Download Muscle

Muscle Tissue/The Muscular
System
• Alternating
contraction and
relaxation of cells
• Chemical energy
changed into
mechanical energy
11-1
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
11-2
3 Types of Muscle Tissue
• Cardiac muscle
– striated in appearance
– involuntary control
– autorhythmic because of built in pacemaker
11-3
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
11-4
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)
11-5
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
11-6
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
11-7
Connective Tissue Components
11-8
Atrophy and Hypertrophy
• Atrophy
– wasting away of muscles
– caused by disuse (disuse atrophy) or severing of the
nerve supply (denervation atrophy)
– the transition to connective tissue can not be reversed
• Hypertrophy
– increase in the diameter of muscle fibers
– resulting from very forceful, repetitive muscular
activity and an increase in myofibrils, SR &
mitochondria
11-9
Exercise-Induced Muscle Damage
• Intense exercise can cause muscle damage
– electron micrographs reveal torn sarcolemmas,
damaged myofibrils an disrupted Z discs
– increased blood levels of myoglobin & creatine
phosphate found only inside muscle cells
• Delayed onset muscle soreness
– 12 to 48 Hours after strenuous exercise
– stiffness, tenderness and swelling due to
microscopic cell damage
11-10
Muscle Tone
• Involuntary contraction of a small number of
motor units (alternately active and inactive in a
constantly shifting pattern)
– keeps muscles firm even though relaxed
– does not produce movement
• Essential for maintaining posture (head upright)
• Important in maintaining blood pressure
– tone of smooth muscles in walls of blood vessels
11-11
Trauma Induced Muscle Damage
Crush Syndrome-
11-12
Case Details
• Rural area• 18 year old patient – 80 Kg
• Working on road, rolled 12 ton steamroller into
ditch and patient trapped under steamroller
• ALS arrival within 15 min- 3 large bore IV started
11-13
Case Details Con’t
•
•
•
•
•
Patient GCS 15 upon ALS arrival –LOAx3
BP >160 systolic
HR 90s, colour good, cap refil N
Resp 18 chest clear
Major injuries - ?crushed pelvis ;pelvis and
lower extremities not accessible
• PMEDHX- unremarkable, no meds
11-14
Details:
• Crane on
site ready to
extricate
• What are
some of the
preparations
you will do?
• What do you
anticipate?
• What
equipment do
you need?
11-15
Case
continuation
• Patient extricated
and a large 8” piece of
metal came out of R
femoral area with moving
the roller off his pelvis
• Immediate arterial bleeding resulted
• Direct pressure added to wound by FP
• Clinical condition change:
-HR increased to 160 from 100 during extrication
Colour became poor (pale-cyanotic)
BP unpalpable
11-16
Treatment Rendered
• Direct pressure to wound all the way to
trauma center
• How to stabilize an unstable pelvis:
– KED?
– Sager?
– Broad bandage to pelvis - ++ tight?
• How is it done?
11-17
Patient Outcome en route and in
Hospital
•
•
•
•
After 3-4L fluid- HR stabilized at 120
BP 98/62
Colour returned somewhat
Arterial bleed continued to be an issue
– Direct pressure
• In hospital developed rhadbodmyolysis due
to crush syndrome
11-18
Crush Syndrome and Rhabdomyolysis
• "Severe systemic manifestation of trauma and
ischemia involving soft tissues, principally
skeletal muscle, due to prolonged severe
crushing.
It leads to increased permeability of the cell
membrane and to the release of potassium,
enzymes, and myoglobin from within cells and
into plasma (rhabdomyolysis). Ischemic renal
dysfunction secondary to hypotension and
diminished renal perfusion results in acute
tubular necrosis and uremia”
11-19
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
11-20
Regeneration of Muscle
• Skeletal muscle fibers cannot divide after 1st year
– growth is enlargement of existing cells
– repair
• satellite cells & bone marrow produce some new cells
• if not enough numbers---fibrosis occurs most often
• Cardiac muscle fibers cannot divide or regenerate
– all healing is done by fibrosis (scar formation)
• Smooth muscle fibers (regeneration is possible)
– cells can grow in size (hypertrophy)
– some cells (uterus) can divide (hyperplasia)
– new fibers can form from stem cells in BV walls11-21
Aging and Muscle Tissue
• Skeletal muscle starts to be replaced by fat
beginning at 30
– “use it or lose it”
• Slowing of reflexes & decrease in maximal
strength
• Change in fiber type to slow oxidative fibers may
be due to lack of use or may be result of aging
11-22
Abnormal Contractions
• Spasm = involuntary contraction of single
muscle
• Cramp = a painful spasm
• Tic = involuntary twitching of muscles
normally under voluntary control--eyelid or
facial muscles
• Tremor = rhythmic, involuntary contraction
of opposing muscle groups
• Fasciculation = involuntary, brief twitch of
a motor unit visible under the skin
11-23
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
11-24
Lever Systems and Leverage
• 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
11-25
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
11-26
How Skeletal Muscle are Named
• Direction the muscle fibers run
• Size, shape, action, number of origins or locations
• Examples from Table 11.2
– triceps brachii -- 3 sites of origin
– quadratus femoris -- square shape
– serratus anterior -- saw-toothed edge
11-27
Muscles of Facial Expression
• Arise from skull &
insert onto skin
• Encircle eyes, nose &
mouth
• Express emotions
• Facial Nerve (VII)
• Bell’s palsy = facial
paralysis due
11-28
Muscles of Facial Expression
• Orbicularis oculi closes
the eye
• Levator palpebrae
superioris opens the eye
• Orbicularis oris puckers
the mouth
• Buccinator forms the
muscular portion of the
cheek & assists in
whistling, blowing,
sucking & chewing
11-29
Muscles that Move the Mandible
• Masseter, temporalis &
pterygoids
• Arise from skull & insert
on mandible
• Cranial nerve V
(trigeminal nerve)
• Protracts, elevates or
retracts mandible
– Temporalis & Masseter
elevate the mandible
(biting)
– temporalis retracts
11-30
Muscles that Move the Head
• Sternocleidomastoid muscle
–
–
–
–
arises from sternum & clavicle & inserts onto mastoid process of skull
innervated by cranial nerve XI (spinal accessory)
contraction of both flexes the cervical vertebrae & extends head
contraction of one, laterally flexes the neck and rotates face in opposite
direction
11-31
Muscles of Abdominal Wall
• Notice 4 layers of muscle in the abdominal wall
11-32
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)
11-33
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
Quadratus lumborum fills in space
between 12th rib & iliac crest to
create posterior body wall
• Diaphragm is innervated by
phrenic nerve (C3-C5) but
intercostals innervated by
thoracic spinal nerves (T2-T12)
11-34
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
11-35
Axial Muscles that Move the Arm
• Pectoralis major & Latissimus dorsi extend from body wall
to humerus.
11-36
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
11-37
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
11-38
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
11-39
Cross-Section Through Forearm
• If I am looking down onto this section is it from right or left arm?
11-40
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
11-41
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 picture
• Pulled groin muscle
– result of quick sprint activity
– stretching or tearing of iliopsoas or
adductor muscle
11-42
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)
11-43
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 hamstring
– tear of origin of muscles
11-44
from ischial tuberosity
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
11-45
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
11-46
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 foot
– tendons pass posteriorly to axis
of ankle joint and into plantar
foot
11-47