Week 4 - Muscle and Skeletal Tissue Flashcards
Describe four functions of muscle tissue
- Produce movement
- Maintain posture and stabilise joints & body positions
- Storing and moving substances in the body
- Skeletal muscle contraction produces heat
What are three functional characteristics of muscle tissue?
- Electrical excitability
- Contractility
- Extensibility
Describe ‘Electrical excitability’
The muscle receives & responds to a stimulus which causes muscle action potentials which in turn cause muscle contraction
Describe ‘Contractility’
The ability of the muscle to contract when stimulated
This enables tension to maintain a body position or causes the muscle to shorten to produce movement
Describe ‘Extensibility’
The ability of muscle to stretch without being damaged (within limits) and to return to its original shape after contraction or extension
Name the three types of muscle
- Cardiac
- Smooth
- Skeletal
Where is skeletal muscle located?
Attached to bones
What is the function of the skeletal muscle?
Produce skeletal movement
Where is Cardiac muscle located?
the Heart
What is the function of cardiac muscle?
Pump blood
Location of Smooth muscle?
Wall of blood vessels, GI tract, airways
Function of smooth muscle?
Regulates diameter of blood vessels and airways, propels food in GI (digestive) tract
What is a tendon?
Is a cord of dense regular connective tissue that attaches a muscle to the periosteum of a bone e.g. Achilles tendon
What is every cell muscle fibre supplied with?
A nerve ending that controls its activity
Muscle cells are also called…
Muscle fibres
What type of tissue do skeletal muscles contain?
Connective Tissue
Explain the process when skeletal muscles contract
- Shortens & pulls one of the articulating bones towards the other.
- The proximal bone usually remains stationary (or near its original position)
- The distal bone is pulled toward it
How does muscle contraction occur?
Through the movement of contractile proteins
What are the 2 contractile proteins?
- Thin Actin Filaments
- Thick Myosin Filaments
What happens with the filaments when the muscles are at rest?
The filaments (contractile proteins) lie in a parallel arrangement with some overlap.
What happens with the filaments when the muscles contract?
Thin filaments are pulled past the thick filaments using ATP.
What is required to enable the binding of myosin to actin?
C02
What does muscle contraction require?
ATP
What is muscle tone?
When relaxed muscles are almost always slightly contracted
What is muscle tone caused by?
Spinal reflexes that activate one group of motor units then another & by motor neurons in the brain.
What type of movement is skeletal muscles?
Voluntary
What does muscle tone help?
- Stabilise joints & maintain posture (e.g. keeping head upright
- Tone of smooth muscles in walls of blood vessels maintains blood pressure
What is Hypotonia?
When motor neurons that control skeletal muscles are damaged the muscle becomes flaccid or limp because muscle tone is lost.
Define Muscle Atrophy
Muscles waste away. It’s usually caused by a lack of physical activity
What is Hypertonia?
Increased muscle tone results from damage to the motor neurons that supply the muscle
What is spasticity?
Stiffness of muscles with hyperreflexia that can result in spastic paralysis (e.g. cerebral palsy)
What is hypertrophy?
Is the increase in the diameter of muscle fibres, from forceful and repetitive muscular activity
What are the 4 abnormal muscle contractions?
- Spasm
- Cramp
- Tremor
- Tic
What is a spasm?
Involuntary contraction of single muscle
What is a Cramp?
A painful spasm
What is a tremor?
Rhythmic, involuntary contraction of opposing muscle groups
What is a tic?
Involuntary, brief twitch of a motor unit visible under the skin - eyelid or facial muscles
What are 6 aged related changes to muscles?
- A slow, progressive loss of skeletal muscle mass
- Skeletal muscle is replaced by fibrous connective tissue & fat
- Decreased muscle strength (due to less muscle mass)
- Decreased smooth muscle tone (think about digestive function & blood pressure)
- Decreased muscle and postural flexibility (due to loss of extensibility of muscle tissue)
- Decreased reflexes (due to slower neuron function)
Where are IM injections most commonly given?
- Gluteus medius (also called ventro-gluteal)
- Lateral quadriceps (vastus lateralis)
- Deltoid muscles
What are lumbar muscles required for?
Maintaining Posture
What are some important muscles within the body (anterior view)
- Sternomastoid
- Trapezius
- Deltoid
- Pectoralis major
- Biceps
- Abdominal muscles
- Quadriceps
- Vastus lateralis
- Tibialis anterior
What are some important muscles within the body (posterior view)
- Triceps
- Latissimus dorsi
- Gluteus maximus
- Hamstring
- Gastrocnemius
- Calcaneal (Achilles) tendon
What does the Masseter do?
Wraps around and elevates the mandible to enable the mouth to open
Where does the Sternomastoid run from?
From the sternum & clavicle to the mastoid process of skull
Function of the Sternomastoid
- Contraction of both together - flexes the head at the neck
- Contraction of one - rotates head/face in opposite direction
Function of the abdominal muscles
- Flexion & rotation of the trunk
- Movement of the vertebral column
- Forced expiration
What happens when our diaphragm contracts?
Inhalation
What happens when our diaphragm relaxes?
Exhalation
2 functions of the pelvic floor muscles
- Support the pelvic organs
- Act as sphincters of the urethra & rectum
Function of the Trapezius?
Elevate the scapulae
Function of Pectoralis major
Flexes the arm & adducts the arm anteriorly
Function of Latissimus dorsi
Extend the arm & adduct the arm posteriorly, elevates the vertebral column & torso
Function of Deltoid
Abducts the arm (at shoulder) & assists with flexion & extension of the forearm
Function of Biceps?
Flexes arm at elbow
Function of triceps?
Extends arm at elbow
Function of Quadriceps
Extends the leg at knee & flexes the thigh
Function of hamstrings
Flexes leg at knee
How many muscles make up the hamstring?
3
Function of Gastrocnemius
Plantarflexes foot at ankle (& flexes knee)
Function of Tibialis anterior
Dorsiflexes ankle
