lecture 10 - muscle/joint action Flashcards
What are the parts of an ‘anatomical lever’?
Bones act as levers, joints as pivot/fulcrum, contracting muscles supply force, load.
What are the position of the components in a first class lever?
Pivot in middle, load and applied force on either side
What are the position of the components in a second class lever?
Pivot and applied force at either end, load in middle
What are the position of the components in a third class lever?
Pivot and load at either end, applied force in the middle
Plantar flex ion involves what class of lever?
Second class
What class of lever is involved with flexion of the elbow joint?
Third class
What are the three factors that affect muscle form/function?
Length, number and arrangement of fibres
How much can muscle fibres shorten?
Up to 50% of their resting length
If a muscle requires a large range of motion, will it be long or short?
Long, so the half-length is long
What is the tension/force of a muscle proportional to?
Cross sectional area of the muscle
The greater the concentration/number of fibres in a given area, the greater the….
tension the muscle can generate
What is the name for muscle fibres arranged vertically in line with tendons?
Parallel fibres
What is the name for muscle fibres arranged oblique to the tendons?
Pennate
Do pennate or parallel fibres have a greater cross sectional area?
Pennate
Why do pennate muscles generate greater force than parallel muscles?
The angle of the muscle fibres allows a greater number of fibres to fit in the same area than parallel muscles, allowing more force to be generated.
Why do muscles consisting of pennate fibres have a small range of motion?
Pennate fibres can only contract by half the length of their shortest fibre. The oblique arrangement leaves some very short fibres on the edges, which creates a small ROM.
What are the three types of pennate muscles?
Unipennate, bipennate, multipennate
What are the three types of muscle contraction?
Concentric, eccentric, isometric
What is concentric muscle action?
Muscle fibres are active, tension exceeds load so muscle shortens/contracts, moving the joint
What is eccentric muscle action?
Muscle fibres are active, developing tension. Load exceeds tension, so muscle lengthens. Usually, another muscle causes this lengthening. Changes joint position
What is isometric muscle action?
Muscle fibres are active, but the load is equal and opposite to the applied force, so there is no change in muscle length or joint position.
What are the four muscle roles at joints?
Agonist, antagonist, stabiliser, neutraliser
What are muscle agonists?
Muscles that act concentrically (shorten to cause the main movement at a joint)
What are muscle antagonists?
Muscles that act eccentrically, and are generally stretched as the result of the shortening of an opposite agonist muscle
What are muscle stabilisers?
Muscles that hold a joint still (isometric action)
What are muscle neutralisers?
Muscles that eliminate unwanted muscle movement, using extension and flexion.
Generally, what kind of movement will a muscle lying anterior to a joint produce?
Flexion
Generally, what kind of movement will a muscle lying posterior to a joint produce?
Extension
Generally, what kind of movement will a muscle lying medial to a joint produce?
Adduction
Generally, what kind of movement will a muscle lying lateral to a joint produce?
Abduction
What joint is the exception to the concentric muscle rules?
The knee joint
What kind of movement will a knee muscle lying anterior to the joint produce?
Extension
What kind of movement will a knee muscle lying posterior to the joint produce?
Flexion
How many heads does the bicep brachii have?
Two
Where is the superior attachment of the biceps brachii?
Scapula
Where does the inferior end of the biceps brachii attach?
The radius - the radial tuberosity
What movement is generated by the biceps brachii at the shoulder and why?
Flexion, muscle anterior to joint
What movement is generated at the elbow by the biceps brachii and why?
Flexion, muscle anterior to joint
How many heads does the triceps brachii muscle have?
Three
What are the three heads of the triceps brachii?
Long, short, medial
Where does the long head of the triceps brachii attach?
The scapula
What heads of the triceps brachii attach to the humerus?
Short and medial
Where does the inferior end of the triceps brachii attach?
The olecranon of the ulna
What movement is generated by the triceps brachii at the shoulder, and why?
Extension, muscle posterior to joint
What movement is generated by the triceps brachii at the elbow, and why?
Extension, muscle posterior to joint
What is the shape of the deltoid muscle?
Triangular
What are the attachment points of the deltoid muscle?
Scapula, clavicle, humerus (deltoid tuberosity)
What part of the humerus does the deltoid muscle attach to?
The deltoid tuberosity
What kind of fibres, and therefore types of movement, exist in the deltoid muscle?
Anterior fibres = flexion, posterior fibres = extension, lateral fibres = abduction
What two muscles make up iliopsoas muscle?
Psoas major, iliacus
What are the attachments of the psoas major muscle?
Starts at end of thoracic vertebrae and attaches down the lumbar vertebrae. Joins to the iliacus muscle
What is the lateral attachment of the iliacus?
Ilium
What movement is generated by the iliopsoas muscles, and why?
Flexion at the hip joint, muscles anterior to joint
Where does the gluteus maximus muscle attach to bone?
the sacrum, hip bones, femur
What movement is generated at the hip joint by the gluteus maximus, and why?
Extension, muscle lies posterior to joint
What are the 4 muscles of the quadriceps femoris?
Rectus femoris, 3 vasti muscles (lateralis, intermedius, medialis)
What is the most superficial muscle of the quadriceps femoris?
Rectus femoris
What are the bone connections of the rectus femoris?
Attaches to the hip bone anteriorly/superiorly, and patella and tibial tuberosity anteriorly/inferiorly
What movement is generated at the hip joint by the rectus femoris, and why?
Flexion, muscle lies anterior to the joint
Where do the vasti muscles attach?
The patella and the femur
What are the names of the vasti muscles?
Vastus lateralis, Vastus medialis, Vastus intermedius
What movement is generated by the vasti muscles at the knee joint, and why?
Extension, muscles lie anterior to joint
How many muscles make up the hamstrings?
3
What are the muscles of the hamstrings?
Biceps femoris, semi-membranosus, semi-tendinosus.
What are the attachments of the heads of the biceps femoris?
One head attaches to the ischium, One head attaches to the femur
Where does the inferior end of the biceps femoris attach?
The fibula
What is the physcial characteristic of the semi-membranosus muscle?
Very thin and flat, resembles a membrane
What is the physical characteristic of the semi-tendinosus muscle?
Thin and long - resembles a tendon
Where do the semi-membranosus and semi-tendinosus muscles attach?
The ischium (ischial tuberosity) and tibia
What movement is generated by the hamstrings at the hip joint, and why?
Extension, muscle posterior to joint
What movement is generated by the hamstrings at the knee joint, and why?
Flexion - posterior to knee joint, as well as rotation when flexed (condylar joint)
What are the attachments of the tibialis anterior muscle?
Anterior of tibia, medial metacarpals
What two types of movement is generated by the tibialis major muscle at the ankle joint, and why?
Flexion (dorsi flexion) - muscle anterior to joint. Adduction (inversion) - muscle medial to joint
What muscles make up the triceps surae?
gastrocnemius and soleus
What is the most superficial muscle of the triceps surae muscle?
gastrocnemius
What is the deeper muscle of the trcieps surae?
Soleus
What are the attachments of the gastrocnemius?
Posterior of the femur, calcaneous tendon (heel bone/ calcaneus)
What movement is generated by the gastrocnemius muscle at the knee joint, and why?
Flexion - muscle is posterior to knee joint
What are the attachments of the soleus muscle?
Head of the fibula, calcaneous tendon (heel bone / calcaneus)
What movement is generated by the trcieps surae at the ankle joint, and why.
Extension (plantar flexion) - muscle lies posterior to joint
Where does the achilles/calcaneous tendon attach?
The heel bone - calcaneous
What is the primary agonist in the extension of the hip joint?
Gluteus maximus
What is the primary agonist in the flexion of the hip joint?
Iliopsoas
What muscle generates supination (rotation of the radius so it lies parallel to the ulna)?
Biceps Brachii, as it has its distal attachment on the radial tuberosity of the radius, allowing it to contract and pull on the radius so it crosses the ulna.
What is a muscle synergist?
A muscle that contracts to help a muscle group work. A larger agonist will initiate the action, and the synergist will work along side to stabilise or provide additional pull
What is the difference between a muscle insertion and a muscle origin?
An origin is a muscle attachment where the bone is fixed in place during muscle action. Contraction of the muscle will pull the muscle insertion towards the origin.
What are the origins of the deltoid?
Clavicle and Scapula
What is the insertion of the deltoid?
Deltoid tuberosity of humerus
What is the origin of the biceps brachii?
Scapula (coracoid process), scapula
What is the insertion of the biceps brachii?
Radius (radial tuberosity)
What are the origins of trcieps brachii?
Humerus, scapula
What is the insertion of trcieps brachii?
Ulna (Olecranon)
What are the key origins of the gluteus maximus?
Ilium (iliac crest), sacrum,
What is the insertion of the gluteus maximus?
Gluteal tuberosity of femur
What is the origin of the iliacus?
Iliac fossa
What is the insertion of the iliacus muscle?
Femur
What is the origin of psoas major?
Lower vertebrae
What is the order of the muscles of the hamstrings, medial to lateral?
Semi-membranous, Semi-tendonosus, Biceps femoris
What is the order of the muscles of the quadriceps femoris (medial to lateral)?
Vastus medialis, Rectus Femoris & Rectus intermedius (the latter is deep to the former), Vastus lateralis.
What is the origin of biceps femoris?
Ischial tuberosity and femur
What is the insertion of biceps femoris?
Head of fibula
What are the origins of semi-membranous and semi-tendonosus?
Ischial tubersoity
In general, where do all of the hamstrings originate?
Ischial tuberosity
Where is the insertion of the semi-membranous and semi-tendonosus?
The tibia
What is the origin of rectus femoris?
Ilium (anterior inferior iliac spine)
What is the insertion of rectus femoris?
Tibia (tibial tuberosity)
What are the origins of the vasti msucles?
Femur
What are the insertions of the vasti muscles?
Tibial tuberosity
What is the origin of tibialis anterior?
Tibia
What is the insertion of tibialis anterior?
Medial metacarpal
What is the origin of gastrocnemius?
Femoral condyles
What is the insertion of gastrocnemius?
Calcaneous via calcaneal tendon
What are the names of the two heads of biceps brachii?
Long head and Short head
Where does the long head of biceps brachii attach?
The scapula
Where does the short head of biceps brachii attach?
The scapula
