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14.10: Axial Muscles of the Head, Neck, and Back - Biology

14.10: Axial Muscles of the Head, Neck, and Back - Biology


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Learning Objectives

  • Identify the axial muscles of the face, head, and neck
  • Identify the movement and function of the face, head, and neck muscles

The skeletal muscles are divided into axial (muscles of the trunk and head) and appendicular (muscles of the arms and legs) categories. This system reflects the bones of the skeleton system, which are also arranged in this manner. The axial muscles are grouped based on location, function, or both. Some of the axial muscles may seem to blur the boundaries because they cross over to the appendicular skeleton. The first grouping of the axial muscles you will review includes the muscles of the head and neck, then you will review the muscles of the vertebral column, and finally you will review the oblique and rectus muscles.

Muscles That Create Facial Expression

The origins of the muscles of facial expression are on the surface of the skull (remember, the origin of a muscle does not move). The insertions of these muscles have fibers intertwined with connective tissue and the dermis of the skin. Because the muscles insert in the skin rather than on bone, when they contract, the skin moves to create facial expression (Figure 1).

The orbicularis oris is a circular muscle that moves the lips, and the orbicularis oculi is a circular muscle that closes the eye. The occipitofrontalis muscle moves up the scalp and eyebrows. The muscle has a frontal belly and an occipital (near the occipital bone on the posterior part of the skull) belly. In other words, there is a muscle on the forehead (frontalis) and one on the back of the head (occipitalis), but there is no muscle across the top of the head. Instead, the two bellies are connected by a broad tendon called the epicranial aponeurosis, or galea aponeurosis (galea = “apple”). The physicians originally studying human anatomy thought the skull looked like an apple.

The majority of the face is composed of the buccinator muscle, which compresses the cheek. This muscle allows you to whistle, blow, and suck; and it contributes to the action of chewing. There are several small facial muscles, one of which is the corrugator supercilii, which is the prime mover of the eyebrows. Place your finger on your eyebrows at the point of the bridge of the nose. Raise your eyebrows as if you were surprised and lower your eyebrows as if you were frowning. With these movements, you can feel the action of the corrugator supercilli. Additional muscles of facial expression are presented in Table 1.

Table 1. Muscles in Facial Expression
MovementTargetTarget motion directionPrime moverOriginInsertion
Brow
Furrowing browSkin of the scalpAnteriorOccipitofrontalis, frontal bellyEpicraneal aponeurosisUnderneath the skin of the forehead
Unfurrowing browSkin of the scalpPosteriorOccipitofrontalis, occipital bellyOccipital bone; mastoid process (temporal bone)Epicraneal aponeurosis
Lowering eyebrows (e.g., scowling, frowningSkin underneath the eyebrowsInferiorCorrugator superciliiFrontal boneSkin underneath the eyebrow
Nose
Flaring nostrilsNasal cartilage (pushes nostrils open when cartilage is compressed)Inferior compression; posterior compressionNasalisMaxillaNasal bone
Mouth
Raising upper lipUpper lip tissueElevationLevator labii superiorisMaxillaUnderneath skin at the corners of the mouth; orbicularis oris
Lowering lower lipLower lipDepressionDepressor labii inferiorisMandibleUnderneath skin of the lower lip
Opening mouth and sliding lower jaw left and rightLower jawDepression, lateralDepressor angulus orisMandibleUnderneath skin at the corners of the mouth
SmilingCorners of the mouthLateral elevationZygomaticus majorZygomatic boneUnderneath skin at the corners of the mouth (dimple area); orbicularis oris
Shaping of lips (as during speech)LipsMultipleOrbicularis orisTissue surrounding the lipsUnderneath skin at the corners of the mouth
Lateral movement of cheeks (e.g., sucking on a straw; also used to compress air in mouth while blowing)CheeksLateralBuccinatorMaxilla, mandible; sphenoid bone (via pterygomandibular raphae)Orbicularis oris
Pursing of lips by straightening them laterallyCorners of the mouthLateralRisoriusFascia of the parotid salivary glandUnderneath skin at the corners of the mouth
Protrusion of lower lip (e.g, pouting expression)Lower lip and the skin of the chinProtractionMentalisMandibleUnderneath skin of the chin
Raising upper lipUpper lipElevationLevator labii superiorisMaxillaUnderneath skin at the corners of the mouth; orbicularis oris

Muscles That Move the Eyes

The movement of the eyeball is under the control of the extrinsic eye muscles, which originate outside the eye and insert onto the outer surface of the white of the eye. These muscles are located inside the eye socket and cannot be seen on any part of the visible eyeball (Figure 2 and Table 2). If you have ever been to a doctor who held up a finger and asked you to follow it up, down, and to both sides, he or she is checking to make sure your eye muscles are acting in a coordinated pattern.

Table 2. Muscles of the Eyes
MovementTargetTarget motion directionPrime moverOriginInsertion
Moves eyes up and toward nose; rotates eyes from 1 o’clock to 3 o’clockEyeballsSuperior (elevates); medial (adducts)Superior rectusCommon tendinous ring (ring attaches to optic foramen)Superior surface of eyeball
Moves eyes down and toward nose; rotates eyes from 6 o’clock to 3 o’clockEyeballsInferior (depresses) medial (adducts)Inferior rectusCommon tendinous rind (ring attaches to optic foramen)Inferior surface of eyeball
Moves eyes away from noseEyeballsLateral (abducts)Lateral rectusCommon tendinous ring (ring attaches to optic foramen)Lateral surface of eyeball
Moves eyes toward noseEyeballsMedial (adducts)Medial rectusCommon tendinous ring (ring attaches to optic foramen)Medial surface of eyeball
Moves eyes up and away from nose; rotates eyeball from 12 o’clock to 9 o’clockEyeballsSuperior (elevates; lateral (abducts)Inferior obliqueFloor of orbit (maxilla)Surface of eyeball between inferior rectus and lateral rectus
Moves eyes down and away from nose; rotates eyeball from 6 o’clock to 9 o’clockEyeballsSuperior (elevates); lateral (abducts)Superior obliqueSphenoid boneSurface of eyeball between superior rectus and lateral rectus
Opens eyesUpper eyelidSuperior (elevates)Levator palpabrae superiorisRoof of orbit (sphenoid bone)Skin of upper eyelids
Closes eyelidsEyelid skinCompression along superior–inferior axisOrbicularis oculiMedial bones composing the orbitCircumference of orbit

Muscles That Move the Lower Jaw

In anatomical terminology, chewing is called mastication. Muscles involved in chewing must be able to exert enough pressure to bite through and then chew food before it is swallowed (Figure 3 and Table 3). The masseter muscle is the main muscle used for chewing because it elevates the mandible (lower jaw) to close the mouth, and it is assisted by the temporalis muscle, which retracts the mandible. You can feel the temporalis move by putting your fingers to your temple as you chew.

Table 3. Muscles of the Lower Jaw
MovementTargetTarget motion directionPrime moverOriginInsertion
Closes mouth; aids chewingMandibleSuperior (elevates)MasseterMaxilla arch; zygomatic arch (for master)Mandible
Closes mouth; pulls lower jaw in under upper jawMandibleSuperior (elevates); posterior (retracts)TemporalisTemporal boneMandible
Opens mouth; pushes lower jaw out under upper jaw; moves lower jaw side-to-sideMandibleInferior (depresses); posterior (protracts); lateral (abducts); medial (adducts)Lateral pterygoidPterygoid process of sphenoid boneMandible
Closes mouth; pushes lower jaw out under upper jaw; moves lower jaw side-to-sideMandibleSuperior (elevates); posterior (protracts); lateral (abducts); medial (adducts)Medial pterygoidSphenoid bone; maxillaMandible; temporo-mandibular joint

Although the masseter and temporalis are responsible for elevating and closing the jaw to break food into digestible pieces, the medial pterygoi and lateral pterygoid muscles provide assistance in chewing and moving food within the mouth.

Muscles That Move the Tongue

Although the tongue is obviously important for tasting food, it is also necessary for mastication, deglutition (swallowing), and speech (Figure 4 and Table 4). Because it is so moveable, the tongue facilitates complex speech patterns and sounds.

Table 4. Muscles for Tongue Movement, Swallowing, and Speech
MovementTargetTarget motion directionPrime moverOriginInsertion
Tongue
Moves the tongue down; sticks tongue out of the mouthTongueInferior (depresses); anterior (protracts)GenioglossusMandibleTongue undersurface; hyoid bone
Moves tongue up; retracts the tongue back into the mouthTongueSuperior (elevates); posterior (retracts)StyloglossusTemporal bone (styloid process)Tongue undersurface and sides
Flattens tongueTongueInferior (depresses)HyoglossusHyoid boneSides of tongue
Bulges tongueTongueSuperior (elevation)PalatoglossusSoft palateSide of tongue
Swallowing and speaking
Raises the hyoid bone in a way that also raises the larynx, allowing the epiglottis to cover the glottis during deglutition; also assists in opening the mouth by depressing the mandibleHyoid bone; larynxSuperior (elevates)DigastricMandible; temporal boneHyoid bone
Raises and retracts the hyoid bone in a way that elongates the oral cavity during deglutitionHyoid boneSuperior (elevates); posterior (retracts)StylohyoidTemporal bone (styloid process)Hyoid bone
Raises the hyoid bone in a way that presses the tongue against the roof of the mouth, pushing food back into the pharynx during deglutitionHyoid boneSuperior (elevates)MylohyoidMandibleHyoid bone; median raphe
Raises and moves the hyoid bone forward, widening the pharynx during deglutitionHyoid boneSuperior (elevates); anterior (protracts)GeniohyoidMandibleHyoid bone
Retracts the hyoid bone and moves it down during later phases of deglutitionHyoid boneInferior (depresses); posterior (retracts)OmohyoidScapulaHyoid bone
Depresses the hyoid bone during swallowing and speakingHyoid boneInferior (depresses)SternohyoidClavicleHyoid bone
Shrinks distance between thyroid cartilage and the hyoid bone, allowing production of high-pitch vocalizationsHyoid bone; thyroid cartilageHyoid bone: inferior (depresses); thyroid cartilage: superior (elevates)ThyrohyoidThyroid cartilageHyoid bone
Depresses larynx, thyroid cartilage, and hyoid bone to create different vocal tonesLarynx; thyroid cartilage; hyoid boneInferior (depresses)SternothyroidSternumThyroid cartilage
Rotates and tilts head to the side and forwardSkull; cervical vertebraeIndividually: medial rotation; lateral flexion; bilaterally; anterior (flexes)Sternocleidomastoid; semispinalis capitisSternum; clavicleTemporal bone (mastoid process); occipital bone
Rotates and tilts the head to the side and backwardsSkull; cervical vertebraeIndividually: lateral rotation; lateral flexion; bilaterally: anterior (flexes)Splenius capitis; longissimus capitisSternum; clavicleTemporal bone (mastoid process); occipital bone

Tongue muscles can be extrinsic or intrinsic. Extrinsic tongue muscles insert into the tongue from outside origins, and the intrinsic tongue muscles insert into the tongue from origins within it. The extrinsic muscles move the whole tongue in different directions, whereas the intrinsic muscles allow the tongue to change its shape (such as, curling the tongue in a loop or flattening it).

The extrinsic muscles all include the word root glossus (glossus = “tongue”), and the muscle names are derived from where the muscle originates. The genioglossus (genio = “chin”) originates on the mandible and allows the tongue to move downward and forward. The styloglossus originates on the styloid bone, and allows upward and backward motion. The palatoglossus originates on the soft palate to elevate the back of the tongue, and the hyoglossus originates on the hyoid bone to move the tongue downward and flatten it.

Try It

Before surgery, a patient must be made ready for general anesthesia. The normal homeostatic controls of the body are put “on hold” so that the patient can be prepped for surgery. Control of respiration must be switched from the patient’s homeostatic control to the control of the anesthesiologist. The drugs used for anesthesia relax a majority of the body’s muscles.

Among the muscles affected during general anesthesia are those that are necessary for breathing and moving the tongue. Under anesthesia, the tongue can relax and partially or fully block the airway, and the muscles of respiration may not move the diaphragm or chest wall. To avoid possible complications, the safest procedure to use on a patient is called endotracheal intubation. Placing a tube into the trachea allows the doctors to maintain a patient’s (open) airway to the lungs and seal the airway off from the oropharynx. Post-surgery, the anesthesiologist gradually changes the mixture of the gases that keep the patient unconscious, and when the muscles of respiration begin to function, the tube is removed. It still takes about 30 minutes for a patient to wake up, and for breathing muscles to regain control of respiration. After surgery, most people have a sore or scratchy throat for a few days.

Muscles of the Anterior Neck

The muscles of the anterior neck assist in deglutition (swallowing) and speech by controlling the positions of the larynx (voice box), and the hyoid bone, a horseshoe-shaped bone that functions as a solid foundation on which the tongue can move. The muscles of the neck are categorized according to their position relative to the hyoid bone (Figure 5). Suprahyoid muscles are superior to it, and the infrahyoid muscles are located inferiorly.

The suprahyoid muscles raise the hyoid bone, the floor of the mouth, and the larynx during deglutition. These include the digastric muscle, which has anterior and posterior bellies that work to elevate the hyoid bone and larynx when one swallows; it also depresses the mandible. The stylohyoid muscle moves the hyoid bone posteriorly, elevating the larynx, and the mylohyoid muscle lifts it and helps press the tongue to the top of the mouth. The geniohyoid depresses the mandible in addition to raising and pulling the hyoid bone anteriorly.

The strap-like infrahyoid muscles generally depress the hyoid bone and control the position of the larynx. The omohyoid muscle, which has superior and inferior bellies, depresses the hyoid bone in conjunction with the sternohyoid and thyrohyoid muscles. The thyrohyoid muscle also elevates the larynx’s thyroid cartilage, whereas the sternothyroid depresses it to create different tones of voice.

Muscles That Move the Head

The head, attached to the top of the vertebral column, is balanced, moved, and rotated by the neck muscles (Table 5). When these muscles act unilaterally, the head rotates. When they contract bilaterally, the head flexes or extends. The major muscle that laterally flexes and rotates the head is the sternocleidomastoid. In addition, both muscles working together are the flexors of the head. Place your fingers on both sides of the neck and turn your head to the left and to the right. You will feel the movement originate there. This muscle divides the neck into anterior and posterior triangles when viewed from the side (Figure 6).

Table 5. Muscles That Move the Head
MovementTargetTarget motion directionPrime moverOriginInsertion
Rotates and tilts head to the side; tilts head forwardSkull; vertebraeIndividually: rotates head to opposite side; bilaterally: flexionSternocleidomastoidSternum; clavicleTemporal bone (mastoid process); occipital bone
Rotates and tilts head backwardSkull; vertebraeIndividually: laterally flexes and rotates head to same side; bilaterally: extensionSemispinalis capitisTransverse and articular processes of cervical and thoracic vertebraOccipital bone
Rotates and tilts head to the side; tilts head backwardSkull; vertebraeIndividually: laterally flexes and rotates head to same side; bilaterally: extensionSplenius capitisSpinous processes of cervical and thoracic vertebraTemporal bone (mastoid process); occipital bone
Rotates and tilts head to the side; tilts head backwardSkull; vertebraeIndividually: laterally flexes and rotates head to same side; bilaterally: extensionLongissimus capitisTransverse and articular processes of cervical and thoracic vertebraTemporal bone (mastoid process)

Muscles of the Posterior Neck and the Back

The posterior muscles of the neck are primarily concerned with head movements, like extension. The back muscles stabilize and move the vertebral column, and are grouped according to the lengths and direction of the fascicles.

The splenius muscles originate at the midline and run laterally and superiorly to their insertions. From the sides and the back of the neck, the splenius capitis inserts onto the head region, and the splenius cervicis extends onto the cervical region. These muscles can extend the head, laterally flex it, and rotate it (Figure 7).

The erector spinae group forms the majority of the muscle mass of the back and it is the primary extensor of the vertebral column. It controls flexion, lateral flexion, and rotation of the vertebral column, and maintains the lumbar curve. The erector spinae comprises the iliocostalis (laterally placed) group, the longissimus (intermediately placed) group, and the spinalis (medially placed) group.

The iliocostalis group includes the iliocostalis cervicis, associated with the cervical region; the iliocostalis thoracis, associated with the thoracic region; and the iliocostalis lumborum, associated with the lumbar region. The three muscles of the longissimus group are the longissimus capitis, associated with the head region; the longissimus cervicis, associated with the cervical region; and the longissimus thoracis, associated with the thoracic region. The third group, the spinalis group, comprises the spinalis capitis (head region), the spinalis cervicis (cervical region), and the spinalis thoracis (thoracic region).

The transversospinales muscles run from the transverse processes to the spinous processes of the vertebrae. Similar to the erector spinae muscles, the semispinalis muscles in this group are named for the areas of the body with which they are associated. The semispinalis muscles include the semispinalis capitis, the semispinalis cervicis, and the semispinalis thoracis. The multifidus muscle of the lumbar region helps extend and laterally flex the vertebral column.

Important in the stabilization of the vertebral column is the segmental muscle group, which includes the interspinales and intertransversarii muscles. These muscles bring together the spinous and transverse processes of each consecutive vertebra. Finally, the scalene muscles work together to flex, laterally flex, and rotate the head. They also contribute to deep inhalation. The scalene muscles include the anterior scalene muscle (anterior to the middle scalene), the middle scalene muscle (the longest, intermediate between the anterior and posterior scalenes), and the posterior scalene muscle (the smallest, posterior to the middle scalene).


BIO 140 - Human Biology I - Textbook

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Chapter 40

Divisions of the Skeletal System

  • Discuss the functions of the skeletal system
  • Distinguish between the axial skeleton and appendicular skeleton
  • Define the axial skeleton and its components
  • Define the appendicular skeleton and its components

The skeletal system includes all of the bones, cartilages, and ligaments of the body that support and give shape to the body and body structures. The skeleton consists of the bones of the body. For adults, there are 206 bones in the skeleton. Younger individuals have higher numbers of bones because some bones fuse together during childhood and adolescence to form an adult bone. The primary functions of the skeleton are to provide a rigid, internal structure that can support the weight of the body against the force of gravity, and to provide a structure upon which muscles can act to produce movements of the body. The lower portion of the skeleton is specialized for stability during walking or running. In contrast, the upper skeleton has greater mobility and ranges of motion, features that allow you to lift and carry objects or turn your head and trunk.

In addition to providing for support and movements of the body, the skeleton has protective and storage functions. It protects the internal organs, including the brain, spinal cord, heart, lungs, and pelvic organs. The bones of the skeleton serve as the primary storage site for important minerals such as calcium and phosphate. The bone marrow found within bones stores fat and houses the blood-cell producing tissue of the body.

The skeleton is subdivided into two major divisions&mdashthe axial and appendicular.

The Axial Skeleton

The skeleton is subdivided into two major divisions&mdashthe axial and appendicular. The axial skeleton forms the vertical, central axis of the body and includes all bones of the head, neck, chest, and back (Figure 1). It serves to protect the brain, spinal cord, heart, and lungs. It also serves as the attachment site for muscles that move the head, neck, and back, and for muscles that act across the shoulder and hip joints to move their corresponding limbs.

The axial skeleton of the adult consists of 80 bones, including the skull , the vertebral column , and the thoracic cage . The skull is formed by 22 bones. Also associated with the head are an additional seven bones, including the hyoid bone and the ear ossicles (three small bones found in each middle ear). The vertebral column consists of 24 bones, each called a vertebra , plus the sacrum and coccyx . The thoracic cage includes the 12 pairs of ribs , and the sternum , the flattened bone of the anterior chest.

Figure 1: The axial skeleton supports the head, neck, back, and chest and thus forms the vertical axis of the body. It consists of the skull, vertebral column (including the sacrum and coccyx), and the thoracic cage, formed by the ribs and sternum. The appendicular skeleton is made up of all bones of the upper and lower limbs.

The Appendicular Skeleton

The appendicular skeleton includes all bones of the upper and lower limbs, plus the bones that attach each limb to the axial skeleton. There are 126 bones in the appendicular skeleton of an adult. The bones of the appendicular skeleton are covered in a separate chapter.

Chapter Review

The skeletal system includes all of the bones, cartilages, and ligaments of the body. It serves to support the body, protect the brain and other internal organs, and provides a rigid structure upon which muscles can pull to generate body movements. It also stores fat and the tissue responsible for the production of blood cells. The skeleton is subdivided into two parts. The axial skeleton forms a vertical axis that includes the head, neck, back, and chest. It has 80 bones and consists of the skull, vertebral column, and thoracic cage. The adult vertebral column consists of 24 vertebrae plus the sacrum and coccyx. The thoracic cage is formed by 12 pairs of ribs and the sternum. The appendicular skeleton consists of 126 bones in the adult and includes all of the bones of the upper and lower limbs plus the bones that anchor each limb to the axial skeleton.


Skull

The skull is a strong, bony capsule that rests on the neck and encloses the brain. It consists of two major parts: the neurocranium (cranial vault) and the viscerocranium (facial skeleton). The neurocranium is the part enveloping the brain and is formed out of two parts the skull base that supports the brain and the calvaria (skullcap) that sits on top of the base, covering the brain. The viscerocranium supports mainly the facial muscles and a variety of anatomical structures.

As you can see from the above skull diagram, there are quite a lot of skull bones. In fact, there are twenty three in total, some of which are paired:

Want an easy method to remember these bones? Flashcards are your friends! Find out why, and how you can make your own.

To make the skull an enclosed and resilient structure, those bones are connected together via joints called sutures. There are quite a few skull sutures in total, each one named according to the bones that form it. The most important ones are the coronal, sagittal, squamous, lambdoid, and palatine sutures, together with the lambda, bregma, and pterion landmarks.

Check the following study unit to learn more about the bones of the skull and how they fit together.


Case report

History

A 37-year-old, right handed mother of two preschool-aged children presented with complaints of posterior and lateral neck pain, occasional facial numbness, and tingling sensation over her left cheek, forehead, tip of her chin and left ear. These facial sensations were often accompanied by a sensation of dizziness, throat pain upon swallowing, jerking of left eyelid, and excessive lacrimation on the same side. She described these symptoms as intermittent, lasting from minutes to a few hours at a time, with a frequency of three to twelve episodes per week. There was no previous history of such symptoms, nor any other muscular or skeletal conditions. The patient appeared to be within healthy weight parameters, and had experienced no recent, unusual weight gain or loss. She had had no history of accident or blunt force impact that could be linked with the onset of symptoms.

The patient stated that her symptoms began more than three months before, during a time when her youngest child was ill and she spent long periods carrying him with her left arm while performing tasks with her right. She also often slept with her toddler in her arms. She reported that her symptoms had been gradually worsening during the course of the previous two months. The patient initially consulted her family physician in order to rule out possible pathological or systemic causes. A series of blood and urine tests were performed which reportedly all proved to be within normal limits. She was then referred to a neurologist. An MRI of her brain and cervical spine was performed and the results were also unremarkable. She was then referred to a dizziness clinic for evaluation and no specific cause for her dizziness was discovered. The patient sought chiropractic care in our office at that point, since no traditional, allopathic treatments had been offered to her.

Examination

Postural evaluation demonstrated decreased cervical lordosis, anterior head carriage, and bilateral protracted and rounded shoulders. Cervical ranges of motion indicated reduced flexion, with right and left rotation decreased by 20%. While other ranges of motion were within normal ranges, all such tests resulted in some degree of discomfort. Neurological evaluation of both upper and lower extremities was unremarkable. Deep tendon reflexes were 2+ and symmetric. Sensory response to pin prick and gentle touch tests was unremarkable. Muscle strength tests were 5/5 and symmetric throughout.

Evaluation of the cervical spine revealed moderate myofascial pain in the para-vertebral musculature. Deep tissue palpation of the upper trapezius muscle bilaterally indicated presence of multiple trigger points, which referred pain to the sub-occipital area when provoked. Palpation of the left SCM muscle also indicated the presence of myofascial trigger points, which created a significant proportion of the patient’s facial pain when provoked. Palpation of left pectoralis- and levator scapular muscles also revealed the presence of trigger points.

Evaluation of the patient’s respiration demonstrated a faulty breathing pattern, involving over-utilization of the scalene and SCM muscles. 7 Motion palpation end range provocative testing revealed the presence of painful inter-segmental joint dysfunction at right C0�, left C2�, C5� and T4 levels. 8 A cervical Davis series was requested by the patient's physician. The cervical x-rays demonstrated moderate degenerative changes at C5� levels. No hyper-mobility was detected at any level, and the x-rays were otherwise unremarkable.

Head and neck flexion coordination tests revealed chin juts, meaning an altered neck flexion pattern – possibly due to weak neck flexors and overactive sub-occipitals and SCM. 9 – 11 Sit-to-stand test was performed, with the patient showing a faulty movement pattern by leading the move with her chin. This test is crucial in distinguishing an over active SCM verses an SCM with trigger points. This test can assist in determining if the injury is recent verses long established faulty patterns. It can also allow the practitioner to observe the SCM muscle in a dynamic setting rather than simply testing for trigger points. 12

Muscle strength- and length tests of the pectoralis, levator scapula, upper trapezious, SCM, and suboccipitals demonstrated muscle hypertonicity. SCM muscle length test resulted in partial facial numbness.

Stepping test was performed to assess the functional integrity of tonic neck muscle reflexes which can have an impact on the function of the entire locomotor system. 8 This test is conducted by standing the patient with eyes closed and arms outstretched, horizontal to the floor and parallel to each other. The patient is instructed to step alternately as if marching, alternately raising the knees to 45 degrees. Typically after 50 steps the patient should have rotated no more than 30 degrees. This particular patient, however, was rotated by 130 degrees. One leg standing test was also performed. The patient was able to stand on one foot an average of 20 seconds with eyes open and 5 seconds with her eyes closed. Normal results for someone her age would be a minimum of 30 seconds with eyes open and 21 seconds with eyes closed. 13 , 14

Treatment

The result of the examination showed that the patient had developed multiple cervical and thoracic subluxations, poor proprioceptive sense of balance and altered neck flexion due to tightness in the SCM-, upper trapezius-, levator scapula- and pectoralis muscles, as well as weakness in deep neck flexors, lower and middle trapezius-, and serratus anterior muscles. The goals of treatment were to stretch and relax the tight muscles, strengthen the weak muscles, restore the motion of restricted spinal segments, and re-educate the sensory motor system through proprioceptive exercises. These multiple goals were pursued through a program of successive passive and active treatments.

Passive care (3x / week for 2 weeks)

The patient received passive care three times per week for the first two weeks. The treatment included diversified manipulative therapy of the affected joints trigger point therapy (ischemic compression) of SCM and upper trapezius muscles passive stretch of SCM, pectoralis, scalenes, suboccipitals, and upper trapezius muscles and post isometric relaxation (PIR) of the SCM muscle. 15 , 16

The SCM stretch was an essential part of the each treatment, with the patient placed in a supine position with her shoulders at the edge of the table, her head held at the base of occiput, rotated away from the affected side, laterally flexed toward the affected side, extended at the lower cervical and flexed at the upper cervical (chin tuck with neck extension). This stretch was held from five to forty-five seconds, dependant on patient tolerance. PIR was accomplished by instructing the patient to actively raise her head slightly when it was rotated. This effort was resisted by the practitioner to allow for an isometric muscle contraction. The SCM muscle was then stretched in the same fashion as before. 10

Postural advice was provided during the course of passive care to prevent further aggravation of the region. The patient was instructed on exercises to carry out at home three to five times a day. These involved standing with her buttocks and shoulder blades gently against a wall, then slowly retracting her head backward until her skull touched the wall. This position would be maintained for thirty seconds. The goal of this exercise is to make the patient aware of their posture and over time to develop better postural habits.

Phase I Rehabilitation (3x / week for 4 weeks)

The second phase of treatment started in week three with the addition of a rehabilitation component to the passive care described above. This phase was performed at a frequency of three times per week, and lasted for four weeks. The patient was re-evaluated once every two weeks so appropriate modifications to the exercises could be implemented.

Initially the patient was trained on proper self stretch of the upper trapezius-, pectoralis major and minor-, sub-occipitals, levator scapula- and SCM muscles. She was then instructed on a number of exercises designed to facilitate the lower-, middle trapezious and deep neck flexors. The muscle facilitation was accomplished through specific exercises, such as the following:

Wall angels (shoulders abducted, elbows flexed, gradually brought back to sides, while retracting scapula)

Bruegger exercise (sit at the edge of chair, anterior pelvic tilt, chin tuck, hands turned outward, thumbs up pointing upward and behind shoulders, fingers wide apart)

Dead bug (supine, knees and hips bent, spine in neutral position, maintain abdominal bracing as arms and legs are moved back and forth)

Quadruped (on hands and knees, spine in neutral position, abdominal bracing, head neutral position, arms and legs raised)

Upper back cat (on hands and knees, chin tuck, move buttocks toward ceiling). 7 , 10

Proprioceptive exercises play an important role in retraining primary stabilizers of the spine and reprogramming subcortical connections to improve balance. 14 Both rocker and wobble boards were used for proprioceptive training with eyes open for the first week and eyes closed for the second and third week. 14 Isometric neck exercises were conducted during the first week using a medium size ball against the wall to strengthen weak neck flexors, extensors, rotators and in lateral bending. During week three the ball was replaced with surgical tubing which would allow full neck ranges of motion with resistance. 11

Phase II Rehabilitation (3x / week for 8 weeks)

In this stage the passive treatments such as manipulation and trigger point therapy were performed only when indicated. Previous exercise programs were continued with increased intensity and free weights were introduced to continue to strengthen the lower and middle traps. This was accomplished using the Zinovieff technique for one arm rows, seated rows, shoulder shrugs, shoulder press and upright row and latismus dorsi pull downs. The Zinovieff technique is a good beginner protocol, made of three sets of ten repetitions with one minute interval rests in between, three times per week. 11 The first set is at 10 repetitions maximum (RM), second set 75% of 10 RM and the third set at 50% of 10 RM.

The patient was also trained on proper breathing techniques. Diaphragm breathing inhibits the involvement of overactive accessory breathing muscles and keeps their activity to a minimum during rest. 8 Accessory breathing muscles are designed to assist breathing only during exertion to further expand the ribs but should remain primarily silent at rest. 8

Once the second phase of rehabilitation was completed, the patient reported experiencing relief from over 80% of her original symptoms. It was clear that the patient's physical and emotional challenges as a mother of two young children could be expected to continue to test her physical limits. Therefore, the importance of a continued self directed exercise program, coupled with occasional supportive care at our office (so as to prevent deterioration of her physical condition to a critical level once again) was discussed. The patient was open to the idea, and appeared determined to follow through with her exercises and an occasional visit to our office to monitor her progress.


Muscles

Muscles allow for movement such as walking, and they also facilitate bodily processes such as respiration and digestion. The body contains three types of muscle tissue: skeletal muscle, cardiac muscle, and smooth muscle (Figure 3).

Figure 3. The body contains three types of muscle tissue: skeletal muscle, smooth muscle, and cardiac muscle. Notice that skeletal muscle cells are long and cylindrical, they have multiple nuclei, and the small, dark nuclei are pushed to the periphery of the cell. Smooth muscle cells are short, tapered at each end, and have only one nucleus each. Cardiac muscle cells are also cylindrical, but short. The cytoplasm may branch, and they have one or two nuclei in the center of the cell. (credit: modification of work by NCI, NIH scale-bar data from Matt Russell)

Skeletal muscle tissue forms skeletal muscles, which attach to bones and sometimes the skin and control locomotion and any other movement that can be consciously controlled. Because it can be controlled intentionally, skeletal muscle is also called voluntary muscle. When viewed under a microscope, skeletal muscle tissue has a striped or striated appearance. This appearance results from the arrangement of the proteins inside the cell that are responsible for contraction. The cells of skeletal muscle are long and tapered and have multiple nuclei on the periphery of each cell.

Smooth muscle tissue occurs in the walls of hollow organs such as the intestines, stomach, and urinary bladder, and around passages such as in the respiratory tract and blood vessels. Smooth muscle has no striations, is not under voluntary control, and is called involuntary muscle. Smooth muscle cells have a single nucleus.

Cardiac muscle tissue is only found in the heart. The contractions of cardiac muscle tissue pump blood throughout the body and maintain blood pressure. Like skeletal muscle, cardiac muscle is striated, but unlike skeletal muscle, cardiac muscle cannot be consciously controlled and is called involuntary muscle. The cells of cardiac muscle tissue are connected to each other through intercalated disks and usually have just one nucleus per cell.


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Anatomical position and directional terms

The healthcare industry has its own terminology, especially anatomy and physiology. In order to provide exquisite care and understand the inner workings of the human body, anatomical terminology is a necessity. We’ll begin by going over “anatomical position and directional terms”.

In order to describe body parts and positions correctly, the medical community has developed a set of anatomical positions and directional terms widely used in the healthcare industry. The anatomical reference point is a standard body position called the anatomical position. In the anatomical position, the body is erect, the palms of the hand face forward, the thumbs point away from the body, and the feet are slightly apart. It’s important to understand the anatomical position because most directional terms are based off it.

Orientation and directional terms

  • Superior (cranial)– toward the head or upper part of the body above
  • Inferior (caudal)– away from the head or toward the lower part of the body below
  • Ventral (anterior)– toward or at the front of the body in front of
  • Dorsal (posterior)– toward or at the back of the body behind
  • Medial– toward or at the midline of the body
  • Lateral– away from the midline of the body
  • Intermediate– between a medial and lateral position
  • Proximal– closer to the origin of the body part or point of attachment of a limb to the body trunk
  • Distal– away from the origin of a body part or point of attachment of a limb to the body trunk
  • Superficial (external)– toward or at the body surface
  • Deep (internal)– Away from the body surface

Directional terms allow us to explain where one body part is when compared to another.

Regional Terms
The two main divisions of the body are its axial and appendicular parts. The axial part makes up the main axis of the body and includes the head, neck, and trunk. The appendicular part consists of the limbs (appendages) attached to the body’s axis. View the image above for an in depth look into all the regional terms used to designate specific areas within the human body . You will have to know them!

For anatomical purposes, the body is often sectioned into flat surfaces called planes. Thost frequently used body planes are the sagittal, transverse, and frontal planes. The image above shows how the body is cut into corresponding planes.


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ISBN10: 1260791505 | ISBN13: 9781260791501

The estimated amount of time this product will be on the market is based on a number of factors, including faculty input to instructional design and the prior revision cycle and updates to academic research-which typically results in a revision cycle ranging from every two to four years for this product. Pricing subject to change at any time.

The estimated amount of time this product will be on the market is based on a number of factors, including faculty input to instructional design and the prior revision cycle and updates to academic research-which typically results in a revision cycle ranging from every two to four years for this product. Pricing subject to change at any time.

Program Details

LABORATORY EXERCISES
1 Introduction to Lab Science, Measurement, and Chemistry
2 Organs, Systems, and Organization of the Body
3 Microscopy
4 Cell Structure and Function
5 Tissues
6 Integumentary System
7 Introduction to the Skeletal System
8 Axial Skeleton
9 Appendicular Skeleton
10 Joints
11 Axial Muscles 1: Muscles of the Head and Neck
12 Axial Muscles 2: Muscles of the Trunk
13 Appendicular Muscles 1: Muscles of the Upper Limb
14 Appendicular Muscles 2: Muscles of the Lower Limb
15 Muscle Physiology
16 Nervous Tissue, the Spinal Cord, and Spinal Nerves
17 The Brain and Cranial Nerves
18 Nervous System Physiology—Stimuli and Reflexes
19 Cutaneous Senses
20 Taste and Smell
21 Eye and Vision
22 Ear, Hearing, and Equilibrium
23 Endocrine System
24 Blood
25 Blood Tests and Typing
26 Anatomy of the Heart
27 Electrical Conductivity of the Heart
28 Functions of the Heart
29 Blood Vessels 1: Introduction to Blood Vessels and Blood Vessels of the Axial Region
30 Blood Vessels 2: Vessels of the Appendicular Region
31 Lymphatic System
32 Blood Vessels and Blood Pressure
33 Anatomy of the Respiratory System
34 Respiratory Physiology
35 Physiology of Exercise and Pulmonary Health
36 Urinary System
37 Urinalysis
38 Anatomy of the Digestive System
39 Digestive Physiology
40 Male Reproductive System
41 Female Reproductive System and Early Development


Bones Edit

The head rests on the top part of the vertebral column, with the skull joining at C1 (the first cervical vertebra known as the atlas). The skeletal section of the head and neck forms the top part of the axial skeleton and is made up of the skull, hyoid bone, auditory ossicles, and cervical spine.

The skull can be further subdivided into:

  1. the cranium (8 bones: frontal, 2-parietal, occipital, 2-temporal, sphenoid, ethmoid), and
  2. the facial bones (14 bones: 2-zygomatic, 2-maxillary, 2-palatine, 2-nasal, 2-lacrimal, vomer, 2-inferior conchae, mandible).

The occipital bone joins with the atlas near the foramen magnum, a large hole (foramen) at the base of the skull. The atlas joins with the occipital condyle above and the axis below. The spinal cord passes through the foramen magnum.

Muscles Edit

Group Name Nerve Function
facial expression Epicranius: Frontalis and Occipitalis facial nerve eyebrows and scalp
facial expression Orbicularis oris facial nerve closes lips
facial expression Zygomaticus major facial nerve smiling
facial expression Zygomaticus minor facial nerve smiling
facial expression Levator labii superioris facial nerve upper lip
facial expression Levator labii superioris alaeque nasi facial nerve upper lip
facial expression Depressor labii inferioris facial nerve lower lip
facial expression Depressor anguli oris facial nerve frowning
facial expression Platysma facial nerve frowning (during fear or shock)
facial expression Buccinator facial nerve cheeks
facial expression Mentalis facial nerve chin
facial expression Platysma facial nerve frowning
facial expression Risorius facial nerve mouth angle
facial expression Orbicularis oculi facial nerve closes eye
facial expression Nasalis facial nerve flare nostrils
facial expression Corrugator supercilli facial nerve eyebrow
facial expression Levator palpebrae superioris oculomotor nerve upper eyelid
chewing – lower mandible Masseter Trigeminal nerve closing and protruding mandible,
chewing – lower mandible Temporalis Trigeminal nerve elevates and controls side to side movement of mandible
chewing – lower mandible Medial pterygoid Trigeminal nerve elevates mandible,
chewing – lower mandible Lateral pterygoid Trigeminal nerve protracts mandible, opens mouth.
tongue – extrinsic Genioglossus hypoglossal nerve protraction,
tongue – extrinsic Styloglossus hypoglossal nerve elevation and retraction,
tongue – extrinsic Hyoglossus hypoglossal nerve depresses tongue
tongue – extrinsic Palatoglossus Pharyngeal plexus, pharyngeal branch of vagus nerve elevates tongue while swallowing
oral cavity floor Digastric Trigeminal nerve and Facial nerve hyoid and mandible movement
oral cavity floor Stylohyoid Facial nerve elevates hyoid
oral cavity floor Mylohyoid Trigeminal nerve hyoid and mandible movement
oral cavity floor Geniohyoid Cervical nerve C-1 hyoid, tongue, and mandible movement
move head Sternocleidomastoid Accessory nerve nodding and turning
move head Semispinalis dorsal rami of cervical nerves extends head, supports turning
move head Splenius capitis dorsal rami of middle and lower cervical nerves extend head, supports turning
move head Longissimus capitis dorsal rami of middle and lower cervical nerves extends head, supports turning
move head Rectus capitis posterior major Suboccipital nerve C-1 extends head
move head Rectus capitis posterior minor Suboccipital nerve C-1 extends head

Skin Edit

The head and neck is covered in skin and its appendages, termed the integumentary system. These include hair, sweat glands, sebaceous glands, and sensory nerves. The skin is made up of three microscopic layers: epidermis, dermis, and hypodermis. The epidermis is composed of stratified squamous epithelium and is divided into the following five sublayers or strata, listed in order from outer to inner:

    , , , , also called stratum basale. The deepest layer is the miotic layer, stratum basale producing daughter cells by mitosis.

Mouth Edit

The mouth, also called the oral cavity, is the entranceway into the digestive system containing both primary and accessory organs of digestion.

Teeth Edit

Two rows of teeth are supported by facial bones of the skull, the maxilla above and the mandible below. Adults have 32 permanent teeth, and children have 20 deciduous teeth. There are various tooth shapes for different jobs. For example, when chewing, the upper teeth work together with the lower teeth of the same shape to bite, chew, and tear food. The names of these teeth are:

  • (1) Incisors, there are eight incisors located in the front of the mouth (four on the top and four on the bottom). They have sharp, chisel-shaped crowns that cut food.
  • (2) Cuspids (or canine tooth), the four cuspids are next to each incisor. Cuspids have a pointed edge to tear food.
  • (3) Premolars (or bicuspids), the four pairs of molars are located next to the cuspids. They crush and tear food.
  • (4) Molars, there are twelve molars, in sets of three, at the back of the mouth. They have wide surfaces that help to grind food.

The white visible part of a tooth is called the crown. The rounded upper projections of the back teeth are cusps. The hard white exterior covering of the tooth is the enamel. As the tooth tapers below the gumline, the neck is formed. Below the neck, holding the tooth into the bone, is the root of the tooth. The inner portions of the tooth consist of the dentin, a bonelike tissue, and the pulp. The pulp is a soft tissue area containing the nerve and blood vessels to nourish and protect the tooth, located within the pulp cavity.

A tooth sits in a specialized socket called the alveolus. The tooth is held in location by a periodontal ligament, with the assistance of cementum. Teeth are surrounded by gingiva, or gums, part of the periodontium, support tissue of oral cavity protection. The periodontium includes all of the support membranes of the dental structures surround and support the teeth such as the gums and the attachment surfaces and membranes. These include epithelial tissues (epithelium), connective tissues, (ligaments and bone), muscle tissue and nervous tissue.

Salivary glands Edit

There are three sets of salivary glands: the parotid, the submandibular and the sublingual glands. The (exocrine) glands secrete saliva for proper mixing of food and provides enzymes to start chemical digestion. Saliva helps to hold together the formed bolus which is swallowed after chewing. Saliva is composed primarily of water, ions, salivary amylase, lysozymes, and trace amounts of urea.

Tongue Edit

The tongue is a specialized skeletal muscle that is specially adapted for the activities of speech, chewing, developing gustatory sense (taste) and swallowing. The tongue contains two sets of muscles, the intrinsic- involved with shape of tongue, and the extrinsic- involved with tongue movement. It is attached to the hyoid bone. Terms meaning tongue include "glosso" (from Greek) and "lingual" ((from Latin).

Nose Edit

Microanatomy Edit

The outer surfaces of the head and neck are lined by epithelium. The protective tissues of the oral cavity are continuous with the digestive tract are called mucosa or mucous membranes. The cells of the inner oral cavity are called the buccal mucosa.

The oral cavity is lined by a stratified squamous epithelium containing about three layers of cells. [ citation needed ] They line the oral, nasal, and external auditory meatus, (ear), providing lubrication and protection against pathogens.

The lips are also protected by specialized sensory cells called Meissner's corpuscles.

Blood supply Edit

Blood circulates from the upper systemic loop originating at the aortic arch, and includes: the brachiocephalic artery, left common carotid artery and left subclavian artery. The head and neck are emptied of blood by the subclavian vein and jugular vein.

The brachiocephalic artery or trunk is the first and largest artery that branches to form the right common carotid artery and the right subclavian artery. This artery provides blood to the right upper chest, right arm, neck, and head, through a branch called right vertebral artery. The right and left vertebral artery feed into the basilar artery and upward to the Posterior cerebral artery, which provides most of the brain with oxygenated blood. The posterior cerebral artery and the posterior communicating artery are within the circle of Willis.

The left common carotid artery divides to form the: internal carotid artery (ICA) and an external carotid artery (ECA). The ICA supplies the brain. The ECA supplies the neck and face.

The left subclavian artery and the right subclavian artery, one on each side of the body form the internal thoracic artery, the vertebral artery, the thyrocervical trunk, and the costocervical trunk. The subclavian becomes the axillary artery at the lateral border of the first rib. The left subclavian artery also provides blood to the left upper chest and left arm.

Blood–brain barrier Edit

The Blood–brain barrier (BBB) is semi-permeable membrane that controls the capillary leak potential of the circulatory system. In most parts of the body, the smallest blood vessels, called capillaries, are lined with endothelial cells, which have small spaces between each individual cell so substances can move readily between the inside and the outside of the capillary. This is not in the case of brain. In the brain, the endothelial cells fit tightly together to create a tight junction and substances cannot pass out of the bloodstream.

Specialized glial cells called astrocytes form a tight junction or protective barrier around brain blood vessels and may be important in the development of the BBB. Astrocytes may also be responsible for transporting ions (electrolytes) from the brain to the blood.

Venous drainage Edit

Blood from the brain and neck flows from: (1) within the cranium via the internal jugular veins, a continuation of the sigmoid sinuses. The right and left external jugular veins drain from the parotid glands, facial muscles, scalp into the subclavian veins. The right and left vertebral veins drain the vertebrae and muscles into the right subclavian vein and into the superior vena cava, into the right atrium of the heart.

Lymphatic system Edit

The lymphatic system drains the head and neck of excess interstitial fluid via lymph vessels or capillaries, equally into the right lymphatic duct and the thoracic duct.

Lymph nodes line the cervical spine and neck regions as well as along the face and jaw.

The tonsils also are lymphatic tissue and help mediate the ingestion of pathogens.

Tonsils in humans include, from superior to inferior: nasopharyngeal tonsils (also known as adenoids), palatine tonsils, and lingual tonsils.

Together this set of lymphatic tissue is called the tonsillar ring or Waldeyer's ring.

Nerve supply Edit

The spinal nerves arise from the spinal column. The top section of the spine is the cervical section, which contains nerves that innervate muscles of the head, neck and thoracic cavity, as well as transmit sensory information to the CNS.

The cervical spine section contains seven vertebrae, C-1 through C-7, and eight nerve pairs, C-1 through C-8.

There is the formation of an extensive network of nerve groups or tracts attaching to the spinal cord in arrangements called rami or plexus.

The sensory branches of spinal nerves include: lesser occipital, C-2, great auricular, (C-2 and C-3) transverse cervical, C-2 and C-3 and supraclavicular, C-3 and C-4. These nerve groups transmit afferent (sensory) information from the scalp, neck, and shoulders to the brain.

The motor branches of spinal nerves include: ansa cervicalis, dividing into a superior root, C-1, and an inferior root, C-2 and C-3, and the phrenic nerve, C-3 to C-5, the segmental nerve branches, C-1 to C-5. These nerve groups transmit efferent nerve (motor) information from the brain to muscle groups of the scalp, neck, diaphragm (anatomy), and shoulders.

Additionally there are: (C5-C8, and T1) Brachial plexus, providing the entire nerve supply of the shoulder and upper limb and includes supraclavicular branches (dorsal scapular, suprascapular, long thoracic) lateral cord (musculocutaneous, lateral antibrachial cutaneous, lateral head of median nerve), medial cord (ulnar, medial head of median nerve, medial antibrachial cutaneous, medial brachial cutaneous), posterior cord (axillary, radial), controlling the arm.

Damage to a person's spinal cord above C-5 may result in respiratory arrest and death if medicinal aid does not intervene.

Cranial nerves Edit

Twelve pairs of cranial nerves emerge from the brain these affect movements and sensation, and some special organs such as hearing of parts of the head and neck.

Movements of the neck includes: flexion, extension, (nodding yes), and rotation (shaking head no).

The mouth has evolved to support chewing, (mastication) and swallowing (deglutition), and speech (phonation).

In addition to the teeth, other structures that aid chewing are the lips, cheeks, tongue, hard palate, soft palate, and floor of the mouth.

Endocrine glands Edit

Several glands of the endocrine system are found within the head and neck. Endocrine means that the secretion is used within the body. Endocrine glands are termed as ductless and release their secretions directly into the blood. The endocrine system is under the direct supervision of the nervous system, using the negative feedback principal of homeostasis, to create hormones which act as chemical instant messengers.

The hypothalamus connects directly to the pituitary gland, both through the circulatory system and by direct connection of neurons. Also, within the cranium, the pineal gland, which attaches to the thalamus, controls the body's 24-hour rhythms circadian rhythm through the release of melatonin.

The pituitary gland secretes hormones that directly impact the body as well as hormones that indirectly control body functions because they activate other endocrine glands, such as the adrenal cortex (ACTH) and the thyroid gland (TSH). These two glands when stimulated by pituitary hormones then release their own hormones. The pituitary gland has two lobes, the anterior lobe and the posterior lobe. The anterior lobe secretes: growth hormone (GH), Luteinizing hormone (LH), Follicle stimulating hormone (FSH), Adrenocorticotropic hormone (ACTH), Thyroid-stimulating hormone (TSH), Prolactin (PRL), and the posterior lobe secretes: Antidieuretic hormone (ADH), and Oxytocin. There is an intermediate lobe, in adult humans it is just a thin layer of cells between the anterior and posterior pituitary, nearly indistinguishable from the anterior lobe. The intermediate lobe produces melanocyte-stimulating hormone (MSH).

In the neck are the thyroid and parathyroid glands, that secrete hormones that control metabolism and blood calcium levels. The four parathyroid glands are situated upon the back surface of the thyroid gland.

Respiratory system Edit

The respiratory system begins in the head and neck, with air entering and leaving the body through the mouth and nose. The respiratory system involving the head and neck includes:

  1. the nasal cavity for filtering, moistening, and warming the air
  2. the pharynx or throat which is the combining point for respiratory and digestive system
  3. the larynx or voice box containing the epiglottis
  4. the trachea, or windpipe

These lead down into the lower respiratory tract. A critical junction between the respiratory and digestive systems is the epiglottis, a cartilage flap which shuts during swallowing to prevent aspiration. The epiglottis is normally open to support respiration and shuts during swallowing to prevent food and fluids from entering the trachea, activating the gag reflex or initiates the choking mechanism.

Central nervous system Edit

The nervous system is composed of a central nervous system (CNS), brain and spinal cord, and the peripheral nervous system (PNS), cranial nerves and spinal nerves. The CNS is located within the dorsal cavity, and the PNS extends through the ventral cavity. The central nervous system provides control and coordination of all eleven body systems and utilizes the endocrine system to form hormone chemical messengers that transport through the blood to influence the activity of individual cells of the body and their associated tissues, organs and systems.

The CNS receives sensory (afferent) input from the PNS and directs the flow of information to association neurons (interneurons) to create chemical synapse responses which in turn cause the formation of motor (efferent nerve) responses to stimulus. Association neurons are located in the grey matter of the spinal cord and the brain.

The CNS is protected by the cranium, vertebral column, meninges, cerebrospinal fluid. The spinal cord is an extension of the brain. The spinal cord and the brain stem are joined at the base of the cranium at the foramen magnum. Most of the functions of the head and neck are directly influenced by the brain and transmitted to the PNS via the cranial nerves and spinal nerves of the cervical portion of the spine.

The PNS has two subdivisions

    (SNS). The SNS is associated with the voluntary control of body movements through the action of skeletal muscles, and also the reception of external stimuli.
  • the autonomic nervous system (ANS). The ANS is divided into subsystems: the sympathetic nervous system (SNS) and the parasympathetic (PNS) nervous systems. The SNS and PNS often have opposing effects in the same organs or physiological systems, and the ANS is a major factor in maintaining homeostasis.

Bones Edit

The facial bones usually form into pairs and then fuse together. As the cranium fuses, sutures are formed that resemble stitching between bone plates. In a newborn, the junction of the parietal bones with the frontal and occipital bones, form the anterior (front) and posterior (back) fontanelle, or soft spots. The separation of the cranial bone plates at time of birth facilitate passage of the head of the fetus through the mother's birth canal, or pelvic girdle. The parietal bones, and occipital bone can overlap each other in the birth canal, and form the unusual looking "cone head" appearance in a newborn when delivered in a natural, or vaginal, delivery.

Teeth Edit

Humans normally will produce two sets of teeth called primary dentition, or deciduous teeth, and secondary dentition, or permanent teeth.

A tooth is the toughest known substance in the body exceeding bones in density and strength. Tooth enamel lends great strength to the tooth structure. The formation of a developing tooth includes the process of dentin formation, (see: Dentinogenesis) and enamel formation, (see: amelogenesis). The tooth breaks through the gum into the mouth in a process called eruption. The formation of teeth begins in early fetal development and goes through six stages:

  • (1) initiation stage, 6th - 7th week
  • (2) bud stage, 8th wk
  • (3) cap stage, 9th-10 wk
  • (4) bell stage, 11th-12th wk
  • (5) apposition
  • (6) maturation stage

Infection Edit

Severe viral infections that affect the mouth, lips, or the oral cavity include: Oral cancer may have a viral link.

  1. Minor viral infections include: Mumps is a viral infection of the parotid salivary glands. Chicken pox is a viral infection that can spread to the mouth.
  2. Thrush (Candidiasis) fungal infection. Tonsillitis is an inflammation of the tonsils and may cause a sore throat and fever. In chronic cases tonsillectomy may be required.

Infected teeth can on rare occasions cause infection to spread leading to cavernous sinus thrombosis, mediastinitis, or Ludwig's angina causing airway blockage.

Diseases may be transmitted by contact of the head, mouth, or body fluids, such as Herpes Simplex Virus Type I (HSV-1), Herpes Simplex Virus Type II (HSV-2) genital herpes, which may present as a lesion on the lips, and contactable via skin to skin contact

Other Edit

  1. Other diseases include: Gingivitis gum disease, periodontal disease, oral forms of syphilis and gonorrhea. Dental caries or dental cavities. diseases and disorders, commonly called TMJ.
  2. Autoimmune diseases such as: Crohn's disease of the oral cavity, see reference below.

Careful observation of the oral cavity, teeth and gums may reveal indicators of other medical conditions. For example, a person suffering from the eating disorder, Bulimia nervosa may show signs of excessive tooth and gum erosion.

Airway obstruction Edit

The airway in the head and neck may be obstructed with swelling associated with an enlarged tongue (macroglossia), tonsils, with swelling associated with anaphylactic shock, angiooedema, or a foreign body.

Anaphylactic shock requires advanced medical care immediately but other first aid measures include rescue breathing (part of CPR) and administration of epinephrine using an EpiPen for immediate administration of epinephrine (adrenaline) to reverse swelling and to keep the respiratory airway (trachea) open.


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ISBN10: 1259880273 | ISBN13: 9781259880278

The estimated amount of time this product will be on the market is based on a number of factors, including faculty input to instructional design and the prior revision cycle and updates to academic research-which typically results in a revision cycle ranging from every two to four years for this product. Pricing subject to change at any time.

The estimated amount of time this product will be on the market is based on a number of factors, including faculty input to instructional design and the prior revision cycle and updates to academic research-which typically results in a revision cycle ranging from every two to four years for this product. Pricing subject to change at any time.


Watch the video: Ασκήσεις για τον αυχένα (December 2022).