Gross Anatomy of the Thigh and Leg - PDF

**GROSS ANATOMY OF THE THIGH AND THE LEG COMPARTMENTS** The thigh muscles are organized into three compartments by intermuscular septa that pass deeply between the muscle groups from the inner surface of the fascia lata to the linea aspera of the femur. The compartments are anterior or extensor, me...

**GROSS ANATOMY OF THE THIGH AND THE LEG COMPARTMENTS** The thigh muscles are organized into three compartments by intermuscular septa that pass deeply between the muscle groups from the inner surface of the fascia lata to the linea aspera of the femur. The compartments are anterior or extensor, medial or adductor, and posterior or flexor, so named on the basis of their location or action at the knee joint. Generally, the anterior group is innervated by the femoral nerve, the medial group by the obturator nerve, and the posterior group by the tibial portion of the sciatic nerve. Although the compartments vary in absolute and relative size depending on the level, the anterior compartment is the largest overall and includes the femur. The large anterior compartment of the thigh contains the anterior thigh muscles, the flexors of the hip and extensors of the knee. The anterior thigh muscles include the pectineus, iliopsoas, sartorius, and quadriceps femoris. The major muscles of the anterior compartment tend to atrophy (diminish) rapidly with disease, and physical therapy is often necessary to restore strength, tone, and symmetry with the opposite limb after immobilization of the thigh or leg. The Femur - Proximal - Distal - Shaft - TeachMeAnatomy **MUSCLES OF ANTERIOR THIGH: FLEXORS OF HIP JOINT** MUSCLES PROXIMAL ATTACHMENT^A^ DISTAL ATTACHMENT INNERVATION^B^ MAIN ACTION(S) ---------------------------------------- ------------------------------------------------------------------------------------------------- ------------------------------------------------------------------ ------------------------------------------------------------------- ------------------------------------------------------------------------------------------------------------------------------------- Pectineus Superior ramus of pubis Pectineal line of femur, just inferior to lesser trochanter Femoral nerve (L2, L3); may receive a branch from obturator nerve Adducts and flexes thigh; assists with medial rotation of thigh Iliopsoas (Fig. 5.21A & C) Psoas major Sides of T12--L5 vertebrae and discs between them; transverse processes of all lumbar vertebrae Lesser trochanter of femur Anterior rami of lumbar nerves (L1, L2, L3) Act conjointly in flexing thigh at hip joint and in stabilizing this joint^c^ Psoas minor Sides of T12--L1 vertebrae and intervertebral discs Pectineal line, iliopectineal eminence via iliopectineal arch Anterior rami of lumbar nerves (L1, L2) Iliacus Iliac crest, iliac fossa, ala of sacrum, and anterior sacro-iliac ligaments Tendon of psoas major, lesser trochanter, and femur distal to it Femoral nerve (L2, L3) Sartorius Anterior superior iliac spine and superior part of notch inferior to it Superior part of medial surface of tibia Femoral nerve (L2, L3) Flexes, abducts, and laterally rotates thigh at hip joint; flexes leg at knee joint, (medially rotating leg when knee is flexed)^d^ *^a^ The Latin word insertio means attachment. The terms insertion and origin (L. origo) have not been used here (or elsewhere) since they change with function.* *^b^ The spinal cord segmental innervation is indicated (e.g., "L1, L2, L3" means that the nerves supplying the psoas major are derived from the first three lumbar segments of the spinal cord). Numbers in boldface (**L1, L2**) indicate the main segmental innervation. Damage to one or more of the listed spinal cord segments, or to the motor nerve roots arising from them, results in paralysis of the muscles concerned.* *^c^ The psoas major is also a postural muscle that helps control the deviation of the trunk and is active during standing.\ ^d^ The four actions of the sartorius (L. sartor, tailor) produce the once common cross-legged sitting position used by tailors, hence the name*  ANTERIOR THIGH MUSCLES **MUSCLES OF ANTERIOR THIGH: EXTENSORS OF KNEE** **MUSCLE** **PROXIMAL ATTACHMENT** **DISTAL ATTACHMENT** **INNERVATION^A^** **MAIN ACTION** -------------------- ---------------------------------------------------------------- -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -------------------------------- ------------------------------------------------------------------------------------------------- Quadriceps femoris Rectus femoris Anterior inferior iliac spine and ilium superior to acetabulum Via common tendinous (quadriceps tendon) and independent attachments to base of patella; indirectly via patellar ligament to tibial tuberosity; medial and lateral vasti also attach to tibia and patella via aponeuroses (medial and lateral patellar retinacula) Femoral nerve (L2, **L3, L4**) Extend leg at knee joint; rectus femoris also steadies hip joint and helps iliopsoas flex thigh Vastus lateralis Greater trochanter and lateral lip of linea aspera of femur Vastus medialis Intertrochanteric line and medial lip of linea aspera of femur Vastus intermedius Anterior and lateral surfaces of shaft of femur *^a^ The spinal cord segmental innervation is indicated (e.g., "L1, L2, L3" means that the nerves supplying the quadriceps femoris are derived from the fi rst three lumbar segments of the spinal cord). Numbers in boldface (**L3, L4**) indicate the main segmental innervation. Damage to one or more of the listed spinal cord segments or to the motor nerve roots arising from them results in paralysis of the muscles concerned* The **quadriceps femoris** 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. The muscles that form the quadriceps femoris unite proximal to the knee and attach to the patella via the **quadriceps tendon**. In turn, the patella is attached to the tibia by the patella ligament. The quadriceps femoris is the main extensor of the knee. In level walking, the quadriceps muscles become active during the termination of the swing phase, preparing the knee to accept weight. The quadriceps is primarily responsible for absorbing the jarring shock of heel strike, and its activity continues as the weight is assumed during the early stance phase (loading response). It also functions as a fixator during bent-knee sports, such as skiing and tennis, and contracts eccentrically during downhill walking and descending stairs. The patella is thus the largest sesamoid bone in the body. The patella provides a bony surface that is able to withstand the compression placed on the quadriceps tendon during kneeling and the friction occurring when the knee is flexed and extended during running. The patellar ligament (L. ligamentum patellae), attached to the tibial tuberosity, is the continuation of the quadriceps tendon in which the patella is embedded.  ***The femur, tibia and patella at the knee joint*** **Testing the quadriceps:** This is performed with the person in the supine position with the knee partly flexed. The person extends the knee against resistance. During the test, contraction of the rectus femoris should be observable and palpable if the muscle is acting normally, indicating that its nerve supply is intact. **MEDIAL THIGH MUSCLES** The muscles of the medial compartment of the thigh comprise the adductor group, consisting of the adductor longus, adductor brevis, adductor magnus, gracilis, and obturator externus. In general, they attach proximally to the antero-inferior external surface of the bony pelvis (pubic bone, ischiopubic ramus, and ischial tuberosity), and adjacent obturator membrane, and distally to the linea aspera of the femur. All adductor muscles, except the "hamstring part" of the adductor magnus and part of the pectineus are supplied by the obturator nerve (L2--L4). The hamstring part of the adductor magnus is supplied by the tibial part of the sciatic nerve (L4). **MUSCLES OF MEDIAL THIGH: ADDUCTORS OF THIGH** +-------------+-------------+-------------+-------------+-------------+ | **MUSCLE** | **PROXIMAL | **DISTAL | **INNERVATI | **MAIN | | | ATTACHMENT* | ATTACHMENT* | ON** | ACTION** | | | * | * | | | +=============+=============+=============+=============+=============+ | Adductor | Body of | Middle | Obturator | Adducts | | longus | pubis | third of | nerve, | thigh | | | inferior to | linea | branch of, | | | | pubic crest | aspera of | anterior | | | | | femur | division | | | | | | (L2, L3, | | | | | | L4) | | +-------------+-------------+-------------+-------------+-------------+ | Adductor | Body and | Pectineal | | Adducts | | brevis | inferior | line and | | thigh; to | | | ramus of | proximal | | some extent | | | pubis | part of | | flexes it | | | | linea | | | | | | aspera of | | | | | | femur | | | +-------------+-------------+-------------+-------------+-------------+ | Adductor | Adductor | Adductor | Adductor | Adducts | | magnus | part: | part: | part: | thigh | | | inferior | gluteal | obturator | Adductor | | | ramus of | tuberosity, | nerve (L2, | part: | | | pubis, | linea | L3, L4), | flexes | | | ramus of | aspera, | branches of | thigh | | | ischium; | medial | posterior | Hamstrings | | | | supracondyl | division | part: | | | Hamstrings | ar | | extends | | | part: | line; | Hamstring | thigh | | | ischial | | part: | | | | tuberosity | Hamstring | tibial part | | | | | part: | of sciatic | | | | | adductor | nerve (L4) | | | | | tubercle of | | | | | | femur | | | +-------------+-------------+-------------+-------------+-------------+ | Gracilis | Body and | Superior | Obturator | Adducts | | | inferior | part of | nerve (L2, | thigh; | | | ramus of | medial | L3) | flexes leg; | | | pubis | surface of | | helps | | | | tibia. | | rotate leg | | | | | | medially | +-------------+-------------+-------------+-------------+-------------+ | Obturator | Margins of | Trochanteri | Obturator | Laterally | | externus | obturator | c | nerve (L3, | rotates | | | foramen and | fossa of | L4) | thigh; | | | obturator | femur | | steadies | | | membrane | | | head of | | | | | | femur in | | | | | | acetabulum | +-------------+-------------+-------------+-------------+-------------+ The **adductor magnus** is the largest, most powerful, and most posterior muscle in the adductor group. This adductor is a composite, triangular muscle with a thick, medial margin that has an adductor part and a hamstring part. The two parts differ in their attachments, nerve supply, and main actions. The **gracilis** (L., slender) is a long, strap-like muscle and is the most medial muscle of the thigh. It is the most superficial of the adductor group and the weakest member. It is the only one of the group to cross the knee joint as well as the hip joint. The gracilis joins with two other two-joint muscles from the other two compartments (the sartorius and semitendinosus muscles). Thus, the three muscles are innervated by three different nerves. They have a common tendinous insertion, the pes anserinus (L., goose's foot), into the superior part of the medial surface of the tibia. ***Testing of the medial thigh muscles*** is performed while the person is lying supine with the knee straight. The individual adducts the thigh against resistance, and if the adductors are normal, the proximal ends of the gracilis and adductor longus can easily be palpated. **The Adductor Hiatus:** The adductor hiatus is an opening or aperture between the aponeurotic distal attachment of the adductor part of the adductor magnus and the tendinous distal attachment of the hamstring part (Fig. 5.23E). The adductor hiatus transmits the femoral artery and vein from the adductor canal in the thigh to the popliteal fossa posterior to the knee. The opening is located just lateral and superior to the adductor tubercle of the femur. Fig 1.0 - Muscles of the medial thigh. The overlying muscles in the anterior compartment have been removed.  Muscles of the medial thigh. The overlying muscles in the anterior compartment have been removed.   View of the medial thigh, with the course of the obturator nerve highlighted **ARTERIES OF ANTERIOR AND MEDIAL THIGH** **ARTERY** **ORIGIN** **COURSE** **DISTRIBUTION** ------------------------------------------------ --------------------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Femoral Continuation of external iliac artery distal to inguinal ligament Descends through femoral triangle bisecting it; then courses through adductor canal; terminates as it traverses adductor hiatus, where its name becomes popliteal artery Branches supply anterior and anteromedial aspects of the thigh Profunda femoris artery (deep artery of thigh) Femoral artery 1--5 cm inferior to inguinal ligament Passes deeply between pectineus and adductor longus; descending posterior to latter on medial side of femur Three to four perforating arteries pass through adductor magnus muscle, winding around femur to supply muscles in medial, posterior, and lateral part of anterior compartments Medial circumflex femoral Profunda femoris artery; may arise from femoral artery Passes medially and posteriorly between pectineus and iliopsoas; enters gluteal region and gives rise to posterior retinacular arteries; then terminates by dividing into transverse and ascending branches Supplies most of blood to head and neck of femur; transverse branch takes part in cruciate anastomosis of thigh; ascending branch joins inferior gluteal artery Lateral circumflex femoral Passes laterally deep to sartorius and rectus femoris, dividing into ascending, transverse, and descending arteries Ascending branch supplies anterior part of gluteal region; transverse branch winds around femur; descending branch joins genicular peri-articular anastomosis Obturator Internal iliac artery or (in ∼20%) as an accessory or replaced obturator artery from the inferior epigastric artery Passes through obturator foramen; enters medial compartment of thigh and divides into anterior and posterior branches, which pass on respective sides of adductor brevis Anterior branch supplies obturator externus, pectineus, adductors of thigh, and gracilis; posterior branch supplies muscles attached to ischial tuberosity Fig 1.0 - The anatomical course of the femoral artery, and its branches.  The anatomical course of the femoral artery, and its branches. **CLINICAL ANATOMY** **PSOAS ABSCESS:** A retroperitoneal pyogenic infection (pusforming) in the abdomen or greater pelvis, characteristically occurring in association with TB of the vertebral column, or secondary to regional enteritis of the ileum (Crohn disease), may result in the formation of a psoas abscess. When the abscess passes between the psoas and its fascia to the inguinal and proximal thigh regions, severe pain may be referred to the hip, thigh, or knee joint. A psoas abscess should always be considered when edema occurs in the proximal part of the thigh. Such an abscess may be palpated or observed in the inguinal region, just inferior or superior to the inguinal ligament, and may be mistaken for an indirect inguinal hernia or a femoral hernia, an enlargement of the inguinal lymph nodes, or a saphenous varix. The lateral border of the psoas is commonly visible in radiographs of the abdomen; an obscured psoas shadow may be an indication of abdominal pathology. **PARALYSIS OF QUADRICEPS**: A person with paralyzed quadriceps muscles cannot extend the leg against resistance and usually presses on the distal end of the thigh during walking to prevent inadvertent flexion of the knee joint. Weakness of the vastus medialis or vastus lateralis, resulting from arthritis or trauma to the knee joint, can result in abnormal patellar movement and loss of joint stability **CHONDROMALACIA PATELLAE** (runner's knee) is a common knee injury for marathon runners. Such overstressing of the knee region can also occur in running sports such as basketball. The soreness and aching around or deep to the patella results from quadriceps imbalance. Chondromalacia patellae may also result from a blow to the patella or extreme flexion of the knee (e.g., during squatting when power lifting). **PATELLAR FRACTURES** A direct blow to the patella may fracture it into two or more fragments. Transverse patellar fractures may result from a blow to the knee or sudden contraction of the quadriceps (e.g., when one slips and attempts to prevent a backward fall). The proximal fragment is pulled superiorly with the quadriceps tendon, and the distal fragment remains with the patellar ligament **PATELLAR TENDON REFLEX** Tapping the patellar ligament with a reflex hammer normally elicits the patellar tendon reflex ("knee jerk"). This myotatic (deep tendon) reflex is routinely tested during a physical examination by having the person sit with the legs dangling. A firm strike on the ligament with a reflex hammer usually causes the leg to extend. If the reflex is normal, a hand on the person's quadriceps should feel the muscle contract. This tendon reflex tests the integrity of the femoral nerve and the L2--L4 spinal cord segments. Tapping the ligament activates muscle spindles in the quadriceps. Afferent impulses from the spindles travel in the femoral nerve to the L2--L4 segments of the spinal cord. From here, efferent impulses are transmitted via motor fibers in the femoral nerve to the quadriceps, resulting in a jerk-like contraction of the muscle and extension of the leg at the knee joint. Diminution or absence of the patellar tendon reflex may result from any lesion that interrupts the innervation of the quadriceps (e.g., peripheral nerve disease). **LECTURE NOTES ON ANA 211** **GROSS ANATOMY OF THE LEG** The leg region (L. regio cruris) is the part that lies between the knee and the narrow, distal part of the leg. It includes most of the tibia (shin bone) and fibula (calf bone). The leg (L., crus) connects the knee and foot. Often laypersons refer incorrectly to the entire lower limb as "the leg." The ankle (L. tarsus) or talocrural region (L. regio talocruralis) includes the medial and lateral prominences (malleoli) that flank the ankle (talocrural) joint. In general sense however, the entire lower [limb](https://en.wikipedia.org/wiki/Limb_(anatomy)) of the [human body](https://en.wikipedia.org/wiki/Human_body), including the [foot](https://en.wikipedia.org/wiki/Foot), [thigh](https://en.wikipedia.org/wiki/Thigh) and even the [hip](https://en.wikipedia.org/wiki/Hip) or [gluteal](https://en.wikipedia.org/wiki/Gluteal_muscles) region is refered to as the leg but in [human anatomy](https://en.wikipedia.org/wiki/Human_anatomy) the leg refers only to the section of the lower limb extending from the [knee](https://en.wikipedia.org/wiki/Knee) to the [ankle](https://en.wikipedia.org/wiki/Ankle). Also known as the **crus** or, especially in non-technical use, the **shank**, Legs are used for [standing](https://en.wikipedia.org/wiki/Standing), and all forms of locomotion including recreational such as [dancing](https://en.wikipedia.org/wiki/Dancing), and constitute a significant portion of a person\'s mass. **BONES OF THE LEG** The tibia and fibula are the bones of the leg. The tibia articulates with the condyles of the femur superiorly and the talus inferiorly, and in so doing transmits the body's weight. The fibula mainly functions as an attachment for muscles, but it is also important for the stability of the ankle joint. The shafts of the tibia and fibula are connected by a dense interosseous membrane composed of strong oblique fibers descending from the tibia to the fibula. **THE TIBIA** The **tibia** is the main bone of the lower leg, forming what is more commonly known as the shin. It expands at its proximal and distal ends; articulating at the knee and ankle joints respectively. The tibia is the second largest bone in the body and it is a key **weight-bearing** structure **PROXIMAL END** The proximal tibia is widened by the medial and lateral condyles, which aid in weight-bearing. The condyles form a flat surface, known as the tibial plateau. This structure articulates with the femoral condyles to form the key articulation of the knee joint. Located between the condyles is a region called the intercondylar eminence -- this projects upwards on either side as the medial and lateral intercondylar tubercles. This area is the main site of attachment for the ligaments and the menisci of the knee joint. The intercondylar tubercles of the tibia articulate with the intercondylar fossa of the femur.  Overview of the tibia in a human skeleton THE SHAFT --------- The shaft of the tibia is **prism-shaped**, with three borders and three surfaces; anterior, posterior and lateral. The **Anterior border **is palpable subcutaneously down the anterior surface of the leg as the shin. The proximal aspect of the anterior border is marked by the tibial tuberosity; the attachment site for the patella ligament. **Posterior surface**: This is marked by a ridge of bone known as soleal line. This line is the site of origin for part of the soleus muscle, and extends inferomedially, eventually blending with the medial border of the tibia. There is usually a nutrient artery proximal to the soleal line. **Lateral border **-- also known as the interosseous border. It gives attachment to the interosseous membrane that binds the tibia and the fibula together. These surfaces and the borders are the anatomically and clinically important ones.  **DISTAL END** The distal end of the tibia **widens** to assist with weight-bearing. The **medial malleolus **is a bony projection continuing inferiorly on the medial aspect of the tibia. It articulates with the tarsal bones to form part of the ankle joint. On the posterior surface of the tibia, there is a groove through which the tendon of tibialis posterior passes. Laterally is the **fibular notch,** where the fibula is bound to the tibia -- forming the distal tibiofibular joint. Image result for the tibia **THE FIBULA** The **fibula** is located within the lateral aspect of the leg. Its main function is to act as an attachment for muscles, and not as a weight-bearer. It has three main articulations: - **Proximal tibiofibular joint** -- articulates with the lateral condyle of the tibia. - **Distal tibiofibular joint** -- articulates with the fibular notch of the tibia. - **Ankle joint** -- articulates with the talus bone of the foot.  Overview of the position of the fibula within the leg **PROXIMAL** At the proximal end, the fibula has an enlarged head, which contains a facet for articulation with the lateral condyle of the tibia. On the posterior and lateral surface of the fibular neck, the common fibular nerve can be found. **SHAFT** The fibular shaft has three surfaces -- anterior, lateral and posterior. The leg is split into three compartments, and each surface faces its respective compartment e.g anterior surface faces the anterior compartment of the leg. **DISTAL** Distally, the lateral surface continues inferiorly, and is called the lateral malleolus. The lateral malleolus is more prominent than the medial malleolus, and can be palpated at the ankle on the lateral side of the leg. **CLINICAL ANATOMY OF THE TIBIA** **Intraosseous Access** Intraosseous access is a form of vascular access used in the emergency setting. It allows the administration of fluids, blood products and medications directly into the bone marrow. IO access is typically used in an emergency when intravenous access is not obtainable. There are two main sites in the tibia that are suitable for IO access: Anteromedial surface, 2-3cm below the tibial tuberosity Proximal to the medial malleolus Complications of IO access include osteomyelitis, iatrogenic fracture and compartment syndrome. IO infusions should be discontinued when IV access has been achieved.  **Fractures of the Tibia** Fractures of the tibia are relatively common. There are two main types: High energy trauma -- occurs predominantly in the younger population. Low energy trauma or insufficiency fractures -- occurs predominantly in the elderly. Fractures most commonly occur at the shaft of the tibia, and are typically associated with fibula fractures. Fractures of the proximal tibia are known as tibial plateau fractures; the condyles may be broken and injury to the menisci and ligaments of the knee is not uncommon. These fractures are classified using the Schatzker classification, and if very displaced will likely required operative management. It is important to monitor patients for signs of compartment syndrome in the pre-and post-operative phases. At the ankle, the medial malleolus can be fractured. This is caused by the ankle being twisted inwards (over-inversion) -- the talus of the foot is forced against the medial malleolus, causing a spiral fracture. This rarely happens in isolation and typically the lateral malleolus is also fractured; potentially producing an unstable fracture that requires operative management. **CLINICAL ANATOMY OF THE FIBULA** **Fractures of the Fibula** At the ankle, the lateral malleolus of the fibula is prone to fracture. There are two main ways in which this occurs. The first way is by forced external rotation of the ankle. This force of the talus against the bone causes a spiral fracture of the lateral malleolus. The other, less common way, by the foot being twisted outwards (called eversion). Again, the talus presses against the lateral malleolus, and this time causes a transverse fracture. **COMPARTMENTS OF THE LEG** The anterior compartment of the leg, or **dorsiflexor (extensor)** compartment, is located anterior to the interosseous membrane, between the lateral surface of the shaft of the tibia and the medial surface of the shaft of the fibula. The anterior compartment is bounded anteriorly by the deep fascia of the leg and skin. The deep fascia overlying the anterior compartment is dense superiorly, providing part of the proximal attachment of the muscle immediately deep to it. Inferiorly, two band-like thickenings of the fascia form retinacula that bind the tendons of the anterior compartment muscles before and after they cross the ankle joint, preventing them from bowstringing anteriorly during dorsiflexion of the joint. The superior extensor retinaculum is a strong, broad band of deep fascia, passing from the fibula to the tibia, proximal to the malleoli. The inferior extensor retinaculum, a Y-shaped band of deep fascia, attaches laterally to the anterosuperior surface of the calcaneus. It forms a strong loop around the tendons of the fibularis tertius and the extensor digitorum longus muscles. **MUSCLES OF ANTERIOR COMPARTMENT OF LEG** The four muscles in the anterior compartment of the leg are the tibialis anterior, extensor digitorum longus, extensor hallucis longus, and fibularis tertius These muscles pass and insert anterior to the transversely oriented axis of the ankle (talocrural) joint and, therefore, are dorsiflexors of the ankle joint, elevating the forefoot and depressing the heel The extensor digitorum longus and extensor hallucis longus also extend the toes. The muscles in this compartment are innervated by the **deep fibular nerve **(L4-S1), and blood is supplied via the **anterior tibial artery**. **Tibialis Anterior** The tibialis anterior muscle is located alongside the lateral surface of the tibia. It is the strongest dorsiflexor of the foot. To test the power of the tibialis anterior, the patient can be asked to stand on their heels. Attachments: Originates from the lateral surface of the tibia, attaches to the medial cuneiform and the base of metatarsal I. Actions: Dorsiflexion and inversion of the foot. Innervation: Deep fibular nerve.  **Extensor digitorum longus** The extensor digitorum longus lies lateral and deep to the tibialis anterior. The tendons of the EDL can be palpated on the dorsal surface of the foot. Attachments: Originates from the lateral condyle of the tibia and the medial surface of the fibula. The fibres converge into a tendon, which travels to the dorsal surface of the foot. The tendon splits into four, each inserting onto a toe. Actions: Extension of the lateral four toes, and dorsiflexion of the foot. Innervation: Deep fibular nerve. **Extensor Hallucis Longus** The extensor hallucis longus is located deep to the Extensor Digitorum Longus and Tibialis Anterior. Attachments: Originates from the medial surface of the fibular shaft.  The tendon crosses anterior to the ankle joint and attaches to the base of the distal phalanx of the great toe. Action: Extension of the great toe and dorsiflexion of the foot. Innervation: Deep fibular nerve. **Fibularis Tertius** The fibularis tertius muscles arises from the most inferior part of the EDL. It is not present in all individuals and is considered by some texts as a part of the extensor digitorum longus. **Attachments**: Originates with the extensor digitorum longus from the medial surface of the fibula. The tendon descends with the EDL, until they reach the dorsal surface of the foot. The fibularis tertius tendon then diverges and attaches to metatarsal V. **Actions**: Eversion and dorsiflexion of the foot. **Innervation**: Deep fibular nerve. **NERVE OF ANTERIOR COMPARTMENT OF LEG** The deep fibular (peroneal) nerve is the nerve of the anterior compartment. It is one of the two terminal branches of the common fibular nerve, arising between the fibularis longus muscle and the neck of the fibula. After its entry into the anterior compartment, the deep fibular nerve accompanies the anterior tibial artery, first between the Tibialis Anterior and EDL and then between the TA and EHL. The deep fibular nerve then exits the compartment, continuing across the ankle joint to supply intrinsic muscles (extensors digitorum and hallucis brevis), and a small area of the skin of the foot. A lesion of this nerve results in an inability to dorsiflex the ankle (footdrop). **LATERAL COMPARTMENT OF THE LEG** The lateral compartment of the leg, or evertor compartment, is the smallest (narrowest) of the leg compartments. It is bounded by the lateral surface of the fibula, the anterior and posterior intermuscular septa, and the deep fascia of the leg. The lateral compartment ends inferiorly at the superior fibular retinaculum, which spans between the distal tip of the fibula and the calcaneus. Here the tendons of the two muscles of the lateral compartment (fibularis longus and brevis) enter a common synovial sheath to accommodate their passage between the superior fibular retinaculum and the lateral malleolus, using the latter as a trochlea as they cross the ankle joint. The lateral compartment contains the fibularis longus and brevis muscles. Both muscles are evertors of the foot, elevating the lateral margin of the foot. To test the fibularis longus and brevis, the foot is everted strongly against resistance; if acting normally, the muscle tendons can be seen and palpated inferior to the lateral malleolus. **Fibularis Longus**. The fibularis longus (FL) is the longer and more superficial of the two fibularis muscles, arising much more superiorly on the shaft of the fibula. The narrow FL extends from the head of the fibula to the sole of the foot. its attachment is the 1st metatarsal and medial cuneiform bones. When a person stands on one foot, the FL helps steady the leg on the foot. **Fibularis Brevis** The fibularis brevis (FB) is a fusiform muscle that lies deep to the FL. The tendon of the FB traverses the superior compartment of the inferior fibular retinaculum to its distal attachment at the base of the 5th metatarsal. The tendon of the fibularis tertius, a slip of muscle from the extensor digitorum longus, often merges with the tendon of the FB. **NERVES IN LATERAL COMPARTMENT OF LEG** The superficial fibular (peroneal) nerve, a terminal branch of the common fibular nerve, is the nerve of the lateral compartment. After supplying the FL and FB, the superficial fibular nerve continues as a cutaneous nerve, supplying the skin on the distal part of the anterior surface of the leg and nearly all the dorsum of the foot. **THE POSTERIOR COMPARTMENT OF THE LEG** The posterior compartment of the leg (plantarflexor compartment) is the largest of the three leg compartments. The posterior compartment and the muscles within it are divided into superficial and deep subcompartments/muscle groups by the transverse intermuscular septum. The tibial nerve and posterior tibial and fibular vessels supply both parts of the posterior compartment but run in the deep subcompartment deep (anterior) to the transverse intermuscular septum. Muscles of the posterior compartment produce plantarflexion at the ankle, inversion at the subtalar and transverse tarsal joints, and flexion of the toes. **SUPERFICIAL MUSCLE GROUP IN POSTERIOR COMPARTMENT** The superficial group of calf muscles (muscles forming prominence of "calf" of posterior leg) includes the gastrocnemius soleus and plantaris. The lateral head of the gastrocnemius arises from the lateral aspect of lateral condyle of femur and the Medial head from the popliteal surface of femur, superior to medial condyle. The soleus from the Posterior aspect of head and superior quarter of posterior surface of fibula; soleal line and middle third of medial border of tibia; and tendinous arch extending between the bony attachments and the plantaris from the Inferior end of lateral supracondylar line of femur; oblique popliteal ligament. These muscles share a common tendon, the calcaneal tendon, which attaches to the calcaneus and collectively they make up the three headed triceps surae (L. sura, calf). These muscles are strong and heavy because they lift, propel, and accelerate the weight of the body when walking, running, jumping, or standing on the toes. **The calcaneal tendon** (L. tendo calcaneus, Achilles tendon) is the most powerful (thickest and strongest) tendon in the body. Approximately 15 cm in length, it is a continuation of the flat aponeurosis formed halfway down the calf where the bellies of the gastrocnemius terminate. **DEEP MUSCLES IN THE POSTERIOR COMPARTMENT** Muscles Proximal Attachment Distal Attachment Innervation Main Action ------------------------- -------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------------------------------------------------------- --------------------------- ----------------------------------------------------------------------------------------------------------------- Popliteus Lateral surface of lateral condyle of femur and lateral meniscus Posterior surface of tibia, superior to soleal line Tibial nerve (L4, L5, S1) Weakly flexes knee and unlocks it by rotating femur 5° on fixed tibia; medially rotates tibia of unplanted limb Flexor hallucis longus Inferior two thirds of posterior surface of fi bula; inferior part of interosseous membrane Base of distal phalanx of great toe (hallux) Tibial nerve (S2, S3) Flexes great toe at all joints; weakly plantarfl exes ankle; supports medial longitudinal arch of foot Flexor digitorum longus Medial part of posterior surface of tibia inferior to soleal line; by a broad tendon to fibula Bases of distal phalanges of lateral four digits Flexes lateral four digits; plantarfl exes ankle; support Tibialis posterior Interosseous membrane; posterior surface of tibia inferior to soleal line; posterior surface of fibula Tuberosity of navicular, cuneiform, cuboid, and sustentaculum tali of calcaneus; bases of 2nd, 3rd, and 4th metatarsals Tibial nerve (L4, L5) Plantarfl exes ankle; inverts foot **CLINICAL RELEVANCE OF THE MUSCLES ** **FOOTDROP** Footdrop is a clinical sign indicating paralysis of the muscles in the anterior compartment of the leg. It typically occurs as a consequence of damage to the common fibular (peroneal) nerve -- from which the deep fibular nerve arises. In footdrop, the muscles in the anterior compartment are paralysed. The unopposed pull of the muscles in the [posterior leg](https://teachmeanatomy.info/lower-limb/muscles/leg/posterior-compartment/) produce permanent plantarflexion. This can interfere with walking -- as the affected limb can drag along the ground. To circumvent this, the patient can flick the foot outwards while walking -- known as an 'eversion flick'. Left footdrop. This can occur following common fibular or deep fibular palsy **THE ANKLE JOINT** The** ankle joint** (or talocrural joint) is a synovial joint located in the lower limb. It is formed by the bones of the leg (tibia and fibula) and the foot (talus). Functionally, it is a **hinge type** joint, permitting dorsiflexion and plantarflexion of the foot.  *The bones of the ankle joint; tibia, fibula and talus. Note that the calcaneous is not considered part of the ankle joint.* **Articulating Surfaces** The ankle joint is formed by three bones; the tibia and fibula of the leg, and the talus of the foot: The tibia and fibula are bound together by strong tibiofibular ligaments. Together, they form a bracket shaped socket, covered in hyaline cartilage. This socket is known as a mortise. The body of the talus fits snugly into the mortise formed by the bones of the leg. The articulating part of the talus is wedge shaped -- it is broad anteriorly, and narrow posteriorly: Dorsiflexion -- the anterior part of the talus is held in the mortise, and the joint is more stable. Plantarflexion -- the posterior part of the talus is held in the mortise, and the joint is less stable **Ligaments** ------------- There are two main sets of ligaments, which originate from each malleolus. ### Medial Ligament The **medial ligament **(or deltoid ligament) is attached to the medial malleolus (a bony prominence projecting from the medial aspect of the distal tibia). It consists of four ligaments, which fan out from the malleolus, attaching to the talus, calcaneus and navicular bones. The primary action of the medial ligament is to resist **over-eversion** of the foot. ### Lateral Ligament The** lateral ligament** originates from the lateral malleolus (a bony prominence projecting from the lateral aspect of the distal fibula). It resists over-inversion of the foot, and is comprised of three distinct and separate ligaments: **Anterior talofibular** -- spans between the lateral malleolus and lateral aspect of the talus. **Posterior talofibular** -- spans between the lateral malleolus and the posterior aspect of the talus. **Calcaneofibular** -- spans between the lateral malleolus and the calcaneus. dons of the foot. *Ligaments of the ankle joint* **Movements and Muscles Involved** ---------------------------------- The ankle joint is a **hinge type joint**, with movement permitted in one plane. Thus, plantarflexion and dorsiflexion are the main movements that occur at the ankle joint. Eversion and inversion are produced at the other joints of the foot, such as the** subtalar joint**. - **Plantarflexion** -- produced by the muscles in the [posterior compartment of the leg](https://teachmeanatomy.info/lower-limb/muscles/leg/posterior-compartment/) (gastrocnemius, soleus, plantaris and posterior tibialis). - **Dorsiflexion** -- produced by the muscles in the [anterior compartment of the leg](https://teachmeanatomy.info/lower-limb/muscles/leg/anterior-compartment/) (tibialis anterior, extensor hallucis longus and extensor digitorum longus). Neurovascular Supply -------------------- The** arterial supply** to the ankle joint is derived from the malleolar branches of the anterior tibial, posterior tibial and fibular arteries. Innervation is provided by tibial, superficial fibular and deep fibular nerves. **Clinical Relevance** **Ankle Sprain** An ankle sprain refers to partial or complete tears in the ligaments of the ankle joint. It usually occurs via excessive inversion to a plantarflexed and weight-bearing foot. The lateral ligament is more likely to be damaged for two main reasons: The lateral ligament is weaker than the medial ligament. The lateral ligament resists inversion. The anterior talofibular ligament is the lateral ligament most at risk of irreversible damage. **Pott's Fracture-Dislocation** A Pott's fracture is a term used to describe a bimalleolar (medial and lateral malleoli) or trimalleolar (medial and lateral malleoli, and distal tibia) fracture. This type of injury is produced by forced eversion of the foot. It occurs in a series of stages: Forced eversion pulls on the medial ligaments, producing an avulsion fracture of the medial malleolus. The talus moves laterally, breaking off the lateral malleolus. ** The Ankle 'Ring'** The ankle joint and associated ligaments can be visualised as a ring in the coronal plane: The upper part of the ring is formed by the articular surfaces of the tibia and fibula. The lower part of the ring is formed by the subtalar joint (between the talus and the calcaneus). The sides of the ring are formed by the medial and lateral ligaments. A ring, when broken, usually breaks in two places (the best way of illustrating this is with a polo mint -- it is very difficult to break one side without breaking the other). When dealing with an injury to the ankle joint, a clinician must bear this in mind. For example, a fracture of the ankle joint may occur in association with ligament damage (which would not be apparent on x-ray). **VEINS OF THE LOWER LIMB** The veins of the lower limb can be divided into two groups -- deep and superficial**:** - **Deep veins** are located underneath the deep fascia of the lower limb, accompanying the major arteries. - **Superficial veins** are found in the subcutaneous tissue. They eventually drain into the deep veins. **Deep Veins of the Lower Limb** The deep venous drainage system of the lower limb is located beneath the deep fascia of the lower limb. As a general rule, the deep veins accompany and share the name of the major arteries in the lower limb. Often, the artery and vein are located within the same vascular sheath -- so that the arterial pulsations aid the venous return. **The Foot and Leg** The main venous structure of the foot is the dorsal venous arch, which mostly drains into the superficial veins. Some veins from the arch penetrate deep into the leg, forming the anterior tibial vein. On the plantar aspect of the foot, medial and lateral plantar veins arise. These veins combine to form the posterior tibial and fibular veins. The posterior tibial vein accompanies the posterior tibial artery, entering the leg posteriorly to the medial malleolus. On the posterior surface of the knee, the anterior tibial, posterior tibial and fibular veins unite to form the popliteal vein. The popliteal vein enters the thigh via the adductor canal. **The Thigh** Once the popliteal vein has entered the thigh, it is known as the femoral vein. It is situated anteriorly, accompanying the femoral artery. The deep vein of the thigh (profunda femoris vein) is the other main venous structure in the thigh. Via perforating veins, it drains blood from the thigh muscles. It then empties into the distal section of the femoral vein. The femoral vein leaves the thigh by running underneath the inguinal ligament, at which point it is known as the external iliac vein. **The Gluteal Region** The gluteal region is drained by inferior and superior gluteal veins. These empty into the internal iliac vein.  *Deep veins of the lower limb* **Clinical Relevance: ** **Deep Vein Thrombosis:** [Deep vein thrombosis](http://teachmesurgery.com/perioperative/cardiorespiratory/venous-thromboembolism/) (DVT) is the formation of the blood clot within the deep veins of the lower limbs, causing blockage of the vessel. Locally, this causes pain, swelling and tenderness of the affected limb. The main complication of a DVT is pulmonary embolism. The thrombus can become dislodged, and travel into pulmonary circulation. Pulmonary occlusion prevents blood from returning to the heart, resulting in mechanical shock. Patients that are considered high risk of developing a DVT undergo prophylactic treatment to prevent thrombosis. **Superficial Veins of the Lower Limb** --------------------------------------- The superficial veins of the lower limb run in the **subcutaneous tissue**. There are two major superficial veins -- the great saphenous vein, and the small saphenous vein. **[The Great Saphenous Vein]** The **great saphenous vein **is formed by the dorsal venous arch of the foot, and the dorsal vein of the great toe. It ascends up the medial side of the leg, passing anteriorly to the **medial malleolus** at the ankle, and posteriorly to the medial condyle at the knee. As the vein moves up the leg, it receives tributaries from other small superficial veins. The great saphenous vein terminates by draining into the femoral vein immediately inferior to the** inguinal ligament**. Surgically, the great saphenous vein can be harvested and used as a vessel in coronary artery bypasses. **[The Small Saphenous Vein]** The **small saphenous vein** is formed by the dorsal venous arch of the foot, and the dorsal vein of the little toe. It moves up the posterior side of the leg, passing posteriorly to the **lateral malleolus**, along the lateral border of the calcaneal tendon. It moves between the two heads of the gastrocnemius muscle and empties into the **popliteal vein** in the [popliteal fossa](https://teachmeanatomy.info/lower-limb/areas/popliteal-fossa/). Fig 1.1 - The two major superficial veins of the lower limb. **Clinical Relevance: Varicose Veins** In the lower limbs, venous blood flows from the skin to superficial veins, which drain into the deep veins.  *Varicose veins on the right leg* With the veins there are valves that prevent back flow of blood. If these valves become incompetent, blood can flow back into the superficial veins. This results in an increased intra-luminal pressure, which the veins cannot withstand, causing them to become dilated and tortuous. This condition is known as [varicose veins](http://teachmesurgery.com/vascular/venous/varicose-veins/). There are various soft tissue changes that can occur with chronic varicose veins. Due to the incompetence of the valves, the pressure in the venous system rises. This damages the cells, causing blood to extrude into skin. Further complications can produce a brown pigmentation and ulceration of the surrounding tissue. Varicose veins can be treated by; Vein ligation, stripping, and avulsion -- making an incision in the groin (or popliteal fossa) and identifying the responsible vein, before tying it off and stripping it away. Foam sclerotherapy -- injecting a sclerosing (irritating) agent directly into the varicosed veins, causing an inflammatory response that closes off the vein. Thermal ablation -- heating the vein from inside (via radiofrequency or laser catheters), causing irreversible damage to the vein which closes it off.