomplishes quiet breathing.
Dome shaped muscle. aids in breathing
rectus abdominis On each side of the linea alba is the
Trapezius rotates scapula
Serratus anterior- pulls scapula anteriorly
Pectoralis major adducts and flexes the arm
Latissimus dorsi medially rotates, adducts, and powerfully extends the arm. “Swimmer muscles”
Deltoid attaches the humerus to the scapula and clavicle, and is the major abductor of the upper limb
Triceps brachii extends forearm
biceps brachii flexes forearm
brachialis flexes forearm
brachioradialis flexes and supinates the forearm
Retinaculum (bracelet) strong band of fibrous connective tissue that covers the flexor and extensor tendons and holds them in place around the wrist so that they do not “bowstring” during muscle contraction.
flexor capri flexes the wrist
extensor capri extends the wrist
flexor digitorum flexes the fingers
extensor digitorum extends the fingers
Gluteus maximus buttocks
Quadriceps femoris extends the leg; anterior thigh muscles
Sartorius “tailors muscle”; flexes the thigh
Hamstring muscles posterior thigh muscles; flexes the leg and extends the thigh.
Gastrocnemius and soleus form the calf muscle.
Created by: carlymeadows23