Vastus intermedius muscle
The vastus intermedius arises from the front and lateral surfaces of the body of the femur in its upper two-thirds, sitting under the rectus femoris muscle and from the lower part of the lateral intermuscular septum. Its fibers end in a superficial aponeurosis, which forms the deep part of the quadriceps femoris tendon; the vastus medialis and vastus intermedius appear to be inseparably united, but when the rectus femoris has been reflected during dissection a narrow interval will be observed extending upward from the medial border of the patella between the two muscles, the separation may be continued as far as the lower part of the intertrochanteric line, however, the two muscles are continuous. Due to being the deeper middle-most of the quadriceps muscle group, the intermedius is the most difficult to stretch once maximum knee flexion is attained, it cannot be further stretched by hip extension as the rectus femoris can, nor is it accessible to manipulate with massage therapy to stretch the fibres sideways as the vastus lateralis and vastus medialis are.
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Extensor digitorum longus muscle
The extensor digitorum longus is a pennate muscle, situated at the lateral part of the front of the leg. It arises from the lateral condyle of the tibia. Between it and the tibialis anterior are the upper portions of the anterior tibial vessels and deep peroneal nerve; the muscle passes under the superior and inferior extensor retinaculum of foot in company with the fibularis tertius, divides into four slips, which run forward on the dorsum of the foot, are inserted into the second and third phalanges of the four lesser toes. The tendons to the second and fourth toes are each joined, opposite the metatarsophalangeal articulations, on the lateral side by a tendon of the extensor digitorum brevis; the tendons are inserted in the following manner: each receives a fibrous expansion from the interossei and lumbricals, spreads out into a broad aponeurosis, which covers the dorsal surface of the first phalanx: this aponeurosis, at the articulation of the first with the second phalanx, divides into three slips—an intermediate, inserted into the base of the second phalanx.
This muscle varies in the modes of origin and the arrangement of its various tendons. The tendons to the second and fifth toes may be found doubled, or extra slips are given off from one or more tendons to their corresponding metatarsal bones, or to the short extensor, or to one of the interosseous muscles. A slip to the great toe from the innermost tendon has been found. Extensor digitorum brevis muscle Extensor digitorum muscle This article incorporates text in the public domain from page 481 of the 20th edition of Gray's Anatomy Anatomy photo:15:st-0401 at the SUNY Downstate Medical Center PTCentral
Extensor hallucis longus muscle
The extensor hallucis longus is a thin muscle, situated between the tibialis anterior and the extensor digitorum longus, that functions to extend the big toe and dorsiflects the foot, assists with foot eversion and inversion. It arises from the anterior surface of the fibula for about the middle two-fourths of its extent, medial to the origin of the Extensor digitorum longus; the anterior tibial vessels and deep peroneal nerve lie between the Tibialis anterior. The fibers pass downward, end in a tendon, which occupies the anterior border of the muscle, passes through a distinct compartment in the cruciate crural ligament, crosses from the lateral to the medial side of the anterior tibial vessels near the bend of the ankle, is inserted into the base of the distal phalanx of the great toe. Opposite the metatarsophalangeal articulation, the tendon gives off a thin prolongation on either side, to cover the surface of the joint. An expansion from the medial side of the tendon is inserted into the base of the proximal phalanx.
United at its origin with the extensor digitorum longus. The extensor ossis metatarsi hallucis, a small muscle, sometimes found as a slip from the extensor hallucis longus, or from the tibialis anterior, or from the extensor digitorum longus, or as a distinct muscle. Deep peroneal nerve, branch of common peroneal nerve; this article incorporates text in the public domain from page 481 of the 20th edition of Gray's Anatomy Anatomy photo:15:st-0402 at the SUNY Downstate Medical Center - "The Leg: Muscles" University of Washington
Vastus lateralis muscle
The vastus lateralis called the"vastus externus" is the largest and most powerful part of the quadriceps femoris, a muscle in the thigh. Together with other muscles of the quadriceps group, it serves to extend the knee joint, moving the lower leg forward, it arises from a series of flat, broad tendons attached to the femur, attaches to the outer border of the patella. It joins with the other muscles that make up the quadriceps in the quadriceps tendon, which travels over the knee to connect to the tibia; the vastus lateralis is the recommended site for intramuscular injection in infants less than 7 months old and those unable to walk, with loss of muscular tone. The vastus lateralis muscle arises from several areas of the femur, including the upper part of the intertrochanteric line; these form a broad flat tendon that covers the upper three-quarters of the muscle. From the inner surface of the aponeurosis, many muscle fibers originate; some additional fibers arise from the tendon of the gluteus maximus muscle, from the septum between the vastus lateralis and short head of the biceps femoris.
The fibers form a large fleshy mass, attached to a second strong aponeurosis, placed on the deep surface of the lower part of the muscle. This lower aponeurosis becomes contracted and thickened into a flat tendon that attaches to the outer border of the patella, subsequently joins with the quadriceps femoris tendon, expanding the capsule of the knee-joint; the vastus lateralis muscle is innervated by the muscular branches of the femoral nerve. Notes This article incorporates text in the public domain from page 470 of the 20th edition of Gray's Anatomy Cross section image: pembody/body18b—Plastination Laboratory at the Medical University of Vienna Cross section image: pelvis/pelvis-e12-15—Plastination Laboratory at the Medical University of Vienna PTCentral
The semitendinosus is a long superficial muscle in the back of the thigh. It is so named because it has a long tendon of insertion, it lies posteromedially in the thigh, superficial to the semimembranosus. The semitendinosus, remarkable for the great length of its tendon of insertion, is situated at the posterior and medial aspect of the thigh, it arises from the lower and medial impression on the upper part of the tuberosity of the ischium, by a tendon common to it and the long head of the biceps femoris. The muscle is fusiform and ends a little below the middle of the thigh in a long round tendon which lies along the medial side of the popliteal fossa; the semitendinosus is more superficial than the semimembranosus. However, because the semimembranosus is wider and flatter than the semitendinosus, it is still possible to palpate the semimembranosus directly. At its insertion it gives off from its lower border a prolongation to the deep fascia of the leg and lies behind the tendon of the sartorius, below that of the gracilis, to which it is united.
These three tendons form what is known as the pes anserinus, so named because it looks like the foot of a goose. A lower motor neuron exits to the sacral plexus exiting through the spinal levels L5-S2. From the sacral plexus, the lower motor neuron travels down the sciatic nerve; the sciatic nerve branches into the deep fibular nerve and the tibial nerve. The tibial nerve innervates the semitendinosus as well as the other hamstring muscles, the semimembranosus and biceps femoris; the semitendinosus muscle is one of three hamstring muscles that are located at the back of the thigh. The other two are the biceps femoris; the semitendinosus muscle lies between the other two. These three muscles work collectively to extend the hip; the muscle helps to medially rotate the tibia on the femur when the knee is flexed and medially rotate the femur when the hip is extended. It counteracts forward bending at the hips as well. Semimembranosus Biceps femoris This article incorporates text in the public domain from page 479 of the 20th edition of Gray's Anatomy Anatomy photo:14:st-0410 at the SUNY Downstate Medical Center Cross section image: pembody/body18b—Plastination Laboratory at the Medical University of Vienna knee/surface/surface4 at the Dartmouth Medical School's Department of Anatomy PTCentral
Anatomical terms of motion
Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints and specific sections of the body; the terminology used describes this motion according to its direction relative to the anatomical position of the joints. Anatomists use a unified set of terms to describe most of the movements, although other, more specialized terms are necessary for describing the uniqueness of the movements such as those of the hands and eyes. In general, motion is classified according to the anatomical plane. Flexion and extension are examples of angular motions, in which two axes of a joint are brought closer together or moved further apart. Rotational motion may occur at other joints, for example the shoulder, are described as internal or external. Other terms, such as elevation and depression, describe movement above or below the horizontal plane. Many anatomical terms derive from Latin terms with the same meaning. Motions are classified after the anatomical planes they occur in, although movement is more than not a combination of different motions occurring in several planes.
Motions can be split into categories relating to the nature of the joints involved: Gliding motions occur between flat surfaces, such as in the intervertebral discs or between the carpal and metacarpal bones of the hand. Angular motions occur over synovial joints and causes them to either increase or decrease angles between bones. Rotational motions move a structure in a rotational motion along a longitudinal axis, such as turning the head to look to either side. Apart from this motions can be divided into: Linear motions, which move in a line between two points. Rectilinear motion is motion in a straight line between two points, whereas curvilinear motion is motion following a curved path. Angular motions occur when an object is around another object decreasing the angle; the different parts of the object do not move the same distance. Examples include a movement of the knee, where the lower leg changes angle compared to the femur, or movements of the ankle; the study of movement is known as kinesiology.
A categoric list of movements of the human body and the muscles involved can be found at list of movements of the human body. The prefix hyper- is sometimes added to describe movement beyond the normal limits, such as in hypermobility, hyperflexion or hyperextension; the range of motion describes the total range of motion. For example, if a part of the body such as a joint is overstretched or "bent backwards" because of exaggerated extension motion it can be described as hyperextended. Hyperextension increases the stress on the ligaments of a joint, is not always because of a voluntary movement, it may be other causes of trauma. It may be used in surgery, such as in temporarily dislocating joints for surgical procedures; these are general terms. Most terms have a clear opposite, so are treated in pairs. Flexion and extension describe movements; these terms come from the Latin words with the same meaning. Flexion describes a bending movement that decreases the angle between a segment and its proximal segment.
For example, bending the elbow, or clenching a hand into a fist, are examples of flexion. When sitting down, the knees are flexed; when a joint can move forward and backward, such as the neck and trunk, flexion refers to movement in the anterior direction. When the chin is against the chest, the head is flexed, the trunk is flexed when a person leans forward. Flexion of the shoulder or hip refers to movement of the leg forward. Extension is the opposite of flexion, describing a straightening movement that increases the angle between body parts. For example, when standing up, the knees are extended; when a joint can move forward and backward, such as the neck and trunk, extension refers to movement in the posterior direction. Extension of the hip or shoulder moves the leg backward. Abduction is the motion of a structure away from the midline while adduction refer to motion towards the center of the body; the centre of the body is defined as the midsagittal plane. These terms come from Latin words with similar meanings, ab- being the Latin prefix indicating "away," ad- indicating "toward," and ducere meaning "to draw or pull".
Abduction refers to a motion that pulls a part away from the midline of the body. In the case of fingers and toes, it refers to spreading the digits apart, away from the centerline of the hand or foot. Abduction of the wrist is called radial deviation. For example, raising the arms up, such as when tightrope-walking, is an example of abduction at the shoulder; when the legs are splayed at the hip, such as when doing a star jump or doing a split, the legs are abducted at the hip. Adduction refers to a motion that pulls a structure or part toward the midline of the body, or towards the midline of a limb. In the case of fingers and toes, it refers to bringing the digits together, towards the centerline of the hand or foot. Adduction of the wrist is called ulnar deviation. Dropping the arms to the sides, bringing the knees together, are examples of adduction. Ulnar deviation is the hand moving towards the ulnar styloid. Radial deviation is the hand moving towards the radial styloid; the terms elevation and depression refer to movement below the horizontal.
They derive from the Latin terms with similar meaningsElevation refers to movement in a superior direction. For example
External obturator muscle
The external obturator muscle, obturator externus muscle is a flat, triangular muscle, which covers the outer surface of the anterior wall of the pelvis. It is sometimes considered part of the medial compartment of thigh, sometimes considered part of the gluteal region, it arises from the margin of bone around the medial side of the obturator membrane and surrounding bone, viz. from the inferior pubic ramus, the ramus of the ischium. The fibers springing from the pubic arch extend on to the inner surface of the bone, where they obtain a narrow origin between the margin of the foramen and the attachment of the obturator membrane; the fibers converge and pass posterolateral and upward, end in a tendon which runs across the back of the neck of the femur and lower part of the capsule of the hip joint and is inserted into the trochanteric fossa of the femur. The obturator vessels lie between the obturator membrane. In 33 % of people a supernumerary muscle is found between the adductor minimus. While this muscle, when present, is similar to its neighbouring adductors, it is formed by separation from the superficial layer of the external obturator, is thus not ontogenetically related to the adductor muscles of the hip.
This muscle originates from the upper part of the inferior pubic ramus from where it runs downwards and laterally. In half of cases, it inserts into the anterior surface of the insertion aponeurosis of the adductor minimus. In the remaining cases, it is either inserted into the upper part of the pectineal line or the posterior part of the lesser trochanter, it has been demonstrated by the course of the posterior branch of obturator nerve that the obturator externus is divided into a superior muscle fascicle and a main belly. The supernumerary muscle described above originates from the superior fascicle, while an anomalous fascicle — derived from the external obturator — originates from the main belly; the "original" external obturator, i.e. without these supernumerary muscular parts occurs in only 20% of cases, the external obturator undergoes ontogenetic variations. The external obturator muscle acts as the lateral rotator of the hip joint; as a short muscle around the hip joint, it stabilizes the hip joint as a postural muscle.
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