<< Neuromuscular Tensions >>

One of the most striking aspects of a sexual performance is the development of neuromuscular tensions throughout the body of the responding individual, female or male. From head to toe, the muscles contract and relax, involuntarily, in steady or more convulsive rhythms. The movements may vary at various times in the experience of each individual, but they may vary even more between different individuals. Sometimes the muscular action is sufficient to effect major movements of the limbs and of still other parts of the body. Sometimes the movements are violent. Sometimes they are so limited that they are hardly noticeable; but in even the most quiescent individuals, whenever there is sexual response there is likely to be some evidence that muscles are rhythmically tensing and relaxing, everywhere in the body. There may be occasional moments when the movements cease and the muscles are held in continuous tension; but in an uninhibited and responding individual there is usually a flow of continuous muscular movement, from the first moment of arousal to the moment of orgasm.

Movements in Buttocks and Pelvis
The most prominent of these muscular activities effect rhythmic movements of the buttocks and of the whole pelvis, and the consequent rhythmic pelvic thrusts during sexual activity are among the distinctive characteristics of the class Mammalia. Without the capacity to make these rhythmic movements, mammalian coitus could not occur. Simple intromission of a male organ into a vagina occurs among a few of the birds and reptiles and among some of the insects, and this is copulation, but it is not coitus in the mammalian sense. The mammals are nearly the only animals in which there are rhythmic alternations of in-and-out movements of the male copulatory organ and, in at least some cases, correspondingly rhythmic movements of the pelvis of the female partner.

Coital movements depend in part upon the gluteal muscles, which are the large muscles in the buttocks, working in conjunction with certain lower vertebral muscles. Even when there is no gross movement of the pelvis, the gluteal muscles may rhythmically contract during erotic arousal. More extended movements of these muscles may crowd or crush the two halves of the buttocks together. Since tensions in these gluteal muscles are correlated with or contribute to a rise in neuromuscular tensions throughout the body, some persons begin their sexual activities by voluntarily moving their buttocks, and thus they may build up their erotic responses.

The erotic significance of gluteal contractions may depend in part upon the fact that movements of the buttocks can stimulate the perineal area, with its abundant supply of nerves. Movements of the buttocks may also stimulate the anal area, which is erotically sensitive in many individuals. In addition, gluteal contractions may stimulate a flow of blood into the genitalia, thereby contributing to the erection of the genital structures. Some males are able to effect full erection by voluntarily tensing and moving their buttocks, and may occasionally reach orgasm without the genitalia being touched. Not a few females have also learned that voluntary contractions of their buttocks and movements of the pelvis may develop their erotic reactions and even effect orgasm in masturbation, petting, coitus, and homosexual activities.

The muscular movements which occur during sexual response are usually involuntary. While most of the muscles which are involved are ordinarily under voluntary control, no such control could effect the coordinated flow of movement which occurs throughout the body of one who is sexually aroused, or the extraordinary rapidity of some of the rhythmic movements which may occur during sexual activity.

Movements of Thighs
Coordinated with the gluteal contractions, there may be movements of the adductor and/or abductor muscles in the upper portions of the legs. The adductor muscles lie toward the front, on the inner surfaces of the thighs, and the abductors lie toward the sides. Rhythmic contractions of the adductors during sexual activity may pull the upper halves of the legs together rhythmically or, sometimes, quite convulsively. Contractions of the abductors may, on the contrary, roll the legs out. The coordination of the gluteal and adductor contractions may bring the buttocks and thighs together simultaneously in rhythmic sweeps of movement. Many persons intensify the force with which the upper halves of the legs come together by crossing their feet, or by placing objects between their legs to increase the muscular tensions. The sexual partner, placed between the legs of an intensely reacting individual, may be caught in a vise of considerable force.

Movements of Feet and Toes
Outside of the movements of gluteal, adductor, and abductor muscles, the muscular reactions which are next most noticeable during sexual activity may involve the feet and the toes. The whole foot may be extended until it falls in liue with the rest of the lower leg, thereby assuming a position which is impossible in non-erotic situations for most persons who are not trained as ballet dancers. The toes of most individuals become curled or, contrariwise, spread when there is erotic arousal. Many persons divide their toes, turning their large toes up or down while the remaining toes curl in the opposite direction. Such activity is rarely recognized by the individual who is sexually aroused and actually doing these things, but the near universality of such action is attested by the graphic record of coitus in the erotic art of the world. For instance, in Japanese erotic art curled toes have, for at least eight centuries, been one of the stylized symbols of erotic response.

Some persons tense so severely during sexual activity that their feet and toes develop cramps as soon as they have experienced orgasm. They rarely recognize such cramps during the sexual activity itself, but upon the sudden release of the tensions at orgasm, they may have to rise and shake their legs to rid themselves of the cramps. 35 Dramatic instances of the development of such tensions are found in the histories of some of the amputees who have contributed to the present study. Although these persons may have nothing but remnants of the nerves that would have served the muscles of their lower limbs, they may build up neuromuscular tensions in the non-existent portions of those limbs which are quite like those of persons who have complete limbs. Consequently the amputee may also have to rise after orgasm and shake the cramps out of his non-existent toes.
Cramps in the feet or limbs are noted in: Roubaud 1876:17. Van de Velde 1930:246.

Movements of Arms and Legs
The legs of a person who is involved in sexual activity may be thrust out in a straight line and held there with considerable tension. The arms may be thrust into similar positions. Or the arms and legs may be bent at the elbows and knees in angular positions which may be rigidly maintained throughout the period of maximum arousal. Contractions of the individual muscles usually become distinctly visible, standing out from the body surfaces as they do in an athlete who is demonstrating his muscular capacities.
Roubaud 1876:17 (who is also quoted by Kisch 1926:288 and Havelock Ellis 1936(11,1):149-150) describes the limbs at the approach of orgasm as becoming “stiff like iron bars.” See also Faller in Hornstein and Faller 1950:238.

The upper halves of the arms and of the legs may move rhythmically, sometimes in a slow rhythm, but often with an increase in speed as orgasm is approached. In amputees, the remaining portions of the arms and legs, being unimpeded by the weight of the limbs, may move in an even more distinctive fashion.

Movements of Hands and Fingers
In the midst of intense sexual activity the hands and fingers may move and curl in a manner which is comparable to the movements of the feet and toes. In some cases the fingers curl under and clench into a tight fist. In other cases the fingers spread in somewhat the same fashion that the toes may spread. Many persons clasp some object when they approach the point of maximum arousal. This may be the side of a chair, some part of the bed, the bed covers, or some other solid object which is available. It may be the body of the sexual companion. Usually the hands and the fingers move rhythmically. Often the movements become spasmodic as the tensions increase, and then the hand may grab objects with considerable force. The tensions are often so great that the sexual partner who is caught in such a situation may be bruised or cut by the fingernails of the reacting individual.

Abdominal Muscles
During sexual arousal the abdominal muscles may contract with considerable force. The “stomach” is pulled in, sometimes being held in continuous tension, but more often contracting with spasmodic jerks which may rock the whole body. In persons with well trained muscles, such as weight-lifters and dancers, the contractions may be phenomenal in their magnitude and intensity. Sometimes the contractions build up to the very moment of orgasm with increasingly prolonged periods of continuous tension. In other cases, the contractions cease to be spasmodic and become more evenly rhythmic at the approach of orgasm. Sometimes the final contractions are slow, but often they become faster. In a few persons, both female and male, the movements immediately before, during, and after orgasm become so fast that the individual elements are no longer discernible to the human eye. The speed of some of these abdominal movements at the approach of orgasm may approach the most rapid rhythmic movements of which the human body is capable. Such rapid abdominal and pelvic movements regularly occur among many human females and males, and in a number of infra-human mammalian species during coitus.

Thoracic Muscles
Because of the fixed skeleton which lies under the thoracic muscles, their movements during sexual arousal are not as prominent as the muscular movements in some other parts of the body. Nevertheless, the tensions of the muscles on the chest and on the sides often become apparent enough to outline the ribs with a typically washboard effect. That these muscles are tensed during sexual response becomes most apparent when they are relaxed after orgasm. Then the thorax assumes a smoothed-out appearance which it did not have during sexual arousal.

The pectoral muscles, on the chest, may protrude prominently under erotic tension. They become so prominent on some males that they may assume something of the appearance of female breasts. The increased prominence of the female breast during sexual arousal may also depend on some protrusion of the underlying pectorals, as well as upon the increased tumescence of the tissue in the breast itself.

Neck Muscles
In most persons the neck becomes rigid during sexual arousal. The tensions may cause the muscles and the tendons to stand out prominently. Under maximum tensions, at the approach of orgasm, the neck may shift in position, moving the head either forward or backward, but often poising it in a fixed position which is maintained until the tensions are released in orgasm. The prolonged maintenance of such a rigid position may account for some of the “rheumatic neck pains” which an occasional patient takes to the physician for treatment.
During extreme arousal the muscular tensions in the neck become quite prominent, especially in the sternocleidomastoid muscle. This phenomenon was also described by Roubaud 1876:17.

Facial Muscles
Some degree of muscular tension is usually apparent in the face of the person who is reacting sexually, and in some individuals such tensions become extreme at the moment of orgasm. This, combined with the fact that the mouth is open to secure air, may cause the face to take on a drawn, tense, and tortured expression which is paralleled only in the facial expressions of persons who are suffering intense pain and agony.

Eye Muscles
The eyes of sexually aroused persons acquire a distinctive glare, particularly at the moment of orgasm. This glare cannot be mistaken, and is one of the things that the sexual partner may sometimes report; but it is difficult to analyze exactly what is involved. The pupil of the eye becomes dilated. The lids are held in a fixed position, and the eyes stare without being focused. This gives them something of the blankness which is evident in the eye of a blind person. The eyeball appears to protrude and the eye glistens to a greater degree than usual, in part because there is an increased lachrymal secretion. 38 There may be some tumescence of the tissues about the eye. Often, however, the eyelids are kept closed.
Changes in the appearance of the eye during sexual arousal have also been noted by: Anon. 1772: The Virgin's Dream, 143-144 (“My Body was all Pulse, my Breath near gone:/ My Cheeks inflam’d, distorted were my eyes . . .”). Roubaud 1876:17. Talmey 1912:61. Moll 1912:164. Kisch 1926:288, 297. Bauer 1927(1):157. Havelock Ellis 1936(11,1):167. Sadler 1944:43.

Scrotum and Testes
During sexual arousal, and especially at the moment of maximum tension, the testes are usually pulled up by their supporting cremaster muscles. The walls of the scrotum also contract and in many males the testes are pulled tight against the shaft of the penis, against the perineal surfaces, or into the groins. In a few human males in whom the inguinal canals are pathologically open, and among some other species of mammals in which the inguinal canals are normally open, the testes may be pulled high enough to enter the canals or even to enter the abdominal cavity. Tins accounts for the near (or more rarely complete) disappearance of the testes of some human males when they are engaged in sexual activity.
The drawing up of the testes in coitus was noted as long ago as Aristotle [4th cent. B.C.]: Problems, Bk. 4, 879a and Bk. 27, 949a.

Other Structures
Sexual responses obviously involve a great deal more than genital structures. In actuality, every part of the mammalian body may be involved whenever there is sexual response, and many parts of the body may respond as notably as the genitalia during sexual contact. The activities of any of these other parts of the body may be as useful as the genital activities for the identification of the onset of the response, the continuity or discontinuity of the response, the gradual rise in the level of response, the sudden approach of the ultimate peak in orgasm, and the moment of release in orgasm. The progress of the response may be as obvious in the neck tensions, the aspect of the eye, the behavior of the fingers or toes, or the movements of the buttocks or abdominal muscles, as it is in the genitalia themselves.

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