Tensor veli palatini muscle
The tensor veli palatini muscle is a broad, ribbon-like muscle in the head that tenses the soft palate. The tensor veli palatini is found anterior-lateral to the levator veli palatini muscle, it arises by a flat lamella from the scaphoid fossa at the base of the medial pterygoid plate, from the spina angularis of the sphenoid and from the lateral wall of the cartilage of the auditory tube. Descending vertically between the medial pterygoid plate and the medial pterygoid muscle, it ends in a tendon which winds around the pterygoid hamulus, being retained in this situation by some of the fibers of origin of the medial pterygoid muscle. Between the tendon and the hamulus is a small bursa; the tendon passes medially and is inserted into the palatine aponeurosis and into the surface behind the transverse ridge on the horizontal part of the palatine bone. The tensor veli palatini is supplied by the medial pterygoid nerve, a branch of mandibular nerve, the third branch of the trigeminal nerve - the only muscle of the palate not innervated by the pharyngeal plexus, formed by the vagal and glossopharyngeal nerves.
The tensor veli palatini tenses the soft palate and by doing so, assists the levator veli palatini in elevating the palate to occlude and prevent entry of food into the nasopharynx during swallowing. The tensed palate provides a stable platform for elevation of the pharynx during swallowing by the pharyngeal muscles. Since it is attached to the lateral cartilaginous lamina of the auditory tube, it assists in its opening during swallowing or yawning to allow air pressure to equalize between the tympanic cavity and the outside air. Equalization of air pressure in the tympanic cavity is essential for preventing damage to the tympanic membrane and a resulting loss of hearing acuity. Levator veli palatini This article incorporates text in the public domain from page 1139 of the 20th edition of Gray's Anatomy
Superior rectus muscle
The superior rectus muscle is a muscle in the orbit. It is one of the extraocular muscles, it is innervated by the superior division of the oculomotor nerve. In the primary position, the superior rectus muscle's primary function is elevation, although it contributes to intorsion and adduction, it elevates and helps intort the eye. The superior rectus muscle is the only muscle, capable of elevating the eye when it is in a abducted position. Anatomy figure: 29:01-02 at Human Anatomy Online, SUNY Downstate Medical Center "Diagram". Archived from the original on March 25, 2010
Tensor tympani muscle
The tensor tympani is a muscle within the ear, located in the bony canal above the osseous portion of the auditory tube. Its role is to damp thunder; because its reaction time is not fast enough, the muscle cannot protect against hearing damage caused by sudden loud sounds, like explosions or gunshots. The tensor tympani arises from the cartilaginous portion of the auditory tube, the adjoining part of the great wing of the sphenoid, as well as from the osseous canal in which it is contained. Passing backward through the canal, it ends in a slender tendon which enters the tympanic cavity, makes a sharp bend around the extremity of the septum, known as the processus cochleariformis, is inserted into the neck of the malleus, near its root; the tensor tympani is the larger of the two muscles of the tympanic cavity, the other being the stapedius. Innervation of the tensor tympani is from the tensor tympani nerve, a branch of the mandibular division of the trigeminal nerve; as the tensor tympani is innervated by motor fibers of the trigeminal nerve, it does not receive fibers from the trigeminal ganglion, which has sensory fibers only.
The tensor tympani muscle develops from mesodermal tissue in the 1st pharyngeal arch. The tensor tympani acts to dampen the noise produced by chewing; when tensed, the muscle pulls the malleus medially, tensing the tympanic membrane and damping vibration in the ear ossicles and thereby reducing the perceived amplitude of sounds. Contracting muscles produce sound. Slow twitch fibers produce 10 to 30 contractions per second. Fast twitch fibers produce 30 to 70 contractions per second; the vibration can be witnessed and felt by tensing one's muscles, as when making a firm fist. The sound can be heard by pressing a tensed muscle against the ear, again a firm fist is a good example; the sound is described as a rumbling sound. Some individuals can voluntarily produce this rumbling sound by contracting the tensor tympani muscle of the middle ear; the rumbling sound can be heard when the neck or jaw muscles are tensed as when yawning deeply. This phenomenon has been known since 1884; the tympanic reflex helps prevent damage to the inner ear by muffling the transmission of vibrations from the tympanic membrane to the oval window.
The reflex has a response time of 40 milliseconds, not fast enough to protect the ear from sudden loud noises such as an explosion or gunshot. Thus, the reflex most developed to protect early humans from loud thunder claps which do not happen in a split second; the reflex works by contracting the muscles of the tensor tympani and the stapedius. This pulls the manubrium of the malleus tightens it; this tightening prevents the vibrations from disturbing the perilymph. Withdrawal from drugs such as benzodiazepines had been known to cause tonic tensor tympani syndrome during withdrawal; the tympanic reflex will activate when loud vibrations are generated by the person themselves. The tensor tympani can be observed vibrating while shouting at an increased volume, dampening the sound somewhat. In many people with hyperacusis, an increased activity develops in the tensor tympani muscle in the middle ear as part of the startle response to some sounds; this lowered reflex threshold for tensor tympani contraction is activated by the perception/anticipation of loud sound, is called tonic tensor tympani syndrome.
In some people with hyperacusis, the tensor tympani muscle can contract just by thinking about a loud sound. Following exposure to intolerable sounds, this contraction of the tensor tympani muscle tightens the ear drum, which can lead to the symptoms of ear pain/a fluttering sensation/a sensation of fullness in the ear; the mechanisms behind dysfunction of the tympanic tensor muscle and their consequences are hypotheses. However, in a published study, researchers studied the case of an acoustic shock whose mechanisms suggest dysfunction of the tympanic tensor muscle; this study appears to be the first to provide experimental support suggesting that middle ear muscles may behave abnormally after an acoustic shock. It is suggested that abnormal contractions of the tympanic tensor muscle may trigger neurogenic inflammation. Indeed, fibers with substances P and CGRP were found in close proximity. Hearing Middle ear Ossicles Stapedius – the other major muscle in the middle ear Acoustic reflex Hyperacusis This article incorporates text in the public domain from page 1046 of the 20th edition of Gray's Anatomy McGill MadSci Network
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
In human anatomy, the head is at the top of the human body. It is maintained by the skull, which itself encloses the brain; the human head consists of a fleshy outer portion. The brain is enclosed within the skull; the head rests on the neck, the seven cervical vertebrae support it. The human head weighs between 5 and 11 pounds The face is the anterior part of the head, containing the eyes and mouth. On either side of the mouth, the cheeks provide a fleshy border to the oral cavity; the ears sit to either side of the head. The head receives blood supply through the external carotid arteries; these supply the area outside of the inside of the skull. The area inside the skull receives blood supply from the vertebral arteries, which travel up through the cervical vertebrae; the twelve pairs of cranial nerves provide the majority of nervous control to the head. The sensation to the face is provided by the branches of the trigeminal nerve, the fifth cranial nerve. Sensation to other portions of the head is provided by the cervical nerves.
Modern texts are in agreement about which areas of the skin are served by which nerves, but there are minor variations in some of the details. The borders designated by diagrams in the 1918 edition of Gray's Anatomy are similar but not identical to those accepted today; the cutaneous innervation of the head is as follows: Ophthalmic nerve Maxillary nerve Mandibular nerve Cervical plexus Dorsal rami of cervical nerves and others are in picture which show following in upper column The head contains sensory organs: two eyes, two ears, a nose and tongue inside of the mouth. It houses the brain. Together, these organs function as a processing center for the body by relaying sensory information to the brain. Humans can process information faster by having this central nerve cluster. For humans, the front of the head is the main distinguishing feature between different people due to its discernible features, such as eye and hair colors, shapes of the sensory organs, the wrinkles. Humans differentiate between faces because of the brain's predisposition toward facial recognition.
When observing a unfamiliar species, all faces seem nearly identical. Human infants are biologically programmed to recognize subtle differences in anthropomorphic facial features. People who have greater than average intelligence are sometimes depicted in cartoons as having bigger heads as a way of notionally indicating that they have a "larger brain". Additionally, in science fiction, an extraterrestrial having a big head is symbolic of high intelligence. Despite this depiction, advances in neurobiology have shown that the functional diversity of the brain means that a difference in overall brain size is only to moderately correlated to differences in overall intelligence between two humans; the head is a source for many metaphors and metonymies in human language, including referring to things near the human head, things physically similar to the way a head is arranged spatially to a body and things that represent some characteristics associated with the head, such as intelligence. Ancient Greeks had a method for evaluating sexual attractiveness based on the Golden ratio, part of which included measurements of the head.
Headpieces can signify status, religious/spiritual beliefs, social grouping, team affiliation, occupation, or fashion choices. In many cultures, covering the head is seen as a sign of respect; some or all of the head must be covered and veiled when entering holy places or places of prayer. For many centuries, women in Europe, the Middle East, South Asia have covered their hair as a sign of modesty; this trend has changed drastically in Europe in the 20th century, although is still observed in other parts of the world. In addition, a number of religions require men to wear specific head clothing—such as the Islamic Taqiyah, Jewish yarmulke, or the Sikh turban; the same goes for Christian nun's habit. A hat is a head covering. Hats may be worn as part of a uniform or used as a protective device, such as a hard hat, a covering for warmth, or a fashion accessory. Hats can be indicative of social status in some areas of the world. While numerous charts detailing head sizes in infants and children exist, most do not measure average head circumference past the age of 21.
Reference charts for adult head circumference generally feature homogeneous samples and fail to take height and weight into account. One study in the United States estimated the average human head circumference to be 55 centimetres in females and 57 centimetres in males. A British study by Newcastle University showed an average size of 55.2 cm for females and 57.2 cm for males with average size varying proportionally with height Macrocephaly can be an indicator of increased risk for some types of cancer in individuals who carry the genetic mutation that causes Cowden syndrome. For adults, this refers to head sizes greater than 58 centimeters in men or greater than 57 centimeters in women. Human body Head and neck anatomy 8. Human head Campbell, Bernard Grant. Human Evolution: An Introduction to Man's Adaptations, 4th edition
A mnemonic device, or memory device, is any learning technique that aids information retention or retrieval in the human memory. Mnemonics make use of elaborative encoding, retrieval cues, imagery as specific tools to encode any given information in a way that allows for efficient storage and retrieval. Mnemonics aid original information in becoming associated with something more accessible or meaningful—which, in turn, provides better retention of the information. Encountered mnemonics are used for lists and in auditory form, such as short poems, acronyms, or memorable phrases, but mnemonics can be used for other types of information and in visual or kinesthetic forms, their use is based on the observation that the human mind more remembers spatial, surprising, sexual, humorous, or otherwise "relatable" information, rather than more abstract or impersonal forms of information. The word "mnemonic" is derived from the Ancient Greek word μνημονικός, meaning "of memory, or relating to memory" and is related to Mnemosyne, the name of the goddess of memory in Greek mythology.
Both of these words are derived from μνήμη, "remembrance, memory". Mnemonics in antiquity were most considered in the context of what is today known as the art of memory. Ancient Greeks and Romans distinguished between two types of memory: the "natural" memory and the "artificial" memory; the former is inborn, is the one that everyone uses instinctively. The latter in contrast has to be trained and developed through the learning and practice of a variety of mnemonic techniques. Mnemonic systems are strategies consciously used to improve memory, they help use information stored in long-term memory to make memorisation an easier task. The general name of mnemonics, or memoria technica, was the name applied to devices for aiding the memory, to enable the mind to reproduce a unfamiliar idea, a series of dissociated ideas, by connecting it, or them, in some artificial whole, the parts of which are mutually suggestive. Mnemonic devices were much cultivated by Greek sophists and philosophers and are referred to by Plato and Aristotle.
In times the poet Simonides was credited for development of these techniques for no reason other than that the power of his memory was famous. Cicero, who attaches considerable importance to the art, but more to the principle of order as the best help to memory, speaks of Carneades of Athens and Metrodorus of Scepsis as distinguished examples of people who used well-ordered images to aid the memory; the Romans valued. The Greek and the Roman system of mnemonics was founded on the use of mental places and signs or pictures, known as "topical" mnemonics; the most usual method was to choose a large house, of which the apartments, windows, furniture, etc. were each associated with certain names, events or ideas, by means of symbolic pictures. To recall these, an individual had only to search over the apartments of the house until discovering the places where images had been placed by the imagination. In accordance with said system, if it were desired to fix a historic date in memory, it was localised in an imaginary town divided into a certain number of districts, each of with ten houses, each house with ten rooms, each room with a hundred quadrates or memory-places on the floor on the four walls on the roof.
Therefore, if it were desired to fix in the memory the date of the invention of printing, an imaginary book, or some other symbol of printing, would be placed in the thirty-sixth quadrate or memory-place of the fourth room of the first house of the historic district of the town. Except that the rules of mnemonics are referred to by Martianus Capella, nothing further is known regarding the practice until the 13th century. Among the voluminous writings of Roger Bacon is a tractate De arte memorativa. Ramon Llull devoted special attention to mnemonics in connection with his ars generalis; the first important modification of the method of the Romans was that invented by the German poet Konrad Celtes, who, in his Epitoma in utramque Ciceronis rhetoricam cum arte memorativa nova, used letters of the alphabet for associations, rather than places. About the end of the 15th century, Petrus de Ravenna provoked such astonishment in Italy by his mnemonic feats that he was believed by many to be a necromancer.
His Phoenix artis memoriae went through as many as nine editions, the seventh being published at Cologne in 1608. About the end of the 16th century, Lambert Schenkel, who taught mnemonics in France and Germany surprised people with his memory, he was denounced as a sorcerer by the University of Louvain, but in 1593 he published his tractate De memoria at Douai with the sanction of that celebrated theological faculty. The most complete account of his system is given in two works by his pupil Martin Sommer, published in Venice in 1619. In 1618 John Willis published Mnemonica. Giordano Bruno included a memoria technica in his treatise De umbris idearum, as part of his study of the ars generalis of Llull. Other writers of this period are the Florentine Publicius. Porta, Ars reminiscendi. In 1648 Stanislaus Mink von Wennsshein revealed what he called the "most fertile secret" in mnemonics — using consonants for figures, thus expressing numbers by words, i
Pterygoid processes of the sphenoid
The pterygoid processes of the sphenoid, one on either side, descend perpendicularly from the regions where the body and the greater wings of the sphenoid bone unite. Each process consists of a medial pterygoid plate and a lateral pterygoid plate, the latter of which serve as the origins of the medial and lateral pterygoid muscles; the medial pterygoid, along with the masseter allows the jaw to move in a vertical direction as it contracts and relaxes. The lateral pterygoid allows the jaw to move in a horizontal direction during mastication. Fracture of either plate are used in clinical medicine to distinguish the Le Fort fracture classification for high impact injuries to the sphenoid and maxillary bones; the superior portion of the pterygoid processes are fused anteriorly. The plates are separated below by an angular cleft, the pterygoid notch, the margins of which are rough for articulation with the pyramidal process of the palatine bone; the two plates diverge behind and enclose between them a V-shaped fossa, the pterygoid fossa, which contains the medial pterygoid muscle and the tensor veli palatini.
Above this fossa is a small, shallow depression, the scaphoid fossa, which gives origin to the tensor veli palatini. The anterior surface of the pterygoid process is broad and triangular near its root, where it forms the posterior wall of the pterygopalatine fossa and presents the anterior orifice of the pterygoid canal. In many mammals it remains, its name is Greek from its shape. The medial pterygoid plate of the sphenoid bone is a horse-shoe shaped process that arises from its underside, it is narrower and longer than the lateral pterygoid plate and curves lateralward at its lower extremity into a hook-like process, the pterygoid hamulus, around which the tendon of the tensor veli palatini glides. The lateral surface of this plate forms part of the pterygoid fossa, the medial surface constitutes the lateral boundary of the choana or posterior aperture of the corresponding nasal cavity. Superiorly the medial plate is prolonged on to the under surface of the body as a thin lamina, named the vaginal process, which articulates in front with the sphenoidal process of the palatine and behind this with the ala of the vomer.
The angular prominence between the posterior margin of the vaginal process and the medial border of the scaphoid fossa is named the pterygoid tubercle, above this is the posterior opening of the pterygoid canal. On the under surface of the vaginal process is a furrow, converted into a canal by the sphenoidal process of the palatine bone, for the transmission of the pharyngeal branch of the internal maxillary artery and the pharyngeal nerve from the sphenopalatine ganglion; the pharyngeal aponeurosis is attached to the entire length of the posterior edge of the medial plate, the constrictor pharyngis superior takes origin from its lower third. Projecting backward from near the middle of the posterior edge of this plate is an angular process, the processus tubarius, which supports the pharyngeal end of the auditory tube; the anterior margin of the plate articulates with the posterior border of the vertical part of the palatine bone. In many animals it is a separate bone called the pterygoid bone.
The lateral pterygoid plate of the sphenoid is broad and everted and forms the lateral part of a horseshoe like process that extends from the inferior aspect of the sphenoid bone, serves as the origin of the lateral pterygoid muscle, which functions in allowing the mandible to move in a lateral and medial direction, or from side-to-side. Its lateral surface forms part of the medial wall of the infratemporal fossa, gives attachment to the lateral pterygoid muscle. Posterior edge is sharp, has sharp projection - pterygospinous process; this article incorporates text in the public domain from page 151 of the 20th edition of Gray's Anatomy "Anatomy diagram: 34257.000-1". Roche Lexicon - illustrated navigator. Elsevier. Archived from the original on 2014-01-01. Anatomy figure: 22:4b-05 at Human Anatomy Online, SUNY Downstate Medical Center "Anatomy diagram: 25420.000-1". Roche Lexicon - illustrated navigator. Elsevier. Archived from the original on 2014-01-01