Skeletal & Muscle Systems (2.2)

3 Types of muscle:

Skeletal, Cardiac, Smooth

Tendons

attach muscle to bone

Ligaments

attach bone to bone

Aponeurosis

connects several muscles

• Flat sheath of dense fibrous connective tissue

Origin

More stable, proximal attachment part of muscle

Insertion

more moveable, distal attachment of muscle

Action

Insertion pulled toward origin

List connective tissue layers Outermost - Innermost

Epimysium > Perimysium > Endomysium

Epimysium houses:

outer, whole muscle

Perimysium houses:

fascicles, and fiber groups

Endomysium houses:

inner, fibers, nerves and capillaries

What factors contribute to muscle strength?

Muscle size (# of fibers) , muscle length

List components of muscle fibers

Myofibrils, Sarcomeres, Myosin/Actin

Myofibrils

protein strands

Sarcomeres

Contractile units of myofibrils

Pennate

Muscle design that is Oblique to tendon

Types of pennate muscles:

• Multipennate

• Bipennate

• Unipennate

Fusiform

Parallel to line of force

Which type of muscle design is easier to move?

Pennate

Agonist

Prime mover

Antagonist

Oppose motion

Fixator

Stabilize at the origin of mover

• “Neutralize” unwanted motion

Synergist

Assist prime mover

Types of Muscle Contraction:

Isotonic

Isometric

Isometric

Muscle contracts without change in length

• Holding something stationary

Isotonic

Muscle contracts, and changes length

• Creates movement

Concentric

Muscle shortens/contracts (agonist)

Eccentric

Muscle lengthens (antagonist)

Muscle insufficiency definition

Muscles cross more than one joint, which limits their ability to act on both joints simultaneously

Passive muscle insufficiency

Muscle can’t lengthen over both joints

ex: trying to touch toes while knees are straight

Active muscle insufficiency

Muscle can’t shorten over both joints

ex: trying to make a tight fist while wrist fully in flexion

Examples of open chain:

• Kicking a ball

• Throwing a ball

Examples of closed chain:

• Push up

• Standing from chair

Hard End feel:

Bone cannot go any further

Soft end feel:

can’t go farther due to muscle, fat, or tissue in the way

Firm end feel:

can’t go farther due to ligament/muscle not being able to extend or flex that far

Closed Chain definition

• Proximal segment moves, and distal segment is fixed

Open Chain definition

• Proximal segment is fixed, and distal segment moves

Abnormal Hard end feel can indicate what?

A bony block

An abnormal firm end feel can indicate what?

Contracture or muscle shortening

An abnormal soft end feel can indicate what?

Infection or edema

Example of hard end feel:

• Elbow Extension

• Knee extension

Example of soft end feel

• Knee flexion

• Elbow flexion

Example of firm end feel:

• Ankle dorsiflexion

• Hip rotation

Example of an Agonist/Antagonist pair: Bending the elbow

Biceps are the agonist (contracting)

Triceps are the antagonist (relaxing)

Example of an Agonist/Antagonist pair: Straightening the elbow

Triceps are the agonist (contracting)

Biceps are the antagonist (relaxing)

Example of Agonist/Antagonist pair: Staightening the knee

Quads are the agonist (contracting)

Hamstrings are the antagonist (relaxing/extending)

How many bones in the entire human skeleton?

206 Bones

• 80 Axial

• 126 Appendicular

Axial bones consist of:

Head, trunk, and thorax: provide stability

Appendicular bones consist of :

extremities: provide mobility

Cortical (compact bone) description and function:

• High in minerals

• Rigid support

• Shaft of long bones

Allows us to be upright and supported

Cancellous Bone description and function:

• High in collagen (spongy)

• Can absorb compressive forces

On the ends of bone, and absorbs force

Bone Membranes:

Periosteum (around/outer)

Endosteum (between/inner)

3 Parts of a bone:

Epiphysis (end)

Metaphysis (midpoint)

Diaphysis (grows as you get older/actual middle)

Long bone example:

appendicular skeleton

Short bone example:

carpals, tarssals

Flat bone example:

cranial, scapula

Irregular bone example:

Vertebrea

Sesamoid bone example and definition:

Bone embedded in tendon: patella

Synarthroidial Joint function:

Designed for stability

• Not moveable

Fibrous joint description:

immovable joint

• held in place by suture, ligament, or peg in socket

• “interlocking”

• Ex: skull, dental socket

Cartilaginous joint description:

Slightly moveable

• Cartilage between joint surfaces

• Allow bend, twist and compression

Diarthroidial (synovial) joints:

Designed for mobility, and no direct contact between joint ends

Non-axial joint:

Flat, gliding, linear movement

ex: joints in wrist/foot

Uniaxial Joint:

One plane, one axis (allows twisting

Hinge, pivot joints

ex: Knee, elbow, Atlanto-axial joint

Biaxial

Two planes, two axis

Elipsoid, Saddle

Ex: Metacarpal, Carpal joints

Multiaxial joint

At least 3 planes, 3 axis

• Ball and Socket (shoulder/hip)

Convex

Moving outward like a ball

Concave

Curve inward like a cave/bowl

Convex moving on Concave

Applies to rolling or gliding motions (mostly ball and socket)

• Distal bone (convex) moves in the OPPOSITE direction of the rotational movement (concave)

• Ex: Wrist (radiocarpal), Shoulder during abduction, Hip Extension

Concave moving on Convex

Applies to rolling or gliding motions

• Distal bone (concave) moves in the SAME direction of the rotational movement (convex)

• Ex: Elbow flexion, Knee flexion