Muscles Of The Head And Neck

MUSCLES OF THE HEAD AND NECK

MUSCLES OF THE HEAD

MUSCLES OF THE HEAD

• Grouped into:
• Muscle of Scalp
• Muscles of Facial Expression

Muscles of Mastication

MUSCLE OF SCALP

THE SCALP:

• The scalp consists of five layers.

the first three of which are intimately bound together and move as a unit.

To assist one in memorizing the names of the five layers of the scalp, use each letter of the word SCALP to denote the layer of the scalp.

• Skin: which is thick and hair bearing and contains numerous sebaceous glands
• Connective tissue

Beneath the skin.

The fibrous septa uniting the skin to the underlying aponeurosis of the occipitofrontalis muscle.

Numerous arteries and veins are found in this layer.

Aponeurosis (epicranial), which is a thin, tendinous sheet that unites the occipital and frontal bellies of the occipitofrontalis muscle.

THE SCALP:

• Loose areolar tissue:

Occupies the subaponeurotic space.

Loosely connects the epicranial aponeurosis to the periosteum of the skull (the pericranium).

The areolar tissue contains a few small arteries, but it also contains some important emissary veins

OCCIPITOFRONTALIS

• Consist of two bells:
• Occipital belly
• Frontal belly

OCCIPITAL BELLY

• ORIGIN: Highest nuchal line of occipital bone
• INSERTION: Epicranial aponeurosis
• NERVE SUPPLY: Facial nerve
• FUNCTION: Moves scalp on skull and raises eyebrows

FRONTAL BELLY

• ORIGIN: Skin and superficial fascia of eyebrows
• INSERTION: Epicranial aponeurosis
• NERVE SUPPLY: Facial nerve

FUNCTION: Moves scalp on skull and raises eyebrows

MUSCLES OF FACIAL EXPRESSION

MUSCLES OF FACIAL EXPRESSION

These are muscles of the face.

Because these muscles control expressions of the face, they are sometimes referred to as muscles of "FACIAL EXPRESSION." They also act as sphincters and dilators of the orifices of the face (i.e., the orbits, nose, and mouth).

ORBITAL GROUP

orbicularis oculi and the corrugator supercilii.

ORBICULARIS OCULI

• The orbicularis oculi is a muscle in the face that closes the eyelids.
• It consist of:
• Palpebral part.
• Orbital part.

PALPEBRAL PART

• ORIGIN: Medial palpebral ligament
• INSERTION: Lateral palpebral raphe
• NERVE SUPPLY: Facial nerve

FUNCTION: Closes eyelids and dilates lacrimal sac

ORBICULARIS OCULI

ORBITAL PART.

• thicker and of a reddish color
• ORIGIN: Medial palpebral ligament and adjoining bone
• INSERTION: Loops return to origin
• NERVE SUPPLY: Facial nerve

FUNCTION: Throws skin around orbit into folds to protect eyeball

CORRUGATOR SUPERCILII

• The second muscle in the orbital group.
• Much smaller.
• Found deep to the eyebrows and the orbicularis oculi muscle and is active when frowning.
• ORIGIN: Superciliary arch
• INSERTION: Skin of eyebrow

NERVE SUPPLY: Facial nerve

FUNCTION: It draws the eyebrows toward the midline, causing vertical wrinkles above the nose.

NASAL GROUP

NASALIS, THE PROCERUS, AND DEPRESSOR SEPTI NASI

NASALIS

• The largest and best developed of the muscles of the nasal group
• Active when the nares are flared
• It consists of:
• transverse part (the compressor naris)
• alar part (the dilator naris)

TRANSVERSE PART OF THE NASALIS:

• ORIGIN: Frontal process of maxilla
• INSERTION: Aponeurosis of bridge of nose
• NERVE SUPPLY: Facial nerve

FUNCTION: Compresses mobile nasal cartilages

ALAR PART OF THE NASALIS

• ORIGIN: Maxilla
• INSERTION: Ala of nose
• NERVE SUPPLY: Facial nerve

FUNCTION: Widens nasal aperture

PROCERUS

• Small muscle superficial to the nasal bone
• Active when an individual frowns
• ORIGIN: Nasal bone
• INSERTION: Skin between eyebrows
• NERVE SUPPLY: Facial nerve

FUNCTION: Wrinkles skin of nose

WRINKLE ON SKIN OF NOSE

DEPRESSOR SEPTI NASI

• ORIGIN: Maxilla
• INSERTION: Lower part of the nasal septum
• NERVE SUPPLY: Facial nerve
• FUNCTION: Pulls the nose inferiorly.

Assisting the alar part of the nasalis in opening the nares.

ORAL GROUP

• Orbicularis oris.
• Buccinators.

Lower group of muscles (depressor anguli oris, depressor labii inferioris and mentalis) Upper group of muscles (risorius, zygomaticus major, zygomaticus minor, levator labii superioris, levator labii superioris alaeque nasi, and levator anguli oris)

THE ORBICULARIS ORIS

• Complex muscle consisting of fibers that completely encircle the mouth,
• Originate near the midline from the maxilla superiorly and the mandible inferiorly.
• It inserts into the skin and mucous membrane of the lips.
• Function is apparent when pursing the lips, as occurs during whistling.

Contraction of the orbicularis oris narrows the mouth and closes the lips.

BUCCINATOR

• The buccinator forms the muscular component of the cheek.

It is in the space between the mandible and the maxilla.

The buccinator arises from the posterior part of the maxilla and mandible opposite the molar teeth and the pterygomandibular raphe.

Contraction of the buccinator presses the cheek against the teeth.

This keeps the cheek taut and aids in mastication by preventing food from accumulating between the teeth and the cheek.

Assists in the forceful expulsion of air from the cheeks.

LOWER GROUP OF ORAL MUSCLES

DEPRESSOR ANGULI ORIS

Is active during frowning.

It arises along the side of the mandible below the canine, premolar, and first molar teeth.

Inserts into skin and the upper part of the orbicularis oris near the corner of the mouth.

FUNCTION: It depresses the corner of the mouth.

DEPRESSOR LABII INFERIORIS

Depressor labii inferioris arises from the front of the mandible, deep to depressor anguli oris.

• Inserting into the lower lip.

It depresses the lower lip and moves it laterally.

MENTALIS

• It is the deepest muscle of the lower group,
• Arising from the mandible just inferior to the incisor teeth.
• Insert into the skin of the chin.

FUNCTION

• It raises and protrudes the lower lip as it wrinkles the skin of the chin.

Helps position the lip when drinking from a cup or when pouting

UPPER GROUP OF ORAL MUSCLES

RISORIUS

• Helps produce a grin it is a thin, superficial muscle that extends laterally.
• From the corner of the mouth in a slightly upward direction.

Contraction of its fibers pulls the corner of the mouth laterally and upward

ZYGOMATICUS MAJOR AND ZYGOMATICUS MINOR

• Zygomaticus major is a superficial muscle that arises deep to the orbicularis oculi.

Inserting into skin at the corner of the mouth.

Zygomaticus minor arises from the zygomatic bone anterior to the origin of zygomaticus major.

• Inserts into the upper lip medial to the corner of the mouth.
• Both zygomaticus muscles raise the corner of the mouth and move it laterally.

Help produce a smile

LEVATOR LABII SUPERIORIS

• Deepens the furrow between the nose and the corner of the mouth during sadness
• It arises from the maxilla just superior to the infra-orbital foramen.

Insert into the skin of the upper lip.

LEVATOR LABII SUPERIORIS ALAEQUE NASI

• Is medial to the levator labii superioris
• Arises from the maxilla next to the nose, and
• Inserts into both the alar cartilage of the nose and skin of the upper lip

It may assist in flaring the nares.

LEVATOR ANGULI ORIS

• Is more deeply placed and covered by the other two levators and the zygomaticus muscles.
• It arises from the maxilla, just inferior to the infra-orbital foramen
• Inserts into the skin at the corner of the mouth.

It elevates the corner of the mouth

And may help deepen the furrow between the nose and the corner of the mouth during sadness

MUSCLES OF MASTICATION

MASSETER

• ORIGIN: Zygomatic arch
• INSERTION: Lateral surface ramus of mandible
• NERVE SUPPLY: Mandibular division of trigeminal Nerve

FUNCTION: Elevates mandible to occlude teeth

TEMPORALIS

• ORIGIN: Floor of temporal fossa
• INSERTION: Coronoid process of Mandible

NERVE SUPPLY: Mandibular division of trigeminal FUNCTION: Nerve Anterior and superior fibers elevate mandible; posterior fibers retract mandible

LATERAL PTERYGOID (TWO

HEADS)

• ORIGIN: Greater wing of sphenoid and lateral Pterygoid plate
• INSERTION: Neck of mandible and articular disc
• NERVE SUPPLY: Mandibular division of trigeminal nerve

FUNCTION: Pulls neck of mandible forward

MEDIAL PTERYGOID (TWO

HEADS)

• ORIGIN: Tuberosity of maxilla and lateral pterygoid plate
• INSERTION: Medial surface of angle of mandible
• NERVE SUPPLY: Mandibular division of trigeminal nerve

FUNCTIO: Elevates mandible

MUSCLES OF THE NECK

INTRODUCTION

The neck is a tube providing continuity from the head to the trunk.

It extends anteriorly from the lower border of the mandible to the upper surface of the manubrium of sternum, and posteriorly from the superior nuchal line on the occipital bone of the skull to the intervertebral disc between the CVII and TI vertebrae.

• It has four compartments:
• visceral compartment (digestive and respiratory systems, and several endocrine glands)

vertebral compartment (cervical vertebrae, spinal cord, cervical nerves, and muscles two vascular compartments, one on each side, are lateral and contain the major blood vessels and the vagus nerve.

INTRODUCTION

• Neck is divided into anterior and posterior triangles.

ANTERIOR TRIANGLE.

• Anterior border: sternocleidomastoid muscle.
• Inferior border: mandible.
• Midline of the neck

POSTERIOR TRIANGLE.

• posterior border: sternocleidomastoid muscle.
• anterior border: trapezius muscle

middle one-third of the clavicle

ANTERIOR TRIANGLE.

• The anterior triangle of the neck is outlined by:
• The anterior border of the sternocleidomastoid muscle laterally.
• The inferior border of the mandible superiorly.
• Midline of the neck medially.
• It is further subdivided into several smaller triangles as follows
• SUBMANDIBULAR TRIANGLE is outlined by:
• The inferior border of the mandible superiorly.
• The anterior and posterior bellies of the digastric muscle inferiorly.
• THE SUBMENTAL TRIANGLE is outlined by:
• the hyoid bone inferiorly,

the anterior belly of the Digastric muscle laterally and the midline

ANTERIOR TRIANGLE.

• MUSCULAR TRIANGLE is outlined by:

The hyoid bone superiorly.

The superior belly of the omohyoid muscle, and the anterior border of the sternocleidomastoid muscle laterally, and the midline.

• CAROTID TRIANGLE is outlined by:

Superior belly of the omohyoid muscle anteroinferiorly.

Stylohyoid muscle and posterior belly of the digastric superiorly, and the anterior border of The sternocleidomastoid muscle posteriorly

MUSCLES OF THE ANTERIOR TRIANGLE OF THE NECK

• can be grouped according to their location relative to the hyoid bone:
• muscles superior to the hyoid are classified as suprahyoid muscles and include:
• Stylohyoid.
• Digastric.
• Mylohyoid.
• Geniohyoid
• Muscles inferior to the hyoid are infrahyoid muscles and include:
• Omohyoid.
• Sternohyoid.
• Thyrohyoid.

Sternothyroid.

SUPRAHYOID MUSCLES

STYLOHYOID:

The stylohyoid muscle arises from the base of the styloid process and passes anteroinferiorly to attach to the lateral area of the body of the hyoid bone During swallowing it pulls the hyoid bone posterosuperiorly and it is innervated by the facial nerve [VII].

DIGASTRIC:

The digastric muscle has two bellies connected by a tendon, which attaches to the body of the hyoid bone.

Posterior belly arises from the mastoid notch on the medial side of the mastoid process of the temporal bone.

Anterior belly arises from the digastric fossa on the lower inside of the mandible.

The tendon between the two bellies, which is attached to the body of the hyoid bone, is the point of insertion of both bellies. Because of this arrangement, the muscle has multiple actions depending on which bone is fixed.

SUPRAHYOID MUSCLES

FUNCTIONS OF DIGASTRIC.

when the mandible is fixed, the digastric muscle raises the hyoid bone;

when the hyoid bone is fixed, the digastric muscle opens the mouth by lowering the mandible.

MYLOHYOID.

The mylohyoid muscle is superior to the anterior belly of the digastric.

It originates from the mylohyoid line on the medial surface of the body of the mandible and inserts into the hyoid bone and also blends with the mylohyoid muscle from the opposite side.

FUNCTIONS: Supports and elevates the floor of the mouth and elevates the hyoid bone.

SUPRAHYOID MUSCLES

GENIOHYOID.

A narrow muscle, it is superior to the medial part of each mylohyoid muscle.

The geniohyoid arises from the inferior mental spine of the mandible and passes backward and downward to insert on the body of the hyoid bone.

FUNCTIONS:

• Fixation of the mandible elevates and pulls the hyoid bone forward;

Fixation of the hyoid bone pulls the mandible downward and inward.

INFRAHYOID MUSCLES

STERNOHYOID.

The sternohyoid muscle is a long, thin muscle originating from the posterior aspect of the sternoclavicular joint and adjacent manubrium of sternum.

• It ascends to insert onto the body of the hyoid bone.
• It depresses the hyoid bone

OMOHYOID.

• Lateral to the sternohyoid muscle is the omohyoid muscle.
• This muscle consists of two bellies:
• inferior belly.
• superior belly.

The omohyoid depresses and fixes the hyoid bone.

INFRAHYOID MUSCLES

THYROHYOID

The thyrohyoid muscle is deep to the superior parts of the omohyoid and sternohyoid.

Originating at the oblique line on the lamina of the thyroid cartilage it passes upward to insert into the greater horn and adjacent aspect of the body of the hyoid bone.

Generally, it depresses the hyoid, but when the hyoid is fixed it raises the larynx.

INFRAHYOID MUSCLES

STERNOTHYROID

It arises from the posterior surface of the manubrium of sternum and passes upward to attach to the oblique line on the lamina of the thyroid cartilage.

The sternothyroid muscle draws the larynx (thyroid cartilage) downward

MUSCLES OF POSTERIOR TRIANGLE

ANTEROLATERAL NECK MUSCLE

• sternocleidomastoid
• Flexes and laterally rotates the head
• scalene

Elevate first two ribs