The Muscular System Structural and functional organization of muscles The system of the little...
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Transcript of The Muscular System Structural and functional organization of muscles The system of the little...
The Muscular System
• Structural and functional organization of muscles
• The system of the little mouse
Structural and Organization of Muscles
• 600 Human skeletal muscles– Also smooth & cardiac muscles
• General structural & functional organization– functions of muscle– connective tissues of muscle– general anatomy of skeletal muscles– muscle shape and function– coordinated actions of muscle groups – intrinsic and extrinsic muscles– muscle innervation
The Functions of Muscles
• Movement of body parts and organ contents
• Maintain posture and prevent movement
• Communication - speech, expression & writing
• Control of openings and passageways
• Body heat production
Non-Verbals
Interspecies non-verbals
Connective Tissues of a Muscle
Perimysium
Epimysium
Endomysium
Tendon
Deep fascia
Connective Tissues of a Muscle• Epimysium
– covers whole muscle belly – blends into connective tissue that separates
muscles
• Perimysium– slightly thicker layer of connective tissue– surrounds a bundle of cells called a fascicle
• Endomysium– thin layer of areolar tissue surrounding each cell– allows room for capillaries and nerve fibers
Fascicle, c.s.
Fascicles, Perimysium & Endomysium
Endomysium
Location of Fascia
Superficial Fascia
Deep Fascia
• Deep fascia– found between adjacent muscles
• Superficial fascia (hypodermis)– found between skin and muscles– contains adipose tissue
Muscle Attachments• Direct (fleshy) attachment to bone
– epimysium is continuous with periosteum– intercostal muscles
• Indirect attachment to bone– epimysium continues as tendon or aponeurosis that
merges into periosteum as perforating fibers– biceps brachii or abdominal muscle
• Attachment to dermis
• Stress will tear the tendon before pulling the tendon loose from either muscle or bone
Parts of a Skeletal Muscle
• Origin– attachment to stationary
end of muscle
• Belly– thicker, middle region of
muscle
• Insertion– attachment to mobile end of
muscle
Skeletal Muscle Shapes
• Fusiform muscles– thick in middle & tapered at
ends
– biceps brachii m.
• Convergent muscle– broad at origin and tapering to
a narrower insertion
• Parallel muscles– parallel fascicles
– rectus abdominis m.
Skeletal Muscle Shapes (2)
• Circular muscles– act as sphincters
– ring around body opening
– orbicularis oris
• Pennate muscles– fascicles insert obliquely
on a tendon
– unipennate, bipennate or multipennate
– palmar interosseus, rectus femoris & deltoid
• Biceps Tendon Rupture: As a result of chronic tendonitis or truama, the long head of the biceps may rupture. When this occurs, the biceps muscle appears as a ball of tissue and there is a loss of function.
Healthy Bicep
In september 2005 Maria Sharapova from Russia withdrew from the China Open due to a pectoral injury
Healthy Pectorals
Top European Golfer: David Howell
• Ranked 30th in the world one of England’s best withdrew from the U.S. Open in June of 2005.
• He suffered a rip
To the left oblique
• You can hit these abdominals with a pike and that pike will shatter
Ptosis
• Ptosis is a drooping of the entire upper eyelid. It can be due to trauma, disorders (IE: neurological, myasthenia, auto-immune), surgery, and medication.
• Terrell Owens, leaving the field and wincing in pain after suffering a regular season ending, lower leg injury against the Cowboys.
• Terrell Owens has been kicked 800 feet up in the air by the lower leg of Chuck Norris
↑
Coordinated Muscle Actions• Prime mover or agonist
– produces most of force
• Synergist aids the prime mover– stabilizes the nearby joint
– modifies the direction of movement that occurs
• Antagonist– opposes the prime mover
– preventing excessive movement and injury
• Fixator– prevents movement of bone that prime mover is attached to
Example
Muscle Actions during Elbow Flexion
• Prime mover (agonist) = biceps brachii m.
• Synergist = brachialis m.
• Antagonist = triceps brachii m.
• Fixator = muscle that holds scapula firmly in place such as rhomboideus m.
Definitions
Methods used to diagnose structural muscle disorders
• Myopathies: Muscle disorders– Can be confused with skeletal/nervous disorders
• Physical tests– Can you lift against gravity?
– Can you lift against resistance?
– Can you lift repeatedly?
• Physicians judge the amount of force and assign a grade; percentage, verbal grade, or numeric
• Myometers/Dynometers measure the amount of force a muscle exerts
• MRIs distinguish soft tissues making them more useful than X-Rays
• Electromyography records electrical activity of a muscle
• Biopsies: remove a small tissue sample
Blood and Urine tests
• Show muscle enzymes that have leaked into blood– Creatine Kinase
– Lactate Dehydrogenase
– Aldolase
– Aspartate transaminase
• Changes in conc. of electrolytes which are usually more conc. in skeletal muscle than blood.
• How much muscle myoglobin is in the urine.
Creatine kinase (CK)
• Its function is the catalysis of the conversion of creatine to phosphocreatine.– Where do you think the phosphorous comes from?
• Creatine/Phosphocreatine help buffer fluctuations in ATP usage.
• Studies suggest taking creatine can improve muscle performance under high energy aerobic training– Creatine use is not considered doping and is not banned
by sport-governing bodies. In some countries however, like France, creatine is banned.
Structural Disorders of Skeletal Muscle
• Rhabdomyolysis• the breakdown of muscle due to injury, either
mechanical, physical or chemical. The principal result of this process is acute renal failure due to accumulation of muscle breakdown products in the bloodstream, several of which are injurous to the kidney. Treatment is with intravenous fluids, and dialysis if necessary.
Photomicrograph of muscle biopsy sample shows swollen and necrotic muscle fibers without any inflammatory infiltrate
Caution• Things get gross from
here on out. Feel free to look at something calming.
• Edema is the medical term for swelling as a result of fluid in the skin or muscle.
• A hematoma is a collection of blood under the skin. It can occur in any soft tissue such as skin or muscle. A hematoma is caused when blood leaks from an injured vessel.
Contracture: Abnormal shortening of muscles
• Dupuytren's contracture is a fixed flexion contracture of the hand where the fingers bend towards the palm and cannot be fully extended.
Myositis Muscle inflammation
• Viral, bacterial, or parasitic infection• Trichinois: Larva of parasitic rounworms Tricinella get
encysted in muscles.
Caused by eating undercooked pork or bear
~ 12 cases a year in US
~500 cases a year in Thailand
Polymyositis
Degenerated skeletal muscle fibers (amorphous pink) with infiltrating macrophages and regenerating fibers with multiple nuclei and more lavender cytoplasm.
• Crush injuries are associated with significant mechanisms of injury. If a force is great enough, soft tissue (muscles, vessels, skin) can be crushed leading to extensive tissue damage and subsequent swelling and pain. Crush injuries in the lower extremities and forearm can lead to compartment syndrome that generally takes a few hours to develop.
• In the eyes of a ranger,The unsuspecting stranger,Had better know the truth of wrong from right,
'Cause the eyes of a ranger are upon you,Any wrong you do, he's gonna see,
When you're in Texas, look behind you,
'Cause that's where the rangers gonna be.
Intrinsic and Extrinsic Muscles
• Intrinsic muscles are contained within a region such as the hand.
• Extrinsic muscles move the fingers but are found outside the region.
Skeletal Muscle Innervation
• Cranial nerves arising from the brain– exit the skull through foramina– numbered I to XII
• Spinal nerves arising from the spinal cord– exit the vertebral column through
intervertebral foramina
How Muscles are Named
• Nomina Anatomica– system of Latin names developed in 1895– updated since then
• English names for muscles are slight modifications of the Latin names.
• Table 10.1 = terms used to name musclesdigiti = of a finger
levator = elevates a body part
profundus = deepest
quadriceps = having 4 heads
Learning Strategy
• Explore the location, origin, insertion and innervation of 160 skeletal muscles using the tabular information in this chapter.
• Increase your retention & understanding by:– examining models and photographic atlases– palpating yourself using the images in Atlas B– observe an articulated skeleton– say the names aloud and check your pronunciation
The Muscular System
Muscles of Facial Expression
• Small muscles that insert into the dermis
• Innervated by facial nerve (CN VII)
• Paralysis causes face to sag
• Found in scalp, forehead, around the eyes, nose and mouth, and in the neck
Occipitofrontalis is found in the scalp. Frontalis m. raises the eyebrows while Occipitalis m. fixes the galea aponeurotica
Muscles of the Scalp and Forehead
Frontalis
Occipitalis
Corrugator supercilii
Muscles around the Eyes
Nasalis
Orbicularis oculi closes the lips. Corrugator draws the eyebrows together. Procerus pulls down the skin of forehead. Nasalis widens nostrils.
Procerus
Orbicularis Oculi
• Orbicularis oris encircles mouth & other mm blend into it• Levator & depressor of labii (lip) & anguli (angle of mouth)• Risorius & zygomaticus curl corner of mouth up in smile• Buccinator keeps food on top of teeth, blowing & sucking
Muscles around the Mouth
Orbicularis oris
Risorius
Depressor labii inferioris
BuccinatorZygomaticus major
Depressor anguli oris
Levator labii superioris
Some of the Muscles used in Facial Expression
Some of the Muscles used in Facial Expression
Musculature of the Tongue• Intrinsic muscles = vertical, transverse & longitudinal• Extrinsic muscles connect tongue to hyoid, styloid
process, palate and inside of chin• Tongue shifts food onto teeth & pushes it into pharynx
Intrinsic tongue muscles
Extrinsic tongue muscles
Muscles of Mastication• 4 Major muscles
• Arise from skull & insert on mandible
• Temporalis & Masseter elevate the mandible
• Medial & Lateral Pterygoids help elevate, but produce lateral Swinging of jaw used to grind with molars
Temporalis
Masseter
Lateral pterygoid
Medial pterygoid
Suprahyoid Muscles and Swallowing• Digastric and Mylohyoid = open mouth• Geniohyoid = widens pharynx during swallowing• Stylohyoid = elevates hyoid• Thyrohyoid (an infrahyoid m.) = elevates larynx, closing glottis
Digastric Mylohyoid
StylohyoidThyrohyoid
Triangles of the Neck
Other Muscles involved in Swallowing
• Pharyngeal constrictors push food down throat• Infrahyoid muscles pulls the larynx downward • Intrinsic laryngeal muscles used to control speech
Pharyngeal constrictors
Muscles of Respiration• Breathing requires the use of muscles
– diaphragm– external intercostal muscles– internal intercostal muscles
• Contraction of the first 2 produces Inspiration• Contraction of the last produces Forced Expiration• Normal Expiration requires little muscular activity
– elastic recoil of tissues and gravity collapsing the chest– only inspiratory muscles active in braking action, so
exhalation is smooth
Muscles of Respiration -- Diaphragm
• Muscular dome between thoracic and abdominal cavities
• Muscle fascicles extend to a fibrous central tendon
• Contraction flattens it– increases the vertical dimension of the thorax drawing air into
the lungs
– raises the abdominal pressure to help expel urine, feces and facilitating childbirth
Central tendon
Muscles of Respiration -- Intercostals
• External intercostals– extend downward and anteriorly
from rib to rib
– pull ribcage up & outward during inspiration
• Internal intercostals– extend upward and anteriorly from
rib to rib
– pull ribcage downward during forced expiration
Muscles of Respiration - Serratus
• Serratus posterior superior– elevates ribs 2-5 during
inspiration
• Serratus posteriori inferior – depresses ribs 9-12 during
inspiration
Muscles of the Abdomen
• 4 Pairs of sheetlike muscles– external oblique– internal oblique– transverse abdominis– rectus abdominis
• Functions– support the viscera– stabilize the vertebral column– help in respiration, urination, defecation & childbirth
Rectus Abdominis & External Oblique• External oblique
– superficial
– downward
– anteriorly
– inguinal ligament
• Rectus abdominis– vertical, straplike
– tendinous intersections
– rectus sheath
– linea alba
External oblique Rectus abdominis
Internal Oblique -Transverse Abdominis
• Internal oblique– anteriorly
– upwards
• Transverse abdominis– horizontal fiber
orientation
– deepest layer
Transverse abdominisInternal oblique
Superficial Muscles of the Back
Trapezius
Latissimus dorsi
SemispinalisSplenius
Levator scapulaeRhomboideusSupraspinatusInfraspinatusTeres major
Gluteus maximusGluteus medius
Muscles of the Back• Erector spinae group
– 3 columns muscle
– extends from sacrum to ribs
– extends vertebral column
• Semispinalis group– vertebrae to vertebrae
– extends neck
• Multifidis– vertebrae to vertebrae
– rotates vertebral column
• Quadratus lumborum– ilium to 12th rib
– lateral flexion
Multifidis
Erector spinae
Quadratus lumborum
Semispinalis
Muscles of the Pelvic Floor• 3 Layers of muscles span pelvic outlet
– support pelvic viscera
• Region is called perineum – diamond-shaped region bounded by pubic symphysis, coccyx
and ischial tuberosities– penetrated by anal canal, urethra & vagina– anteriorly = urogenital triangle; posteriorly= anal triangle
• 3 Layers or compartments of the perineum– superficial layer = Superficial perineal space– middle layer = Urogenital diaphragm & Anal sphincter– deep layer = Pelvic diaphragm
•
Muscles in Superficial Perineal Space
• 3 Muscles found just deep to the skin• Ischiocavernosus = arises from ischial & pubic ramus• Bulbospongiosus = covers bulb of penis or encloses vagina• Superficial transverse perineus = extends from the ischial tuberosities to the central tendon
of the perineum• Function during sexual intercourse & voiding of urine
Bulbospongiosus
Ischiocavernosus
Superficial transverse perineus
Muscles of the UG diaphragm
• Middle layer of pelvic floor contains Urogenital diaphragm and External anal sphincter
• Urogenital diaphragm = 2 muscles– deep transverse perineus m. supports pelvic viscera– external urethral sphincter m. inhibits urination
External anal sphincter
Urogenital diaphragm
Muscles of the Pelvic Diaphragm
• Deepest compartment of the perineum • Pelvic diaphragm = 2 muscles
– levator ani m. supports viscera & functions during defecation
– coccygeus m. supports and elevates pelvic floor
Levator ani
Coccygeus
Hernias• Protrusion of viscera through muscular wall of
abdominopelvic cavity
• Inguinal hernia– most common type of hernia (rare in women)– viscera enter inguinal canal or even the scrotum
• Hiatal hernia– stomach protrudes through diaphragm into thorax– overweight people over 40
• Umbilical hernia– viscera protrude through the navel
Muscles Acting on the Pectoral Girdle
• Originate on axial skeleton & insert onto clavicle or scapula
• Anterior muscle group = 2 muscles
• Posterior muscle group = 4 muscles
• Scapular movements produced include– medial and lateral rotation of the scapula– elevation and depression of the scapula– protraction and retraction of the scapula
• Clavicle braces the shoulder & limits movement
Anterior Scapular Muscle Group• Pectoralis Minor
– ribs 3-5 to coracoid process of scapula
– protracts & depresses scapula
– lifts ribs during forced expiration
• Serratus Anterior– ribs 1-9 to medial
border of scapula
– abducts & rotates or depresses scapula
– throwing muscle
Muscles Acting on the Scapula
Posterior Scapular Muscle Group
• 4 Muscles – superficial = Trapezius– deep = Rhomboids & Levator scapulae
• Trapezius– rotate scapula upward– retract scapula– depress scapula
• With Levator scapulae & Rhomboids elevates scapula
• With Serratus anterior depresses scapula
• Rhomboideus mm.– medial border of
scapula to C7-T1
Posterior Scapular Muscle Group
• Levator scapulae– from superior angle of
scapula to C1-C4
Muscles Acting on the Humerus• 9 Muscles cross the shoulder joint to the humerus
– 2 axial muscles arise from axial skeleton– prime movers of humerus in flexion & extension– arise from sternum & clavicle OR T7-L5 & ilium
Pectoralis major Latissimus dorsi
• 7 scapular muscles arise from scapula
– Deltoid is prime mover• flexion, extension and abduction
of humerus
– Coracobrachialis assists in flexion
– Teres major assists in extension
– Remaining 4 form the rotator cuff muscles that reinforce the shoulder joint capsule
Muscles Acting on the Humerus
Posterior View of Chest in Cadaver
Rotator Cuff Muscles
• Extending from posterior scapula to humerus – supraspinatus
– infraspinatus
– teres Minor
• Extending from anterior scapula to humerus – subscapularis
All 4 help reinforce joint capsule.
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
Anterior View of Chest in Cadaver
Muscles Acting on the Elbow• Principal flexors
– biceps brachii • inserts on radius
– brachialis • inserts on ulna
• Synergistic flexor– brachioradialis
• Prime extensor– triceps brachii
• inserts onto ulna
CS Through Upper Limb & Forearm
Supination & Pronation of the Forearm
Supination• Supinator muscle• Palm facing anteriorly
Pronation• Pronator teres and Pronator
quadratus mm.• Palm faces posteriorly
Muscles of the Anterior Forearm• Flex/extend wrist and fingers, adduct/abduct wrist• Digitorum = inserts into fingers• Carpi = inserts onto carpal bones• Pollicis = inserts into thumb
Muscles of the Posterior Forearm• Extension of wrist and fingers, Adduct/abduct wrist• Extension and abduction of thumb (pollicis)• Brevis = short, Ulnaris = on ulna side of forearm
Extensors
• Thenar group = fleshy base of thumb muscles• Hypothenar group = base of little finger muscles• Midpalmar group = Interosseus mm. & Lumbrical mm.
Intrinsic Hand Muscles
Interosseus
Lumbrical
Carpal Tunnel Syndrome
repetitive motions causes inflammation and
pressure on median nerve
Anterior Muscles Acting on the Hip
• Iliopsoas muscle– crosses anterior surface of hip joint & inserts on femur
– iliacus portion arises from iliac fossa
– psoas portion arises from lumbar vertebrae
– major hip flexor
Iliopsoas
Posterior Muscles Acting on the Hip
• Gluteus maximus– forms mass of the
buttock
– prime hip extensor
– provides most of lift when you climb stairs
• Iliotibial band– band of fascia lata
attached to the tibia
Gluteus maximus
Gluteus medius
Iliotibial band
Deep Gluteal Muscles
• Most laterally rotate femur• Except: Gluteus minimus medially rotates femur• Important in walking to shift body weight when foot is
lifted• Quadratus femoris is adductor of hip• Piriformis & Gluteus minimus are abductors of hip
Quadratus femoris
Piriformis
Gluteus minimus
Adductors of the Hip Joint
• 5 muscles act as adductors• Adductor magnus is also an
extensor of hip joint• Gracilis also is flexor of knee• Pectineus, Adductor brevis
and Adductor longus adduct the femur
Adductor longus
Adductor brevis
Pectineus
Adductor magnus
Muscles Acting on the Knee
• 4 headed muscle attaches to tibial tuberosity– extends knee joint
• rectus femoris arises from ilium so flexes hip joint
• quadriceps femoris tendon attaches to patella
• patellar ligament attaches to tibia
Anterior Thigh Muscles in Cadaver
Muscles of the Leg
• Crural muscles are separated into 3 compartments.– anterior compartment (green)– fibular (lateral) compartment (blue)– posterior (superficial = brown) (deep = purple)
Anterior Compartment of the Leg
• Extensor digitorum longus = extension of toes & ankle• Extensor hallucis longus = extension of big toe & ankle• Fibularis tertius = dorsiflexes and everts foot• Tibialis anterior = dorsiflexes and inverts foot
Extensor digitorum longus
Peroneus tertius
Extensor hallucis longus
Tibialis anterior
Posterior Compartment of the LegSuperficial Group of Plantar Flexors
• Gastrocnemius = flexes knee and plantar flexes ankle• Soleus = plantar flexes ankle• Plantaris = flexes knee and plantar flexes ankle
GastrocnemiusSoleus
Plantaris
Posterior Compartment of the LegDeep Group of Plantar Flexors
• Tibialis posterior, Flexor digitorum longus, and Flexor hallucis longus and are plantar flexors.
• Popliteus unlocks the knee joint for knee flexion.
Lateral Compartment of the Leg
• 2 muscles in this compartment
• Both plantar flex and evert the foot
• Provides lift and forward thrust
Fibularis brevis
Fibularis longus
Leg Muscles in the Cadaver
Intrinsic Muscles of the Sole
• Four muscle layers • Support for the arches
– abduct & adduct the toes
– flex the toes
• One dorsal muscle– extensor digitorum brevis
extends toes
Dorsal view
Athletic Injuries• Vulnerable to sudden and intense stress
• Proper conditioning and warm-up is needed
• Common injuries – shinsplints– pulled hamstrings– tennis elbow
• Treat initially with rest, ice, compression and elevation
• “No pain, no gain” is a dangerous misconception.