Thigh
In human anatomy, the thigh is the area between the hip and the knee. Anatomically, it is part of the lower limb; the single bone in the thigh is called the femur. This bone is thick and strong, forms a ball and socket joint at the hip, a modified hinge joint at the knee; the femur is the only bone in the thigh and serves for an attachment site for all muscles in the thigh. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with the tibia and kneecap forming the knee. By most measures the femur is the strongest bone in the body; the femur is the longest bone in the body. The femur is categorised as a long bone and comprises a diaphysis, the shaft and two epiphysis or extremities that articulate with adjacent bones in the hip and knee. In cross-section, the thigh is divided up into three separate compartments, divided by fascia, each containing muscles; these compartments use the femur as an axis, are separated by tough connective tissue membranes.
Each of these compartments has its own blood and nerve supply, contains a different group of muscles. Medial fascial compartment of thigh, adductor Posterior fascial compartment of thigh, hamstring Anterior fascial compartment of thigh, extensionAnterior compartment muscles of the thigh include sartorius, the four muscles that comprise the quadriceps muscles- rectus femoris, vastus medialis, vastus intermedius and vastus lateralis. Posterior compartment muscles of the thigh are the hamstring muscles, which include semimembranosus and biceps femoris. Medial compartment muscles are pectineus, adductor magnus, adductor longus and adductor brevis, gracilis; because the major muscles of the thigh are the largest muscles of the body, resistance exercises of them stimulate blood flow more than any other localized activity. The arterial supply is by the obturator artery; the lymphatic drainage follows the arterial supply and drains to the lumbar lymphatic trunks on the corresponding side, which in turn drains to the cisterna chyli.
The deep venous system of the thigh consists of the femoral vein, the proximal part of the popliteal vein, various smaller vessels. The venae perfortantes connect the deep and the superficial system, which consists of the saphenous veins. Thigh weakness can result in a positive Gowers' sign on physical examination; the thigh meat of some animals such as chicken and cow is consumed as a food in many parts of the world
Sacrotuberous ligament
The sacrotuberous ligament is situated at the lower and back part of the pelvis. It is flat, triangular in form, it runs from the sacrum to the tuberosity of the ischium. It is a remnant of part of Biceps femoris muscle; the sacrotuberous ligament is attached by its broad base to the posterior superior iliac spine, the posterior sacroiliac ligaments, to the lower transverse sacral tubercles and the lateral margins of the lower sacrum and upper coccyx. Its oblique fibres descend laterally, converging to form a thick, narrow band that widens again below and is attached to the medial margin of the ischial tuberosity, it spreads along the ischial ramus as the falciform process, whose concave edge blends with the fascial sheath of the internal pudendal vessels and pudendal nerve. The lowest fibres of gluteus maximus are attached to the posterior surface of the ligament; the ligament is pierced by the coccygeal branches of the inferior gluteal artery, the perforating cutaneous nerve and filaments of the coccygeal plexus.
The membranous falciform process of the sacrotuberous ligament was found to be absent in 13% of cadavers. When present it extends towards the ischioanal fossa travelling along the ischial ramus and fusing with the obturator fascia; the lower border of the ligament was found to be directly continuous with the tendon of origin of the long head of the Biceps femoris in 50% of subjects. Biceps femoris could therefore act to stabilise the sacroiliac joint via the sacrotuberous ligament; the sacrotuberous ligament contains the coccygeal branch of the inferior gluteal artery. If the pudendal nerve becomes entrapped between this ligament and the sacrospinous ligament causing perineal pain, the sacrotuberous ligament is surgically severed to relieve the pain; this article incorporates text in the public domain from page 309 of the 20th edition of Gray's Anatomy Anatomy figure: 13:03-04 at Human Anatomy Online, SUNY Downstate Medical Center – "Deep muscles of the gluteal region with gluteus medius and maximus muscles removed."
Anatomy figure: 17:02-05 at Human Anatomy Online, SUNY Downstate Medical Center – "Posterior view of the bones and ligaments of the hip joint." Anatomy photo:41:os-0114 at the SUNY Downstate Medical Center – "The Female Perineum" Anatomy photo:42:12-0102 at the SUNY Downstate Medical Center – "The Male Perineum and the Penis: Boundaries of the Ischioanal fossa" Anatomy image:9075 at the SUNY Downstate Medical Center hip/hip%20ligaments/ligaments7 at the Dartmouth Medical School's Department of Anatomy
Lateral rotator group
The lateral rotator group is a group of six small muscles of the hip which all externally rotate the femur in the hip joint. It consists of the following muscles: Piriformis, gemellus superior, obturator internus, gemellus inferior, quadratus femoris and the obturator externus. All muscles in the lateral rotator group originate from the hip bone and insert on to the upper extremity of the femur; the muscles are innervated by the sacral plexus, except the obturator externus muscle, innervated by the lumbar plexus. This group does not include all muscles which aid in lateral rotation of the hip joint: rather it is a collection of ones which are known for performing this action. Other muscles that contribute to lateral rotation of the hip include: Gluteus maximus muscle Gluteus medius muscle and gluteus minimus muscle when the hip is extended Psoas major muscle Psoas minor muscle Sartorius muscle Hip anatomy Glutealregion at The Anatomy Lesson by Wesley Norman
Anatomical terms of muscle
Muscles are described using unique anatomical terminology according to their actions and structure. There are three types of muscle tissue in the human body: skeletal and cardiac. Skeletal striated muscle, or "voluntary muscle" joins to bone with tendons. Skeletal muscle maintains posture. Smooth muscle tissue is found in parts of the body; the majority of this type of muscle tissue is found in the digestive and urinary systems where it acts by propelling forward food and feces in the former and urine in the latter. Other places smooth muscle can be found are within the uterus, where it helps facilitate birth, the eye, where the pupillary sphincter controls pupil size. Cardiac muscle is specific to the heart, it is involuntary in its movement, is additionally self-excitatory, contracting without outside stimuli. As well as anatomical terms of motion, which describe the motion made by a muscle, unique terminology is used to describe the action of a set of muscles. Agonist muscles and antagonist muscles refer to muscles that inhibit a movement.
Agonist muscles cause a movement to occur through their own activation. For example, the triceps brachii contracts, producing a shortening contraction, during the up phase of a push-up. During the down phase of a push-up, the same triceps brachii controls elbow flexion while producing a lengthening contraction, it is still the agonist, because while resisting gravity during relaxing, the triceps brachii continues to be the prime mover, or controller, of the joint action. Agonists are interchangeably referred to as "prime movers," since they are the muscles considered responsible for generating or controlling a specific movement. Another example is the dumbbell curl at the elbow; the "elbow flexor" group is the agonist. During the lowering phase the "elbow flexor" muscles lengthen, remaining the agonists because they are controlling the load and the movement. For both the lifting and lowering phase, the "elbow extensor" muscles are the antagonists, they shorten during the dumbbell lowering phase.
Here it is important to understand that it is common practice to give a name to a muscle group based on the joint action they produce during a shortening contraction. However, this naming convention does not mean; this term describes the function of skeletal muscles. Antagonist muscles are the muscles that produce an opposing joint torque to the agonist muscles; this torque can aid in controlling a motion. The opposing torque can slow movement down - in the case of a ballistic movement. For example, during a rapid discrete movement of the elbow, such as throwing a dart, the triceps muscles will be activated briefly and to accelerate the extension movement at the elbow, followed immediately by a "burst" of activation to the elbow flexor muscles that decelerates the elbow movement to arrive at a quick stop. To use an automotive analogy, this would be similar to pressing your gas pedal and immediately pressing the brake. Antagonism is not an intrinsic property of a particular muscle group. During slower joint actions that involve gravity, just as with the agonist muscle, the antagonist muscle can shorten and lengthen.
Using the example above of the triceps brachii during a push-up, the elbow flexor muscles are the antagonists at the elbow during both the up phase and down phase of the movement. During the dumbbell curl, the elbow extensors are the antagonists for both the lifting and lowering phases. Antagonist and agonist muscles occur in pairs, called antagonistic pairs; as one muscle contracts, the other relaxes. An example of an antagonistic pair is the triceps. "Reverse motions" need antagonistic pairs located in opposite sides of a joint or bone, including abductor-adductor pairs and flexor-extensor pairs. These consist of an extensor muscle, which "opens" the joint and a flexor muscle, which does the opposite by decreasing the angle between two bones. However, muscles don't always work this way. Sometimes during a joint action controlled by an agonist muscle, the antagonist will be activated, naturally; this occurs and is not considered to be a problem unless it is excessive or uncontrolled and disturbs the control of the joint action.
This serves to mechanically stiffen the joint. Not all muscles are paired in this way. An example of an exception is the deltoid. Synergist muscles help perform, the same set of joint motion as the agonists. Synergists muscles act on movable joints. Synergists are sometimes referred to as "neutralizers" because they help cancel out, or neutralize, extra motion from the agonists to make sure that the force generated works within the desired plane of motion. Muscle fibers can only contract up to 40% of their stretched length, thus the short fibers of pennate muscles are more suitable where power rather than range of contraction is required. This limitation in the range of contraction affects all muscles, those that act over several joints may be unable to shorten sufficiently to produce
Tendon
A tendon or sinew is a tough band of fibrous connective tissue that connects muscle to bone and is capable of withstanding tension. Tendons are similar to ligaments. Ligaments join one bone to bone, while tendons connect muscle to bone for a proper functioning of the body. Histologically, tendons consist of dense regular connective tissue fascicles encased in dense irregular connective tissue sheaths. Normal healthy tendons are composed of parallel arrays of collagen fibers packed together, they are anchored to bone by Sharpey's fibres. The dry mass of normal tendons, which makes up about 30% of their total mass, is composed of about 86% collagen, 2% elastin, 1–5% proteoglycans, 0.2% inorganic components such as copper and calcium. The collagen portion is made up of 97–98% type I collagen, with small amounts of other types of collagen; these include type II collagen in the cartilaginous zones, type III collagen in the reticulin fibres of the vascular walls, type IX collagen, type IV collagen in the basement membranes of the capillaries, type V collagen in the vascular walls, type X collagen in the mineralized fibrocartilage near the interface with the bone.
Collagen fibres coalesce into macroaggregates. After secretion from the cell, the cleaved by procollagen N- and C-proteinases, the tropocollagen molecules spontaneously assemble into insoluble fibrils. A collagen molecule is about 300 nm long and 1–2 nm wide, the diameter of the fibrils that are formed can range from 50–500 nm. In tendons, the fibrils assemble further to form fascicles, which are about 10 mm in length with a diameter of 50–300 μm, into a tendon fibre with a diameter of 100–500 μm. Fascicles are bound by the endotendineum, a delicate loose connective tissue containing thin collagen fibrils. and elastic fibres. Groups of fascicles are bounded by the epitenon. Filling the interstitia within the fascia where the tendon is located is the paratenon a fatty areolar tissue; the collagen in tendons are held together with proteoglycan components including decorin and, in compressed regions of tendon, which are capable of binding to the collagen fibrils at specific locations. The proteoglycans are interwoven with the collagen fibrils – their glycosaminoglycan side chains have multiple interactions with the surface of the fibrils – showing that the proteoglycans are important structurally in the interconnection of the fibrils.
The major GAG components of the tendon are dermatan sulfate and chondroitin sulfate, which associate with collagen and are involved in the fibril assembly process during tendon development. Dermatan sulfate is thought to be responsible for forming associations between fibrils, while chondroitin sulfate is thought to be more involved with occupying volume between the fibrils to keep them separated and help withstand deformation; the dermatan sulfate side chains of decorin aggregate in solution, this behavior can assist with the assembly of the collagen fibrils. When decorin molecules are bound to a collagen fibril, their dermatan sulfate chains may extend and associate with other dermatan sulfate chains on decorin, bound to separate fibrils, therefore creating interfibrillar bridges and causing parallel alignment of the fibrils; the tenocytes produce the collagen molecules, which aggregate end-to-end and side-to-side to produce collagen fibrils. Fibril bundles are organized to form fibres with the elongated tenocytes packed between them.
There is a three-dimensional network of cell processes associated with collagen in the tendon. The cells communicate with each other through gap junctions, this signalling gives them the ability to detect and respond to mechanical loading. Blood vessels may be visualized within the endotendon running parallel to collagen fibres, with occasional branching transverse anastomoses; the internal tendon bulk is thought to contain no nerve fibres, but the epitenon and paratenon contain nerve endings, while Golgi tendon organs are present at the junction between tendon and muscle. Tendon length varies from person to person. Tendon length is, in practice, the deciding factor regarding potential muscle size. For example, all other relevant biological factors being equal, a man with a shorter tendons and a longer biceps muscle will have greater potential for muscle mass than a man with a longer tendon and a shorter muscle. Successful bodybuilders will have shorter tendons. Conversely, in sports requiring athletes to excel in actions such as running or jumping, it is beneficial to have longer than average Achilles tendon and a shorter calf muscle.
Tendon length is determined by genetic predisposition, has not been shown to either increase or decrease in response to environment, unlike muscles, which can be shortened by trauma, use imbalances and a lack of recovery and stretching. Traditionally, tendons have been considered to be a mechanism by which muscles connect to bone as well as muscles itself, functioning to transmit forces; this connection allows tendons to passively modulate forces during locomotion, providing additional stability with no active work. However, over the past two decades, much research focused on the elastic properties of some tendons and their ability to function as springs. Not all tendons are required to perform the same functional role, with some predominantly positioning limbs, such as the fingers when writing and others acting as springs to make locomotion more efficient. Energy storing tendons can recover energy at high efficiency. For example, during a human stride, the Achilles tendon stretches as the ankle joint dorsiflexes.
During the last portion of the stride, as the foot plantar-flexes (pointing the
Gluteus medius
The gluteus medius one of the three gluteal muscles, is a broad, radiating muscle, situated on the outer surface of the pelvis. Its posterior third is covered by the gluteus maximus, its anterior two-thirds by the gluteal aponeurosis, which separates it from the superficial fascia and integument; the gluteus medius muscle starts, or "originates," on the outer surface of the ilium between the iliac crest and the posterior gluteal line above, the anterior gluteal line below. The fibers of the muscle converge into a strong flattened tendon that inserts on the lateral surface of the greater trochanter. More the muscle's tendon inserts into an oblique ridge that runs downward and forward on the lateral surface of the greater trochanter. A bursa separates the tendon of the muscle from the surface of the trochanter; the posterior border may be more or less united to the piriformis, or some of the fibers end on its tendon. The posterior fibres of gluteus medius contract to produce hip extension, lateral rotation and abduction.
During gait, the posterior fibres help to decelerate internal rotation of the femur at the end of swing phase. • The anterior part acting alone helps to flex and internally rotate the hip. • The posterior part acting alone helps to extend and externally rotate the hip. • The anterior and posterior parts working together abduct the hip and stabilize the pelvis in the coronal plane. Dysfunction of the gluteus medius or the superior gluteal nerve can be indicated by a positive Trendelenburg's sign. Trendelenburg gait This article incorporates text in the public domain from page 474 of the 20th edition of Gray's Anatomy Anatomy photo:13:st-0404 at the SUNY Downstate Medical Center Cross section image: pelvis/pelvis-e12-15—Plastination Laboratory at the Medical University of Vienna
Gluteal muscles
The gluteal muscles are a group of three muscles which make up the buttocks: the gluteus maximus, gluteus medius and gluteus minimus. The three muscles insert on the femur; the functions of the muscles include extension, external rotation and internal rotation of the hip joint. The gluteus maximus is the most superficial of the three gluteal muscles, it makes up a large portion of the appearance of the hips. It is a narrow and thick fleshy mass of a quadrilateral shape, forms the prominence of the nates; the gluteus medius is a broad, radiating muscle, situated on the outer surface of the pelvis. It lies profound to the gluteus maximus and its posterior third is covered by the gluteus maximus, its anterior two-thirds by the gluteal aponeurosis, which separates it from the superficial fascia and integument; the gluteus minimus is the smallest of the three gluteal muscles and is situated beneath the gluteus medius. The bulk of the gluteal muscle mass contributes only to shape of the buttocks; the other major contributing factor is that of the panniculus adiposus of the buttocks, well developed in this area, gives the buttock its characteristic rounded shape.
The gluteal muscle bulk and tone can be improved with exercise. However, it is predominantly the disposition of the overlying panniculus adiposus which may cause sagging in this region of the body. Exercise in general which can contribute to fat loss can lead to reduction of mass in subcutaneal fat storage locations on the body which includes the panniculus, so for leaner and more active individuals, the glutes will more predominantly contribute to the shape than someone less active with a fattier composition; the degree of body fat stored in various locations such as the panniculus is dictated by genetic and hormonal profiles. The gluteus maximus arises from the posterior gluteal line of the inner upper ilium, the rough portion of bone including the crest above and behind it; the fibers are lateralward. Its action is to extend and to laterally rotate the hip, to extend the trunk; the gluteus medius muscle originates on the outer surface of the ilium between the iliac crest and the posterior gluteal line above, the anterior gluteal line below.
The fibers of the muscle converge into a strong flattened tendon that inserts on the lateral surface of the greater trochanter. More the muscle's tendon inserts into an oblique ridge that runs downward and forward on the lateral surface of the greater trochanter; the gluteus minimus is fan-shaped, arising from the outer surface of the ilium, between the anterior and inferior gluteal lines, behind, from the margin of the greater sciatic notch. The fibers converge to the deep surface of a radiated aponeurosis, this ends in a tendon, inserted into an impression on the anterior border of the greater trochanter, gives an expansion to the capsule of the hip joint; the functions of muscles includes extension, lateral rotation and medial rotation of the hip joint. The gluteus maximus supports the extended knee through the iliotibial tract. Sitting for long periods can lead to the gluteal muscles atrophying through constant pressure and disuse; this may be associated with lower back pain, difficulty with some movements that require the gluteal muscles, such as rising from the seated position, climbing stairs.
Any exercise that works and/or stretches the buttocks is suitable, for example lunges, hip thrusts, climbing stairs, bicycling, squats, arabesque and various specific exercises for the bottom. Weight training exercises which are known to strengthen the gluteal muscles include the squat, leg press, any other movements involving external hip rotation and hip extension. Gluteal crease McMinn, RMH Last applied. London: Churchill Livingstone. ISBN 0-443-04662-X 8b; the Muscles and Fasciæ of the Thigh Bartleby.com, Henry Gray, Anatomy of the Human Body, 1918
