Session 13 | Muscles of the Lower Body
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SETTING THE SCENE Let’s get stuck into the muscles of the lower body! Where do they start, where do they end up and what do they do? It’s essential for all fitness professionals to know and understand where muscles attach and what actions they are responsible for at the joints. This is the basis of writing safe, effective, functional exercise programs that work. Let’s have some fun using various learning techniques. We will say the muscles ‘out loud’ and encourage you to use colour, draw pictures and locate the muscles on yourself. By all means give your muscles a squeeze or a flex as you learn about them – as muscles are really cool! The muscles of the lower body are larger and more powerful than those of the upper body due to their role in walking, running, jumping and providing a stable base for the body. Many of these muscles cross two joints so let’s learn about biarticular muscles now. Biarticular Muscles (two-joint muscles) Many of the muscles of the lower body cross two joints rather than just one such as rectus femoris, hamstrings and the gastrocnemius. Depending on where the muscles attach, biarticular muscles may be able to create movement at both joints, for example, the rectus femoris flexes the hip and joins the other quadriceps to extend the knee. Likewise the hamstrings can extend the hip and flex the knee. The gastrocnemius crosses both the knee and ankle joints, however, the attachment is so close to the axis of rotation of the knee joint that it is biomechanically disadvantaged in moving the knee but is biomechanically biased to plantarflex the ankle joint. The muscles of the lower body create movement at the hip, knee and ankle joints. We will study these muscles in detail; we will look at the derivation of the muscle name, the attachments of the muscle, the actions and relevant movement patterns and exercises.
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Muscles Moving the Hip These muscles originate on the pelvic girdle, cross the hip joint (and two joint muscles also cross the knee joint) and insert at various points on the bones of the lower limb. While these muscles are involved in various joint movements, we have grouped them according to the main action used to develop the muscle in exercise prescription. Hip Flexors Psoas major Iliacus Rectus femoris Sartorius Hip Adductors Pectineus Adductor longus Gracilis Adductor brevis Adductor magnus
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Hip Extensors Gluteus maximus Hamstrings Biceps femoris Semitendinosus Semimembranosus Hip Abductors Gluteus medius Gluteus minimis Tensor fascia latae
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Muscles Moving the Knee Muscles that produce movements across the knee may be grouped as anterior (quadriceps) and posterior (hamstring) muscles. The quadriceps group extend the lower leg and one biarticular muscle also flexes the hip. The hamstring group flex the lower leg and most of them also extend the hip, once again, due to the biarticular nature. Quadriceps (knee extensors) consisting of: Rectus femoris Vastus lateralis Vastus medialis Vastus intermedius Hamstrings (knee flexors) consisting of: Biceps femoris Semitendinosus Semimembranosus
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Muscles Moving the Ankle These muscles produce movements at the ankle and hence move the foot. The most familiar muscles of the lower leg are referred to as the calf muscle group. This group consists of two muscles located on the posterior aspect of the lower leg. They are accompanied anteriorly by one major muscle, the tibialis anterior. Gastrocnemius
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Soleus
Tibialis anterior
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MUSCLES THAT MOVE THE HIP The key movements available at the hip which are common in exercise are flexion (lower limb moving forwards), extension (lower limb moving backwards), abduction (lower limb moving sideways, away from the midline) and adduction (lower limb moving back towards the midline). As such hip flexion and extension are performed in the sagittal plane and hip abduction and adduction are performed in the frontal plane. As the hip joint is a ball and socket joint, it allows a lot of other movements. Some are less likely to be found in gym exercises and include horizontal flexion, horizontal extension and circumduction. The hip can also perform medial rotation (lower limb turns inwards so that the toe points in) and lateral rotation (toes point out like a ballerina) which are important in positioning the lower limb for correct alignment so that the hip, knee and ankle are in line. Make sure you stand up and practice these movements to refresh your memory of how the hip moves.
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Snapshot - Anterior View Muscle
Origin
Insertion
Joint
Action
Psoas major
Lumbar Vertebrae Transverse processes of lumbar vertebrae
Femur Lesser trochanter Patella and tibial tuberosity via patella tendon
Hip
Hip Flexion Trunk Flexion Lateral Rotation
Iliacus
Ilium Iliac fossa
Femur Lesser trochanter
Hip
Hip Flexion Lateral Rotation
Rectus Femoris (quadricep muscle)
Ilium Anterior inferior iliac crest (AIIS)
Tibia
Hip and knee
Hip Flexion Knee Extension
Sartorius
Ilium Tibia Anterior superior Medial surface
Hip
Hip Flexion Lateral Rotation
Hip
Hip Flexion Hip Abduction
Tensor Fascia Iliac Crest Latae
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Tibia Via iliotibial tract
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Snapshot - Posterior View Muscle
Origin
Insertion
Joint
Action
Gluteus Maximus
Iliac crest, sacrum & coccyx
Femur & Iliotibial tract
Hip
Hip Extension Lateral Rotation
Gluteus Medius Ilium and Minimus Outer surface
Femur Greater trochanter
Hip
Hip Abduction Medial Rotation
Hamstrings
Tibia & Fibula
Hip/Knee
Hip Extension
Ischium
Biceps Femoris
Knee Flexion
Long head
Ischial Tuberosity
Short head
Femur linea aspera
Semimembranosus Semitendinosus
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Lateral condyle of tibia & fibula head
Hip extension & Knee flexion
Ischial Tuberosity
Tibia Medial surface
Hip extension & Knee flexion
Ischial Tuberosity
Tibia Medial surface
Hip extension & Knee flexion
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MUSCLES THAT MOVE THE HIP - FLEXORS The hip flexor muscles are positioned anteriorly and originate on the pelvis, cross the hip joint and the single joint muscles attach onto the femur, whilst the biarticular muscles also cross the knee joint and insert at the tibia. These muscles have a common function which is to flex the hip joint and include: Psoas major Iliacus Rectus femoris Sartorius The first two are very deep and functionally known as iliopsoas (silent p). Rectus femoris is one of the quadriceps muscle group and if you lift your knee up and palpate the front of your hip, you can feel this muscle working. Sartorius is of lesser importance in exercise but assists in a range of hip movements.
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Psoas Major Remember that the 'p' is silent in the pronounciation of this muscle. Derivation
psoas – loin (low back) major – large
Attachments Origin to the Insertion – in simple terms: Lumbar vertebrae
to the Femur
Specifically: Anterolaterally on the bodies of T12-L5 and the intervertebral to the Lesser trochanter of the femur discs between and anteriorly on the TP of L1-5 Actions Hip flexion Trunk flexion Lateral hip rotation Anteriorly tilts the pelvis
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Iliacus Derivation
iliacus – refers to the ilium
Attachments Origin to the Insertion – in simple terms: Ilium
to the Femur
Specifically: Upper two thirds of the iliac fossa, the anterior inferior iliac spine (AIIS) and the sacral ala
to the
Lesser trochanter of the femur
Actions Hip flexion Lateral hip rotation Anteriorly tilts the pelvis
Iliopsoas The iliacus and psoas major together are called the iliopsoas.
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Coach Tip
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Rectus Femoris Rectus femoris, a cylindrical, superficial muscle on the thigh, is the only quadriceps muscle that crosses two joints – the hip and knee. It is included here in its role as a hip flexor. Derivation
rectus – straight femoris – refers the femur
Attachments Origin to the Insertion – in simple terms: Iliac crest
to the
Tibia via patella
to the
Tibial tuberosity via the patella and the patellar ligament
Specifically: Anterior Inferior Iliac Spine (AIIS) just superior to the brim of the acetabulum
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Sartorius Derivation
sartorius – tailor
Attachments Origin to the Insertion – in simple terms: Ilium
to the Tibia
Specifically: Anterior superior iliac spine (ASIS)
to the
Proximal anteromedial tibia via the pes anserine tendon
Actions Hip flexion Hip abduction Lateral hip rotation Knee flexion Tilts the pelvis anteriorly
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MUSCLES THAT MOVE THE HIP EXTENSORS The main muscle that extends the hip is the gluteus maximus and the hamstrings assist. The 'glutes' are positioned posteriorly on the hip and the hamstrings are also posterior at the back of the thigh. A great example of these muscles working together is in running as show below, when the lower limb moves backwards and propels the body forwards. Specific exercises that target the hip extensors are squats and deadlifts. You will learn more about the 'hammies', as they are affectionately known, in muscles that move the knee.
Let's Learn More About the "Glutes" The three gluteal muscles – gluteus maximus, gluteus medius and gluteus minimus – are located in the buttock region, deep to the surrounding adipose tissue. The large, superficial gluteus maximus is the most posterior of the group and has fibres that run diagonally across the buttock. The gluteus medius is located on the outside of the hip and is also superficial, except for the posterior position which is deep to the maximus. The gluteus minimus lies deep to the gluteus medius. The gluteus maximus is the main hip extensor. While the gluteus medius is a strong abductor of the hip, its convergent fibres pull the femur in multiple directions and hence, it could be thought of as the deltoid muscle of the hip joint. Gluteus maximus is the key extensor of the hip (assisted by hamstrings) while the gluteus medius and minimus are more involved with hip abduction and as such, are discussed in the abductor section.
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Gluteus Maximus Derivation
gluteus – rump maximus – greatest
Attachments Origin to the Insertion – in simple terms: Iliac crest, sacrum and coccyx
to the
Femur and iliotibial band
to the
Iliotibial band and the gluteal tuberosity of the femur
Specifically: Posterior iliac crest, the posterolateral sacrum and the coccyx Actions Hip extension as evident in exercises such as squat, lunge and deadlift. Lateral hip rotation The hamstrings assist the gluteus maximus in hip extension and are discussed in muscles that move the knee.
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MUSCLES THAT MOVE THE HIP ABDUCTORS The hip abductor muscles are positioned more laterally on the hip and originate on the pelvis, cross the hip joint and the single joint muscles (gluteus medius and minimus) attach onto the femur, whilst the biarticular muscle (tensor fascia latae) crosses the knee joint and inserts at the tibia via the iliotibial band. These muscles have a common function which is to abduct the hip joint as well as stabilise the pelvis and include: Gluteus medius Gluteus minimis Tensor fascia latae See the anterior and posterior snapshots under 'Muscles that Move the Hip' for a table representation of these muscles.
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Gluteus Medius and Minimus Gluteus Medius Derivation
gluteus – rump medius – middle
Attachments Origin to the Insertion – in simple terms: Ilium
to the
Femur
Specifically: External ilium, inferior to the iliac crest and between the anterior and to the posterior gluteal lines
The lateral surface of the greater trochanter of the femur
Actions Hip abduction (entire fibres) Lateral hip rotation as hip abducts (posterior fibres) Medial hip rotation (anterior fibres)
Gluteus Minimus This muscle (meaning least) is very deep and lays underneath gluteus medius. It also abducts and medially rotates the hip.
Functionally, gluteus medius and minimis stabilise the hip joints and pelvis by preventing the hip © Australian Institute of Fitness
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from collapsing when the body is supporting its own weight as in standing, walking and running. Single leg exercises and many core exercises aim to improve stabilisation when performed correctly An exercise such as a side plank specifically targets the hip abductors as pelvic stabilisers to keep the pelvis alligned with the spine. A lateral cable abduction specifically strengthens the hip abductors. Side Plank
Lateral Cable Abduction
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Tensor Fascia Latae The tensor fascia latae (TFL) is a small, superficial muscle located on the lateral side of the upper thigh. Approximately three fingers wide, the TFL is easily accessible between the upper fibres of the rectus femoris and the gluteus medius. The TFL attaches to the iliotibial tract along with the gluteus maximus. The iliotibial tract (ITB) is a superficial sheet of fascia with vertical fibres that run along the lateral thigh. It emerges from the gluteal fascia, is wide and dense over the vastus lateralis muscle and funnels into a strong cable along the side of the knee before inserting at the tibial tubercle. The fibres of tensor fasciae latae and some fibres of gluteus maximus attach to the proximal aspect of the iliotibial tract. The iliotibial tract has a thick, matted texture (similar to packing tape) that makes it a strong stabiliser of the hip and knee. Derivation
tensor – tightens fascia – bandage latae – broad
Attachments Origin to the Insertion – in simple terms: Iliac crest
to the
Tibia
to the
Iliotibial band (ITB) and tibia
Specifically: Anterior superior iliac spine and anterior iliac crest
Actions Hip abduction Hip flexion Medial hip rotation
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Iliotibial Band (ITB) Syndrome The iliotibial band (ITB) is also known as the iliotibial tract and iliotibial tendon. It begins at the iliac crest of the pelvis and runs on the lateral part of the thigh until it attaches into the tibia (shinbone). It consists of a thick band of fascia (stiff connective tissue) and is easily palpated. Let's locate it on your body. Stand up which your knees flexed (semi squat position) and run your fingers laterally above your knee - you should feel a very thick strong band. As mentioned, both the gluteus maximus and tensor fascia latae muscles attach into the ITB and the band acts to coordinate muscle function and stabilise the knee laterally during walking and running. It stabilises the knee both in extension and in partial flexion, and is therefore used constantly during walking and running. What is ITB syndrome? Fascia is like shrink-wrap and if it becomes tight, it tends to stay tight. In the case of a tight ITB, the distal portion of the iliotibial tendon at the knee rubs against the lateral femoral condyle, or less commonly, the greater tuberosity and can result in irritation and inflammation. When this happens, it is known as the ITB syndrome and is a common cause of lateral knee pain, particularly among runners and cyclists. Considered an overuse syndrome, it is typically observed in people who exercise vigorously and frequently. The overuse creates stress that the body cannot repair, and soft tissue breakdown occurs. When the band is excessively tight or stressed, the ITB rubs more vigorously. Pain is felt along the lateral knee, and can also include the hip. Pain is worse on downhill running and becomes worse with activity after a pain-free start. So what causes ITB syndrome? It is usually caused by overuse and due to errors in training. Sudden changes in: surface (ie, soft to hard, flat to uneven or decline), speed, distance, shoes and frequency, can result in a rate of break down faster than what the body can heal, causing injury. Other factors frequently reported include limb length discrepancy, genu varum (bow legs), over pronation (feet roll inwards), hip adductor weakness, inadequate stretching and myofascial restriction.
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Clients complaining of knee pain should be directed to an allied health professional for a proper diagnosis.
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MUSCLES THAT MOVE THE HIP ADDUCTORS The five adductors – adductor magnus, adductor longus, adductor brevis, pectineus and gracilis – are located along the medial thigh between the hamstrings and quadriceps femoris muscles. Their proximal tendons attach at specific locations along the base of the pelvis, predominantly the pubis. When the thigh is viewed anteriorly, the muscle bellies of the adductors lie in three layers. The pectineus and adductor longus are most anterior. Behind them is the adductor magnus. The broad span of adductor magnus, known as the “floor of the adductors,” lies anterior to the hamstrings. These four muscles tuck posteriorly to the quadriceps group and insert on the posterior femur. The fifth adductor, gracilis, lies superficially on the medial thigh. It is the only adductor that crosses the knee.
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Snapshot - Medial View Muscle
Origin
Insertion
Joint
Action
Pectineus
Pubis
Femur Proximal posterior
Hip
Hip adduction Hip flexion
Gracilis
Pubis
Tibia Medial proximal
Hip/Knee
Hip adduction Hip flexion Knee flexion
Hip
Hip adduction Hip flexion Hip adduction Hip flexion Hip adduction Hip extension
Adductor Group Pubis and ischium Femur Longus Pubis Brevis Pubis Femur Femur Magnus Pubis and ischium Femur
The image below is from the medial aspect, that is, looking at the inside of the thigh.
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Hip Adductor Group Derivation
pectineus gracilis – slender, graceful longus – long brevis – short magnus – great, large
Attachments Origin to the Insertion – in simple terms: Pubis
to the Femur
Specifically:
Pubis and ischium
to the
Linea aspera of the femur and tibia
Actions: All adductors – adduct the hip, medially rotate the hip, assist to flex the hip
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MUSCLES THAT MOVE THE KNEE QUADRICEPS The four large quadriceps muscles positioned anteriorly on the thigh – rectus femoris, vastus medialis, vastus lateralis and vastus intermedius – primarily extend the knee. The superficial rectus femoris is the only quadriceps muscle that crosses two joints – the hip and knee – and acts to flex the hip as previously discussed. Vastus intermedius is deep to the rectus femoris. All four quadriceps muscles converge into a single tendon above the knee – the quadriceps tendon. The tendon connects to the top and sides of the patella before attaching to the tibial tuberosity. The distal tendon of the quadriceps and the patellar ligament are one and the same structure. Because the tendon attaches one bone to another (the patella to the tibia), it is actually considered a ligament.
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Snapshot - Anterior View Muscles that produce movements across the knee may also be viewed as anterior and posterior groups. The anterior grouping of muscles extend the lower leg and some of the muscles also flex the hip. Muscle
Origin
Insertion
Joint
Action
Quadriceps
Ilium & Femur
Tibia via Patella
Hip/Knee
Hip Flexion Knee Extension
Rectus Femoris Iliac crest Anterior inferior iliac spine (AIIS)
Patella Superior border
Hip flexion Knee extension
Vastus Lateralis Femur Greater trochanter & linea aspera
Tibia Tibial tuberosity
Knee extension
Vastus Intermedius
Femur Anterior lateral
Knee extension
Vastus Medialis
Femur Linea aspera
Knee extension
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Rectus Femoris Derivation
rectus – straight femoris – refers the femur
Attachments Origin to the Insertion – in simple terms: Iliac crest
to the
Tibia via patella
to the
Tibial tuberosity via the patella and the patellar ligament
Specifically: Anterior Inferior Iliac Spine (AIIS) just superior to the brim of the acetabulum Actions Knee extension Hip flexion
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Vastus Lateralis Derivation
vastus – vast lateralis – lateral
Attachments Origin to the Insertion – in simple terms: Femur
to the
Tibia via patella
to the
Tibial tuberosity via the patella and the patellar ligament and the lateral patella expansion
Specifically:
Linea aspera of the femur and gluteal tuberosity of the femur
Actions Knee extension
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Vastus Intermedius Derivation
vastus – vast inter – between medius – middle
Attachments Origin to the Insertion – in simple terms: Femur
to the
Tibia via patella
Specifically: Anterior shaft and linea aspera of to the the femur
Tibial tuberosity via the patella and the patellar ligament
Actions Knee extension Note that this muscle is deep.
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Vastus Medialis Derivation
vastus – vast medialis – medial
Attachments Origin to the Insertion – in simple terms: Femur
to the
Tibia via patella
Specifically: Linea aspera of the femur and the intertrochanteric line and the to the medial supracondylar line of the femur
Tibial tuberosity via the patella and the patellar ligament and the medial patella expansion
Actions Knee extension
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Coach Tip
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MUSCLES THAT MOVE THE KNEE HAMSTRINGS The hamstrings muscle group – biceps femoris, semitendinosus and semimembranosus – are located along the posterior thigh between the vastus lateralis and adductor magnus. Comparatively, the hamstrings are not as massive as the quadriceps femoris group, but are nonetheless very strong. They are primarily knee flexors and secondarily hip extensors. All three hamstrings have a common origin at the ischial tuberosity. Their muscle bellies extend superficially down the thigh before becoming long, thin tendons that stretch behind the knee. As a group, the hamstrings and their distal tendons are easily palpable. Biceps femoris is the lateral hamstring. It has two heads – a superficial long head and a deeper short head. The two “semi” muscles are medial. The semitendinosus lies superficial to the broader and deeper semimembranosus. The term “hamstring” originated in eighteenth century England. Back then, butchers would display pig carcasses in their shop windows hanging them from the long tendons at the back of the knee – hence the term “ham-strings”!
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Snapshot - Posterior View Muscles that produce movements across the knee may also be viewed as anterior and posterior groups. The posterior grouping of muscles flex the lower leg and some may extend the hip. Hamstrings
Ischium
Tibia & Fibula
Biceps Femoris Ischial Tuberosity
Tibia & Fibula
Long head
Ischial Tuberosity
Lateral condyle & head of fibula
Short head
Femur linea aspera
Semimembranosus
Ischial Tuberosity
Tibia Medial surface
Semitendinosus
Ischial Tuberosity
Tibia Medial surface
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Hip/Knee
Hip Extension Knee Flexion
Hip extension & Knee flexion Hip extension & Knee flexion Hip extension & Knee flexion
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Biceps Femoris Derivation
bi – two ceps – head femoris – refers to the femur
Attachments Origin to the Insertion – in simple terms: to the
Tibia and fibula
to the
Posterior surface of the head of the fibula and the lateral tibial condyle
Short head: linea aspera of femur to the
Posterior surface of the head of the fibula and the lateral tibial condyle
Ischium and femur Specifically:
Long head: Ischial tuberosity
Actions Knee flexion (entire muscle) Hip extension (long head) Lateral hip rotation (long head)
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Semitendinosus Derivation
semitendinosus – refers to its long tendon
Attachments Origin to the Insertion – in simple terms: Ischium
to the
Tibia
to the
Proximal anteromedial tibia via the pes anserine tendon
Specifically:
Ischial tuberosity
Actions Knee flexion Hip extension Medial hip rotation
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Semimembranosus Derivation
semimembranosus – refers to its flattened, membranous tendon
Attachments Origin to the Insertion – in simple terms: Ischium
to the
Tibia
to the
The posterior surface of the medial condyle of the tibia
Specifically:
Ischial tuberosity
Actions Knee flexion Hip extension Medial hip rotation
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Coach Tip Collectively, the hamstrings extend the hip during movements involving 'standing up' as in squats and lunges. They also extend the hip from a bent-over position as in a deadlift shown below. These exercises are all considered sound, functional choices for training the hamstrings.
The hamstrings also flex the knee as in the machine leg curl shown below. As this exercise is both open chain and isolated thus less functional, it would not be prescribed as frequently in total body strength programs.
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MUSCLES THAT MOVE THE ANKLE The most familiar muscles of the lower leg are referred to as the calf. This group is composed of two muscles, the gastrocnemius and soleus, on the posterior aspect of the lower leg. On the anterior aspect is one major muscle, the tibialis anterior.
Snapshot - Anterior View Muscle
Origin
Insertion
Joint
Action
Tibialis Anterior
Tibia Lateral condyle & body of the tibia
Metatarsals
Ankle
Ankle dorsiflexion Ankle Inversion
Insertion
Joint
Snapshot - Posterior View Muscle
Origin
Action
Gastrocnemius Femur Lateral & Medial condyles
Tarsals Knee/Ankle Calcaneus via Achilles tendon
Ankle Plantar flexion Knee Flexion
Soleus
Tarsals Ankle Calcaneus via Achilles tendon
Ankle Plantar flexion
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Tibia & Fibula Medial border of tibia & head of fibula
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More About the Calf The large muscle mass of the posterior leg is composed of the gastrocnemius and the soleus muscles. The superficial gastrocnemius has two heads and crosses two joints – the knee and ankle. Emerging from between the hamstring tendons, the gastrocnemius heads extend halfway down the leg before blending into the calcaneal tendon. Although its name (Greek for “belly of the leg”) suggests that the gastrocnemius is rotund, it is actually quite thin when compared to the thick soleus. The soleus is deep and its distal end is inferior to the gastrocnemius – its medial and lateral fibres can be felt on the sides of the lower leg. Together, they insert to the strong calcaneal tendon also known as the Achilles’ tendon. So why the name Achilles tendon. Legend says that as a baby, the Greek mythological warrior Achilles was dipped in the River Styx by his mother to make him invulnerable. He was completely immersed except for the ankle by which she held him. After fighting in the Trojan War, Achilles was mortally wounded when an arrow penetrated his heel. Hence, “Achilles’ heel” refers to a small but fatal weakness.
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Gastrocnemius Derivation
gastro – stomach nemius – leg
Attachments In simple terms: Femur
to the
Tarsals
to the
Posterior surface of the calcaneus via the calcaneal (Achilles) tendon
Specifically: Medial and lateral femoral condyles Actions Ankle plantar flexion Knee flexion NB: in the diagram below to the right, the origin of gastrocnemius is indicated by the 'O' alongside the condyles at the bottom of the femur and the insertion is shown by 'I' at the calcaneus (tarsal/heel bone).
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Soleus Derivation
soleus – sole of the foot
Attachments In simple terms: to the
Tarsals, specifically the calcaneus
The soleal line of the tibia and the head and proximal third of the to the fibula
Posterior surface of the calcaneus via the calcaneal (Achilles) tendon
Tibia and fibula Specifically:
Actions Ankle plantarflexion (it assists gastrocnemius) NB: in the diagram below to the right, the origin of soleus is indicated by the 'O' alongside the fibula and tibia and the insertion is shown by 'I' at the calcaneus (tarsal/heel bone).
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Tibialis Anterior Derivation
tibialis – refers to the tibia anterior – before, in front of
Attachments In simple terms: Tibia
to the
Metatarsals
Specifically: The lateral tibial condyle, the proximal two thirds of the anterior to the tibia and the proximal two thirds of the interosseous membrane
Medial foot, the 1st cuneiform and the 1st metatarsal
Actions Ankle dorsiflexion Inversion of the tarsal joints The tibialis anterior aides in the activities of walking, running, kicking a ball, or any activity that requires the toes to lift. It also functions to stabilise the ankle as the foot hits the ground during the contact phase of walking (eccentric contraction) and acts later to pull the foot clear of the ground during the swing phase (concentric contraction). As the insertion allows the toe to be pulled up and held in a locked position, it can 'lock' the ankle, as in toe-kicking a ball, when held in an isometric contraction.
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About the Plantar Fascia The plantar fascia is a thick ligament that runs along the bottom of the foot from the calcaneus to the base of the toes, and functions to support the arch of the foot and facilitate foot movement. Plantar fasciitis is a painful inflammation of the plantar fascia where pain is usually felt on the underside of the heel. This condition requires proper diagnosis and treatment by an appropriately qualified allied health professional.
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YOUR TURN | LOWER BODY MUSCLES It's time to test your memory and cement your lower body anatomy knowledge. Visit your Your Turn Diary to complete a series of tables to identify attachment, joint crossed, joint actions and target exercises.
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MOVEMENT ANALYSIS We investigated movement analysis (JAM) in muscles of the upper body so let’s get straight into JAM for the lower body. In the table below, we achieve two things (1) revisit JAM and (2) analyse an isolated exercise, the machine leg curl. In this exercise, we analyse the down phase as the ankles push the pads down and the knees bend. As only one joint is moving, the analysis is more straight forward than analysing a compound exercise. JAM
Description
Machine Leg Curl
Joint
Refers to the joints moving
Knee
Action
Refers to the actions at those joints (concentric phase)
Knee flexion
Muscle
Refers to the muscles creating those actions Hamstrings (gastrocnemius assists)
Let's now analyse a compound exercise – remember to analyse each joint one at a time from proximal to distal as shown in the squat example below.
Example – Squat (concentric is up) Joint
Action
Muscle/s
Role/s
Hip
Hip extension
Gluteus maximus Hamstrings
Agonist Assistant synergist
Knee
Knee extension
Quadriceps
Agonist
Ankle
Ankle plantarflexion
Gatrocnemius Soleus
Agonist Assistant synergist
Out of all the agonists listed, the number 1 target muscle is the quadriceps – the key reason for prescribing the squat. How are you going with the concentric or working phase of the muscle? You may get confused with the concentric phase of a squat because you can feel your muscles © Australian Institute of Fitness
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really working on both the up (concentric) and down (eccentric) phases especially when lifting a heavy load. But, if you ask yourself, which phase is harder? Which phase do I ‘fail’ on (reach muscular exhaustion)? It should be the up phase – the concentric contraction where the muscles causing the joint actions are shortening. Remember, 'c' for concentic, 'c' for ceiling where the load moves towards the ceiling.
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Quick Quiz Complete movement analysis/JAM tables for each of the compound exercises below listed – remember to analyse the joints from proximal to distal. We recommend that you attempt these before viewing the video then again afterwards. If you prefer to write the answers in, remember that you can print these pages when you open the session PDF.
Exercise 1 – Leg Press Squat (concentric is _________) Joint
Action
Muscle/s
Role/s
Exercise 2 – Lunge (analyse the front leg) (concentric is _________) Joint
Action
Muscle/s
Role/s
Exercise 3 – Modified Deadlift (concentric is _________) Joint
Action
Muscle/s
Role/s
Have you heard people say that the ‘back’ is the target muscle for this exercise. Well, which back muscle? What people are referring to here are the back muscles known as erector spinae which work to stabilise the torso hence the 'back' is involved but is not the agonist or target muscle. View the video for the answers. NB: In the demonstration of the modified deadlift, be aware that the ankle is actually quite still and the knee has minimal movement. The reduced movement of the modified deadlift in comparison to the deadlift to the floor, is an advantage when prescribing this movement pattern to beginners. For the analysis, imagine a greater movement where all three joints would move.
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ROUND UP AND REFERENCES Did you know that you just learned 25 different muscles of the lower body. Congratulations champion! For easier learning, we grouped the muscles as follows: Muscles that move the hip Hip flexors Hip extensors Hip abductors Hip adductors Muscles that move the knee Quadriceps muscle group Hamstrings muscle group Muscles that move the ankle The following resources were used in the compilation of this session: Biel, A. (2005). Trail Guide to the Body. Books of Discovery: Boulder Thompson, C.W. and Floyd, R.T. (2004). Manual of Structural Kinesiology, 15th edition. WCB/McGraw Hill
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