Muscular System

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Muscular System

• Human Anatomy and Physiology I
• Oklahoma City Community College

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Muscles
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Flexion
The angle of the joint is decreased
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Extension
Angle of joint is increased
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Hyperextension
Extended past the anatomical position
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Dorsiflexion Plantar Flexion
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Abduction, Adduction Circumduction
Abduction away from median plane Adduction
toward median plane Circumduction inscribes a
circle
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Rotation
Bone turns on its own axis e.g. shake head no
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Gliding
One bone slides over another
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Muscle Attachments
Moves the most
Moves the least
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Sternocleidomastoideus

• Flexes and Rotates Head

O Sternum Manubrium Clavicle
I Mastoid process
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Masseter

• Elevate Mandible

O Zygomatic Arch
I Mandible
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Temporalis

• Elevate Retract Mandible

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Trapezius

• Extend Head, Adduct, Elevate or Depress Scapula

Trapezius
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Latissimus Dorsi

• Extend, Adduct Rotate Arm Medially

Latissimus dorsi
O Vertebrae, Ilium, Ribs, Scapula
I Humerus
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Deltoid

• Abduct, Flex Extend Arm

O Clavicle and Scapula
I Deltoid Tuberosity of Humerus
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Supraspinatus

• Abduct arm

Synergistic with deltoid. Synergistic muscles
that work together.
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Infraspinatus

• Rotates Humerus Laterally

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Pectoralis Major

• Flexes, adducts rotates arm medially

O Clavicle and Sternum
I Greater Tubercle of Humerus
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Biceps Brachii

• Flexes Elbow Joint

O Coracoid Process Glenoid Cavity
I Radial Tuberosity
Anterior side of upper arm
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Triceps Brachii

• Extend Elbow Joint

O Humerus Scapula
I Olecranon
Back of upper arm
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Rectus Abdominus

• Flexes Abdomen

O Pubis
I Xiphoid Process Cartilage of Ribs
Contraction flexes abdomen
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External Oblique

• Compress Abdomen

Contraction compresses abdomen
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External Intercostals

• Elevate ribs

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Internal Intercostals

• Depress ribs

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Diaphragm

• Inspiration (when contracted)

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Forearm Muscles

• Flexor carpiFlexes wrist
• Extensor carpiExtends wrist
• Flexor digitorumFlexes fingers
• Extensor digitorumExtends fingers
• PronatorPronates
• SupinatorSupinates

supine
pronated
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Gluteus Maximus

• Extends Rotates Thigh Laterally

O Ilium, Sacrum Coccyx
I Gluteal Tuberosity
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Rectus Femoris

• Flexes Thigh, Extends Lower Leg

O Ilium
I Patella Tibial Tuberosity
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Vastus Lateralis

• Extends Lower Leg

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Vastus Medialis

• Extends Lower Leg

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Adductor Longus

• Adduct, Rotate Flex Thigh Laterally

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Gracilis

• Adducts and Flexes Thigh

Medial side of thigh
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Sartorius

• Flexes Thigh, Rotates Thigh Laterally

O Anterior Superior Iliac Spine
I Medial Side of Tibia
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Biceps Femoris

• Extends Thigh Flexes Lower Leg

O Ischial Tuberosity
I Tibia Fibula
One of the hamstrings
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Semitendinosus

• Extends Thigh Flexes Lower Leg

Another hamstring
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Semimembranosus

• Extends Thigh Flexes Lower Leg

Third hamstring
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Gastrocnemius

• Plantar Flexes Foot Flex Lower Leg

O Femur
I Calcaneus of Foot
Calf muscle
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Tibialis Anterior

• Dorsiflexes and Inverts Foot

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Muscle Stimulation
Motor Neuron
Muscle
End of neuron attaches to muscle acetylcholine
stimulates muscle to contract.
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Motor Neuron
Vesicles store acetylcholine which is released
when the nerve impulse reaches the end of the
neuron
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Myoneural Junction
Where muscle neuron connect Acetylcholine
diffuses across small space
muscle
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Acetylcholine Receptors
Muscle membrane
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Acetylcholine Stimulates Muscle to Contract
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Acetylcholinesterase

• Breaks Down Acetylcholine

muscle
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Nerve Stimulus Stops
Motor Neuron
Muscle
No nerve impulse ? no acetylcholine released ?
muscle will not contract
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Origin

• Muscle attachment that moves the least

Insertion
Muscle attachment that moves the most
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Neuromuscular Junction

• The connection between a nerve cell and a muscle
  cell

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Motor Neuron

• A nerve cell that carries an impulse away from
  the brain
• Stimulates a muscle to contract

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Atrophy

• Shrinkage of a muscle
• Caused by inactivity of a muscle

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Hypertrophy

• Enlargement of a muscle
• Enhanced by lifting weights and male hormones

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Stimulus

• Something that causes a response
• Nerve impulse
• Stimulus for muscle cells to contract

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Tendon

• The end of a muscle that attaches to a bone

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Acetylcholine

• A neurotransmitter that stimulates muscles to
  contract

Acetylcholinesterase

• An enzyme
• Breaks down acetylcholine in the myoneural
  junction

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Muscular Dystrophy

• Degeneration of muscle tissue
• May be inherited
• Body does not produce the protein dystrophin
• Muscle cell membrane distorted

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Myasthenia Gravis

• Receptors on muscle membrane for acetylcholine
  are destroyed

Normal receptor
Defective receptors
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Muscle Strain or Pull

• Excessive stretching of a muscle
• Muscle tissue may tear
• Muscle becomes inflamed and sore

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Shin Splints

• Pain in the anterior region of the tibia
• Inflamed tibialis anterior muscle
• Muscle tear
• Unusual exercise

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