Chapter 11 - The Muscular System Notes Flashcards
Lever
(Bone)
- Rigid structure
Fulcrum
(Joint)
- Fixed point
Muscles (produce what)
- Apply the forces that produce MOVEMENT
Basic Muscle Concept
When a muscle contracts (shortens), a force is generated that acts on bones (or surrounding tissues) to create motion
Components of typical skeletal muscle
- Origin
2, Insertion - Muscle Belly
- Tendons
Origin
- “Fixed” end; may be called the head of the muscle
Insertion
- “Moveable end
Muscle Belly
- The largest portion of the muscle. It lies between the origin and insertion
Tendons
- Attach muscles to bones
Aponeurosis
- (Sheet-like)
- Is a thin, flat tendon located where the muscles attach to large flat regions on the body
Synergists
- Muscles working together to cause a movement
Agonist
- Prime Mover
- If one muscle in a group does most of the work involved
Antagonists
- Muscles that cause a movement opposite that of the synergists
- flexors/extensosr
- adductors/abductors
Stabilizers
- Stabilize the joints
Number of Muscles Identified
- Over 700
- Averaging just over 3 per every bone
Naming Schema for Muscles
- Origin and Insertion
- Size
- Shape
- Direction of muscle fibers
- Location
- Number of Heads
- Action/Function
Naming: Origin & Insertion
- named landmarks found on the bones
- origin is fixed end
- insertion moveable end
Naming: Size
- Maximus
- Minimus
- Brevis
- Major
- Minor
- Longus/Longissimus
- Teres
Naming: Shape
- Triangular
- Trapezoid
- Saw-Toothed
- Rhomboid
- Round
Naming: Direction of Muscle Fibers
- Rectus: runs parrell to the midline of the body
- Perpendicular: runs at a right angle to the midline of the body
- Angle
Naming: Location
-May indicate a nearby bone or body region
Naming: Number of Heads
- multiple heads or attachments
Naming: Action/Function
- Terms such as FLEXOR, EXTENSOR, ABDUCTOR, and ADDUCTOR are all added to muscle names to indicate the kind of movement generated by the muscle.
Muscle Shapes
- Pennate: feather-shaped
- Parallel: fasciculi run in line w/tendon
3, Convergent: triangle shaped - Circular: circle shaped
Fascicles
- Muscle fibers are grouped into bundles called Fascicles
Levers
- Three classes of levers with respect to skeletal muscle function:
1. Class I - see saw R-F-AF
2. Class II - loaded wheel barrel F - R - AF
3. Class III (most common in the body)
ladder against building - F - AF - R
Frontalis
- Forehead
- Raises eye brows, wrinkles forehead
Orbicularis oculi
- Around the eyelids
- Closes the eyes
Buccinator
- Lines the cheeks
- Compresses cheek
Orbicularis oris
- Around the lips
- Purses the lips
Zygomaticus
- Upper cheek
- Elevates corner of mouth
Depressor Anguli Oris
- Side of the chin
- Depresses corner of the mouth
Temporalis
- Side of head above ear
- Elevates mandible
Masseter
- Rear of the cheek
- strongest muscle in the jaw
- Elevated mandible
SCM
- Side of the neck
- Rotates the neck opposite side, laterally flex same side
Platysma
- Side of neck superficial
- Tenses neck, depresses mandible
Scalenes
- Deep, side of neck
- Elevated ribs, flexes neck
Torticollis
- “pinched nerve” in neck
- Acute spasm of the SCM
- Usually caused by a cervical acceleration - deceleration injury
Erector Spinae - Iliocostalis
- Deep posterior trunk muscles
- Extension of the spine
Erector Spinae - Longissimus
- Along the back, from head to sacrum
- Extension of the spine
Erector Spinae - Spinalis
- ??
- Extension of the Spine