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
Abductor hallucis muscle
The abductor hallucis muscle is an intrinsic muscle of the foot. It participates in the flexion of the great toe; the abductor hallucis muscle is located in the medial border of the foot and contributes to form the prominence, observed on the region. It is inserted behind on the tuberosity of the calcaneus, the flexor retinaculum, the plantar aponeurosis, its muscle body thick behind, flattens as it goes forward. It ends in a common tendon with the medial head of the flexor hallucis brevis that inserts on the medial surface of the base of the first proximal phalanx and its related sesamoid bone, its medial surface is covered with the muscle's fascia and the skin. Abductor hallucis is innervated by the medial plantar nerve; the nerves that supply it enter the muscle from its upper border. The deep tendon reflex of the abductor hallucis. was first described and demonstrated by Dr. M. W. Spanakos. Intrinsic muscles of the foot Sole of the foot This article incorporates text in the public domain from page 491 of the 20th edition of Gray's Anatomy Anatomy photo:16:st-0402 at the SUNY Downstate Medical Center PTCentral
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.
This article incorporates text in the public domain from page 471 of the 20th edition of Gray's Anatomy PTCentral
The gluteus maximus is the main extensor muscle of the hip. It is the largest and most superficial of the three gluteal muscles and makes up a large portion of the shape and appearance of each side of the hips, its thick fleshy mass, in a quadrilateral shape, forms the prominence of the buttocks. Its large size is one of the most characteristic features of the muscular system in humans, connected as it is with the power of maintaining the trunk in the erect posture. Other primates can not sustain standing erectly; the muscle is remarkably coarse in function and structure, being made up of muscle fascicles lying parallel with one another, collected together into larger bundles separated by fibrous septa. It arises from the posterior gluteal line of the inner upper ilium, a pelvic bone, the portion of the bone including the crest of the ilium above and behind it; the fibers are lateralward. Three bursae are found in relation with the deep surface of this muscle: One of these, of large size, separates it from the greater trochanter.
When the gluteus maximus takes its fixed point from the pelvis, it extends the acetabulofemoral joint and brings the bent thigh into a line with the body. Taking its fixed point from below, it acts upon the pelvis, supporting it and the trunk upon the head of the femur, its most powerful action is to cause the body to regain the erect position after stooping, by drawing the pelvis backward, being assisted in this action by the biceps femoris, semitendinosus and adductor magnus. The gluteus maximus is a tensor of the fascia lata, by its connection with the iliotibial band steadies the femur on the articular surfaces of the tibia during standing, when the extensor muscles are relaxed; the lower part of the muscle acts as an adductor and external rotator of the limb. The upper fibers act as abductors of the hip joints; the gluteus maximus is involved from running to weight-lifting. A number of exercises focus on the gluteus maximus as well as other muscles of the upper leg. Hip thrusts Glute bridge Quadruped hip extensions Kettlebell swings Squats and variations like split squats, pistol squats and wide-stance lunges Deadlift Reverse hyperextension Four-way hip extensions Glute-ham raise Functional assessment can be useful in assessing injuries to the gluteus maximus and surrounding muscles.
These tests include: 30 Second Chair to Stand testThis test measures a participant's ability to stand up from a seated position as many times as possible in a thirty-second period of time. Testing the number of times a person can stand up in a thirty-second period helps assess strength, flexibility and endurance, which can help determine how far along a person is in rehabilitation, or how much work is still to be done. Passive piriformis stretch; the piriformis test measures flexibility of the gluteus maximus. This requires a trained professional and is based on the angle of external and internal rotation in relation to normal range of motion without injury or impingement. In other primates, gluteus maximus consists of ischiofemoralis, a small muscle that corresponds to the human gluteus maximus and originates from the ilium and the sacroiliac ligament, gluteus maximus proprius, a large muscle that extends from the ischial tuberosity to a more distant insertion on the femur. In adapting to bipedal gait, reorganization of the attachment of the muscle as well as the moment arm was required.
Table of muscles of the human body Coccyx This article incorporates text in the public domain from page 474 of the 20th edition of Gray's Anatomy Anatomy photo:13:st-0403 at the SUNY Downstate Medical Center Cross section image: pelvis/pelvis-female-17—Plastination Laboratory at the Medical University of Vienna Cross section image: pelvis/pelvis-e12-15—Plastination Laboratory at the Medical University of Vienna Cross section image: pembody/body18b—Plastination Laboratory at the Medical University of Vienna Muscles/GluteusMaximus at exrx.net
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
Anterior compartment of thigh
The anterior compartment of thigh contains muscles which extend the knee and flex the hip. The anterior compartment is one of the fascial compartments of the thigh that contains groups of muscles together with their nerves and blood supply; the anterior compartment contains the sartorius muscle and the quadriceps femoris group, which consists of the rectus femoris muscle and the three vasti muscles – the vastus lateralis, vastus intermedius, the vastus medialis. The iliopsoas is sometimes considered a member of the anterior compartment muscles, as is the articularis genus muscle; the anterior compartment is separated from the posterior compartment by the lateral intermuscular septum and from the medial compartment by the medial intermuscular septum. The nerve of the anterior compartment of thigh is the femoral nerve. Innervation for the quadriceps muscles come from the posterior division of the femoral nerve, while the anterior division gives a lateral and a medial branch, the second being responsible for the innervation of the sartorius muscle.
The iliacus and the psoas major and psoas minor muscles, sometimes considered part of the anterior compartment, do not share the same innervation. Whereas the iliacus is innervated by the femoral nerve, the psoas is innervated by ventral rami of L1-L3; when the external iliac artery crosses the inguinal ligament, it becomes the femoral artery, which supplies blood to the anterior compartment and is the largest blood vessel of the inferior member. The anterior compartment of thigh contains muscles which are extensors of the knee and flexors of the hip joints; the anterior compartment may be affected as part of a compartment syndrome. Antthigh at The Anatomy Lesson by Wesley Norman knee/muscles/thigh1 at the Dartmouth Medical School's Department of Anatomy Overview at stanford.edu
Internal obturator muscle
The internal obturator muscle or obturator internus muscle originates on the medial surface of the obturator membrane, the ischium near the membrane, the rim of the pubis. It exits the pelvic cavity through the lesser sciatic foramen; the internal obturator is situated within the lesser pelvis, at the back of the hip-joint. It functions to help laterally rotate femur with hip extension and abduct femur with hip flexion, as well as to steady the femoral head in the acetabulum, it arises from the inner surface of the antero-lateral wall of the pelvis, where it surrounds the greater part of the obturator foramen, being attached to the inferior pubic ramus and ischium, at the side to the inner surface of the hip bone below and behind the pelvic brim, reaching from the upper part of the greater sciatic foramen above and behind to the obturator foramen below and in front. It arises from the pelvic surface of the obturator membrane except in the posterior part, from the tendinous arch which completes the canal for the passage of the obturator vessels and nerve, to a slight extent from the obturator fascia, which covers the muscle.
The fibers converge toward the lesser sciatic foramen, end in four or five tendinous bands, which are found on the deep surface of the muscle. The tendon inserts on the greater trochanter of the proximal femur; the internal obturator muscle is innervated by the nerve to internal obturator. This bony surface is covered by smooth cartilage, separated from the tendon by a bursa, presents one or more ridges corresponding with the furrows between the tendinous bands; these bands leave the pelvis through the lesser sciatic foramen and unite into a single flattened tendon, which passes horizontally across the capsule of the hip-joint, after receiving the attachments of the superior and inferior gemellus muscles, is inserted into the forepart of the medial surface of the greater trochanter above the trochanteric fossa. A bursa and elongated in form, is found between the tendon and the capsule of the hip-joint; this article incorporates text in the public domain from page 477 of the 20th edition of Gray's Anatomy Anatomy photo:13:st-0407 at the SUNY Downstate Medical Center - "Gluteal Region: Muscles" Anatomy photo:43:st-0603 at the SUNY Downstate Medical Center - "The Female Pelvis: Muscles" Cross section image: pelvis/pelvis-e12-15—Plastination Laboratory at the Medical University of Vienna pelvis at The Anatomy Lesson by Wesley Norman perineum at The Anatomy Lesson by Wesley Norman Int.
J. Morphol. 25:95-98, 2007