Severe Tighting In The Sternohyoid Muscle

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There are some features unique to the skull. The individual bones do not always dictate the larger shapes of the skull. A suture, or meeting of two different bones, is found in the middle of a larger form. You can see this meeting particularly in the zygomatic arch as well as in the ocular orbit.

The frontal bone, the ethmoid and the maxilla have within them empty spaces called sinuses. The ethmoid bone, if cut in half, looks like a cluster of bubbles, and the walls of the sinuses are almost as thin as the wall of a bubble and are very fragile. If the skull were solid bone it would be so heavy you wouldn't be able to hold your head up. By having empty spaces within the bones and therefore making them lighter, the sinuses are nature's way of solving that problem. They can present other problems, however, for they are lined with mucous membranes that can become infected and get clogged up. Each sinus has a small opening into the nasal cavity which allows drainage.

THE SKULL FROM A 3/4 FRONTAL VIEW

The skull is made up of 19 bones, 12 of which are pairs. You can see most of these bones in the illustration. Where the bones join is called a suture. Little fingers of bone interdigi-tate with adjoining little fingers to make the joining solid. The bones shown are: the frontal bone, the nasal bones, the lacrimal bones, the ethmoid bones, the sphenoid bones, the zygomatic bones, the maxilla, the mandible, the parietal bones, the temporal bones, the occipital bone, the palatine bones (not seen, since they are inside the orbit of the eye), and the vomer (not seen, since it is inside the nasal cavity).

There are two bones that you cannot see in the illustration, the palatine and the vomer. The palatine bones are paired and are buried deep in the skull behind the nose. They make up the rear part of the palate, part of the base of the nasal cavity, and a small part of the floor or the orbit. The vomer is a thin bone which forms part of the nasal septum separating the two sides of the nasal cavity.

Lacrimal, meaning tear producing, is from the Latin lachrymal, meaning a small vase, of the kind found in ancient Roman sepulchers that was used for collecting tears shed in

Bones The Skull Coronoid Process

Frontal B

Sphenoid B

Ethmoid B

Temporal B

Frontal process

Zygomatic B

Occipital

Mastoid

Ramus

Coronoid Process

THE SKULL

mourning. (The lacrimal bone forms half of the receptacle, which holds the lacrimal sac, a structure that receives the tears and directs them into the nasal cavity. That explains why we blow our noses in cold weather, or when we cry, we are blowing out the tears that have drained into the cavity. The other half of the receptacle for the lacrimal sac is made from the frontal process of the maxilla.) Ethmoid, so-named because it is full of holes, is from the Greek ethmo and oied.es, meaning "formed like a strainer." Sphenoid is from the Greek spheno and eidos together meaning wedge-shaped. Zygomatic or zygoma comes from the Greek zygon, which means yoke, the kind used to harness oxen. Maxilla is from the Latin mala meaning jaw, particularly the upper jaw. Mandible derives from the Latin mandíbula, which stems from mandare meaning to chew and pertains particularly to the lower jaw, which has most of the chewing motion. Parietal is from the Latin paries, pañetes, meaning "walls of a hollow cavity." Temporal indicates the temple, from the Latin témpora, meaning "temple, the right place, the fatal spot.."(As well as indicating a place on the skull where death can easily be afflicted, this word coveys a sense of reverence for life.) Occipital is from the Latin occiput, meaning "the back of the head." Palatine is from the Latin palatum, meaning the hard palate and is the base for the words palatable and palliative. Vomer is the Latin word for plowshare.

THE SKULL SEEN FROM THE SIDE

Here you can clearly see the temporal region and the ramus of the mandible. The frontal process of the maxilla should not be confused with the frontal bone. A process, which is a projection from a larger structure, is less important than a ramus.

Nasal

Ramus comes from the Latin word for branch.

Maxilla

Parietal B.

Parietal B.

Occipital Muscles

THE SKULL

THE FRONTALIS AND THE OCCIPITAL MUSCLES

Both part of the epicranius, these muscles create expressions of surprise and fright by tightening the entire scalp. The epicranius is a broad sheet of muscle and aponeurotic tissue covering the top, the front, and the back of the head. Aponeurotic tissue, or an aponeurosis, is a broad, glistening white tendinous tissue. On the head it is known as the galea aponeurotica. In front (anteriorly) it becomes the frontalis muscle. The frontalis muscle arises out of muscles that are over the bridge of the nose-the procerus, the corrugator supercilii muscles, and the orbicularis oculi muscle-and inserts into the posterior edge of the galea aponeruotica. The galea aponeurotica travels over the top of the skull. The occipitalis muscle arises along the superior nuchal line at the base of the occipital bone of the skull and courses upward to insert into the posterior edge of the galea.

Occipitalis comes from two Latin words: ob, meaning over or against, and caput, meaning head. Galea derives from the Latin word for helmet. Aponeurosis is from the Greek apo-, meaning from and neuro, meaning nerve.

Epicranius

Epicranius

Frontalis M.

Occipital M

THE EPICRANIUS

In their anatomy studies both the Greeks and Romans confused nerve tissue with tendons and ligaments, which looked similar, all three being white and glistening. It took until later centuries for the function of the nerves to be understood.

THE CORRUGATOR SUPERCILII AND THE PROCERUS MUSCLES

These are the frowning muscles. Both have fibers that originate with the frontalis muscle and insert just above the root of the nose.

Corrugator comes from the Latin meaning to wrinkle. Supercilii is from the Latin, meaning hairs above the eyelashes or the eyebrows. Super- or supra- are frequently used prefixes meaning above something. Cilia in Latin refers to the lashes of the lid. Procerus is Greek, meaning "before the horn."

Corrugator Supercilii

Procerus M

Corrugator M

THE PALPEBRAL LEVATOR SUPERIORIS MUSCLE

This muscle lifts the upper lid in the second part of the blinking action and maintains the correct level of the upper lid when the eye is open. The levator, as this muscle is commonly called, arises from the small wing of the sphenoid bone, at the apex of its orbit. It then courses forward, broadening out over the eye and its muscles. At this point the muscle fibers become an aponeurosis which bends over the front of the eye as it blends with the orbital septum. It ends as many tiny fiber-like attachments to the inner surface of the skin of the lids forming the lid crease. The septum separates the contents of the orbit from the exterior lid structures and helps to hold the contents of the orbit in place. The levator passes through the barrier created by the septum without compromising its function.

Septum is Latin for hedge, barrier, or fence. Palpebral levator superioris in Latin means "upper eyelid lifter."

Palpebral Levator M.

Orbital Septum

Levator Palpebral Origin

Orbital Septum

Palpebral Levator M.

THE ORBICULARIS OCULI MUSCLE

This muscle, which closes the lids when blinking and allows you to squint or wink your eye, is one of two muscles that affect the functions of the lids. (The palpebral levator superi-oris opens the lids. See p. 18.) Fibers of the orbicularis lie right over the entrance to the lacrimal sac, and when the eye blinks they aid in pressing the tears down into the lacrimal sac. The muscle has fibers that form two semicircles, one above and one below the eye. These fibers arise on the nasal part of the frontal bone, on the frontal process of the maxilla in front of the lacrimal goove, and on the borders of the medial can thai tendon. They insert at the outer edge of the eye into the lateral palpebral raphe. A raphe is an interdigita-tion of fibers, in this case the fibers that come from beneath and above the eye.

Orbicularis is Latin for disk.

Pterygomandibular Raphe

THE AURICULARIS MUSCLES

Most people cannot use these muscles, but if they can, they are able to wiggle their ears—good for amusing young children. There are three of them: anterior, superior, and posterior. The anterior muscle is in front, the superior muscle above and the posterior muscle behind the ear. These are very superficial muscles whose attachments are not to bone but to underlying fascia.

Auricula is Latin for ear.

Auricularis Anterior

upenor

Posterior

.nier

AURICULARIS MUSCLES

THE NASALIS MUSCLE

The nasalis muscle allows you to flare your nostrils. One part arises from the tendinous end of the procerus muscle at the bridge of the nose, on each side of the nose, and the other part goes from the tip and over the outside of the nostrils.

THE DEPRESSOR SEPTI MUSCLE

The depressor septi muscle draws the nose downward. It arises from the maxilla, just under the nose, and inserts into the septum of the nose.

Procerus M.

Depressor Septi M.

Caput Met Nose Muscle

Nasalis M.

Procerus M.

Depressor Septi M.

Nasalis M.

THE ORBICULARIS ORIS MUSCLE

This muscle is used when you to close your mouth and to pout. It has some similarities with the orbicularis oculi muscle, discussed above, in that its fibers encircle the mouth just as the fibers of the oculi muscle encircle the eye, and both are sphincter muscles. However, the oris is more complicated because it is comprised of fibers that feed into it from radiating muscles. Most of these fibers go around the mouth, but unlike the fibers of the oculi muscle, they are in four sections with some of the fibers attaching to the underside of the skin. One section joins in the middle of the upper lip forming a little "gutter" under the nose. Another is in the middle of the lower lip without a gutter. The two others are at the corners of the mouth. The orbicularis arises from several places: from the maxilla, the mandible, the lips, and the buccinator muscle.

Maxilla is the diminutive of the Latin mala, meaning upper-jawbone.

Levator Anguli Oris M.

Orbicularis Oris M.

Ligament Pterigomandibular

Pterigomandibular Raphé

Buccinator M.

Levator Anguli Oris M.

Orbicularis Oris M.

Pterigomandibular Raphé

Buccinator M.

THE BUCCINATOR MUSCLE

The buccinator is the muscle of the cheek which aids in chewing by holding the cheek close to the teeth. It is also the muscle used for horn blowing. It arises from the outer surfaces of the maxilla, the mandible, and the superior constrictor pharyngis muscle, and is joined to that muscle by the pterygomandibular raphe. It inserts into the orbicularis oris and the modiolus, beneath the risorius muscle.

Buccinator is from the Latin buccinare meaning "to blow a trumpet". Buccinator is pronounced "booksinator," the oo's as in goose. Raphe is from the Greek rhaphé, meaning seam or suture, suture referring to a joining.

THE LEVATOR ANGULI ORIS MUSCLE

This muscle contributes to the naso-labial fold in the cheek. It lefts the upper lip exposing the teeth when smiling. It orginates on the maxilla just below the infraorbital foramrn and inserts into the modiolus.

THE ZYGOMATICUS MAJOR MUSCLE

The zygomaticus major muscle assists the risorious muscle in laughing and smiling by lifting the corners of the mouth. It inserts into the orbicularis at the modiolus and arises on the zygomatic bone. The modiolus is a tendinous tissue found at the corners of the mouth to which many of the muscles of expression attach.

THE ZYGOMATICUS MINOR MUSCLE

The zygomaticus minor muscle is also a lip lifter and aids in smiling. It inserts on the orbicularis oris just next to and above the zygomaticus major and arises from the malar surface of the zygomatic bone just nasal to the place where the zygomaticus major muscle arises.

THE LEVATOR LABII SUPERIORIS MUSCLE

The levator labii superioris muscle lies nasal to the zygomaticus minor muscle. It is the upper lip lifter, as its name implies. It inserts on the orbicularis, between the levator anguli oris and the levator labii superioris alaeque nase.

Levator Anguli Oris Muscle

Levator Anguli Oris M.

Levator Labii Superioris M.

Levator Labii Superiori Alaeque Nasi M.

Orbicularis Oris M

Zygomaticus Major M.

ygomaticus Minor M.

Risorius M. Modiolus

Mentalis M.

Depressor Anguli Oris

Depressor Labii Inferioris M.

MUSCLES OF EXPRESSION

THE LEVATOR ANGULI ORIS MUSCLE

This muscle is already shown in the previous illustration. The name of the levator anguli oris muscle tells what it does. It translates from the Latin as "lifter of mouth at corners." It is not parallel with the above three muscles but instead it inserts at the modiolus, as do the zygomaticus major and the risori-ous. It lies beneath them, coursing under the levator labii superioris, then arising just outside of and beneath the orbital rim.

THE LEVATOR LABII SUPERIORIS ALAEQUE NASI MUSCLE

The levator labii superioris alaeque nasi muscle is the most nasal of the levator labii muscles and is the one which allows you to sneer.

In Latin it means "upper-lips lifter next to noses."

THE DEPRESSOR ANGULI ORIS MUSCLE

The depressor anguli oris muscle of the lower lip aids in drawing the lower lip downward. It inserts at the modiolus, mingling its fibers with the risiorious and the orbicularis oris, and arises out of the fibers of the platysma muscle.(The platysma is a broad thin sheath of muscle which connects with the lower jaw muscles and covers the neck and clavicle.)

THE DEPPRESSOR LABII INFERIORIS MUSCLE

The deppressor labii inferioris muscle is the main depressor or drawing down muscle of the lower lip. It lies next to the depressor anguli oris muscle, going toward the center, or medially. This muscle inserts on the orbicularis oris and rises from the mental region of the lower mandible.

The term mental comes from the Latin word for the chin and translates literally as "depressor of the lower lips."

THE MENTALIS MUSCLE

The mentalis muscle allows you to dimple your chin when this muscles is contracted because it pulls on the skin. It is included with this group because in some people, but not all, fibers of this muscle arise from and mingle with the orbicularis oris. Note that this is an origin, not an insertion. The insertion is into the skin near the point of the chin.

THE RISORIOUS MUSCLE

The risorious muscle is the "laughing muscle," the one used when you laugh or smile. It inserts into the underside of the skin over the modiolus, with some fibers inserting into the orbicularis oris in the area of the modiolus. It arises in the fascia of the cheek.

THE TEMPORALIS MUSCLE

The temporalis muscle helps to close the mouth, in grinding the teeth and to move the mouth from side to side when chewing. This muscle arises along the entire rim of the temporal fossa of the skull. The fibers of the muscle cover the temporal region and converge into a tendon which inserts on the coronoid process of the mandible.

Coronoid is from the Greek korone which means "like the beak of a crow."

Coronoid Plexus Ventricle

Temporalis M

Coronoid Process

THE MASSETER MUSCLE

The jaw's masseter muscle is one of the strongest muscles in the body. It is a very thick muscle, noticeable when someone clenches his teeth. It is the primary chewing muscle for closing the jaws. Its outer portion originates along the zygomatic arch and inserts on the surface of the ramus of the mandible. Its inner portion also originates from the zygomatic arch but further to the rear, posteriorly, and it inserts on the upper surface of the ramus of the mandible.

The name of this muscle comes from the Latin and Greek maseter, meaning chewer.

Individual Risorius Muscle

Masseter M

THE PTERYGOID MUSCLES

The pterygoid muscles, which are found on the inside of the ramus of the mandible, work together with the masseter muscle in chewing. My illustration cuts away part of the ramus so that the muscles can be seen. There are of two of them, the lateral pterygoid muscle and the medial pterygoid muscle. The lateral muscle assists in opening the mouth, and they both assist in jaw rotation and side-to-side movement as well as in the projection of the lower jaw. Each of these muscles has two heads. The lateral pterygoid muscle is the more superior, or higher of the two muscles. The upper head of the lateral pterygoid muscle arises from the lateral plate of the ethmoid bone, the lower from the pterygoid plate Both parts join to insert onto the articular capsule which covers the condyle of the mandible's ramus. The superficial head of the medial muscle, the one closest to the surface, arises from the pterygoid plate, and the deep head arises from the palatine bone. Both heads join in a broad insertion on the inner, inferior, surface of the mandible's ramus.

Pterygoid is from the Greek word for wing-like. It refers to the pterygoid plate, a part of the sphenoid bone of the skull.

Pterygoid Plate Sphenoid Bone

THE BONES OF THE NECK

In this illustration you should note the first seven vertebrae, called the cervical vertebrae; three thoracic vertebrae; part of the shoulder girdle, made up of the scapula (partly seen), the clavicle and head of the humerus; the first two ribs; the clavicle, which goes from the spine of the scapula to the top of the sternum, the part called the manubrium; the hyoid bone; and a side view of the skull showing the occipital bone and the mastoid process.

The hyoid bone is situated at the angle of the throat where the chin meets the neck just above the thyroid cartilage—the Adam's Apple. It is the one bone in the body that is not articulated with another bone, rather it is held in place by the suprahyoid and infrahyoid muscles—those involved with swallowing.

Hyoid means shaped like the Greek letter upsilon: u. Oid at the end of a word means like, as in resemble.

Digastric Muscle

THE DIGASTRIC MUSCLE

The digastric muscle becomes tendinous in the middle so that it can go through a fibrous ring which is attached to the hyoid bone. It arises in the rear of the mastoid process, a boney process just below and behind the ear, slopes down and forward though its ring on the hyoid bone and then swings forward to insert on the inside of the chin on the mandible.

The name digastric derives from the Greek di, meaning two and gaster, meaning bellies.

Digastric Anterior Belly

THE STYLOID MUSCLE

The styloid muscle is a slender muscle which arises from the styloid process of the temporal bone and passes straight down to insert on the body of the hyoid bone. If you look at the drawing of the skull's side view, you can see the styloid process as a little finger of bone just below where the ear would be.

Styloid derives from the Latin word for pointed and refers to the shape of the bone.

Central Raphe Mylohyoid

Tendon of Digastric M

THE MYLOHYOID MUSCLE

The mylohyoid muscle lies beneath the anterior belly of the digastric muscle and the stylohyoid muscle discussed above and forms the whole floor of the mouth. It arises near the molars of the lower jaw and attaches all the way around the inner rim of the mandible. Its fibers converge downward to insert on the body of the hyoid bone.

Mylo is the Greek word for mill, a place where grinding is done and hence relates to the molars.

Mylohyoid Muscle

THE GONIOHYOID MUSCLE

The goniohyoid muscle, which lies beneath the mylohyoid muscle, arises from behind the point of the chin and inserts on the body of the hyoid bone.

Gonio is the Greek word for angle, and refers here to the angle of the lower jaw.

Lower Jaw Muscle

Goniohyoid M

The following muscles work to lower the hyoid bone when swallowing, except for the sternothyroid muscle, which moves the thyroid cartilage backward when swallowing. The thyroid cartilage is known as the Adam's Apple. The infrahyoid muscles are those below the hyoid bone.

THE THYROHYOID MUSCLE

The thyrohyoid muscle arises from the thyroid cartilage and inserts on the hyoid bone.

THE STERNOTHYROID MUSCLE

The sternothyroid muscle arises from the back upper surface of the sternum and inserts on the upper rim of the thyroid cartilage.

Thyroid is from the Greek thyreos and eides meaning shield shaped.

Sternothyroid

Thyrohyoid M. Thyroid

Sternothyroid M

THE STERNOHYOID MUSCLE

The sternohyoid muscle arises from the tip end of the sternum called the manubrium, and inserts on the hyoid bone.

THE OMOHYOID MUSCLE

The omohyoid muscle has two bellies connected by a tendon, the front portion lying just next to the sternohyoid muscle. It arises from the upper border of the scapula, passes through a tendinous loop attached to the clavicle, and then continues upward to insert on the hyoid bone.

Omo is Greek for shoulder.

Sternohyoid

Omohyoid M.

Manubrium

Bones The Neck And Hyoid Bone

Sternohyoid

Omohyoid M.

Manubrium

THE BONES OF THE NECK: INTERIOR-ANTERIOR VIEW

Here you see the seven cervical vertebrae along with the next three thoracic vertebrae, a section of the skull showing the mastoid process, and two ribs, all seen from the ventral (front) view. The transverse processes of the vertebrae can be clearly seen.

Thoracic Vertebrae

Cervicle

Thoracic Vertebra Frontal

Process

Transverse Process

Thoracic Vertebrae

Process

Cervicle

Transverse Process

THE SKULL, NECK, AND UPPER BACK: POSTERIOR VIEW

In this illustration you see the skull, seven cervical vertebrae, and eleven of the twelve thoracic vertebrae with ribs attached, from the back or posterior view. The scapula, a bit of the clavicle, and the top of the humerus can also be seen.

Clavicle Uneven

THE STERNOCLEIDOMASTOID MUSCLE

The sternocleidomastoid muscle aids in rotating the head and neck and in lowering the chin to each side. It also assists breathing by lifting the sternum when you inhale. It arises in two places—on the top of the manibrium of the sternum and on the clavicle. It joins together about one third of the way up its diagonally upward course to its point of insertion on the mastoid process.

Sterno is from the Latin sternum, meaning breastbone; cleido is from the Greek "pertaining to the clavicle," and mastoid comes from the Greek word mastos, meaning nipple or breastlike.

Rectus Capitis Anterior

THE RECTUS CAPITIS LATERALIS AND THE RECTUS CAPITIS ANTERIOR MUSCLES

Here you see two small muscles which form the deepest layer of the neck muscles: the rectus capitis lateralis muscle, and the rectus capitis anterior muscle. The former, a small, flat, squarish muscle, moves the head from side to side. It arises from the upper surface of the transverse process of the atlas (the first cervical vertebra) and inserts on the occipital bone of the skull. The latter muscle allows the head to bend forward. It arises from the transverse process and the adjacent body of the atlas and inserts just in front of the magnum foremen of the skull, the opening through which the spinal column passes to join the brain stem.

Brainstem Occipitalis

THE RECTUS CAPITIS POSTERIOR MINOR MUSCLE

The rectus capitis posterior minor muscle is a head extender: It helps lift the head up. It arises from the tubercle of the posterior arch of the atlas in the form of a narrow tendon from which the muscles rises to insert on the inferior nuchal line of the occipital bone of the skull.

THE RECTUS CAPITIS POSTERIOR MAJOR MUSCLE

The rectus capitis posterior major muscle is another head extender and also assists in turning the head to the side. It arises from the spinous process of the axis and courses upward to insert on the inferior nuchal line just next to the rectus capitis posterior minor muscle.

THE OBLIQUUS CAPITIS SUPERIOR MUSCLE

The obliquus capitis superior muscle assists in holding the head erect as well as helping to bend it to the side. It arises from the transverse process of the atlas and inserts onto the occipital bone just over the rectus capitis posterior major muscle along the inferior nuchal line.

Rectus Capitis Posterior Minor M.

Rectus Capitis Posterior Major M

Rectus Capitis Posterior Minor Muscle

Obliquus Capitis Inferior M.

Obliquus Capitis Superior M.

Rectus Capitis Posterior Minor M.

Obliquus Capitis Inferior M.

Rectus Capitis Posterior Major M

Obliquus Capitis Superior M.

THE OBLIQUUS CAPITIS INFERIOR MUSCLE

The obliquus capitis inferior muscle helps to turn the head to the side by rotating the axis, the second cervical vertebra It arises from the spinous process of the axis and rises obliquely to insert on the transverse process of the atlas in the same area where the superior muscle arises.

THE SCALENUS MUSCLE

The scalenus muscle helps lift the ribcage, assisting in breathing. It also assists in some rotation of the neck and flexion of the upper spinal column. This muscle, too, is in three parts. The posterior part arises on the transverse processes of the top two or three cervical vertebrae and courses downward to insert on the top middle edge of the second rib. The medial part, the largest of the three sections, arises on the transverse processes of all the cervical vertebrae except the atlas and descends to attach on the top surface of the first rib. The anterior part arises from the transverse processes of the third through sixth cervical vertebrae and inserts on the top of the first rib, just in front of the medial portion's insertion. Whereas the longus colli and the longus capitis muscles course upward, the scalenus muscle courses downward. Muscles always shorten in the direction of their origin.

Scalenus is a Latin word derived from the Greek skalenos meaning odd or uneven. In geometry the word refers to a triangle with unequal sides.

Longus Colli

THE LONGUS COLLI MUSCLES

In the next layer of neck muscles, going inward, are the longus colli muscles, which help the neck to bend and rotate. It is in three parts: upper (superior) and lower oblique muscle and, joining these, a vertical muscle. The superior oblique portion arises from the transverse process of the third, fourth, and fifth cervical vertebrae and rises obliquely inward to insert on the inner central portion of the atlas, called the anterior arch. The lower oblique arises from the bodies of the first two or three thoracic vertebrae and inserts on the bodies of the top three cervical vertebrae. The vertical part arises from the bodies of the first three thoracic vertebrae and inserts on the bodies of the top three cervical vertebrae.

Collum is Latin for neck and the source of the word collar.

THE LONGUS CAPITIS MUSCLE

Overlying the longus colli muscle is the longus capitis muscle, which flexes the head. It arises from tendons

Superior

LONGUS COLLI M.

Inferior Oblique

Longus Capitis
Longus Capitis M.

Superior

LONGUS COLLI M.

Inferior Oblique attached to the transverse processes of the third through sixth cervical vertebrae and courses upward to insert on the middle portion of the occipital bone, the basilar portion (the base), just in front of the insertion of the rectus capitis anterior muscle.

THE PLATYSMA MUSCLE

When your collar is too tight it is the constriction of the platysma muscle that helps loosen it. Otherwise this muscle doesn't have much function. Laxness of this muscle is often a major factor in causing the sag under the chin in older people (this is not just aging skin, or from accumulating fat). This muscle forms the outermost layer of the neck muscles. The muscle fibers arise from the fascia at the top part of the torso covering the pectoral muscles and the deltoids and course over the clavicle and up each side of the neck. They meet with intertwining fibers just under the chin and then continue, passing over the edge of the mandible, to join the fibers of the lower facial muscles. It is a broad, thin muscle.

Platy in Greek means flat or plate like.

Orbicularis Oris M.

Mentalis M.

Platysma M.

Orbicularis Oris Muscle

Orbicularis Oris M.

Mentalis M.

Platysma M.

The shoulder is the most complicated joint in the body. The humerus, the upper arm bone, has a round head that fits into a socket called the glenoid cavity of the scapula, which lies on the rear of the ribcage. You see the clavicle in the front. The medial end of the clavicle attaches to the manubrium, the top section of the sternum. The scapula, the clavicle, and the manubrium together form what is called the shoulder girdle. Numerous muscles pass above, around, through and beside these bones. (If you look at the movement of the shoulder area from a broader view, you would have to involve muscles that cover the chest and back as well. I shall discuss the pectoralis and latissimus dorsi muscles, which fan out over the chest and lower back, in the section on the arm, since they directly affect arm movement). When you look at the deltoid muscle and the pectoral muscles, which lie right next to each other, it's hard to see where one ends and the other begins. Similarly with the actions of these two muscles, it is hard to tell when one takes over from the other, when one stops and the other starts.

The muscles of the shoulder girdle are involved with the movement of the scapula. The muscles of the shoulder joint are involved with the movement of the arm, specifically the humerus, which articulates with the glenoid cavity of the scapula.

The rotator cuff muscles maintain the position of the head of the humerus in the glenoid cavity (shoulder joint) even as the upper arm is moving. They are: the subscapularis, the supraspinatus, the infraspinatus, and the teres minor muscles.

THE BONES OF THE SHOULDER: ANTERIOR VIEW

Here you can see the clavicle, the humerus and the scapula, as well as the manubruim and two ribs. The features you should note on the scapula are the coracoid process, the acromion and the glenoid cavity. The head of the humerus fits into the glenoid cavity. Behind the head are the greater and lesser tubercles.

Coracoid Process

Clavicle

Greater Tubercle

Lesser Tubercle

Humerus

Head of the Humerus

Greater Tubercle Humerus And Scapula

Manubrium

Scapula

Greater Tubercle

Lesser Tubercle

Humerus

Scapula

Coracoid Process

Head of the Humerus

Clavicle

Manubrium

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Responses

  • shay
    What is the muscle called on the styloid process?
    8 years ago
  • miranda
    What muscle is attached to the coronoid process?
    8 years ago
  • kisanet
    What is the meaning of styloid?
    7 years ago
  • Where is the corrugator supercilii?
    7 years ago
  • Colomba
    What attaches on the styloid process?
    7 years ago
  • EVELIINA
    Which muscle or group of muscles would you use to wink your eye?
    7 years ago
  • semolina
    What Is The Hyoid Bone For?
    7 years ago
  • rina
    How to loosen corrugator supercilii muscles?
    6 years ago
  • piia-noora
    What muscle inserts on the hyoid bone?
    6 years ago
  • mikael
    Why is sternohyoid muscle swollen?
    6 years ago
  • gundahar
    Can a muscle relaxer help loosen tight procerus and corrugator?
    6 years ago
  • cheryl
    What is the shape of a sternohyoid muscle?
    5 years ago
  • selassie
    How to loosen suprahyoid muscles?
    5 years ago
  • cora
    How to work the sternohyoid muscle?
    4 years ago
  • mauri
    How to loosen digastric?
    4 years ago
  • kristy
    How to work the sternohyoid muscles?
    4 years ago
  • kayley
    What is the cause if pain arises in frontal parietal occiptal ethqmoidal?
    3 years ago
  • artemio
    What causes the omohyoid, thyrohyoid and sternohyoid to get tight and very sore?
    12 months ago

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