Muscular systemnaming muscle

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Chapter 9

• Muscular system-naming muscle

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Anatomy of a skeletal muscle

• Most muscles are attached to different bones at
  each end.
• The attachment at the stationary end is the
  origin
• The attachment at the moveable end is the
  insertion (usually crosses a joint)
• The thick middle part is a belly or gaster.

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Fascicle orientation-5 types

• Fusiform-thick in middle, taper at end (biceps
  brachii)
• Parallel-long, straplike muscle (rectus
  abdominis)
• Convergent-fan shaped, broad origin, narrow
  insertion (pectoralis major)
• Pennate-feather like (unipennate, bipennate,
  multipennate)-example is rectus femoris-bipennate
• Circular-sphincter, fascicles in a ring
  (orbicularis oris)

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Coordinated actions of groups

• Movement produced by muscle is its action.
• Muscles typically function in groups and can be
  classified by their actions
• Prime mover (agonist)-muscle that produces the
  most movement (flex elbow-prime mover is biceps
  brachii)
• Synergist-helps the prime mover (flex
  elbow-synergist is brachialis)

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Actions continued

• Antagonist-opposes the prime mover (the triceps
  brachii is the antagonist when you flex your
  elbow)
• Fixator-prevents a bone from moving (fixator
  muscles keep the scapula from moving when you
  contract your biceps brachii)

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Naming muscle

• Size -major, minor, minimus, maximus, longus,
  brevis
• Shape -trapezoidal (trapezius), deltoid
  (triangular)
• Location -pectoralis, femoris, carpi, etc
• Number of heads (origins) -biceps, triceps,
  quadriceps
• Orientation -rectus, transverse, oblique
• Action -adductor, abductor, extensor, flexor, etc
• Origin/insertion -sternocleidomastoid

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The muscles to know for exam

• You are about to see a bunch of muscles youll
  need to know for the exam.
• Each muscle will have its action written out
  beside it.
• Youll have to know the actions for ALL the
  muscles.
• In addition, some will be highlighted in yellow.
  You have to look up the origins and insertions on
  those muscles and you will be tested on them.

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MUSCLES of HEAD and NECK

• Muscles of Facial expression
• Occipitofrontalis (connected by galea
  aponeurotica) also called epicranius
• occipitalis-retracts scalp
• frontalis-raises eyebrows, draws scalp forward
• Orbicularis oculi- closes eye
• Levator palpebrae superioris-opens eye, raises
  eyelid

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Muscles of Facial Expression continued

• Orbicularis oris-closes lips, protrudes lips as
  in kissing, aids in speech
• Zygomaticus major and minor-draw corners of mouth
  upward as in smiling
• Mentalis-elevates and protrudes lower lip as in
  pouting
• Buccinator-compresses cheek, creates suction as
  in blowing and sucking (trumpeter muscle)
• Platysma-depresses mandible, opens and widens
  mouth, tenses skin of neck (look of horror)

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Muscles of Chewing and Swallowing

• Genioglossus, hypoglossus, styloglossus, and
  palatoglossus move the tongue and are called the
  extrinsic muscles of the tongue and they connect
  the tongue to other structures in the head and
  neck
• Masseter-elevates mandible for biting and chewing
• Temporalis-elevates mandible for biting and
  chewing

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Muscles that move the head and vertebral column

• Sternocleidomastoid-one side contracts to turn
  face toward opposite side, when both sides
  contract you bend head toward chest
• Splenius capitis-strap like muscle in the neck
  that hold the head erect
• Semispinalis capitis-sheet like muscle in neck,
  extends head, bends it to one side, or rotates
  it.
• Erector spinae-run along the back, extend and
  rotate head, maintain erect position of vertebral
  column
• Trapezius-abducts and extends neck when scapula
  is fixed.

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Muscles of respiration

• Diaphragm-contracts and increases volume of
  thoracic cage to allow air flow into lungs
• External intercostals-pull ribs upward and
  outward, helping inflate lungs
• Internal intercostals-draw ribs downward and
  inward to compress thoracic cavity and force air
  out of lungs

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Muscles of the abdomen

• Rectus abdominis-supports abdominal viscera,
  flexes waist (sit ups), depresses ribs, stabilize
  pelvis while walking, helps with defecation and
  urination (and childbirth)
• External oblique-flexes waist (sit ups), flex and
  rotate vertebral column
• Internal oblique-similar to external oblique
• Transverse abdominis-compress abdomen, increase
  intra-abdominal pressure, flexes vertebral column

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Muscles of the back-extend, rotate, and abduct
the vertebral column

• Superficial group-erector spinae group-prime
  mover of spinal extension
• Divided into 3 columns iliocostalis, longissimus,
  and spinalis (cervical, thoracic, and lumbar
  portions)
• Most of your lower back muscles are in the
  longissimus group
• Major deep muscle is semispinalis which also
  divides into 3 parts
• Semispinalis capitis, semispinalis cervicis, and
  semispinalis thoracis
• See table 9.5 for full names

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Muscles that move the pectoral girdle (act on the
scapula)

• Trapezius -superior fibers elevate or rotate
  scapula, middle fibers retract scapula, inferior
  fibers depress scapula
• Levator scapulae-elevates scapula
• Rhomboideus major and minor-retract and elevate
  scapula (major also rotates scapula)
• Serratus anterior-elevates ribs, abducts and
  rotates scapula, depresses scapula, prime mover
  in thrusting, pushing, throwing (boxers muscle)
• Pectoralis minor-protracts and depresses scapula
  (forward and downward), raises ribs

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Muscles that move the arm (act on the humerus)

• Pectoralis major-adducts and rotates humerus,
  prime mover of flexion, aids in climbing,
  pushing, throwing and (hugging)
• Latissimus dorsi -adducts and medially rotates
  humerus, extends shoulder joint, allows downward
  strokes of the arm (swimming)
• Deltoid-lateral fibers abduct, anterior fibers
  flex and rotate medially, posterior fibers extend
  and laterally rotate humerus
• Teres major-adducts and medially rotates humerus,
  extends shoulder joint

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Acting on the humerus continued

• Coracobrachialis-adducts arm, flexes shoulder
  joint
• ROTATOR CUFF MUSCLES-hold head of humerus in
  glenoid cavity
• Infraspinatus-extends and laterally rotates
  humerus
• Supraspinatus-abducts humerus, resists downward
  displacement when carrying things
• Subscapularis-medially rotates humerus
• Teres minor-adducts and laterally rotates humerus

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Muscles that move the forearm

• Biceps brachii-flexes forearm, supinates hand
  (rotates laterally), helps hold head of humerus
  in glenoid cavity
• Brachialis-flexes forearm at elbow
• Brachioradialis-flexes forearm at elbow
• Triceps brachii-extends forearm at elbow, long
  head adducts humerus
• Pronator teres-pronates forearm (rotates
  medially)
• Pronator quadratus-pronates forearm (rotates
  medially)
• Supinator-supinates forearm (rotates laterally)

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Muscles that move the wrist and hand

• Remember exs are OUT! (posterior compartment)
• Extensor carpi radialis longus-extends wrist and
  abducts the hand
• Extensor carpi radialis brevis-extends wrist,
  abducts hand, fixes wrist during finger flexion
• Extensor carpi ulnaris-extends wrist and adducts
  hand
• Extensor digitorum-extends fingers II-V

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Anterior compartment (muscles acting on wrist and
hand)

• Flexor carpi radialis-flexes wrist and abducts
  hand (powerful)
• Flexor carpi ulnaris-flex wrist and adducts hand
• Palmaris longus-weak flexor of wrist, may be
  absent
• Flexor digitorum superficialis-flexes fingers
  II-V and wrist

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Muscles that move the hip and femur

• Iliacus-flexes femur
• Psoas major-flexes femur
• Tensor fasciae latae-flexes hip joint, abducts
  and medially rotates femur
• Gluteus maximus-extends hip joint, abducts and
  laterally rotates femur
• Gluteus medius and minimus-abduct and medially
  rotate femur, maintain balance by shifting weight
  when walking

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Muscles that move the hip and femur continued

• Adductor longus and brevis-adduct and laterally
  rotate femur, flex hip joint
• Adductor magnus-anterior part adducts and
  laterally rotates femur, flexes hip joint,
  posterior part extends hip joint
• Gracilis-adducts femur, flexes leg at knee,
  medially rotates tibia
• Pectineus-adducts and laterally rotates femur,
  flexes hip

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Muscles that move the knee

• Quadriceps femoris-extends leg at knee
• Rectus femoris-also flexes hip
• Vastus lateralis
• Vastus medialis
• Vastus intermedius
• Sartorius-flexes leg and thigh, abducts and
  rotates thigh laterally (tailor muscle used to
  cross legs)

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Continued

• Hamstrings-
• Biceps femoris-flex leg at knee, extends thigh,
  laterally rotate leg
• Semimembranosus-flex leg knee, extends thigh,
  medially rotates tibia
• Semitendinosus-flex leg knee, extends thigh,
  medially rotates tibia

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Muscles that move the foot

• Extensor digitorum longus-extends toes II-V
  dorsiflex and everts foot
• Peroneus (fibularis) tertius-dorsiflex and everts
  foot
• Tibialis anterior-dorsiflex and invert foot
• Gastrocnemius-flexes leg at knee, plantar flex
  foot
• Soleus-plantar flex foot
• Flexor digitorum longus-flex toes II-V plantar
  flex and invert foot
• Peroneus (fibularis) longus-plantar flex and
  everts foot

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Muscles that move the eyeball

• Superior oblique-moves eyeball inferiorly and
  laterally and rotates eye medially
• Inferior oblique- moves eyeball superiorly, and
  laterally and rotates it laterally
• Medial rectus-moves eyeball medially
• Lateral rectus-moves eyeball laterally
• Superior rectus-moves eyeball superiorly
• Inferior rectus-moves eyeball inferiorly

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Injury

• Hamstring pull-strain or partial tear in
  hamstring, usually the semitendinous region
• Tennis elbow-inflammation of the origin of the
  extensor carpi muscles on the lateral epicondyle
• Pulled groin-strain in the adductor muscles of
  the thigh
• Charley horse-tear, stiffness, or blood clotting
  in a muscle (football tackles cause of charley
  horse in quadriceps)
• RICE-rest, ice, compression, elevation is usually
  the treatment for muscle injury
• Carpal tunnel syndrome-repetitive motions like
  typing cause swelling of carpel tunnel, which
  puts pressure on median nerve of wrist

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Intramuscular injections

• Amounts of up to 2 ml are injected into deltoid
• Amounts over 2 ml are injected into gluteus
  medius
• In children and infants often use the vastus
  lateralis because their deltoid and gluteus
  medius arent well developed yet.