Transcript Chapter 10

The muscular
system
PART A
1
Interactions of Skeletal Muscles
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Skeletal muscles work together or in
opposition
Muscles only pull (never push)
As muscles shorten, the insertion
generally moves toward the origin
Whatever a muscle (or group of
muscles) does, another muscle (or
group) “undoes
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Muscle Classification: Functional
Groups
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Prime movers – provide the major force
for producing a specific movement
Antagonists – oppose or reverse a
particular movement
Synergists
 Add force to a movement
 Reduce undesirable or unnecessary
movement
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Muscle Classification: Functional
Groups
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Fixators – synergists that immobilize a
bone or muscle’s origin
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Names of skeletal muscles
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Names give clues to muscle
characteristics
 Location: femoris, temporalis, etc
 Fascicle organization: rectus, oblique,
etc
 Relative position: profundus,
superficialis, etc
 Structure: biceps, triceps, etc
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Names of skeletal muscles
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Size: maximus, longus, etc
Shape: trapezius, deltoid, etc
Origin and insertion:
sternocleidomastoid, etc
Action: flexor, pronator, etc
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Organization of skeletal muscle fibers
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Parallel muscle
Convergent muscle
Pennate muscle
 Unipennate
 Bipennate
 Multipennate
Circular muscle (sphincter)
Fusiform
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Arrangement of Fascicles
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Muscles of the Head
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Muscles of the Head
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Muscles of the Head
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Facial expression muscles
 Orbicularis oris
 O: maxilla and mandible
 I: lips
 A: compresses lips
 Buccinator
 O: maxilla and mandible
 I: orbicularis oris
 A: compresses the cheek
(whistling)
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Muscles of the Head
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Occipitofrontalis muscles
 Occipital
 O: occipital bone
 I: galea aponeurotic
 A: pulls the scalp posteriorly
 Frontalis
 O: galea aponeurotic
 I: skin of the eyebrow
 A: raise the eyebrow
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Muscles of the Head
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Orbicularis oculi
 O: frontal and maxillary bones
 I: eyelid
 A: closes eyes
Corrugator supercilli
 O: frontal bone
 I: skin of eyebrow
 A: draws eyebrow inferiorly and
medially
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Muscles of the Head
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Levator labii superioris
 O: zigomatic and maxilla bone
 I: upper lip
 A: raises upper lips
Depressor labii inferioris
 O: mandible
 I: lower lip
 A: pulls lower lip inferiorly
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Muscles of the Head
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Depressor anguli oris
 O: mandible
 I: angle of mouth
 A: pulls corner of mouth down and
laterally
Mentalis
 O: mandible
 I: skin of chin
 A: protudes lower lip
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Muscles of the Head
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Zigomatics
 O: zigomatic bone
 I: corner the mouth
 A: smiling muscle
Risorius
 O: masseter
 I: angle of the mouth
 A: pulls corner of lips laterally
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Muscles of Mastication
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Muscles of Mastication
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Muscles of Mastication
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Masseter muscles
 O: zigomatic and maxilla bones
 I: mandible
 A: closes the jaw
Temporalis muscles
 O: temporal fossa
 I: mandible
 A: closes the jaw
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Muscles of Mastication
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Pterygoids
 O: sphenoid, palatine and maxillary
bones
 I: mandible
 A: elevates mandible
Buccinator
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Extrinsic muscles of the eye
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Extrinsic muscles of the eye
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Inferior and superior rectus muscles
Lateral and medial rectus muscles
Inferior oblique muscles
 Elevates the eye and turns it laterally
Superior oblique muscles
 Depresses the eye and turns it
laterally
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Summary of Cranial Nerves and
Muscle Actions
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Figure 15.3c
Muscles of the Neck
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Muscles of the Neck
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Muscles of the Neck
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Platysma
 O: fascia of chest and deltoid
 I: mandible, skin, corner of the
mouth
 A: depresses mandible, pulls lip
back and down
Sternocleidomastoid
 O: manubrium and clavicle
 I: temporal and occipital bones
 A: flexion forward of the neck
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Muscles of the Neck
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Scalenes – anterior, middle, posterior
 O: cervical vertebrae
 I: first 2 ribs
 A: elevates first 2 ribs
Digastric
 O: mandible and mastoid process
 I: hyoid
 A: elevates hyoid bone
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Muscles of the Neck
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Mylohyoid
 O: mandible
 I: hyoid bone
 A: elevates hyoid bone
Sternohyoid
 O: manubrium and clavicle
 I: hyoid bone
 A: depresses hyoid bone
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Muscles of the Thorax
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Muscles inserting on the scapula:
 Rhomboid muscles
 O: vertebrae
 A: adducts and stabilizes scapula
 Levator scapulae muscles
 O: vertebrae
 A: elevates scapula
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Muscles of the Thorax
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Muscles of the Thorax
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Abductors of the shoulder joint:
 Deltoid muscles (major
abductor)
 O: clavicle and scapula
 I: humerus
 Supraspinatus muscles
 O: scapula
 I: humerus
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Muscles of the Thorax
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Muscles of the Thorax
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Lateral rotation of the shoulder
joint:
 Infraspinatus muscles
 O: scapula
 I: humerus
 Teres minor muscles
 O: scapula
 I: humerus
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Muscles of the Thorax
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Medial rotators of the shoulder joint
 Teres major muscles
 O: scapula
 I: humerus (anterior surface)
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Muscles of the Thorax
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Muscles of the Thorax
Origin on the ribs and insertion on
the scapula:
 Serratus anterior muscles
 A: fixates, protracts the scapula
 Pectoralis minor muscles
 A: ribs fixed: moves scapula
forward and inferiorly and with
scapula fixed it moves up the rib
cage
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Muscles of the Thorax
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Muscles of the Thorax
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Flexion of the shoulder joint (agonist):
 Pectoralis major muscles
 O: clavicle, sternum, ribs, external
oblique muscle
 I: humerus
Extension of the shoulder joint
(agonist):
 Latissimus dorsi muscles
 O: vertebrae, ribs, ilium
 I: humerus
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Muscles of the Thorax
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Muscles of the Thorax
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Muscles of respiration
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External intercostal
 O: rib above
 I: rib below
 A: elevates rib cage
Internal intercostal
 O: rib below
 I: rib above
 A: depresses rib cage
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Muscles of Respiration
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Muscles of Respiration
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Muscles of Respiration
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Diaphragm
 O: ribs and its cartilage, sternum,
vertebrae
 I: central tendon of the cartilage
 A: prime action in inspiration
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Muscles of Respiration
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Muscles of the Abdomen
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Rectus abdominis
 O: pubis
 I: xiphoid process, ribs
 A: flexes vertebral column,increase
abdominal pressure
External oblique
 O: ribs
 I: linea alba, ilium
 A: see above, helps trunk rotation
and lateral flexion
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Muscles of the Abdomen
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Internal oblique
 O: lumbar fascia, ilium, inguinal
ligament
 I: linea alba, pubis, ribs
 A: same as external oblique
Transversus abdominis
 O: ribs, inguinal ligament, ilium,
lumbar fascia
 I: linea alba, pubis
 A: compresses abdominal content
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Muscles of the Abdomen
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Muscles of the Arm
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Muscles of the Arm
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Biceps brachii muscle
 O: scapula, shoulder joint
 I: radius
 A: agonist flexor of the elbow
Brachioradialis
 O: humerus
 I: radius
 A: synergists for flexion of the elbow
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Muscles of the Arm
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Brachialis
 O:humerus
 I: ulna
 A: synergist for flexion of the elbow
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Muscles of the Arm
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Triceps brachii muscle (long, lateral
and medial heads)
 O: scapula, humerus
 I: ulna
 A: agonist extensor of the elbow
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Muscles of the Arm
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Rotator Cuff Muscles
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supraspinatus, infraspinatus, teres
minor, and subscapularis
 Function mainly to reinforce the
capsule of the shoulder
 Secondarily act as synergists and
fixators
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Rotator Cuff Muscles
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Rotator Cuff Muscles
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Muscles of the forearm
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Flexion of the wrist (O: humerus)
 Flexor carpi ulnaris
 I: metacarpus and carpus
 Flexor carpi radialis
 I: metacarpals
 Palmaris longus
 I: palm of the hand
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Muscles of the forearm
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Muscles of the forearm
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Extension of the wrist (O: humerus)
 Extensor carpi radialis
 I: metacarpus
 Extensor carpi ulnaris
 I: metacarpus
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Muscles of the forearm
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Muscles of the forearm
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Pronation of the forearm (I: radius)
 Pronator teres muscle
 O: humerus
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Muscles of the forearm
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Muscles that move the hand
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Muscles that move the hand
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Muscles of the pelvis and lower limb
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Gluteal muscles (O: ilium; I: femur)
 Gluteus maximus
 A: extension and lateral rotation of
thigh
 Gluteus medius and minimus
 A: abduction and medial rotation of
thigh
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Muscles of the pelvis and lower limb
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Muscles of the pelvis and lower limb
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Sartorios
 O: ilium
 I: tibia
 A: flexes the thigh and helps in
crossing the leg
Adductors of the leg
 O: pubis
 I: femur
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Muscles of the pelvis and lower limb
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Gracilis
 O: pubis
 I: tibia
 A: adducts, flexes and medially
rotates the thigh
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Muscles of the pelvis and lower limb
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Iliopsoas muscle
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Formed from the merging of the
psoas major and the iliacus
muscles
O: ilium, vertebrae
I: femur
Flexor of the trunk, flexor of the leg
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Muscles of the pelvis and lower limb
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Muscles of the leg
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Quadriceps (I: tibia; A: extends the
knee)
 Rectus femoris
 O: ilium
 Vastus medialis, intermedius,
lateralis
 O: femur
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Muscles of the leg
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Muscles of the leg
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Tensor fasciae latae
 O: ilium
 I: fasciae latae
 A: flexes, abducts the thigh; tenses
the fasciae latae
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Muscles of the leg
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The hamstrings (O: ischium; I: tibia; A:
extend thigh, flexes knee)
 Biceps femoris muscles
 Semimembranosus muscles
 Semitendinosis muscles
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Muscles of the leg
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Muscles of the leg
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Plantar flexion (I: calcaneal tendon)
 Gastrocnemius muscle
 O: femur
 Soleus muscle
 O: fibula and tibia
Eversion and plantar flexion
 Fibularis muscle
 O: fibula
 I: foot
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Flexors of the knee
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Popliteus muscle
 O: femur
 I: tibia
 A: unlocks the knee joint
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Muscles of the leg
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Muscles of the leg
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Tibialis anterior
 O: tibia
 I: metatarsal and cuneiform bones
 A: dorsiflexion of the foot
Tibialis posterior
 O: tibia
 I: tarsal and metatarsal bones
 A: foot inversion
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Muscles of the leg
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Muscles of the leg
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Muscles That Move the Toes
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Extensors digitorum
 O: Tibia, fibula
 I: Digits
 A: Extends the digits
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