the muscular system part a 1. interactions of skeletal muscles skeletal muscles work together or in...
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The muscular system
PART A
1
Interactions of Skeletal Muscles
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
2
Muscle Classification: Functional Groups
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
Fixators – synergists that immobilize a bone or muscle’s origin
4
Names of skeletal muscles
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
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
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
Facial expression muscles Orbicularis oris
O: maxilla and mandible I: lipsA: compresses lips
BuccinatorO: maxilla and mandible I: orbicularis orisA: compresses the cheek
(whistling)11
Muscles of the Head
Occipitofrontalis musclesOccipital
O: occipital boneI: galea aponeuroticA: pulls the scalp posteriorly
FrontalisO: galea aponeuroticI: skin of the eyebrowA: raise the eyebrow
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Muscles of the Head
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
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
14
Muscles of the Head
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
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
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
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
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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Figure 15.3c
Summary of Cranial Nerves and Muscle Actions
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Muscles of the Neck
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Muscles of the Neck
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Muscles of the Neck
PlatysmaO: fascia of chest and deltoid I: mandible, skin, corner of the
mouthA: depresses mandible, pulls lip
back and down Sternocleidomastoid
O: manubrium and clavicle I: temporal and occipital bonesA: flexion forward of the neck
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Muscles of the Neck
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
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
Muscles inserting on the scapula:Rhomboid muscles
O: vertebraeA: adducts and stabilizes scapula
Levator scapulae musclesO: vertebraeA: elevates scapula
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Muscles of the Thorax
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Muscles of the Thorax
Abductors of the shoulder joint:Deltoid muscles (major
abductor)O: clavicle and scapulaI: humerus
Supraspinatus musclesO: scapulaI: humerus
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Muscles of the Thorax
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Muscles of the Thorax
Lateral rotation of the shoulder joint:Infraspinatus muscles
O: scapulaI: humerus
Teres minor musclesO: scapulaI: humerus
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Muscles of the Thorax
Medial rotators of the shoulder jointTeres major muscles
O: scapulaI: 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 musclesA: 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
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 musclesO: 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
External intercostalO: rib aboveI: rib belowA: elevates rib cage
Internal intercostalO: rib belowI: rib aboveA: depresses rib cage
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Muscles of Respiration
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Muscles of Respiration
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Muscles of Respiration
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
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 flexion46
Muscles of the Abdomen
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
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
Brachialis O:humerus I: ulna A: synergist for flexion of the elbow
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Muscles of the Arm
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
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
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
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
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
Gluteal muscles (O: ilium; I: femur) Gluteus maximus
A: extension and lateral rotation of thigh
Gluteus medius and minimusA: 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
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
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
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
Quadriceps (I: tibia; A: extends the knee) Rectus femoris
O: ilium Vastus medialis, intermedius,
lateralisO: femur
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Muscles of the leg
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Muscles of the leg
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
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
Plantar flexion (I: calcaneal tendon) Gastrocnemius muscle
O: femur Soleus muscle
O: fibula and tibia Eversion and plantar flexion
Fibularis muscleO: fibula I: foot
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Flexors of the knee
Popliteus muscle O: femur I: tibia A: unlocks the knee joint
78
Muscles of the leg
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Muscles of the leg
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
80
Muscles of the leg
81
Muscles of the leg
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Muscles That Move the Toes
Extensors digitorum O: Tibia, fibula I: Digits A: Extends the digits
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