Chapter 4 SEHS Muscle Tissue Lecture Outline Principles of Human Anatomy and Physiology 11e 3 INTRODUCTION Motion results from alternating contraction shortening and relaxation of muscles the skeletal system provides leverage and a supportive framework for this movement ID: 934925
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Slide1
Musculoskeletal
muscles
Slide22
Chapter
4 SEHS
Muscle Tissue
Lecture Outline
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INTRODUCTION
Motion results from alternating contraction (shortening) and relaxation of muscles; the skeletal system provides leverage and a supportive framework for this movement.
The scientific study of muscles is known as
myology
.
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Chapter 10
Muscle Tissue
Alternating contraction and relaxation of cells
Chemical energy changed into mechanical energy
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OVERVIEW OF MUSCLE TISSUE
Types of Muscle Tissue
Skeletal muscle tissue is primarily attached to bones. It is striated and voluntary.
Cardiac muscle tissue forms the wall of the heart. It is striated and involuntary.
Smooth (visceral) muscle tissue is located in viscera. It is nonstraited (smooth) and involuntary.
Table 4.4 compares the different types of muscle.
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3 Types of Muscle Tissue
Skeletal muscle
attaches to bone, skin or fascia
striated with light & dark bands visible with scope
voluntary control of contraction & relaxation
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3 Types of Muscle Tissue
Cardiac muscle
striated in appearance
involuntary control
autorhythmic because of built in pacemaker
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3 Types of Muscle Tissue
Smooth muscle
attached to hair follicles in skin
in walls of hollow organs -- blood vessels & GI
nonstriated in appearance
involuntary
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Functions of Muscle Tissue
Producing body movements
Stabilizing body positions
Regulating organ volumes
bands of smooth muscle called sphincters
Movement of substances within the body
blood, lymph, urine, air, food and fluids, sperm
Producing heat
involuntary contractions of skeletal muscle (shivering)
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Properties of Muscle Tissue
Excitability
respond to chemicals released from nerve cells
Conductivity
ability to propagate electrical signals over membrane
Contractility
ability to shorten and generate force
Extensibility
ability to be stretched without damaging the tissue
Elasticity
ability to return to original shape after being stretched
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SKELETAL MUSCLE TISSUE
Each skeletal muscle is a separate organ composed of cells called
fibers
.
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Skeletal Muscle --
Connective Tissue
Superficial fascia is
loose connective tissue & fat underlying the skin
Deep fascia = dense irregular connective tissue around muscle
Connective tissue components of the muscle include
epimysium = surrounds the whole muscle
perimysium = surrounds bundles (fascicles) of 10-100 muscle cells
endomysium = separates individual muscle cells
All these connective tissue layers extend beyond the muscle belly to form the tendon
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Connective Tissue Components
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Muscle Fiber or Myofibers
Muscle cells are long, cylindrical & multinucleated
Sarcolemma = muscle cell membrane
Sarcoplasm filled with tiny threads called myofibrils & myoglobin (red-colored, oxygen-binding protein)
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Myofibrils & Myofilaments
Muscle fibers are filled with threads called myofibrils separated by SR (sarcoplasmic reticulum)
The
sarcoplasmic reticulum
encircles each myofibril. It is similar to smooth endoplasmic reticulum in nonmuscle cells and in the relaxed muscle stores calcium ions.
Myofilaments (thick & thin filaments) are the contractile proteins of muscle
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Sarcoplasmic Reticulum (SR)
System of tubular sacs similar to smooth ER in nonmuscle cells
Stores Ca+2 in a relaxed muscle
Release of Ca+2 triggers muscle contraction
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Filaments and the Sarcomere
Thick and thin filaments overlap each other in a pattern that creates striations (light I bands and dark A bands)
The I band region contains only thin filaments.
They are arranged in compartments called sarcomeres, separated by Z discs.
In the overlap region, six thin filaments surround each thick filament
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Sarcomere
Figure 10.5 shows the relationships of the zones, bands, and lines as seen in a transmission electron micrograph.
Exercise can result in torn sarcolemma, damaged myofibrils, and disrupted Z discs (Clinical Application).
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Thick & Thin Myofilaments
Supporting proteins (M line, titin and Z disc help anchor the thick and thin filaments in place)
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Thick & Thin Myofilaments Overlap
Dark(A) & light(I) bands (electron microscope)
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The Proteins of Muscle
Myofibrils are built of 3 kinds of protein
contractile proteins
myosin and actin
regulatory proteins which turn contraction on & off
troponin and tropomyosin
structural proteins which provide proper alignment, elasticity and extensibility
titin, myomesin, nebulin and dystrophin
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The Proteins of Muscle -- Myosin
Thick filaments are composed of myosin
each molecule resembles two golf clubs twisted together
myosin heads (cross bridges) extend toward the thin filaments
Held in place by the M line proteins.
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The Proteins of Muscle -- Actin
Thin filaments are made of actin, troponin, & tropomyosin
The myosin-binding site on each actin molecule is covered by tropomyosin in relaxed muscle
The thin filaments are held in place by Z lines. From one Z line to the next is a sarcomere.
Slide24http://www.youtube.com/watch?v=0kFmbrRJq4w
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Slide25http://www.blackwellpublishing.com/matthews/myosin.html
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Slide26Human back muscles
http://www.scivee.tv/node/2413
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Structural Proteins
Structural proteins keep the thick and thin filaments in the proper alignment, give the myofibril elasticity and extensibility, and link the myofibrils to the sarcolemma and extracellular matrix.
Titin
helps a sarcomere return to its resting length after a muscle has contracted or been stretched.
Myomesin
forms the M line.
Nebulin
helps maintain alignment of the thin filaments in the sarcomere.
Dystrophin
reinforces the sarcolemma and helps transmit the tension generated by the sarcomeres to the tendons.
Table 10.1 reviews the type of proteins in skeletal muscle.
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The Proteins of Muscle -- Titin
Titan anchors thick filament to the M line and the Z disc.
The portion of the molecule between the Z disc and the end of the thick filament can stretch to 4 times its resting length and spring back unharmed.
Role in recovery of the muscle from being stretched.
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Structural Proteins
The M line (myomesin) connects to titin and adjacent thick filaments.
Nebulin, an inelastic protein helps align the thin filaments.
Dystrophin links thin filaments to sarcolemma and transmits the tension generated to the tendon.
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Sliding Filament Mechanism Of Contraction
Myosin cross bridges
pull on thin filaments
Thin filaments slide
inward
Z Discs come toward
each other
Sarcomeres shorten.The muscle fiber shortens. The muscle shortens
Notice :Thick & thin filaments do not change in length
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Overview: From Start to Finish
Basic Structures
Nerve ending
Neurotransmitter
Muscle membrane
Stored Ca
+2
ATP
Muscle proteins
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How Does Contraction Begin?
Nerve impulse reaches an axon terminal & synaptic vesicles release acetylcholine (ACh)
ACh diffuses to receptors on the sarcolemma & Na
+
channels open and Na
+
rushes into the cell
A muscle action potential spreads over sarcolemma and down into the transverse tubules
SR releases Ca
+2
into the sarcoplasm
Ca
+2 binds to troponin & causes troponin-tropomyosin complex to move & reveal myosin binding sites on actin--the contraction cycle begins
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Contraction Cycle
Repeating sequence of events that cause the thick & thin filaments to move past each other.
4 steps to contraction cycle
ATP hydrolysis
attachment of myosin to actin to form crossbridges
power stroke
detachment of myosin from actin
Cycle keeps repeating as long as there is ATP available & there is a high Ca
+2
level near the filaments.
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Steps in the Contraction Cycle
Notice how the myosin head attaches and pulls on the thin filament with the energy released from ATP
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ATP and Myosin
Myosin heads are activated by ATP
Activated heads attach to actin & pull (power stroke)
ADP is released. (ATP released P & ADP & energy)
Thin filaments slide past the thick filaments
ATP binds to myosin head & detaches it from actin
All of these steps repeat over and over
if ATP is available &
Ca+ level near the troponin-tropomyosin complex is high
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Excitation - Contraction Coupling
All the steps that occur from the muscle action potential reaching the T tubule to contraction of the muscle fiber.
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Relaxation
Acetylcholinesterase (AChE) breaks down ACh within the synaptic cleft
Muscle action potential ceases
Ca
+2
release channels close
Active transport pumps Ca
+2
back into storage in the sarcoplasmic reticulum
Calcium-binding protein (calsequestrin) helps hold Ca
+2
in SR (Ca+2 concentration 10,000 times higher than in cytosol)Tropomyosin-troponin complex recovers binding site on the actin
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Overview: From Start to Finish
Nerve ending
Neurotransmittor
Muscle membrane
Stored Ca
+2
ATP
Muscle proteins
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CARDIAC MUSCLE TISSUE - Overview
Cardiac muscle tissue is found only in the heart
walland
top
of Aorta (see Chapter 20).
Its fibers are arranged similarly to skeletal muscle fibers.
Cardiac muscle fibers
connect to adjacent fibers by
intercalated discs
which contain
desmosomes
and gap junctions (Figure 4.1e).Cardiac muscle contractions last longer than the skeletal muscle twitch due to the prolonged delivery of calcium ions from the sarcoplasmic reticulum and the extracellular fluid.
Cardiac muscle fibers contract when stimulated by their own autorhythmic fibers.
This continuous, rhythmic activity is a major physiological difference between cardiac and skeletal muscle tissue.
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Cardiac versus Skeletal Muscle
More sarcoplasm and mitochondria
Larger transverse tubules located at Z discs, rather than at A-l band junctions
Less well-developed SR
Limited intracellular Ca+2 reserves
more Ca+2 enters cell from extracellular fluid during contraction
Prolonged delivery of Ca+2 to sarcoplasm, produces a contraction that last 10 -15 times longer than in skeletal muscle
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SMOOTH MUSCLE
Smooth muscle
tissue is nonstriated and involuntary and is classified into two types:
visceral (single unit) smooth muscle
(Figure 10.18a) and
multiunit smooth muscle
(Figure 10.18b).
Visceral (single unit) smooth muscle
is found in the walls of hollow viscera and small blood vessels; the fibers are arranged in a network and function as a “single unit.”
Multiunit smooth muscle
is found in large blood vessels, large airways, arrector pili muscles, and the iris of the eye. The fibers operate singly rather than as a unit.
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Two Types of Smooth Muscle
Visceral (single-unit)
in the walls of hollow viscera & small BV
autorhythmic
gap junctions cause fibers to contract in unison
Multiunit
individual fibers with own motor neuron ending
found in large arteries, large airways, arrector pili muscles,iris & ciliary body
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INTRODUCTION
The voluntarily controlled muscles of the body make up the
muscular system
.
The muscular system and muscle tissue contribute to homeostasis by producing movement, stabilizing body position, regulating organ volume, moving substances within the body, and producing heat.
This chapter discusses how skeletal muscles produce movement and describes the principal skeletal muscles.
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Chapter 11
The Muscular System
Skeletal muscle major groupings
How movements occur at specific joints
Learn the origin, insertion, function and innervation of all major muscles
Important to allied health care and physical rehabilitation students
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Muscle Attachment Sites:
Origin and Insertion
Skeletal muscles shorten & pull on the bones they are attached to
Origin is the bone that does not move when muscle shortens (normally proximal)
Insertion is the movable bone (some 2 joint muscles)
Fleshy portion of the muscle in between attachment sites = belly
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Tenosynovitis
Inflammation of tendon and associated connective tissues at certain joints
wrist, elbows and shoulder commonly affected
Pain associated with movement
Causes
trauma, strain or excessive exercise
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Lever Systems and Leverage
A lever is a rigid structure that moves around a fixed point, the
fulcrum
(F)
The lever is acted on by two different forces: (Figure 11.1b).
resistance
(
load
) (L), which opposes movement
effort
(E) which causes movement Bones serve as levers and joints serve as
fulcrums.Leverage, the mechanical advantage gained by a lever, is largely responsible for a muscle’s strength and range of motion (ROM), i.e., the maximum ability to move the bones of a joint through an arc.
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Levers
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Levers are categorized into three types –
First class levers (EFL) e.g. a seesaw – the head on the vertebral column (Figure 11.2a)
Second-class (FLE) eg. a wheelbarrow(Figure 11.2b)
Third-class (FEL) (Figure 11.1b) e.g. forceps - the elbow joint (Figure 11.2c).
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Muscle acts on rigid rod (bone)
that moves around a
fixed point called a fulcrum
Resistance is weight of body
part & perhaps an object
Effort or load is work done
by muscle contraction
Mechanical advantage
the muscle whose attachment is farther from the joint will produce the most force
the muscle attaching closer to the joint has the greater range of motion and the faster the speed it can produce
Lever Systems and Leverage
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First - Class Lever
Can produce mechanical advantage or not depending on location of effort & resistance
if effort is further from fulcrum than resistance, then a strong resistance can be moved
Head resting on vertebral column
weight of face is the resistance
joint between skull & atlas is fulcrum
posterior neck muscles provide effort
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Second - Class Lever
Similar to a wheelbarrow
Always produce mechanical advantage
resistance is always closer to fulcrum than the effort
Sacrifice of speed for force
Raising up on your toes
resistance is body weight
fulcrum is ball of foot
effort is contraction of calf muscles which pull heel up off of floor
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Third - Class Lever
Most common levers in the body
Always produce a mechanical disadvantage
effort is always closer to fulcrum than resistance
Favors speed and range of motion over force
Flexor muscles at the elbow
resistance is weight in hand
fulcrum is elbow joint
effort is contraction of biceps brachii muscle
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Fascicle Arrangements
A contracting muscle shortens to about 70% of its length
Fascicular arrangement represents a compromise between force of contraction (power) and range of motion
muscles with longer fibers have a greater range of motion
a short fiber can contract as forcefully as a long one.
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Coordination Within Muscle Groups
Most movement is the result of several muscle working at the same time
Most muscles are arranged in opposing pairs at joints
prime mover or agonist contracts to cause the desired action
antagonist stretches and yields to prime mover
synergists contract to stabilize nearby joints
fixators stabilize the origin of the prime mover
scapula held steady so deltoid can raise arm
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HOW SKELETAL MUSCLES ARE NAMED
The names of most of the nearly 700 skeletal muscles are based on several types of characteristics.
These characteristics may be reflected in the name of the muscle.
The most important characteristics include the direction in which the muscle fibers run, the size, shape, action, numbers of origins, and location of the muscle, and the sites of origin and insertion of the muscle
Examples from Table 11.2
triceps brachii -- 3 sites of origin
quadratus femoris -- square shape
serratus anterior -- saw-toothed edge
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PRINCIPLE SKELETAL MUSCLES
Exhibits 11.1 through 11.20 list the principle skeletal muscles in various regions of the body.
Figure 11.3 shows general anterior and posterior views of the muscular system.
The exhibits contain objectives, an overview which provides a general orientation to the muscles, muscle names, origins, insertions, and actions, “relating muscles to movements,” innervation, and Figures (11.4-11.23) that show the muscles under consideration.
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Muscles of Abdominal Wall
Notice 4 layers of muscle in the abdominal wall
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Muscles of Abdominal Wall
4 pairs of sheetlike muscles
rectus abdominis = vertically oriented
external & internal obliques and transverses abdominis
wrap around body to form anterior body wall
form rectus sheath and linea alba
Inguinal ligament from anterior superior iliac spine to upper surface of body of pubis
Inguinal canal = passageway from pelvis through body wall musculature opening seen as superficial inguinal ring
Inguinal hernia = rupture or separation of abdominal wall allowing protrusion of part of the small intestine (more common in males)
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Transverse Section of Body Wall
Rectus sheath formed from connective tissue aponeuroses of other abdominal muscles as they insert in the midline connective tissue called the linea alba
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Muscles Used in Breathing
Breathing requires a change in size of the thorax
During inspiration, thoracic cavity increases in size
external intercostal lift the ribs
diaphragm contracts & dome is flattened
During expiration, thoracic cavity decreases in size
internal intercostal mm used in forced expiration
Diaphragm is innervated by phrenic nerve (C3-C5) but intercostals innervated by thoracic spinal nerves (T2-T12)
Quadratus lumborum fills in space between 12th rib & iliac crest to create posterior body wall
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Muscles Used in Breathing
Breathing requires a change in size of the thorax
During inspiration, thoracic cavity increases in size
external intercostal lift the ribs
diaphragm contracts & dome is flattened
During expiration, thoracic cavity decreases in size
internal intercostal mm used in forced expiration
Diaphragm is innervated by phrenic nerve (C3-C5) but intercostals innervated by thoracic spinal nerves (T2-T12)
Quadratus lumborum fills in space between 12th rib & iliac crest to create posterior body wall
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Stabilizing the Pectoral Girdle
Anterior thoracic muscles
Subclavius extends from 1st rib to clavicle
Pectoralis minor extends from ribs to coracoid process
Serratus anterior extends from ribs to inner surface of scapula
Posterior thoracic muscle
Trapezius extends from skull & vertebrae to clavicle & scapula
Levator scapulae extends from cervical vertebrae to scapula
Rhomboideus extends from thoracic vertebrae to vertebral border of scapula
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Axial Muscles that Move the Arm
Pectoralis major & Latissimus dorsi extend from body wall to humerus.
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Muscles that Move the Arm
Deltoid arises from acromion & spine of scapula & inserts on arm
abducts, flexes & extends arm
Rotator cuff muscles extend from scapula posterior to shoulder joint to attach to the humerus
supraspinatus & infraspinatus: above & below spine of scapula
subscapularis on inner surface of scapula
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Flexors of the Forearm (elbow)
Cross anterior surface of elbow joint & form flexor muscle compartment
Biceps brachii
scapula to radial tuberosity
flexes shoulder and elbow & supinates hand
Brachialis
humerus to ulna
flexion of elbow
Brachioradialis
humerus to radius
flexes elbow
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Extensors of the Forearm (elbow)
Cross posterior surface of elbow joint & forms extensor muscle compartment
Triceps brachii
long head arises scapula
medial & lateral heads from humerus
inserts on ulna
extends elbow & shoulder joints
Anconeus
assists triceps brachii in extending the elbow
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Cross-Section Through Forearm
If I am looking down onto this section is it from right or left arm?
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Muscle that Pronate & Flex
Pronator teres
medial epicondyle to radius so contraction turns palm of hand down towards floor
Flexor carpi muscles
radialis
ulnaris
Flexor digitorum muscles
superficialis
profundus
Flexor pollicis
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Muscles that Supinate & Extend
Supinator
lateral epicondyle of humerus to radius
supinates hand
Extensors of wrist and fingers
extensor carpi
extensor digitorum
extensor pollicis
extensor indicis
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Muscles that Move the Vertebrae
Quite complex due to overlap
Erector spinae fibers run longitudinally
3 groupings
spinalis
iliocostalis
longissimus
extend vertebral column
Smaller, deeper muscles
transversospinalis group
semispinalis, multifidis & rotatores
run from transverse process to dorsal spine of vertebrae above & help rotate vertebrae
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Muscles Crossing the Hip Joint
Iliopsoas flexes hip joint
arises lumbar vertebrae & ilium
inserts on lesser trochanter
Quadriceps femoris has 4 heads
Rectus femoris crosses hip
3 heads arise from femur
all act to extend the knee
Adductor muscles
bring legs together
cross hip joint medially
see next picturePulled groin muscleresult of quick sprint activitystretching or tearing of iliopsoas or adductor muscle
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Adductor Muscles of the Thigh
Adductor group of muscle extends from pelvis to linea aspera on posterior surface of femur
pectineus
adductor longus
adductor brevis
gracilis
adductor magnus (hip extensor)
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Muscles of the Butt & Thigh
Gluteus muscles
maximus, medius & minimus
maximus extends hip
medius & minimus abduct
Deeper muscles laterally rotate femur
Hamstring muscles
semimembranosus (medial)
semitendinosus (medial)
biceps femoris (lateral)
extend hip & flex knee
Pulled hamstringtear of origin of muscles from ischial tuberosity
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Cross-Section through Thigh
3 compartments of muscle with unique innervation
anterior compartment is quadriceps femoris innervated by femoral nerve
medial compartment is adductors innervated by obturator nerve
posterior compartment is hamstrings innervated by sciatic nerve
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Muscles of the Calf (posterior leg)
3 muscles insert onto calcaneus
gastrocnemius arises femur
flexes knee and ankle
plantaris & soleus arise from leg
flexes ankle
Deeper mm arise from tibia or fibula
cross ankle joint to insert into foot
tibialis posterior
flexor digitorum longus
flexor hallucis longus
flexing ankle joint & toes
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Muscles of the Leg and Foot
Anterior compartment of leg
extensors of ankle & toes
tibialis anterior
extensor digitorum longus
extensor hallucis longus
tendons pass under retinaculum
Shinsplits syndrome
pain or soreness on anterior tibia
running on hard surfaces
Lateral compartment of leg
peroneus mm plantarflex the foottendons pass posteriorly to axis of ankle joint and into plantar foot
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Muscles of the Plantar Foot
Intrinsic muscles
arise & insert in foot
4 layers of muscles
get shorter as go into deeper layers
Flex, adduct & abduct toes
Digiti minimi muscles move little toe
Hallucis muscles move big toe
Plantar fasciitis (painful heel syndrome) chronic irritation of plantar aponeurosis at calcaneus
improper shoes & weight gain
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Compartment Syndrome
Skeletal muscles in the limbs are organized in units called
compartments
.
In
compartment syndrome
, some external or internal pressure constricts the structures within a compartment, resulting in damaged blood vessels and subsequent reduction of the blood supply to the structures within the compartment.
Without intervention, nerves suffer damage, and muscle develop scar tissue that results in permanent shortening of the muscles, a condition called
contracture
.
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IM injection
Intramuscular injection penetrates the skin, subcutaneous tissue and enters the muscle.
They are given when rapid absorption is necessary, for large doses, or when a drug is irritating to subcutaneous tissue.
Common sites of injection are the gluteus medius, vastul lateralis, and deltoid.
Intramuscular injections are faster than oral medications, but slower than IV.