Ankle / Knees / Hips Flashcards
Rectus femoris – The rectus femoris covers a large portion of the middle of the thigh. It completely covers the deep vastus intermedius and a large portion of the other two vasti. In a lean individual a strong knee extension will reveal an apparent V-shaped muscle belly lying between and generally superior to the vastus medialis and vastus lateralis. It has two proximal attachments, the anterior inferior iliac spine and just superior to the acetabulum (where the femur articulates at the hip). Use of the term rectus in its name implies a vertical and straight orientation along the femur. The rectus femoris attaches distally to the tibial tuberosity by way of the patellar tendon-patella-patellar ligament series. The rectus shares its distal function with the vasti, knee extension. Its contribution to knee extension is strongest when the hip is extended (straight) as a flexed (bent) hip invokes the muscles proximal function, hip flexion. With a flexed hip, the rectus is already pre-shortened and cannot greatly contribute to knee extension. This is one reason that an isolation exercise, like the machine leg extension, is not adequate to fully develop strength in the knee musculature. If there is no upright back support on a leg extension machine, watch how people use it. Instead of sitting upright, they will lean back. The body is intuitively aligning itself to generate more force during the exercise.
Vastus lateralis – This muscle is sometimes called the vastus externus and is proximally attached to the femur along to the anterior and inferior borders of the greater trochanter, the lateral aspect of the gluteal tuberosity, and to the upper portion of the lateral side of the linea aspera. The linea aspera is a long vertical ridge on the posterior surface of the femur. The muscle also attaches distally to the lateral portion of the patella and then to the tibial tuberosity. It has but one function, to extend the knee. A simple strong extension of the knee will make the vastus lateralis visually apparent as a prominent muscle belly about two inches superior and lateral to the knee.
Rectus femoris – The rectus femoris covers a large portion of the middle of the thigh. It completely covers the deep vastus intermedius and a large portion of the other two vasti. In a lean individual a strong knee extension will reveal an apparent V-shaped muscle belly lying between and generally superior to the vastus medialis and vastus lateralis. It has two proximal attachments, the anterior inferior iliac spine and just superior to the acetabulum (where the femur articulates at the hip). Use of the term rectus in its name implies a vertical and straight orientation along the femur. The rectus femoris attaches distally to the tibial tuberosity by way of the patellar tendon-patella-patellar ligament series. The rectus shares its distal function with the vasti, knee extension. Its contribution to knee extension is strongest when the hip is extended (straight) as a flexed (bent) hip invokes the muscles proximal function, hip flexion. With a flexed hip, the rectus is already pre-shortened and cannot greatly contribute to knee extension.
Rectus femoris crosses HIP JOINT where Vasti do not
Vastus lateralis – This muscle is sometimes called the vastus externus and is proximally attached to the femur along to the anterior and inferior borders of the greater trochanter, the lateral aspect of the gluteal tuberosity, and to the upper portion of the lateral side of the linea aspera. The linea aspera is a long vertical ridge on the posterior surface of the femur. The muscle also attaches distally to the lateral portion of the patella and then to the tibial tuberosity. It has but one function, to extend the knee. A simple strong extension of the knee will make the vastus lateralis visually apparent as a prominent muscle belly about two inches superior and lateral to the knee.
Vastus medialis – This muscle is attached proximally from the inner side of the neck of the femur, along the entire length of the linea aspera, and to the medial, anterior, and lateral aspects of the upper three fourths of the femur. It attaches distally to the medial portion of the patella and then to the tibial tuberosity. It has an identical function to the vastus lateralis, extension of the knee. A simple strong extension of the knee will make the vastus medialis visually apparent as a prominent tear-drop shaped muscle belly at the level of the superior and medial border of the patella. You will see this muscle referred to as the VMO frequently in popular fitness and some clinical literature – its short for vastus medialis obliquus, obliquus referring to the angle of the muscle fibers in the muscle. Using vastus medialis is fine and proper. They use VMO because they think it sounds cool … or because they have a hard time pronouncing ‘obliquus’.
Vastus intermedius – Sometimes referred to as the vastus cruraeus (derived from Latin and referring to the lower leg) this muscle attaches proximally along the anterior and lateral surfaces of the upper two thirds of the femur. The intermedus lies under the superficial rectus femoris. The muscle attaches to the superior under-portion of the patella by way of the patellar tendon then to the tibial tuberosity. The vastus intermedius is a deep muscle and is not palpable but it is active in the same action as the other two vasti, knee extension.
Biceps femoris – This is the muscle most people will equate to the ‘hamstrings’ on the back of the leg, however there are two other muscles, the semimembranosis and the semitendinosis, that comprise the hamstrings. The biceps femoris, as its name indicates, has two heads. The long head has a proximal attachment on the ischial tuberosity (seat bone) and on the lower part of the sacrum. The short head attaches along the upper posterior aspect of the linea aspera of the femur. Afterwards the muscle runs down, medial to lateral, across the back of the leg. Its distal tendon attaches to the head of the fibula and to a lesser degree the lateral condyle of the tibia. The tendon of the biceps femoris is closely associated with the lateral collateral ligament of the knee. The short head of the muscle is a knee flexor. The long head crosses both the knee and hip joint so its distal function is knee flexion and its proximal function is hip extension. If the knee is flexed, the biceps femoris is pre-shortened and is a weak hip extensor. If the knee is extended, the biceps femoris is a weak hip flexor.
biceps femoris attaches distally and laterally to the fibula.
Semimembranosis – The second component of the hamstrings, the semimembranosis, attaches proximally at the ischial tuberosity and attaches distally to the posterior aspect of the medial condyle of the tibia. It runs medial to the biceps femoris. The muscle crosses two joints and acts at both the hip and knee. The distal function at the knee is flexion of the knee. You can palpate the tendinous attachment to the medial tibial condyle by flexing the knee to ninety degrees against resistance. Place your fingers on the medial aspect of the tibia until you find two prominent tendons. Follow the most inferior of the two and follow it medially and upwards until you find the bulk of the muscle.
Semitendinosis – The final element of the hamstrings is the semitendinosis. The muscle attaches proximally at the ischial tuberosity and shares much of its attachment architecture with the biceps femoris. The semitendinosis is notable in that the muscle ends at approximately mid-thigh and attaches distally to the medial upper face of the tibia by way of a long tendon. Many of the flexors of the knee have tendons that attach in a type of wrap-around orientation to the tibia. The semitendinosis runs around the medial condyle and insinuates itself over the medial collateral ligament before its final termination. The semitendinosus has a proximal hip function but its distal function at the knee is flexion. You can palpate the tendinous attachment to the behind the medial tibial condyle by flexing the knee to ninety degrees against resistance. Place your fingers on the medial aspect of the tibia until you find two prominent tendons. Follow the most superior of the two and follow it medially and upwards until you find the bulk of the muscle. You will note also that tendon is also slightly more lateral than that of the semimembranosis.
Sartorius – The sartorius is a very long and thin muscle that crosses diagonally, lateral to medial, the anterior length of the thigh – it is the longest muscle in the human body. Its body crosses over the upper portion of the rectus femoris, runs over the middle portion of the vastus medialis and then borders it medially until reaching their distal attachments. The muscle proximally attaches at the anterior superior iliac spine, passes behind the medial condyle of the femur and attaches distally to the proximal, medial, and posterior surface the tibia. The sartorius has four movement functions with three of those occurring at the hip. At the knee however it is a simple flexor.
Popleitis – This is a deep and very small muscle that attaches proximally at the lateral femoral condyle and attaches distally to the posterior tibia below the medial tibial condyle. It crosses the back of the knee from lateral to medial. Given its small mass and attachment orientation, it is a weak knee flexor. The poplietis also acts on the lateral meniscus by way of a section of its tendon attaching to the posterior lateral meniscus. When the knee is flexed actively, the popleitis draws the meniscus to the posterior and prevents pinching of the meniscus between the tibia and femur. There is a surface landmark of interest here, the poplietal fossa, the depression on the back of the knee. Its superior border is formed by the transition from hamstring muscles to tendon, to the inferior by the vergence of the gastrocnemius, and by the tendons attached to the lateral and medial tibial condyles. You can palpate the fossa but the muscle is deep and cannot be palpated.
Plantaris – The plantaris is a relatively famous muscle in the muscle hypertrophy (increased muscle mass) research community. It is quite large in some animals, such as the great apes, but it has little function in modern human beings and may be completely absent in up to ten percent of the population. The plantaris in the mouse and rat are frequently used in exercise physiology experiments that explore the mechanisms of muscle hypertrophy through the ablation of the gastrocnemius. When the superficial gastrocnemius is removed, the underlying plantaris and soleus must pick up the load once carried by the gastrocnemius. As a result they hypertrophy. In the mouse there are also relatively few cells in these muscles (in the thousands) so it is easier to enumerate and measure the cells. You can see by the close proximity of the two attachment sites, that the muscle and tendon together will not be more than about four inches long. The primary, and proximal, function of the plantaris is knee flexion but its tendon also connects to the calcaneal tendon of the gastrocnemius. It thus has a distal function as a weak plantarflexor.
Gastrocnemius – The gastrocnemius’ proximal function, flexion of the knee, is of interest here. Its lateral and medial heads attach to, proximally and respectively, the lateral and medial condyles of the femur. It attaches distally to the calcaneus via the calcaneal or Achilles tendon. Its distal function, plantarflexion of the ankle, and its palpation were discussed in the previous chapter.
KNEE LIGAMENTS
Patellar ligament – This ligament is sometimes a confusing structure. But it shouldn’t be. The patellar ligament connects the inferior surface of the patella to the tibial tuberosity (Figure 11.4). Bone connected to bone. Occasionally some sources will claim that the patella is a sesamoid bone (bone imbedded in a ligament) and refer only to a patellar tendon connecting the combined tendons of the quadriceps to the tibial tuberosity. Careful examination of the structure and centuries of study by many many amazing anatomists support the presence of the patellar ligament (and a separate patellar tendon described later). Palpating the tendon is quite easy. With the leg relaxed and the knee at ninety degrees, place your finger at the inferior and middle aspect of the patella then using moderate pressure walk your fingers down to the tibial tuberosity. You should feel a slightly flat and rebounding structure about an inch wide between the points of attachment. This is the structure the physician whacks with the little hammer to invoke the knee-jerk reflex.
Collateral ligaments – There are two collaterals ligaments, 1. medial
2. latera
provide lateral stability to the knee by reinforcing normal muscular tone in preventing excessive side-to-side movements. AKA as the tibial and fibular collateral ligaments.
Medial collateral ligament connects the medial epicondyle of the femur and the medial tibial surface.
Lateral collateral ligament runs between the lateral epicondyle of the femur and the head of the fibula. You can find both of these ligaments by placing your fingers on the sides of the knee and repeatedly flexing and extending the knee. Once you discriminate the gap between the femur and the tibia and fibula, with a little pressure you should be able to feel a fairly resilient and rebounding cord. The collaterals are injured frequently by lateral impacts to the opposite side of the ligaments location (eg., a blow from the medial side stretches and disrupts the structure of the lateral collateral).
Cruciate Ligaments – Limiters of joint separation, the cruciates.
Anterior cruciate ligament attaches at the lateral condyle of the femur and to the anterior intercondylar surface of the tibia. It acts to limit the excursion of the tibia too far forward (or femur too far backward) if muscular tension is inadequate.
Posterior cruciate ligament runs from the medial condyle of the femur to the posterior intercondylar surface. It prevents displacement of the tibia to the posterior (or femur too far forward).
The cruciates are also responsible for limiting the amount of rotation possible along the long axis of the knee. In plant-and-twist sports, such as soccer, football, basketball, volleyball, rugby, ad nasueum, there is an elevated risk of injuring these ligaments as compared to linear sports such as running, cycling, lifting, etc.
Menisci – The term meniscus is a quite broad term derived from the Greek and means a crescent shaped curved surface (convex or concave), usually used in reference to the curved interface between a liquid in a tube and the atmosphere. However, in the knee a meniscus is one of two roughly horseshoe shaped cartilages located on the articular surfaces of the tibia, with the horseshoes pointed towards the middle of the joint. The menisci are thicker towards the outer borders and thinner as they approach the middle. The shallow bowl like shapes formed via their position on top of the tibia help to provide a modicum of stability to the knee, as the condyles of the femur sit in the bowls. Their primary function however, is to reduce friction between the femur and tibia during movement. The menisci are intimate with the cruciate ligaments. The lateral meniscus in fact has a ligament, the meniscofemoral ligament that parallels the larger posterior cruciate. The menisci are often torn at the same time cruciate or collateral ligaments are injured.
Bursae – A bursa is a fluid filled sac bounded by fibrocartilage and situated around various condyloid joints like the knee, usually just underneath tendons and ligments. They vary in size and function to cushion the joint around which they are situated. An example would be the prepatellar bursa which lies just behind the patella and helps maintain the position of the patella and dampens forces between the patella and the underlying femur.
ANKLE MUSCLES
Tibialis Anterior – Nomenclature cues make localizing this muscle elementary, it is found along the anterior surface of the tibia, specifically the anterior and lateral surface. The muscle is quite superficial and attaches proximally along a line from just inferior to the tibial plateau and medial to the tibial tuberosity down approximately two thirds of the length of tibia. It attaches distally to the medial cuneiform and the proximal and inferior surface at the base of the first metatarsal. This muscle is easily palpated. With the foot on the ground, place your fingers on the lateral surface of the tibia, a few centimeters lateral to the tibial tuberosity and elevate the forefoot while keeping the heel on the ground (dorsiflexion). You will feel the muscle’s apparent contraction. Repeat the contraction-relaxation cycle as you walk your fingers down the length of the muscle. As you approach the distal portion of the tibia, you will feel the muscle mass give way to the more rigid tendinous portion just superior to the ankle. You may be able to palpate the tendon to its distal attachment, but care must be taken as several other tendons are in very close anatomical proximity and their muscles are active simultaneously with the tibialis anterior. As the orientation of the muscle angles across the lower leg lateral to medial, you can surmise that the muscle will also assist in inversion at the ankle.
Extensor Digitorum Longus – Although not as readily apparent as the nomenclature clues in the tibialis anterior, there are some helpful hints found in this muscle’s name. The term extensor in the name implies the muscle and/or tendon will course to the anterior of the talocrural joint and digitorum suggests the distal attachment will be at the phalanges. The extensor digitorum longus lies posterior and lateral to the tibialis anterior. It attaches proximally along a narrow line from the lateral condyle of the tibia, down along the upper three fourths of its length, then attaches distally to the bases of the second and third phalanx of the second through fifth phalanges. This muscle is fairly easy to palpate. With the foot on the ground, place your fingers on the calf lateral and posterior to the tibialis anterior elevate the forefoot while keeping the heel on the ground (dorsiflexion). Try to discriminate between the active anterior musculature and the inactive posterior musculature, as the upper portion of the extensor digitorum longus is covered in part by the posterior gastrocnemius and peroneus longus. The distribution of the distal tendinous attachments across the second through fifth phalanges should suggest to you that these are toe extensors. Their placement across the foot indicates little role in eversion or inversion.
Extensor retinaculum prevents “bowing” of the tendons of the extensor digitorum longus
Extensor Hallucis Longus – There are two major clues in the name of this muscle. Hallucis refers to the hallux (big or great toe) and extensor indicates that the muscle will extend or lift the toe, thus the tendon will be anterior to the ankle and on the foot’s dorsal surface. The muscles proximal attachment is the central half of the fibula and attach distally at the base of the second phalanx of the first phalange or hallux. The muscle itself usually cannot be palpated by beginners as both the tibialis anterior and the extensor digitorum longus lie over the majority of the muscle. With careful palpation of the anterior tendons during dorsiflexion, you can isolate the extensor hallucis longus tendon. Simply start by palpating the tibialis anterior tendon, then walk your fingers laterally and locate three side-by-side tendons. The tibialis anterior tendon is the most medial, the extensor hallucis longus tendon is slightly lateral, and the extensor digitorum longus tendon is the most lateral of the three. Owing to its mildly diagonal track from the fibula to the first phalange, the flexor hallucis longus can contribute to inversion of the foot.
Peroneus Longus – It may be easier to remember the alternate name to this muscle in order to locate it, the fibularis longus. Its proximal attachment runs from just inferior to the fibular head and down approximately one half the fibula’s length. The tendon is quite long and runs behind the lateral malleolus and attaches distally at the first metatarsal bone and on lateral side of the medial cuneiform (crosses the bottom of the foot at about a 45 degree angle – this is why it is an everter). This muscle is quite superficial and can usually be visually identified in its location between the tibialis anterior and the gastrocnemius (a posterior muscle). You can identify this muscle in two ways, either evert the foot, identify the muscle belly then walk your fingers down the length of the muscle and tendon around the ankle or start with the easily palpated tendon at the ankle and walk your fingers up to the muscle.
Peroneus Brevis – Like the peroneus longus, the brevis might be easier to locate using the alternate name, fibularis brevis. Frequently the pair of peroneus muscles are considered as a single unit as they are extremely close in anatomy and function. The brevis attaches proximally along the lower two thirds of the fibular shaft with the tendon becoming apparent just superior to the ankle. The tendon passes to the posterior and inferior aspects of the ankle and attaches distally at the base of the fifth metatarsal. The peroneus brevis has a primary function as a plantar flexor but does contribute some to eversion of the foot. The muscle is not palpable as it lies under the peroneus longus. The tendon from the ankle to the base of the fifth metatarsal may be palpable is some individuals during combined eversion and plantar flexion.
Gastrocnemius – The gastrocnemius, frequently referred to as a gastroc, is the largest muscle of the posterior group. It is pennate and has two distinct heads and a distal tendon of attachment it shares with its underlying musculature. Its proximal attachments occur with each muscular head, medial and lateral, attaching at the posterior surface of the medial and lateral femoral epicondyles, just superior to the condyles. Both heads fuse into a single distal tendon that attaches to the posterior and anterior surface of the calcaneous. This distal tendon is commonly called the Achilles tendon but can also be called the calcaneal tendon. The gastrocnemius crosses two joints and as such has both a proximal and distal function. The acknowledged proximal function is flexion of the knee. If the foot is the least stable end of the system this is correct and the proximal action will be lower leg movement rearwards in an arc around the knee. If the foot is immobile, as it is during most of our ambulatory life, the proximal function will be to assist in ‘locking out’ the knee, pulling the distal femur into vertical alignment with the proximal tibia. The accepted distal function of the gastrocnemius is plantar flexion at the ankle with the foot pushing a resistance down or pushing the body up. This occurs with every stride of locomotion we take and is part of many exercise and sport movements. However if the foot is held immobile, flat on the floor, then the distal function is strictly postural and pulls the mass of the body to the rear – to cooperatively balance the actions of the anterior musculature to maintain the center of gravity over the base provided by the feet. If the knee is bent, the gastrocnemius is limited in its ability to produce force. Since knee flexion reduces the distance between proximal and distal attachments, the sarcomeres present cannot shorten sufficiently to produce high force (this is a physiological concept – the length tension curve). You can test this out on someone, have them stand up and go on their toes as hard as they can then have them sit down and go up on their toes again. Press your fingers into the bellies of the gastrocnemius in both conditions and you will notice a difference in muscle rigidity.
Soleus – The soleus lies beneath the gastrocnemius and is a fairly thin muscle but it is almost as wide as the gastrocnemius. In lean individuals it can be seen protruding slightly just inferior and anterior to the major bellies of the gastrocnemius. The soleus attaches proximally to both the tibia and the fibula. The attachment sites form an inverted ‘V’ on the upper quarter of the tibia and the upper third of the fibula. Distally the tendon of the soleus fuses with that of the gastrocnemius to form the calcaneal tendon. The soleus crosses one joint, the ankle, and by virtue of its central orientation, if the foot is the least stable structure, it will produce plantar flexion as with the distal function of the gastrocnemius. If the foot is held fixed to the floor it will act as a postural muscle and pull the mass of the body posteriorly. This latter role is the primary function of the soleus as it contributes greatly to maintaining standing balance. It is comprised of 60% or more of slow oxidative fibers making it well adapted to its function. Palpating this muscle depends on your ability to palpate the separation between the inferior border of the gastrocnemius and underlying soleus. You can use the knee flexion trick from the gastrocnemius above to help. Bend the knee to 90 degrees and elevate the heel firmly. The soleus will be the prime mover and more rigid than the gastrocnemius. It is relevant to note that you will see references in the literature to the ‘triceps surae.’ This term refers to a more antiquated grouping of the gastrocnemius (two heads) and soleus into one muscle group.
Flexor Digitorum Longus – The flexor digitorum longus muscle is, as the name implies, a long one. It is also a flexor of the digits, meaning that it will pass behind the medial malleolus and attach inferiorly to the phalanges. The muscle attaches proximally on the middle third of the medial aspect of the tibia, its central tendon will pass behind the medial malleolus then angle laterally and split into four slips of tendon attaching to the base of each distal phalanx of phalanges two through five. The muscle is deep and cannot be palpated but the tendon of the flexor digitorum longus can be palpated just inferior to the medial malleolus during repeated strong flexion of the toes. It is also possible to palpate the tendon distal to the metatarsophalangeal joints on the plantar surface of the lateral four digits. Although it is named according to its function to flex the toes, the primary function of the flexor digitorum longus is to plantar flex the ankle during locomotion. As with other members of the extrinsic posterior group, it is also active in postural control when the foot is the most stable structure.
Tibialis Posterior – The nomenclature yields the clues needed to localize this muscle located on the posterior surface of the tibia. The name is not completely descriptive as the proximal attachment of the tibialis posterior is divided between the lateral aspect of the shaft of the tibia, the medial aspect of the fibula, and the interosseus membrane from the level just inferior to the head of the fibula to approximately half way down the length of the fibula. After the tendon passes behind the medial malleolus, the distal attachment is quite complex with connections on the plantar surface of seven bones; the navicular, all three cuneiforms, and the second, third, and fourth metatarsals. The muscle is quite deep but you can identify the tendon by strongly plantar flexing and inverting the ankle and subtalar joint simultaneously, then palpating the area just posterior to the medial malleolus. Aside from the plantar flexion and inversion functions, the tibialis posterior is quite involved in both anterio-posterior and medio-lateral postural control.
Flexor Hallucis Longus – Yet another muscle with great clues in its name. As you would expect, the flexor hallucis longus flexes the hallux. ‘Flexor’ indicates it is a posterior group muscle.
Attaches proximally on the posterior of roughly the middle third of the fibula it then crosses the tibia and passes behind the medial malleolus. It attaches distally at the base of the hallux. As it passes behind the medial malleolus, it contributes to plantar flexion as a function along with its namesake function of flexing the hallux. Palpation of the muscle is not possible, but the tendon can be palpated on the plantar surface of the foot.
