Lectures 10 and 11 Flashcards
Muscle form determines function … depends on:
Length of muscle fibres
Number of muscle fibres
Arrangement of muscle fibres
Describe length of muscle fibres
Fibres can shorten up to 50% of their resting length (based on the sliding filament theory) therefore longer fibres means a larger ROM.
Describe this image (at rest and contracting)
Find image on desktop
At rest ….
LHS - Long muscle fibres and the tendons are very short
RHS - Distal tendon is longer which creates a shorter muscle fibre as a result. Shorter resting length therefore means a shorter contracting length.
Contracting….
LHS - Larger movement is possible due to larger muscle fibres
RHS - Shorter resting length means that its contraction length cannot go as far. Tendons have no capability to contract so the amount of movement with the linger tendon is lower than that of the one with the shorter tendon
Tension (force) is directly proportional to
Cross sectional area (the thickness of a muscle)
A greater number of fibres means …
Is equal to greater CSA which is equal to a greater amount of tension being able to be created
CSA comparison of abdominal muscles vs gluteus maximus
The abdominal muscles are relatively thin, lots of parallel fibres, it is therefore not going to be able to produce as much force. Gluteus Maximus is very thick, has a large CSA therefore it is a very powerful muscle in terms of the amount of force produced
Explain what the arrangement of muscle fibres means
Number of fibres you can fit into an area depends on how you arrange them relative to the tendons
Parallel muscle fibre arrangement
Fibres arrange vertically between muscle tendons
Pennate fibre arrangement
Fibres oblique to muscle tendon
Muscle with fascicles that attach obliquely (in a slanting position) to its tendon. These types of muscles generally allow higher force production but smaller range of motion. When a muscle contracts and shortens, the pennation angle increases.
What does having the pennate muscle arrangement mean?
Having a pennate arrangement means that more fibres fit into the same space. In a pennate muscle, as a consequence of their arrangement, fibres are shorter than they would be if they ran from one end of the muscle to the other therefore the larger the pennation angle is, the shorter are the fibres.
Pennate arrangement means that there are more fibres within the same space therefore an increase in CSA and more force is generated.
Unipennate
A type of pennate muscle where the muscle fibres or fascicles are all in one side of the tendon
Bipennate
Type of pennate muscle where the muscle fibres or fascicles are on opposite sides of the central tendon
Multipennate
A type of pennate muscle where the diagonal muscle fibres are in multiple rows with the central tendon branching into two or more tendons
Describe the parts of an anatomical lever
Bones = lever
Joint = pivot or fulcrum
Muscle contraction = pull
Load = external or internal
First order lever and draw
First class levers stabilise joint position (however they are rare in the human body)
A first-class lever has the axis (fulcrum) located between the weight (resistance) and the force
Axis lying between the force and resistance
Refer to desktop
What kind of lever is at the head and neck?
It is a first class lever.
This area contains the brain, large muscles, tongue and in addition to that a load is acting which is gravity therefore there is a natural tendency for the head to tilt forward when no muscles are present. This would be problematic in interacting with the external environment.
Axis = where your skull meets the top of the spine Force = neck muscles Resistance = head
Second order lever
The load is placed between the fulcrum and effort, while the force of the effort is directed in an opposite direction to counter that of the load.
Second order levers are effective at over coming loads (big weights)
Resistance is lying between the axis and force
What kind of lever is acting when plantarflexion of the ankle is occurring?
It is a second class lever.
The fulcrum in this example is at the front of the foot and what is trying to occur is going up onto tippy toes which is essentially trying to create plantar flexion at the ankle, so all of the body weight is now sitting at the back of the ankle. In order to overcome this load and allow for movement at this particular lever, we need to produce a huge amount of applied force through the muscle lying posteriorly to the ankle.
Axis = toes Resistance = body weight Force = calf muscles
Third order lever
In third-class levers, the fulcrum remains at one end of the beam—however, the force of the effort is now located between the fulcrum and the force of the load.
Third class levers allow for a large range of movement and speed. They are generally associated with longer muscles of the body and more often than not they will cross over multiple joints. They are also generally for speedy movements as well.
Force is lying between the axis and resistance
What kind of lever is acting when flexion at the elbow joint is occurring?
It is a third class lever.
Axis = elbow joint Force = biceps brachii muscle Resistance = hand
Concentric
A concentric contraction causes muscles to shorten, thereby generating force.
Muscle is active, develops tension. There is a change in joint position and the shortening of muscle.
Isometric
Muscle is activated, but instead of being allowed to lengthen or shorten, it is held at a constant length.
The muscle is active, developing tension but there is no change in joint position, it remains stationary
Eccentric
The muscle is active, developing tension to oppose the movement being generated, allowing for joints to change position in a controlled manner. There is a change in joint position and there is a lengthening of muscle.
Agonist
Agonists acts concentrically or shortens to move a muscle
Antagonist
A muscle that moves in opposition to an agonist. Antagonists act eccentrically or lengthens when a joint is moving
Stabiliser
A muscle acts as a stabiliser when it contracts isometrically to hold a joint still. When a muscle is active to hold a joint still, it is a stabiliser.
Neutraliser and example
A muscle acts as a neutraliser when it counteracts, or neutralises, an undesired action of another muscle.
For example, biceps brachii which is a supinator of the arm and is also a flexor of the elbow joint. When you are drinking from a glass you want flexion to occur however you do not want supination to occur otherwise you would spill the water. Therefore the ‘pronator’ muse neutralise supinating effect of biceps brachii.
Describe doing flexion at the elbow using the terms - agonist and antagonist
The agonist is biceps brachii and biceps brachii shortens for flexion at the elbow. The antagonist is triceps brachii and triceps brachii lengthens.
Describe what is done by the biceps brachii when holding a heavy book
The role of the biceps brachii is being a stabiliser and the action of the biceps brachii is isometric. Remember that there is no change in the length of biceps brachii.
Deltoid - joint associated
Shoulder
Deltoid - location
It has a proximal attachment to the pectorial girdle (clavicle and scapula) and a distal attachment distally at the shaft of the humerus
Deltoid - principal movement
At the shoulder….
The concentric action of the anterior fibres causes flexion
The concentric action of the lateral fibres causes abduction (this is the only abducting muscle in the course)
The concentric action of the posterior fibres causes extension
Biceps brachii - joint associated
elbow
Biceps brachii - location
The biceps brachii has two heads. Both heads attach on the scapula. Both heads converge into one muscle, sometimes referred to as the ‘belly,’ that runs the length of the humerus. The biceps brachii crosses the inside of the elbow and attaches at the radial tuberosity.
Biceps brachii principal movement
At the shoulder ….
The concentric action of the anterior fibres causes flexion
At the elbow …
The concentric action of the anterior fibres causes flexion
At the radioulnar joint…
1. Supination - Biceps brachii has a role for being a supinator. When you go into prone position of the forearm, that tendon which was inserting into that medial aspect of the radius when that bone has turned over, that tendon has gone around and underneath that bone (gone out of the anatomical position) so when this muscle contracts what it is actually doing is pulling on that tuberosity and flipping the radius back over again.
Triceps brachii - joint associated
Elbow
Triceps brachii - location
Proximal attachment = long head to scapula, medial and lateral heads to shaft of humerus
Distal attachment = to the olecranon of ulna
Triceps brachii - principal movement
At the shoulder…
The concentric action of the posterior fibres causes extension
At the elbow …
The concentric action of the posterior fibres causes extension
The triceps brachii is a powerful extensor of the elbow but also one of its heads (the long head) also crosses over the shoulder joint so in addition to very powerful extension of the elbow, triceps brachii can assist deltoid with extension of the shoulder
It attaches distally into the ulna and has no interaction with the radius therefore it can’t have a role in pronation or supination as the radius is the bone that moves in pronation and supination.
Why is triceps brachii not a supinator or pronator?
Because it attaches to the ulna which is fixed, not the radius
Iliopsoas- Joint associated
Hip
Iliopsoas - Location
Illiopsoas lies anterior to the hip joint. Psoas major and illiacus merge together to cross over the same position on the anterior part of the hip.
Proximal attachment = iliac crest and lumbar vertebrae
Distal attachment = femur
Iliopsoas - principal movement
At the hip….
1. The concentric action of the anterior fibres causes flexion
Concentric actions of muscles … anterior
If a muscle lies anterior to a joint, it produces flexion
Concentric actions of muscles … lateral
If a muscle lies lateral to a joint, it produces abduction (only one muscle this semester produces abduction (deltoid))
Concentric actions of muscles … posterior
If a muscle lies posterior to a joint, it produces extension
Concentric actions of muscles … medial
If a muscle lies medial to a joint, it produces adduction (no muscles this semester produce adduction)
What joint is the exception for concentric actions of muscles?
the knee
Gluteus maximus - joint associated
Hip
Gluteus maximus - location
Located on the posterior aspect of the hip.
Proximal attachment = hip bone
Distal attachment = IT band (iliotibial band) and femur
Gluteus maximus - principal movement
At the hip…
1. The concentric action of the posterior fibres causes extension
Quadriceps femoris - joint associated
Knee
Quadriceps femoris - location
It consists of four individual muscles; three vastus muscles and the rectus femoris. They form the main bulk of the thigh, and collectively are one of the most powerful muscles in the body. It is located in the anterior compartment of the thigh.
Proximal attachment = Rectus femoris to hip bone, vasti to femur
Distal attachment = Patella tendon
Quadriceps femoris - principal movement
At the knee…
1. The concentric action of the anterior fibres causes extension (REMEMBER THAT THIS ONE OF THE EXCEPTIONS AS IT AT THE KNEE)
The rectus femoris passes over the knee and hip. Its main function is as a knee extender; however, the proximal attachment at the anterior inferior iliac spine and the acetabulum allows for this muscle to act as a hip flexor as well.
Vasti muscles
The vasti muscles are three of the four muscles that make up the quadriceps femoris muscle of the thigh. The three muscles are the vastus intermedius, the vastus lateralis, and the vastus medialis located in the middle, on the outside, and inside of the thigh, respectively.
Rectus Femoris
The rectus femoris is the large quadriceps muscle running down the middle of the anterior surface of the thigh. This muscle runs parallel to the femur. This is the only one of the four muscles that make up quadriceps femoris that crosses over the hip as well. It is the most superficial muscle in this group of muscles. This muscle is important for stability in hip joints and helps to produce flexion of the hip in addition of the illiopsoas.
Vastus lateralis
The largest and most powerful part of the quadriceps femoris on the lateral surface. This muscle helps in the extension of the knee.
Vastus intermedius
Vastus Intermedius is located centrally, underneath Rectus femoris (this muscle is deep to rectus femoris) in the anterior compartment of the thigh and on each side of it: Vastus medialis and Vastus Lateralis respectively. It is one of the four muscles that form the quadriceps femoris muscle.
Vastus medialis
Vastus medialis is one of the four muscles that make up the quadriceps group of muscles. It originates from the upper part of the femoral shaft and inserts as a flattened tendon into the quadriceps femoris tendon, which inserts into the upper border of the patella. The bulk of the muscle distally on the medial surface of the thigh.
Hamstrings - joint associated
Hip/knee
Hamstrings - location
Posterior surface of thigh.
Proximal attachment = Hip bone
Distal attachment = Medial and lateral epicondyles of the knee
The hamstring muscles cross posteriorly over the hip so it can aid gluteus maximus in extension of the hip joint. They then cross over the knee posteriorly and can therefore aid in flexion of the knee. The hamstrings is made up of three muscles in the posterior component of the thigh - biceps femoris, semi-membranosus and semi-tendinosus
Hamstrings - principal movement
The hamstrings are a group of three muscles which predominatly act to flex the knee.
At the hip….
The concentric action of the posterior fibres causes extension
At the knee…
1. The concentric action of the posterior fibres causes flexion AND rotation when knee is flexed
Biceps femoris
Biceps femoris is a muscle of the posterior compartment of the thigh, and lies in the lateral aspect. It arises proximally by two ‘heads’, termed the ‘long head’ (superficial) and the ‘short head’ (deep). It is part of the hamstrings.
Semi-membranosus
Semimembranosis is one of a group of muscles called the Hamstrings. It is located on the posterior medial aspect of the thigh, deep to Semitendinosus. Its origin is the ischial tuberosity on the inferior pelvis and the insertion is the medial tibial condyle. It’s primary action is knee flexion, hip extension and knee internal rotation. It has very membrane like proximal and distal tendons.
Posterior medial attachment distally
Semi- tendinosus
Semitendinosus is one of the three muscles that make up the hamstrings muscle group, and it is located at the posterior and medial aspect of the thigh. The semitendinosus is so named due to it having a long tendon of insertion.The semitendinosus is more superficial than the semimembranosus (with which it shares very close insertion and attachment points). However, because the semimembranosus is wider and flatter than the semitendinosus, it is still possible to palpate the semimembranosus directly.
Distal attachment to the anterior medial tibia
Tibialis anterior - joint associated
Ankle
Tibialis anterior - location
The tibialis anterior is situated on the lateral side of the tibia; it is thick and fleshy above, tendinous below. This muscle does not cross over the knee therefore it has no role at the knee joint. The bulk of it muscle mass starts on the lateral aspect but then crosses medially after it passes the ankle and into the foot.
There is a sheath of connective tissue at the ankle which holds this tendon down. This creates a pulley on the aspect where it inserts into the bones of the foot. So contraction here is going to lift the foot upwards, and when that contraction occurs it is going to create some tension on the medial aspect of the foot which pulls the foot upwards and inwards.
Proximal attachment = Tibia
Distal attachment = 1st metatarsal
Tibialis anterior - principal movement
At the ankle ….
1. It is the primary dorsiflexor of the ankle
At the foot…
1. Inversion of the foot
Triceps surae- joint associated
Ankle
Triceps surae- location
The triceps surae is a pair of muscles located at the calf – the two-headed gastrocnemius and the soleus. These muscles both insert into the calcaneus, the bone of the heel of the human foot, and form the major part of the muscle of the posterior leg, commonly known as the calf muscle.
Triceps surae- principal movement
At the ankle …
- plantarflexion
Gastrocnemius
Gastrocnemius forms the major bulk at the back of lower leg and is a very powerful muscle. Ithas two heads that cross over the knee and run from here to the heel. Gastrocnemius also flexes the knee as it is the only muscle in triceps surae that crosses the knee joint.
Proximal attachment = Soleus to lateral epicondyle of tibia, gastrocnemius to femoral condyles
Distal attachment = Calcaneal tendon to calcaneus
Soleus
Soleus is a powerful lower limb muscle which along with gastronemius forms the calf muscle or triceps surae. It runs from back of knee to the ankle and is multipennate. It plays no role at the knee as to does not cross the knee joint. It actors past the ankle joint like Gastrocnemius into the calcanius via the achilles tendon which also causes plantar flexion. Soleus is deep to gastrocnemius.
Proximal attachment to the condyles of the tibia
Quadrupedal standing
Standing on all four limbs. There is a very good base of support however this stance requires a lot of energy expenditure as the limbs are active at many different joints.
Bipedal standing
Bipedal standing is standing on two limbs. There is a relatively small area of contact with the ground. This process is energy efficient way of maintaining the upright position as muscle activation is minimal.
Why is bipedal standing energy efficient?
This process is energy efficient way of maintaining the upright position. The reason is that we have a relatively small area of contact with the ground but our joints and our soft tissues around out joints are designed in a way to have energy efficiency.
Line of gravity on the body
Line of gravity (where all our weight goes through) is posterior to the hip joint and anterior to the knee and ankle. Therefore the hip and knee joints are locked into extension by tight ligaments and therefore no energy is consumed when standing. The ankle however is not locked, the joint is stabilised by Soleus and gastrocnemius (plantarflexors) therefore this consumes energy
Hip in bipedal standing
Line of gravity is posterior to the hip joint. The joint is ‘pushed’ into extension. It being in extension means that the ligaments are tight which means that the joint is locked.
Why are ligaments good for locking joint position?
Muscle is very energy dependent whereas ligaments do not need much energy to lock a joint and maintains stability at a particular position
Capsular ligaments of the hip joint and how they act in extension and flexion …
Reinforcing ligaments - pubofemoral ligament, illiofemoral ligament and ischiofemoral ligament
When the hip is in flexion - relaxed anteriorly, and taut posteriorly
When the hip is in extension - taut anteriorly, and relaxed posteriorly
Knee in bipedal standing
The line of gravity is anterior to the knee joint which also ‘pushes’ the knee into extension. With it being in extension, it means that the ligaments are tight and therefore the joint is locked and there is not much energy required to maintain this position.
Ankle in bipedal standing
The line of gravity falls anterior to the ankle joint The ankle joint ‘falls’ into dorsiflexion however this joint does not become locked. Instead the plantar flexors stabilise (continuously work against gravity). Therefore there is some energy consumed at this joint. After long periods of standing, there is a natural tendency to lean forwards therefore you constantly have to use plantar flexors to counteract gravity and the weight of the body. Therefore there is energy consumed and this area becomes very energy inefficient as the body has to play a large role in stabilising this joint.
Describe the muscles you have seen that cross anteriorly over joints of the lower limb. In your answer, include the movements they can produce at these joint
Illiopsoas (produces flexion at the hip)
Quadriceps femoris (produces extension of the knee, and also rectus femoris produces flexion at the hip)
Tibialis anterior (produces dorsiflexion at the ankle and inversion of the foot)
The tibialis anterior muscle has two major roles…
1 - dorsiflexion at the ankle
2 - inversion at the foot
Gait
Gait is the manner or pattern of walking
It is a learned movement strategy
Gait is characteristic
The basic pattern in the gait cycle
Two main phase categories - the stance and swing phases
Gravity will influence it
It is intended to be a smooth continuous movement with exchange of movement between the 2 limbs to propel you forwards
Name the eight phases of the gait cycle in order
Early stance (Initial contact) Mid stance Late stance (Terminal stance) Early swing Mid swing Late swing (Terminal swing)
Two main phases of the gait cycles
The two phases of limb movement during walking are the stance phase, when the foot
is on the ground, and the swing phase, when the foot is off the ground. These phases overlap between the limbs to some extent, so that both feet are on the ground for a short time. This is called ‘double-stance’ and increases the stability of walking. Walking, as opposed to running, is defined as having a ‘double-stance’ phase.
Transition of phases between stance and swing
Transitions between these phases of stance and swing occur at heel-strike (end of the swing phase) and toe-off (end of the stance phase).
Most muscles of the lower limb (as well as other muscles in body used to maintain balance) are active at heel- strike and toe-off. During mid-stance and mid-swing there is minimal muscle activity, although this is the time of maximum angular displacement of the limbs. The principal function of the muscles during walking is to accelerate and decelerate the angular motions of the lower limb.
Other movements in the phases of gait
• the rise and fall of the body
• the rotation of the pelvis as the body weight is
transferred from limb to limb
• the rotation of pectoral girdle and thorax
• the swinging of the upper limbs
stabilisation of the head
What are preswing and pre stance (heel strike) ?
These are just transition points in the gait cycle between the stance and swing phases. These are normally only included in the gait cycle to reinforce the idea of continual cycling of this pattern.
Early stance
1st one
Hip …
Joint position - The hip is in flexion but moving into extension (up until this point they have been agonists of flexion but soon they are going to become antagonists acting eccentrically to the extension happening in the posterior part of the hip)
Muscles involved and their contraction type - Concentric activity of gluteus maximus and hamstrings. Eccentric activity of Illiopsoas
Ligaments: Hip ligaments are taux posteriorly and lax anteriorly.
Knee …
Joint position - In extension (locked for stability)
Muscles involved and their contraction type - Quadriceps femoris put the knee into extension to lock this joint. Isometric activity of quadriceps femoris and hamstrings/gastrocnemius
Ligaments: are tight.
Ankle …
Joint position - In dorsiflexion (most stable as there is the best bony congruence), moving into plantar flexion
Muscles involved and their contraction type - Concentric activity of triceps surae, and eccentric activity of tibialis anterior (to control the rate of foot drop to the ground)
Mid stance
2nd one
Starting to move weight over hip, knee and ankle, transversing the line of gravity with our body and this phase therefore starts to use a lot of energy.
Hip
Joint position - Moving into extension by using gluteus Maximus, anterior muscles/flexors are slowing down how fast this movement can occur
Muscles involved and their contraction type - Concentric activity of gluteus Maximus and hamstrings, eccentric activity of illiopsoas (acts as an antagonist)
Ligaments: Hip ligaments are becoming taux anteriorly and lax posteriorly.
Knee
Joint position - Moving from extension to slight flexion
Muscles involved and their contraction type - Concentric activity of hamstrings and gastrocnemius
Ligaments are becoming slightly loose.
Ankle
Joint position - Moving into plantar flexion. There are two forces creating plantar flexion, the first is Gastrocnemius and Soleus ( the two muscles that make up triceps surae which we know by nature are plantar flexors). The second force acting is gravity which is acting to bring the foot down so you actively start to use tibialis anterior in order to counteract the rate at which gastrocnemius and Soleus are plantar flexing (therefore it is acting eccentrically to slow the rate at which the foot drops onto the ground)
Muscles involved and their contraction type - Concentric activity of the triceps surae. Eccentric activity of tibialis anterior
Late stance
3rd one
Hip
Joint position - In full extension
Muscles involved and their contraction type - Concentric activity of gluteus Maximus and hamstrings. Eccentric activity of Iliopsoas.
Ligaments: Hip ligaments are taux anteriorly and lax posteriorly.
Knee
Joint position - In extension as ankle moves into full plantar flexion
Muscles involved and their contraction type - Concentric activity of hamstrings and gastrocnemius
Ligaments becoming slightly loose.
Ankle
Joint position - in full plantar flexion
Muscles involved and their contraction type - Concentric activity of triceps surae (strong for propulsion)
Early swing
4th one
Hip
Joint position - In extension, but moving into flexion (to swing the limb through the sagittal plane, this is about propulsion)
Muscles involved and their contraction type - Concentric activity of illiopsoas and rectus femoris. Eccentric activity of Hamstrings and gluteus Maximus (to control the rate of the swing)
Ligaments: Hip ligaments are becoming taux posteriorly and lax anteriorly.
Knee
Joint position - In flexion (help to bring the toes off the ground)
Muscles involved and their contraction type - Concentric activity of hamstrings and gastrocnemius
Ankle
Joint position - In dorsiflexion (clearance of toes during swing)
Muscles involved and their contraction type - Concentric activity of tibialis anterior
Mid swing
5th one
Hip
Joint position - In flexion
Muscles involved and their contraction type - Concentric activity of illiopsoas and rectus femoris. Eccentric activity of gluteus Maximus and hamstrings (to control rate of swing)
Ligaments: Hip ligaments are taut posteriorly and lax anteriorly
Knee
Joint position - In flexion
Muscles involved and their contraction type - Concentric activity of hamstrings and gastrocnemius
Ankle
Joint position - In dorsiflexion ( to allow for clearance of toes during swing)
Muscles involved and their contraction type - Concentric activity of tibialis anterior
Late swing
6th one
Hip
Joint position - In flexion
Muscles involved and their contraction type - Concentric activity of illiopsoas and rectus femoris. Eccentric activity of gluteus Maximus and hamstrings (to control the rate of swing)
Hip ligaments are taux posteriorly, Lax anteriorly
Knee
Joint position - In flexion but moving into extension to prepare for heel strike and knee locking (for stability)
Muscles involved and their contraction type - Concentric activity of quadriceps femoris
Ankle
Joint position - In dorsiflexion for most stable joint position for heel strike.
Muscles involved and their contraction type - Concentric activity of tibialis anterior. Isometric activity of triceps surae to keep the ankle stable
Deltoid summary
Large powerful muscle, attached to the pectorial girdle, runs down and attaches to the lateral aspect of the humerus. The fibres run in a multipennate direction. It is a strong, stabilising muscle at the shoulder joint. When it shortens (concentric action) it produces abduction at the shoulder joint. Deltoid also assists in flexion and extension of the arm.
Biceps brachii summary
Located on the anterior aspect of the arm, it is a two headed muscle. It has a parallel arrangement of fibres and the fibres run distally and a strong tendon dives deep into the forearm, and attaches to the radius. When this muscle shortens, it produces flexion at the elbow joint and because of its attachment to the radius, it is also involved in supination of the forearm. Lies anterior to the shoulder joint and so concentric action would lead to flexion at the shoulder.
Triceps brachii summary
Located on the posterior aspect of the arm, it is a three headed muscle (lateral, medial and long head). The long head extends all the way up under deltoid and crosses the posterior aspect of the shoulder joint, attaches distally to the ulna. Lies posterior to the shoulder joint and so concentric action would lead to extension at the shoulder. Lies posterior to the elbow joint and so concentric action would lead to extension at the elbow.
Iliopsoas summary
Anterior muscle of the hip joint, located deep on the anterior aspect of the hip joint. It is made up of two muscles (illiacus and psoas major) and together they run distally and cross deep underneath this structure. This muscle when it shortens provides powerful flexion at the hip joint.
Gluteus maximus summary
Posterior muscle of the hip joint, quite a lot of musculature. Has large bundles of muscle fibres all running in parallel, crossing the hip joint attaching from the pelvis and running posterior and laterally to attach on the femur. This muscle produces strong extension at the hip joint.
Quadriceps femoris summary
Anterior muscle crossing the knee joint. This muscle has 4 heads (superficial, lateral, medial and one deep to the most superficial head), together these muscles make up a group called the quadriceps femoris. It consists of very long pennate arrangement of fibres and collectively comes together to cross the anterior part of the knee joint and this distal attachment is quite interesting because the connective tissues of the muscles are coming together to form a tendon that takes quadriceps femoris onto the patella and then the connective tissues run over the patella distally and attach on to the tibial tuberosity (as a ligament).
Rectus femoris lies anterior to the hip joint and so concentric action would lead to hip flexion.
Quadriceps femoris lies anterior to the knee joint and so concentric action would lead to knee extension.
Hamstrings summary
Posterior aspect of the thigh. There are three muscles that collectively make up the hamstrings. One runs medially and has a very long tendon on it (semitendinosus) alongside it is another muscle that runs medially and is a very thick membranous muscle (semimembranosus), the muscle that runs laterally has two heads ( a long thick head and a much shorter head) (called biceps femoris). Hamstrings arise from the posterior aspect of the hip joint and run distally to cross the posterior aspect of the knee joint. When it shortens the two movements it can produce is extension at the hip joint as they cross posteriorly to it and flexion at the knee joint.
Triceps surae group summary
Posterior aspect of leg and crosses posteriorly down the ankle joint. Two muscles with three heads in total. There is a pennate fibre arrangement and the muscles that make up triceps surae are gastrocnemius and soleus. Interesting distal attachment where a large tendon comes down distally and attaches to the heel bone (tendon is commonly known as the achilles tendon). When this muscle shortens it produces powerful plantar flexion.
Gastrocnemius lies posterior to the knee joint and so concentric action would lead to knee flexion.
Tibialis anterior summary
Large muscle belly with very long tendon crossing anteriorly on the ankle joint, lies anteriorly on the tibia. Tibialis anterior lies anterior to the ankle joint and so concentric action would lead to dorsiflexion at the ankle joint.
Which ligaments might restrict the femur from sliding anteriorly and posteriorly on the tibia?
ACL and PCL (intracapsular ligaments)
From the location of the collateral ligaments, what movements do they allow and which do they restrict?
Restrict - adduction and abduction
Allow - flexion and extension
When standing in anatomical position is quadriceps femoris resting or active?
It is resting. The quadriceps tendon/ligament is loose as no muscle activity results in no tension in the tendon/ligament
How does the difference in appearance of Triceps Surae and tibialis anterior relate to the difference in function and force?
Dorsiflexion requires less force therefore tibialis anterior is smaller (has less mass). Plantarflexion requires more force as it lifts the entire weight of the body therefore triceps sure is larger (has more mass).
Agonist and antagonist with concentric and eccentric…
The agonist produces the movement (concentric) and the antagonist (on the other side of the joint) smooths and controls the movement by acting eccentrically.
During which phase of the gait cycle is the knee flexed?
Second half of stance phase, and first half of swing to allow the foot to clear the floor
Which position is the ankle held in at heel-strike?
Dorsiflexion
Fibular collateral ligament
nothing
