What are the biological functions of the tongue?
The tongue serves as the primary organ of taste, participates in mastication (chewing), and aids in the process of swallowing (deglutition).
Besides its biological functions, what other role does the tongue play?
The tongue is involved in the formulation of speech sounds and is responsible for modifying the resonant characteristics of the vocal tract.
What are the two primary parts of the tongue?
The two primary parts of the tongue are the blade and the root.
Where is the blade of the tongue located?
The blade is the visible part of the tongue.
Where is the root of the tongue located?
The root of the tongue is below the blade and cannot be easily seen.
How is the blade of the tongue further divided?
The blade of the tongue is divided into a tip, blade, front, and back.
If the tongue is pressed flat against the ceiling of the oral cavity, where will the tip, blade, front, and back rest?
The tip of the tongue will rest against the anterior teeth, the blade will rest against the alveolar ridge, the front will rest against the hard palate, and the back will rest against the velum (soft palate).
What is the longitudinal median sulcus?
The longitudinal median sulcus is a furrow that runs lengthwise down the center of the tongue.
Where does the longitudinal median sulcus intersect with a chevron-shaped landmark?
The longitudinal median sulcus intersects with the sulcus terminalis approximately two-thirds of the way down the length of the dorsum of the tongue from its tip.
What is the foramen cecum?
The foramen cecum is a small pit located at the point where the longitudinal median sulcus intersects the sulcus terminalis.
What are the three slips of tissue that anchor the base of the tongue to the epiglottis?
The three slips of tissue are the median and lateral glossoepiglottic folds.
What are the small depressions between the median glossoepiglottic fold and each of the lateral glossoepiglottic folds called?
The small depressions are called valleculae.
What gives the surface of the tongue a rough appearance?
The presence of papillae all over the surface of the tongue anterior to the sulcus terminalis gives it a rough appearance.
What are the four types of papillae found on the surface of the tongue?
The four types of papillae are filiform, fungiform, simple, and vallate.
What is the function of the papillae?
The papillae house the taste buds, which are the essential organs for the sense of taste.
How does the posterior one-third of the tongue differ in appearance from the anterior portion?
The posterior one-third of the tongue is smoother in appearance compared to the anterior portion.
What structures are found in the posterior one-third of the tongue?
In the posterior one-third of the tongue, several mucous glands and lymphoid tissue known as the lingual tonsil are found.
What is the lingual frenulum?
The lingual frenulum is a vertically oriented slip of mucous membrane that extends from the inferior surface of the tongue to the floor of the oral cavity.
Where is the lingual frenulum located?
The lingual frenulum is located on the under-surface of the tongue, towards the anterior portion.
What can cause a person to be "tongue tied" in the literal sense?
In some cases, a person may have a lingual frenulum (the membrane connecting the tongue to the floor of the mouth) that is too short, limiting the mobility of the tongue and affecting speech articulation.
How does the mucous membrane on the outer surface of the tongue differ from the mucous membrane on the inferior surface?
The mucous membrane on the outer surface of the tongue is continuous with the covering of all other structures in the oral cavity. On the inferior surface of the tongue, the mucous membrane is relatively thin.
How is the mucous membrane in the region posterior to the sulcus terminalis described?
The mucous membrane in the region posterior to the sulcus terminalis is thick, loose, and freely movable.
How does the mucous membrane anterior to the sulcus terminalis differ from the posterior region?
The mucous membrane anterior to the sulcus terminalis is thin and closely adheres to the underlying muscle tissue.
What is the corium and what role does it play in the tongue?
The corium is a dense and somewhat felt-like connective tissue layer that can be thought of as the "skeleton" of the tongue. It provides structure and support to the tongue.
What are the two types of muscles found in the tongue?
The tongue contains intrinsic muscles, which are entirely housed within the tongue, and extrinsic muscles, which originate outside the tongue but attach to it.
What provides skeletal support for the tongue, apart from the hyoid bone and corium?
The tongue has relatively little skeletal support. Instead, it relies on its ability to change shape and position without reducing its volume.
What is the concept of the tongue acting like a fluid-filled structure called?
The tongue's ability to change shape and position without diminishing its volume is referred to as a muscular hydrostat.
What is a muscular hydrostat?
A muscular hydrostat is a structure, such as the tongue, composed of muscle tissue that can change its shape and position without changing its volume, similar to a fluid-filled structure.
How many muscles rely on the leverage provided by the corium of the tongue?
Eight muscles, consisting of four intrinsic muscles and four extrinsic muscles, rely on the leverage provided by the corium of the tongue.
How do the muscles of the tongue interact with each other?
The muscles of the tongue, aided by the corium, play off each other to effect the various movements the tongue is capable of making.
How does the tongue preserve its volume while changing shape and position?
The tongue's hydrostatic property allows it to preserve its volume. When one area of the tongue undergoes inward displacement, another area experiences outward displacement, maintaining the overall volume of the tongue.
What are some of the movements that the tongue is capable of performing?
The tongue, with its hydrostatic property, can perform a wide range of movements, including bulging, centralizing, curling, flattening, grooving, lateralizing, pointing, protruding, retracting, and moving from side to side, among others.
What are the four intrinsic muscles of the tongue?
The four intrinsic muscles of the tongue are the inferior longitudinal, superior longitudinal, transverse, and vertical muscles.
What is the characteristic feature of the intrinsic muscles of the tongue?
The intrinsic muscles are considered paired due to the presence of a vertically oriented cavity within the tongue called the fibrous midline septum.
How are the fibers of the superior longitudinal muscles and inferior longitudinal muscles distributed within the tongue?
The fibers of the superior longitudinal muscles are primarily confined to the mid-region of the tongue, while the inferior longitudinal muscles can be found more laterally. Both muscles have fibers that course along the length of the tongue.
How are the fibers arranged in the transverse and vertical muscles of the tongue?
The transverse muscle has fibers arranged in the transverse plane, while the vertical muscle has fibers arranged in the vertical plane.
What are the primary functions of the intrinsic muscles of the tongue?
The intrinsic muscles of the tongue are primarily responsible for refined tongue movements and postures, such as elongating, flattening, narrowing, and shortening.
How does the neural innervation and blood supply of the interior of the tongue differ between its two halves?
The two halves of the interior of the tongue receive independent neural innervation and blood supply.
What happens when one half of the tongue is affected by a neurological disorder?
In cases of unilateral paralysis, where one half of the tongue is affected, the unaffected half will still function properly.
What is a clinical sign of unilateral paralysis of the tongue?
A clinical sign of unilateral paralysis of the tongue is the deviation of the tongue to the paralyzed side when the patient is asked to stick out their tongue.
Why does the tongue deviate to the paralyzed side in cases of unilateral paralysis?
When one side of the tongue is paralyzed, the unaffected muscles on the other side will overbalance and mechanically turn the tongue toward the side of least resistance, which is the paralyzed side.
What are the four extrinsic muscles responsible for gross posturing of the tongue?
The four extrinsic muscles responsible for gross posturing of the tongue are the genioglossus, styloglossus, palatoglossus, and hyoglossus.
Which muscle among the extrinsic muscles also functions as a muscle of the velum?
The palatoglossus muscle functions as both a muscle of the tongue and a muscle of the velum.
How are the extrinsic muscles of the tongue named?
The extrinsic muscles of the tongue are named with the term "-glossus" (referring to the tongue) as the second half of their name. The first half of the name refers to the other structure to which the muscle is attached. For example, "genio-" refers to the chin or inside of the mandible, "stylo-" refers to the styloid process, and "palato-" and "hyo-" refer to the palatal and hyoid bone, respectively.
What are the anterior and posterior muscle fibers of the genioglossus responsible for?
The anterior and posterior muscle fibers of the genioglossus contribute to the bulk of the tongue tissue. They play a role in shaping and positioning the tongue.
How does the strength and size of the genioglossus compare to other tongue muscles?
The genioglossus is the largest and strongest of all the tongue muscles.
What is the relationship between the genioglossus and the styloglossus muscles?
The styloglossus muscle acts as an antagonist to the genioglossus, meaning its action is opposite to that of the genioglossus.
What are the functions of the palatoglossus muscle?
The palatoglossus muscle has three functions: (a) pulling the velum down, (b) elevating the posterior portion of the tongue, or (c) performing both actions. The specific action depends on whether the tongue or the velum is anchored or if both structures are free to move.
How do the intrinsic and extrinsic muscles of the tongue work together to allow for intricate posturing and maneuvering?
The hydrostatic interplay between the intrinsic and extrinsic muscles enables intricate posturing and maneuvering of the tongue.
What are the functions of the superior longitudinal, inferior longitudinal, and transverse muscles of the tongue?
The superior longitudinal muscle elevates the tongue tip, while the inferior longitudinal muscle performs the opposite function. The transverse muscle narrows the tongue.
How is tongue protrusion accomplished, and which muscles are involved?
Tongue protrusion is primarily accomplished by the contraction of the posterior fibers of the genioglossus muscle. However, for effective protrusion, the superior longitudinal, inferior longitudinal, and vertical muscles assist by pointing the tongue tip and narrowing the tongue body.
What muscles are involved in retracting the tongue, and how do they contribute?
Retraction of the tongue is primarily achieved by the anterior fibers of the genioglossus muscle. The superior and inferior longitudinal muscles help shorten the tongue during retraction, while the hyoglossus muscle depresses the sides of the tongue.
How would you retract the tongue all the way back into the pharynx, such as during swallowing?
To retract the tongue fully into the pharynx, the styloglossus muscle would be contracted.
How is movement of the tongue from side to side achieved?
Contraction of the superior and inferior longitudinal muscles allows for movement of the tongue from side to side. Simultaneous contraction of these muscles on the right will turn the tongue tip to the right, while contraction on the left will turn the tongue tip to the left.
What muscles are involved in the depression of the body of the tongue?
The genioglossus muscle, located in the medial portion of the tongue, and the hyoglossus muscle, which acts on the lateral edges of the tongue, are responsible for the depression of the body of the tongue.
How is the posterior tongue elevated?
Contraction of the palatoglossus muscle is necessary to elevate the posterior part of the tongue.
What role does the transverse muscle play in tongue elevation?
The transverse muscle assists the palatoglossus by bunching up the back of the tongue, contributing to its elevation.
What muscles are involved in creating a longitudinal groove along the middle of the tongue?
To create a longitudinal groove along the middle of the tongue, you would need to contract the geniohyoid and vertical muscles.
How can you create a shallow groove on the tongue?
Contracting only a part of the geniohyoid muscle would create a shallow groove on the tongue.
What would create a deep groove on the tongue?
Contraction of the entire geniohyoid muscle would create a deep groove on the tongue.
How can the lateral edges of the tongue be relaxed?
Relaxation of the lateral edges of the tongue is achieved by contracting the posterior fibers of the genioglossus muscle, as well as the superior longitudinal and transverse muscles.
What impression do these intricate muscle actions give about the tongue's capabilities?
These intricate muscle actions highlight the tongue's capacity for refined movement and posturing, requiring coordination between the intrinsic and extrinsic tongue muscles.
What is the temporomandibular joint (TMJ)?
The temporomandibular joint (TMJ) is the joint formed by the articulation between the mandible and the temporal bone of the skull.
Can you provide a brief description of the mandible?
The mandible is the lower jawbone and is illustrated in Figure 10-4. It is one of the bones of the skull and has been described in detail in previous sections.
What specific parts of the mandible and temporal bone form the temporomandibular joint (TMJ)?
The temporomandibular joint (TMJ) is formed by the articulation of the condylar process of the mandible with the mandibular fossa of the temporal bone.
What separates the mandibular condyle from the mandibular fossa in the TMJ?
The mandibular condyle is separated from the mandibular fossa by the articular meniscus.
How are the articulating surfaces of the condyle and mandibular fossa protected in the TMJ?
The articulating surfaces of the condyle and mandibular fossa are covered by a fibrocartilage. This is different from typical joint architecture where hyaline cartilage is usually present.
What type of joint is the TMJ classified as?
The TMJ is classified as a ginglymoarthrodial joint, which allows for hinge-like movement with limited gliding.
What ligaments hold the condyle in place within the TMJ?
The condyle is held in place by the temporomandibular (or lateral), sphenomandibular, and stylomandibular ligaments.
What dimensions of movement are possible in the TMJ?
The TMJ allows for movement in three dimensions: vertically (opening and closing), anteroposteriorly (protruding and retracting), and transversely (from side to side). These movements occur during activities such as chewing and speaking.
What is the potential impact of TMJ dysfunction syndrome?
TMJ dysfunction syndrome can severely restrict one's ability to utilize the mandible for chewing or speech purposes.
What are some symptoms of TMJ dysfunction syndrome?
Symptoms of TMJ dysfunction syndrome may include facial pain and spasm, reduced mandibular movement, and noises in the joint.
How can TMJ dysfunction be treated?
Treatment for TMJ dysfunction may include surgery or the use of an orthodontic prosthesis to reduce teeth grinding.
What are the primary movements of the mandible?
The primary movements of the mandible are elevation (closing the mouth) and depression (opening the mouth).
Which muscles are responsible for mandibular elevation?
The mandibular elevator muscles include the masseter, medial pterygoid, and temporalis.
Which muscle is the most powerful of all muscles of mastication?
The masseter is the most powerful muscle of mastication.
What is the action of the temporalis muscle?
The temporalis muscle is quicker in its action and is responsible for snapping movements.
What are the mandibular sling muscles?
The medial pterygoid and masseter muscles are referred to as the mandibular sling muscles because they suspend the mandible in place along with the mandibular ligaments.
Which muscles are responsible for mandibular depression?
The mandibular depressor muscles include the digastricus, mylohyoid, geniohyoid, and lateral pterygoid.