Muscles Flashcards
Striated or Skeletal Muscle
Also called Voluntary Muscle
type of muscle that makes up most of the structures that are responsible for speech production
characteristics of voluntary muscle
under direct control - you can move it freely
Found in the muscles of the articulation and chewing or mastication
Characteristics of Striated or Skeletal Muscle
- Voluntary
- contracts rapidly, but tires easily
- responsible for body motility or movement
- varies greatly in size
What is muscle architecture?
refers to the way that muscles may be described by their appearance
Types of muscle architecture
PRP
1. Parallel - spindle-shaped muscle that has a good range of motion and endurance. e.g. bicep muscles
- Radiating - a fan-shaped muscle (found in cranium around the temporal lobe)
- Pennate - AKA penniform. muscle resembles a feather. good force, less range of motion. e.g. pectoral muscles
What are the points of attachments for muscles?
two points -1. stabilization 2. movement
- ORIGIN: proximal end of the muscle. no movement. will STABILIZE or fix the muscle
- INSERTION: distal end of muscle. This one will give movement
Muscle Contraction
When a muscle contracts, the distance between the origin and the insertion of the muscle will shorten or decrease
This is what allows a structure to move
The insertion point tells you what?
what structure will be allowed to move when the muscle contracts
e.g. when biceps contract, arm bends
e.g. Zygomatic major (facial muscle responsible for raising corners of mouth for smile/laughs)
Origin: zygomatic bone (cheek bone)
Insertion: angle of the mouth
Function: produces a broad smile with contraction of the zygomatic major
Origin and Insertion Examples: Posterior Cricoarytenoid (PCA)
Origin: posterior (back) aspect of cricoid cartilage
Insertion: Muscular process (elevation) of the arytenoid cartilage
Function: will abduct or open the vocal folds
Origin and Insertion Examples: Masseter (muscle in mastication)
Origin: Maxillary process (elevation/projection) of zyygomatic bone
Insertion: Mandible
Function: Elevate or close the jaw. Important for mastication/chewing
What does NOMENCLATURE mean?
Name
Refer to the way in which muscles are named according to their
- Shape (geometric names)
- Location in the body
- Function
Geometric Names
Reflect SHAPE
e.g. quadratus (quad or rectangular shape)
e.g. Deltoid - means triangular
General Form
Refers to APPEARANCE
e.g. serratus - saw like (serratus anterior around ribs)
Location in the Body
Refers to LOCATION of muscle
e.g. temporalis (at the temporal bone of the cranium)
Descriptive terms of the muscles
Usually paired muscles
Include:
Major
Minor
External
Internal
e.g. pec muscles - pectoralis major/minor
Rib Muscles
external intercostal
internal intercostal
Number of Heads
Points of connection at the origin of a muscle
e.g. Biceps (2) + Triceps (3)
Muscle Function
describes function of muscle aka what it does when it contracts
e.g. Tensor Tympani tenses the middle ear
Structure of Skeletal Muscle
muscle consists of many muscle fibers, as well as other types of connective tissue (epimysium)
Epimysium
Coarse, fibrous tissue that forms the outermost covering of a muscle
Muscle cells or muscle fibers
The smallest unit of skeletal muscle tissue
Make up skeletal muscle
Surround by a covering called PERIMYSIUM
Perimysium
Surrounds the cluster of muscle cells of skeletal muscle tissue
Muscle Cells/fibers are Made up of?
MYOFIBRILS - densely packed + surrounded by
SARCOPLASM that contain
MYOGLOBIN (gives muscle reddish color)
Myofibrils
Make up most of the muscle volume
Contain SARCOMERES - Basic units of all myofibrils
sarcomeres (sarco = flesh; mere = piece - a piece of the muscle)
smallest contractile unit of muscle (functional unit of the muscle)
many sarcomeres link together in order to form a muscle
What are the two proteins found in sarcomere?
MA
Myosin + Actin
Light or I Bands (isotropic) house Actin Filaments (AKA thin filaments)
Dark or A Bands (anisotropic) house Myosin Filaments (AKA Thick Filaments)
Endomysium
connective tissue that surrounds the individual muscle fibers
Contraction
SHORTENS the distance between the origin and insertion of a muscle
When a muscle contracts, it shortens (e.g. bending of arm as bicep contracts)
Muscle Contraction Theory and where it begins
Cross Bridge Theory of Muscle Contraction or Sliding Filament Theory
All muscle contractions begin in the brain. The brain generates the initial signal that tells the muscle to contract
How Muscle Contraction Occurs
- Start is called Action Potential (AP). Begins in brain when brain sends the signal that tells the muscle to contract
- AP travels down nerves to muscles
- When it reaches the sarcomere, a chemical reaction causes “Cross Bridges” to form between the actin and myosin (thin + thick proteins)
- Cross Bridge Formation refers to the LINKING of the Light/I Bands to the Dark/A Bands
- As the Light/I Bands join with Dark/A Bands, they shorten the sarcomere
- When sarcomeres get shorter, the myofibril shortens
- When myofibril shortens, the muscle fibers shorten
- When muscle fibers shorten, the muscle shortens (contracts)
Length- Tension Relationship
the amount of force a muscle can produce at different lengths
When does muscle generate its greatest force?
when it is at its resting length
The amount of force a muscle can produce at different lengths
Length - Tension Relationship
What are the 2 types of muscle contraction
- Isometric - muscle generates force but does not produce movement
e.g. holding onto a bag of groceries
- Isotonic - length of the muscle changes + movement occurs
Muscles will shorten with isotonic contraction. When muscles shorten, it will contract and movement will occur.
e.g. running, weightlifting, picking up a pencil.
Muscle Tone
residual or background muscle tension or tonus of a muscle that is always present to some degree
constant, partial contraction of muscle tissue that helps you maintain posture + balance
Why is muscle tone important?
maintenance of posture and balance
important in controlling the function of other organ systems
refers to overall stiffness of a muscle
How is muscle tone regulated and what happens in sleep?
Regulated by several structures + neural pathways in brain
decreased during sleep, coma, and unconsciousness
Hypotonicity
Lack of muscle tone or diminished muscle tone
Can range from mild to severe - adversely affect speech production, walking, chewing, eating
Clinical dx: Might be present in patients with CP, Muscular Dystrophy, stroke
Hypertonicity
too much muscle tone. Increased or rigid muscle tone. also affect speech production, chewing, walking etc.
Clinical dx where it is present: CP, PD, stroke
