The Muscular System

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The Muscular System

• Part I

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Review

• Cardiac
• Smooth
• Skeletal

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Bones operate as a system of levers, but muscles
provide the power to make them move.
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Skeletal muscles

• How skeletal muscles attach. They attach to one
  bone at one end and across a joint at its other
  end. When the muscle contracts, one bone is
  pulled toward or away from the other
• One will contract, while the other relaxes
  (shorten vs lengthen)
• You have about 600 skeletal muscles in your body.

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How muscles are named

• Shape - deltoid
• Size gluteus maximus
• Location - supraspinatus
• Attachment sites - sternohyoid
• Number of heads of origin - biceps
• Action extensor digitorum
• Direction of fibers - transversus

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Attachment of Muscles

• Component parts
• Usually attached to a bone or cartilage
• Attached by a tendon
• Tough cord of connective tissue
• Extends into the periosteum and the bone
• Aponeurosis broad flat sheet (such as abdominal
  wall)

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Origin and Insertion

• When a muscle contracts, one of the bones
  attached to it remains stationary (origin) while
  the other bone moves along with the contractions
  (insertion)
• They can be reversed upon a different action.

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SITS muscles

• Are also called the rotator cuff muscles
• Supraspinatus
• Teres minor
• Teres major
• Infraspinatus
• Subscapularis

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Head muscles

• Masseter, temporalis and buccinator are all
  responsible for chewing.
• Frontalis raises the eyebrows, wrinkles forehead
  skin
• Occipitalis fixes aponeurosis and pulls scalp
  posteriorly
• Zygomaticus smiling muscle
• Orbicularis oris kissing muscle
• Buccinator whistling, blowing holds food
  between teeth

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Neck muscles

• Sternocleidomastoid head flexion

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Hernia

• The protrusion of a body part or organ through a
  weakness in the muscular or abdominal wall.
• Hiatal
• Inguinal

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Hiatal Hernias

• Occurs when part of the stomach bulges out of the
  abdomen and into the chest cavity.
• The upper stomach bulges through the diaphragm at
  the esophageal connection or a similar opening

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Inguinal Hernia

• A bulge of soft tissue through a weak spot in the
  abdominal wall in the groin area.
• The weak spot can be a result of living and
  aging, lifting heavy objects or other activities
  that put excessive stress and pressure on the
  abdominal wall.
• The weak spot can also occur due to an opening
  that usually closes before birth.

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Charley Horse

• An injury to muscle resulting in tearing, leading
  to intense, prolonged pain. Bleeding into
  adjacent tissues usually follows forming sub
  dermal discoloration (bruising).
• Common sports injury in contact sports
  frequently in the quadriceps

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Cramp

• A painful, involuntary contraction of a muscle.
• Overexertion and dehydration electrolyte
  imbalance
• Inactivity

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Myalgia

• A condition of muscle pain that accompanies many
  infectious diseases such as influenza, measles
  and rheumatic fever

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Strain

• Overuse
• Muscle stretched without warmup
• Growth spurt

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Interaction of skeletal muscles

• Skeletal muscles function in groups
• A prime mover is responsible for most of a
  movement
• Synergists aid prime movers.
• Antagonists can resist the action of a prime
  mover

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Muscles of facial expression

• Orbicularis oculi
• Orbicularis oris
• Buccinator
• Zygomaticus

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Muscles of mastication

• Masseter
• Temporalis

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Moving the head

• Sternocleidomastoid
• Tennis match
• NIGHT AT THE ROXBERRY

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Pectoral girdle

• Trapezius
• Pectoralis minor

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Move the arm

• Pectoralis major
• SITS
• Deltoid
• Latissimus dorsi

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Move the forearm

• Biceps bracii
• Triceps

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Move the wrist, hand and fingers

• Flexor carpi radialis
• Flexor carpi ulnaris
• Extensor carpi ulnaris
• Extensor digitorum

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Muscles of the abdominal wall

• External oblique
• Internal oblique
• Transversus abdominis
• Rectus abdominus

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Move the thigh

• Gluteus maximum
• Gluteus medius
• Adductors

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Move the leg

• Hamstrings
• Quadriceps
• Sartorius

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Move the ankle, foot and toes

• Tibialis anterior
• Gastrocnemius
• Soleus
• Fibialis group