Musculoskeletal Anatomy

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Musculoskeletal Anatomy

• Toby J. Brooks, PhD, ATC, CSCS

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Anatomical Kinesiology Foundations

• What the heck is it?
• The study of muscles as they are involved in the
  science of movement
• Who needs to learn about it?
• Why do I need to take it?

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Overview

• Directional terminology
• Planes of motion
• Axes of rotation
• Types of bones
• Types of joints

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Foundations

• Directional terminology
• Must be familiar with directional termswe will
  use them everyday and it is assumed you learned
  these terms in prerequisite courses (namely A
  P)
• Review terms on pages 3-5

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Foundations

• Group assignment
• Start at the belly button. Move laterally about
  one hand width to the right. Then move inferiorly
  and distally until you reach a hinge joint. Move
  to the posterior side of the joint and travel
  distally until you reach a large tendon. Move to
  the contralateral side (continued)

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Foundations

• Travel superiorly past a hinge joint and a ball
  and socket joint, up the dorsal surface until you
  reach another ball and socket joint. Move to the
  anterior side and medially about two hand widths.
  You are now over a large flat bone. Move
  superiorly approximately two hand LENGTHS, then
  move to the right, lateral-most aspect of this
  structure.

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Foundations

• Where are you?
• Right ear

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Foundations

• Planes
• Frontal or Coronal
• Divides body into anterior and posterior portions
• Sagittal
• Divides body into left and right portions
• Transverse or horizontal
• Divides body into inferior and superior portions

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Planes
Frontal/AP Sagittal Transverse
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Axes of Rotation

• Sagittal/AP
• Lateral
• Vertical

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Types of Bones

• Long
• Ex.- Femur
• Short
• Ex.- calcaneus
• Flat
• Ex.- Scapula

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Types of Bones

• Irregular
• Ex.- Spine
• Sesamoid
• Ex.- Patella

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Types of Joints

• Synarthroidial (immovable)
• Example Cranial sutures

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Types of Joints

• Amphiarthroidial (slightly movable)
• Syndesmosis
• Ex.- tib./Fib
• Synchondrosis
• Ex.- symphysis pubis

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Types of Joints

• Diarthrodial
• Arthrodial (gliding)
• Condyloidal (ball socket)
• Enarthodial (multiax. ball socket)
• Ginglymus (hinge)
• Sellar (saddle)
• Trochoidal (pivot)

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Types of Joint Movements

• 2 classifications
• General
• Can occur at multiple joints
• Specific
• Only occur at one joint
• Measurement quantification
• Goniometery

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General Movements

• Abduction
• Move away from midline
• Occurs in frontal plane on AP axis

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General Movements

• Adduction
• Movement toward midline
• Occurs in frontal plane on AP axis

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General Movements

• Flexion
• Movement that results in decreased joint angle
• Usually occurs in sagittal plane on frontal axis

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General Movements

• Extension
• Movement that results in increased joint angle
• Usually occurs in sagittal plane on frontal axis

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General Movements

• Circumduction
• Circular movement that forms an arc in the shape
  of a cone

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General Movements

• Internal rotation
• Rotary movement around the longitudinal axis
  toward the midline of the body
• Occurs in the transverse plane

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General Movements

• External rotation
• Rotary movement around the longitudinal axis away
  from the midline of the body
• Occurs in the transverse plane

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Specific Movements

• Ankle
• Inversion
• Turn sole inward
• Occurs in frontal plane on AP axis
• Eversion
• Turn sole outward
• Occurs in frontal plane on AP axis

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Specific Movements

• Ankle
• Dorsiflexion
• Toes up
• Occurs in sagittal plane on lateral axis
• Plantarflexion
• Actually an extension
• Gas pedal
• Occurs in sagittal plane on lateral axis

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Specific Movements

• Radioulnar joint
• Pronation
• Internally rotating radius in transverse plane on
  longitudinal axis
• Palm down
• Supination
• Externally rotating radius in transverse plane on
  longitudinal axis
• Hold your soup

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Specific Movements

• Shoulder girdle shoulder joint
• Depression
• Inferior movement in frontal plane
• Elevation
• Superior movement in frontal plane

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Specific Movements

• Shoulder girdle shoulder joint
• Horizontal abduction
• Mvmt. Of humerus in transverse plane away from
  midline
• Horizontal adduction
• Mvmt. Of humerus in transverse plane toward
  midline

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Specific Movements

• Shoulder girdle and shoulder joint
• Protraction
• In horizontal plane
• Retraction
• In horizontal plane
• Downward rotation (scapula)
• In frontal plane
• Upward rotation (scapula)
• In frontal plane

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Specific Movements

• Spine
• Lateral flexion
• Sidebending in the frontal plane

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Specific Movements

• Wrist hand
• Radial deviation
• Abduction movement of wrist
• Occurs in frontal plane on AP axis

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Specific Movements

• Wrist hand
• Ulnar deviation
• Adduction movement of wrist
• Occurs in frontal plane on AP axis
• Thumb opposition

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Muscle Terminology

• Origin
• Usually refers to the proximal, more fixed
  attachment point
• Insertion
• Usually refers to the distal, more moveable
  attachment point

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Muscle Terminology

• Intrinsic
• Works only where it isusually too little to do
  much else!
• Extrinsic
• Usually originate proximal to where they act

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Types of Muscular Contraction

• Get into six small groups. Try to come up with
  the four types of muscular actions. Discuss what
  they are, and give an example of one use of that
  action during sport performance.

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Types of Muscular Contraction

• Isometric
• Isosame, metriclength
• No change in length, but force developed is equal
  to resistance
• Example arm wrasslin, flexin

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Types of Muscular Contraction

• Isotonic
• Isosame, tonictension
• Change in length and force developed may be lt or
  gt resistance

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Types of Muscular Contraction

• Concentric
• Force developed gt resistance, therefore movement
  occurs
• Also known as positive contraction
• Example acceleration phase of kicking

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Types of Muscular Contraction

• Eccentric
• Force developed lt resistance, therefore movement
  occurs
• Also known as negative contraction
• Example defensive lineman who gets pancaked

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Role of Muscles

• Agonist
• Antagonist
• Stabilizer
• Synergist
• Neutralizer

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Role of Muscles

• For each role listed, answer the following
  questions
• What is it?
• What does it do?
• What is an example?

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Agonist

• What is it?
• Prime mover
• What does it do?
• Most (or all) of the work
• What is an example?
• Biceps brachii in a biceps curl

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Antagonist

• What is it?
• Opposite of prime mover
• What does it do?
• Provides control Opposes motion
• What is an example?
• Triceps brachii in a biceps curl

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Stabilizer

• What is it?
• Dynamic support Fixator
• What does it do?
• Establishes fixed points to provide movement
• What is an example?
• Peri-scapular muscles (trapezius I, II, III,
  rhomboids, teres major, etc.) in UE exercise

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Synergist

• What is it?
• Guiding muscle(s)
• What does it do?
• Assists prime mover and refines motion
• What is an example?
• Brachioradialis in biceps curl

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Neutralizers

• What is it?
• Muscle that counteracts another muscle
• What does it do?
• Prevents unwanted motion or movement
• What is an example?
• Hip adductors abductors during kicking motion

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Neuromuscular Concepts

• All or none principle of motor units (not nerve
  cells!)
• Refers to the motor unit (motor neuron all
  innervated sarcomeres), NOT the muscle itself
• Force produced depends on RECRUITMENT
• Recruitment depends on both the of motor units
  called into action their INNERVATION DENSITY
• Example hand fingers high density (precision
  control) Trunk low density (power speed)

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Length-tension Relationship
Force Production Min Max
50 90 130 of Resting Length
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Single Joint Vs. Multi-joint Muscles

• Single joint
• Cross only one joint, therefore can produce only
  one action
• Example soleus
• Multi-joint
• Cross multiple joints, therefore action at one
  joint depends on position of other
• Example gastrocnemius
• Important clinical/training implications

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Reciprocal Inhibition

• Agonists antagonists wiredoppositely
• If brain is telling agonist contract maximally
  then antagonist is told to contract minimally
• This results in inability to produce maximal
  force in force couple (agonist/antagonist pair)
  simultaneously

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Active Insufficiency

• Muscle contracts maximally, its structural limits
  (myosin available to form cross-bridges) are
  reached
• Cannot generate or maintain contraction due to
  the limited contractile capacity of the sarcomere

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Passive Insufficiency

• Antagonist muscle becomes taut before agonist can
  fully contract (or vice versa)
• Multi-joint muscles most affected
• Example finger flexion w/ wrist flexion
• Squeeze your neighbors fingers w/ your wrist in
  neutral
• Now fully flex your wrist and try againwhat
  happens? Why?