Chapter 2I Musculoskeletal Anatomy

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Chapter 2-I Musculoskeletal Anatomy
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Bones

• Bones of the skeleton are organs because they
  contain several different tissues.
• Besides giving you shape, bones
• Support the weight of the body
• Protect sensitive organs (skull, rib cage)
• Move via connection to tendons
• Provide mineral storage
• Allow blood cell formation

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Classification of Bones

• Long Bones longer than wide have a shaft plus
  two ends. Includes legs, arms, fingers, toes.
• Short Bones roughly cube shaped. Includes
  wrist, kneecap.
• Flat Bones thin, flattened, and usually curved.
  Includes ribs, skull.
• Irregular Bones dont fit other types.
  Includes vertebrae, hip bones.

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Structure of Bones

• Most have a dense outer layer compact bone, and
  a spongy cancellous bone interior filled with
  marrow.
• Blood vessels run through bones up to 11 of the
  bodys blood supply is in the skeleton

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Bone Fractures

• Fractures are repaired via reduction
• Closed (physician manipulates into place)
• Open (bone ends are surgically joined with pins
  or wires)

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The Skull
The skull is the most complex of our bony
structures
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Construction of the Skull

• Composed of
• Cranial bones
• Enclose and protect the brain
• Provide attachment for head and neck muscles
• Facial bones
• Form framework of face
• Form cavities for sense organs (sight, taste,
  smell)
• Provide passage for air/food
• Hold the teeth
• Anchor the muscles of the face

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The Spine
Composed of four regions -Cervical -Lumbar -Thorac
ic -Sacrum Lumbar 4 and 5 are the biggest
problem areas because they angle downward. Disc
pressure there is 50-100 greater when sitting
than standing.
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Composition of the Spine

• Formed by 26 bones providing the major axis
  extending from the skull to the pelvis
• Each bone is cushioned from the next by an
  intervertebral disc
• These discs have a gel nucleus with 12 concentric
  annulus rings
• These discs act as shock absorbers and allow the
  spine to bend
• The discs can wear out from cumulative
  microdamage until they leak or bulge
• Warning! Damage can occur with lack of pain

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Upper Extremities

• The shoulder is stabilized by tendons, not
  mechanical fit of bones
• The rotator cuff is the co-joined sheet of 3
  tendons surrounded by connective tissue

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Shoulder Problems

• Tendinitis rotator cuff tendons inflamed or
  damaged
• Bursitis inflammation of the bursa between the
  tendons and shoulder bone (the bursa is a fluid
  filled sac that acts like ball bearings)
• Tendon or muscle tear
• Frozen shoulder inflammation of the shoulder
  capsule

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The Hand / Wrist

• The hand consists of
• Carpus bones in the wrist
• Metacarpus bones- in the palm
• Phalanges finger bones

• The carpus contains 8 marble-sized short bones
  called carpals, closely united by ligaments and
  surrounds a median nerve

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Lower Extremities

• Sound structurally except for ankles, feet
• People constantly shift weight from side to side,
  even when supposedly standing still
• Back pain occurs when there is leg length
  discrepancy

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The Feet

• Approximately 80 of foot injuries involve broken
  toes. These injuries could be avoided with
  safety shoes.
• The heel supports 50 of body weight, another 25
  with first two toes, remaining 25 with other
  three toes.
• In between heel and toes running longitudinally
  are the lateral and medial arches. Along with
  the transverse arch, they distribute weight to
  heels and toes while walking or standing.

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Skeletal Changes

• Throughout life, not only does our height change,
  but also our proportions
• At birth, the head and trunk are gt1.5 times
  longer than the legs
• By age 10, the ratio is 11 (upper-lower body)
• By middle age, the skeleton loses mass and
  osteoporosis and fractures are more common

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The Joints

• Joints are formed by two or more bones connected
  by thick tissues.
• The ends of bones are covered by cartilage to
  prevent bone-to-bone contact.
• Many joints are enclosed by a capsule that
  produces lubricant.
• Arthritis is a disease that causes joint
  inflammation.

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Types of Joints

• Ball-and-socket a large round ended bone fits
  into the hollow of another allows
  swinging/rotating motion.
• Ex.- hips, shoulders
• Hinge operates like door hinge.
• Ex. knees
• Pivot allows rotation.
• Ex. elbow (can rotate palm up or down)
• Fixed dont move, except to absorb shock.
• Ex. - skull

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Ligaments

• Connects bones to bones
• Both ligaments and tendons are made of collagen
• Ligaments are a flat sheet of collagen fibers in
  differing orientations with lots of nerves and
  blood vessels
• Sprains are a tearing of the ligament

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Tendons

• Connects muscles to bones
• Are made of collagen fibers running in the same
  direction like a rope surrounded by a lubricating
  sheath
• Have few blood vessels
• Strains are tearing apart of tendon fibers

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Tendon Problems

• Besides strains, other tendon problems
• Tendinitis inflamed tendon
• Tenosynovitis swelling from excess synovial
  fluid causes pain to sheath heals slowly
• Stenosing tenosynovitis constricted sheath
• Trigger finger tendon locked in swollen sheath
• Elbow problems unsheathed tendons golfers
  elbow (inner arm), tennis elbow (outer arm)
• Deformation cannot easily recover from gt6
• Rupture deformation above 8-10

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Nervous System

• Master control and communications system of the
  body
• Every thought, action, instinct, and emotion
  reflects its activity
• Communicates via electrical signals
• The human body contains billions of neurons or
  nerve cells

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Nerves

• Central nervous system (CNSbrain and spinal
  cord)
• Peripheral nervous system (PNS-communication with
  body)
• Motor nerves bring messages (efferent signals)
  from brain to muscles.
• Sensory nerves bring messages (pain, pressure)
  from muscles to brain.
• Autonomic nerves control functions, such as
  sweating.

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Muscle
Functions
Unique Features

• Contractility
• Excitability nerves signal electrical impulses
• Extensibility can stretch back by contraction
  of an opposing muscle
• Elasticity can recoil

• Movement by moving bones
• Maintenance of posture
• Joint stabilization
• Heat generation maintains normal body temps

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Types of Muscles

• Cardiac muscle (heart)
• Smooth muscle (internal organs, walls of blood
  vessels)
• Skeletal muscles (attached to bones)
• Striated
• Usually attached in pairs
• Controlled by neurons
• Nourished by arteries

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Skeletal Muscles Span Joints
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First-class lever

• Fulcrum in the middle (e.g. seesaw)

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Second-class lever

• Fulcrum at one end (e.g. wheelbarrow)

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Third-class lever

• Fulcrum at one end, resistance has mechanical
  advantage (e.g. forceps)

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Force Capability
Forces (kg) exertable on a vertical handgrip
with the right arm at various elbow angles
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Gender, Age, and Training Effects

• On average females have 2/3 strength of males.
• Primarily due to smaller size and muscle mass.
• Speed of movement and grip strength decrease with
  age.
• Training may increase gender differences.
• Increased job endurance can come from improved
  micro-motions and coordination.

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Electromyography

• Electrodes measure activity of specific muscles.
• Provides information about
• Whether muscle is in use
• Relative activity level
• Force generation
• Muscle fatigue