Download The Muscular System

The Muscular System
CH. 10 Part 2
Muscles of the Head and Face
• Important in facial expressions
• All but one innervated by CN VII (facial nerve)
– Levator palpebrae superioris
Fig. 10.7a
Fig. 10.7b
Bell Palsy
• Idoipathic facial nerve paralysis
• Results from disease or injury
to CN VII
• Treatments include steroids
and antiviral medication
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
Muscles of the Neck
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Neck Muscles
• Sternocleidomastoid
– O – manubrium and medial part of clavicle
– I – Mastoid process and lateral side of nuchal line
– Action
• bilateral, flexion of head
• Unilateral, tilting head up and to side, rotating head.
• Digastric
– O – mastoid notch of temporal bone, digastric fossa of mandible
– I – hyoid bone
– Action
• When hyoid fixed, opens mouth wide
• When mandible fixed, elevates hyoid
• Mylohyoid
– O – Mylohyoid line near inferior margin of mandible
– I – hyoid bone
– Action
• Forms floor of mouth, elevates floor of mouth during initial phases of swallowing
Muscles of the Arm
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Muscles of the Arm
• Biceps Brachii
– O – long head, sup. margin of glenoid cavity; short head, coracoid process
– I – tuberosity of radius, fascia
– Action
• Synergist in elbow flexion, supination of wrist
• Brachialis
– O – anterior surface of distal humerus
– I – Coronoid process and tuberosity of ulna
– Action
• Prime mover in elbow flexion
• Triceps Brachii
– O – Long head, inf. margin of glenoid cavity; lateral head, posterior surface of
proximal end of humerus; medial head, posterior surface of humeral shaft
– I – olecranon, fascia of forearm
– Action
• Extends elbow, long head extends and adducts humerus
Muscles of the Forearm
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Muscles of the Forearm
• Brachioradialis
– O – lateral supracondylar ridge of humerus
– I – Lateral surface of radius near styloid process
– Action
• Flexes elbow
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• http://patticarothersonline.org/cat_muscles_
of_the_forearm_photo.htm
Muscles of the Chest, Abdomen, and
Back
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Muscles of the Back
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Muscles of the Neck, Chest, and Back
• Trapezius
– O – External occipital protuberance, medial third
of superior nuchal line and nuchal ligament,
spinous processes of vertebrae C7-T3 or T4
– I – acromion and spine of scapula, lateral third of
clavicle
– Action
• Extends and laterally flexes neck
• Stabilizes scapula and shoulder during arm movements
• Elevates and depresses apex of shoulders
Muscles of the Neck, Chest, and Back
• Erector spinae
– Function to maintain posture and to help stand erect
• Bilateral contraction – extend vertebral column
• Unilateral contraction – lateral flexion of vertebral column
– Organized into three groups
• Iliocostalis
– Cervicis, thoracis, lumborum
• Longissimus
– Capitis, cervicis, thoracis
• Spinalis
– Capitis, cervicis, thoracis
Fig. 10.17
Fig. 10.18
Muscles of Neck, Chest, and Back
• Latissimus Dorsi
– O – Vertebrae T7 – L5, lower 3-4 ribs, iliac crest, thoracolumbar
fascia
– I – Floor of intertubercular sulcus of humerus
– Action
• Adducts and medially rotates humerus , extends shoulder joint,
produces backward swing of arm
• Pectoralis major
– O – Medial half of clavicle, costal cartilages 1-7, aponeurosis of
external oblique
– I – Lateral lip of intertubercular sulcus of humerus
– Action
• Flexes, adducts, and medially rotates humerus
Muscles of the Legs
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Muscles of the Legs
•
Rectus Femoris
– O – Ilium at anterior inferior spine and superior margin of acetabulum, capsule of hip joint
– I – patella, tibial tuberosity, lateral and medial condyles of tibia
– Action
•
•
Extends the knee, flexes thigh at hip, flexes trunk on hip of thigh is fixed
Vastus Lateralis
– O – greater trochanter and intertrochanteric line, gluteal tuberosity, and linea aspera
– I – same as rectus femoris
– Action
•
•
Extends knee, retains patella during knee movements
Vastus Medialis
– O – Femur at intertrochanteric line, spiral line, linea aspera, and medial supracondylar line
– I – Same as rectus femoris
– Action
•
•
Same as vastus lateralis
Sartorius
– O – on and near anterior superior spine of ilium
– I – medial surface of proximal end of tibia
– Action
•
Aids in knee and hip flexion, abducts and laterally rotates thigh
Muscles of the Legs
• Biceps Femoris
– O – Long head, ischial tuberosity; short head linea aspera and lateral
supracondylar line of femur
– I – head of fibula
– Action
• Flexes knee, extends hip , laterally rotates femur when hip is extended
• Semitendinosis
– O – ischial tuberosity
– I – Medial surface of upper tibia
– Action
• Flexes knee, medially rotates tibia on femor when knee is flexed, medially rotates femur
when hip is extended
• Semimembranosus
– O – Ischial tuberosity
– I – medial condyle and margin of tibia, intercondylar line and lateral condyle of
femur, ligament of popliteal region
– Action
• Same as semitendinosus
Muscles of the Lower Leg
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Compartment Syndrome
• Limb muscles organized into
compartments
– Area of functionally related muscles,
blood vessels and nerves surrounded
by deep fascia
• If blood vessels damaged
– Fluid can accumulate in compartment
– Pressure build up results in
degenerative events
• Nerve cell and muscle cell death result
from ischemia
• Treatments
– Resting and immobilizing limb
– fasciotomy
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