Which Muscle Tenses The Skin Of The Neck And Assists In Depression Of The Mandible?

Facial Muscles

The human face up is equanimous of multiple muscles that control the fine movements that produce facial expressions.

Learning Objectives

Characterize the muscles involved in creating facial expressions

Key Takeaways

Key Points

• The homo face is composed of numerous muscles that control fine movement to produce facial expressions.
• Unlike other muscles, these muscles originate on bone or fascia of the face and attach directly to the skin, assuasive information technology to be manipulated.

Fundamental Terms

• depressor labii inferioris: An analogous muscle that lowers the bottom lipEndFragment
• Buccinator: This muscle is located betwixt the upper and lower jaws in the cheek, deep to the other muscles of the face.
• zygomatic: This musculus controls the cheeks to create smiles and frowns.
• Procerus: The most superior of all facial muscles.
• depressor anguli oris: This muscle is contrary to the levator anguli oris and pulls the corners of the mouth downwards, producing a frown.
• levator labii superiori: Abroad musculus responsible for elevation of the upper lip.
• Orbicularis Oris: Muscle fibers that enclose the opening to the oral cavity.
• Nasalis: The largest of the nasal muscles. Information technology is separate into 2 sections: alar and transverse.
• risorius: This muscle pulls the mouth back mimicking a smile, but does not affect the skin effectually the grin.
• Corrugator Supercilii: A small muscle located superiorly to the orbicularis oculi.
• Orbicularis Oculi: A thin musculus that surrounds the eye socket.
• mentalis: This muscle pushes the lower lip uppers and wrinkles the chin.
• levator labii superioris alaeque nasi: The muscle of the upper lip. It acts to lift the upper lift and dilates nostril, producing a snarling expression.

The human face is composed of numerous muscles that control fine movement to produce facial expressions. Unlike other muscles, these muscles originate on the bone or fascia of the confront and attach straight onto the skin, allowing it to be manipulated. The facial muscles can exist divide into iii groups: orbital, nasal and oral.

Orbital Group

Schematic of head and neck muscles.: Locations of facial muscles noted.

• Orbicularis Oculi: A thin muscle that surrounds the eye socket.
  • Attachments: Originates from the skull around the centre socket and attaches to ligaments found in the eyelid.
  • Actions: Closes the eyelid.
• Corrugator Supercilii: A pocket-size muscle located superiorly to the orbicularis oculi.
  • Attachments: Originates from the bone beneath the eyebrow and attaches to the pare direct in a higher place.
  • Actions: Draws the eyebrows together.

Nasal Group

The nasal group of muscles are associated with movements of the nose and surrounding skin.

• Nasalis: The largest of the nasal muscles. It is split up into two sections: alar and transverse.
  • Attachments: Originates from the upper jaw. The alar section attaches to the cartilage of the nose and the transverse department to an aponeurosis covering the bridge of the nose.
  • Actions:  The transverse section closes the nostrils and the alar function opens them.
• Procerus: The most superior of all facial muscles.
  • Attachments: Originates from the nasal os attaching to the pare of the forehead.
  • Actions: Pulls the eyebrows down.

Oral Group

Location of the buccinator muscle: Highlighted in orangish, the buccinator is associated with the cheeks direct lateral to the mouth

Muscles of the oral group play cardinal roles in respiration, communication, eating, and drinking. The lips in item are controlled by numerous small muscles.

• Orbicularis Oris: Muscle fibers that enclose the opening to the oral fissure.
  • Attachments: Originates from the upper jaw and muscles of the cheek and attaches to the lips.
  • Action: Purses the lips.
• Buccinator: This muscle is located between the upper and lower jaws in the cheek, deep to the other muscles of the face.
  • Attachments: It originates from upper and lower jaw and attaches to the lips and orbicularis oris.
  • Actions: The buccinator pulls the cheek inwards.

Other Muscles of the Oral cavity

• The levator labii superioris alaeque nasi is the muscle of the upper lip. It acts to lift the upper lift and dilates nostril, producing a snarling expression.
• The levator anguli oris (caninus) inserts at the corners of the mouth at an angle, and is associated with other muscles including the zygomaticus, triangularis, and orbicularis oris. When innervated, this muscle contracts to elevator the corners of the rima oris, producing part of the expression of a smiling.
• The depressor anguli oris (triangularis) is besides associated with the corners of the rima oris. Located contrary to the levator anguli oris, it pulls the corners of the rima oris downwardly, producing a pout.
• The levator labii superioris is a broad muscle responsible for elevation of the upper lip. This muscle originates at the side of the nose and has several insertion points on either side of the olfactory organ, extending down to the lip, and inserting at both lateral and frontal portions of the upper lip.
• The depressor labii inferioris is an coordinating muscle that lowers the bottom lip.
• The zygomatic muscle, associated with the cheeks, is divided into ii parts: the major and the minor. The zygomaticus major draws the mouth upward and outward to generate a smile. The zygomaticus minor inserts into the outer role of the upper lip, not the angle of the mouth equally with the major. When innervated, contraction of this muscle draws the lip astern, upward, and outward and is associated with facial expressions conveying sadness.
• The mentalis, associated with the tip of the chin, is a paired muscle. Sometimes referred to as the pouting muscle, contraction of the mentalis causes the lower lip to be pushed upward and wrinkles the mentum.
• The risorius muscle is lateral to the orbicularis oris and inserts into the bending of the mouth. When innervated, the risorius pulls the mouth dorsum mimicking a smile, simply does non affect the skin around the smile Equally a result, this facial expression is oft interpreted as insincere.

Chewing Muscles

Mastication, or chewing, involves the adduction and lateral motions of the jaw bone. It is controlled past 4 muscles of the face.

Learning Objectives

Differentiate betwixt the actions of the masseter and the temporalis muscles in chewing

Key Takeaways

Key Points

• The masseter elevates the jaw, closing the mouth.
• The temporalis elevates and retracts the jaw.
• The lateral pterygoid is the only muscle of mastication that actively opens the jaw. Unilateral action of a lateral pterygoid produces lateral motility in the jaw, commonly performed in concert with the medial pterygoids.
• The medial pterygoid elevates and closes the jaw, contributes to protrusion of the mandible, and assists in mastication.

Fundamental Terms

• medial pterygoid: A muscle of mastication with two heads. It lies inferiorly to the medial pterygoid.
• temporalis: A wide muscle that fans out to cover much of the temporal bone on the side of the skull.
• lateral pterygoid: A muscle of mastication with ii heads. It lies superiorly to the medial pterygoid.
• masseter: The large musculus which raises the lower jaw, and assists in mastication.

Mastication, or the act of chewing, involves adduction and lateral motion of the jaw bone. It is controlled past four bilateral muscles in the confront. The lower jaw, or mandible, connects to the temporal os of the skull via the temporomandibular joint, which allows movement in all planes.

Location of the masseter muscle: The masseter muscle spans the opening of the oral cavity.

• Masseter: The most powerful muscle of mastication. It is quadrangular in shape and split into two regions, deep and superficial. It covers the other muscles of mastication.
  • Attachments: The superficial region originates from the skull below the heart socket, while the deep part originates from the skull to a higher place the jaw. Both parts attach to the jaw.
  • Actions: Elevates the jaw.
• Temporalis: A broad muscle that fans out to cover much of the temporal bone on the side of the skull.
  • Attachments: The temporalis musculus has a wide, fan-shaped origin on the side of the skull and condenses into a tendon which attaches to the jaw.
  • Deportment: Elevates and retracts the jaw.
• Lateral Pterygoid: The lateral pterygoid muscle has a triangular shape with two caput, superior and inferior. Information technology is the major protractor (opener) of the jaw.
  • Attachments: Both heads originate adjacent to the eye socket and converge into a tendon which attaches to the jaw.
  • Actions: Together, the lateral pterygoids protract the jaw, working independently to produce lateral motion.
• Medial Pterygoid: The medial pterygoid muscle has a quadrangular shape with ii heads, deep and superficial. Information technology is located junior to the lateral pterygoid.
  • Attachments: The superficial head originates from the front of the skull and the deep head attaches to the skull side by side to the middle socket. Both heads attach to the jaw.
  • Deportment: Elevates the jaw and assists in the production of lateral movement.

Location of the temporalis musculus and the lateral pterygoid: (a) Highlighted in orange, the temporalis muscle is a broad muscle extending from zygomatic bone. (b) Arrows indicate the location of the lateral pterygoid, highlighted with the medial pterygoid in orange.

Key Movements

• Elevation of the Jaw: Produced by the masseter, temporalis and medial pterygoid.
• Depression of the Jaw: Produced by the lateral pterygoid, assisted past the digastric, mylohyoid and geniohyoid muscles found in the neck.
• Protraction of the Jaw: Produced by the lateral pterygoid.
• Retraction of the Jaw: Produced by the temporalis.
• Lateral Move of the Jaw: Produced by the lateral and medial pterygoid.

Neck Muscles

Cervical muscles are those associated with the front end of the neck; vertebral muscles are associated with the vertebral column.

Learning Objectives

Outline the neck muscles and their movements

Key Takeaways

Key Points

• Numerous muscles contribute to the processes of speaking and swallowing.
• These muscles can be divided into suprahyoid and ingrahyoid groups based on their locations relative to the hyoid bone.
• The hyoid bone, located below the mandible, acts every bit a fundamental zipper point for muscles involved in speaking and swallowing.
• Numerous muscles contribute to both the stabilization and fine movements of the head and neck.

Key Terms

• suprahyoid muscles: A group of muscles located above the hyoid os, responsible for its elevation which widens the esophagus.
• hyoid os: A -shaped bone which sits below the mandible
  and in front end of the esophagus, facilitating the broad range of movements associated with speaking and swallowing.
• infrahyoid muscles: A group of muscles located below the hyoid bone, responsible for its low which narrows the esophagus.

Muscles of the neck play important roles in mastication (chewing), swallowing, speaking and supporting and moving the head. All muscles plant in the neck are paired, meaning they be to both the left and right side of the spine. The muscles involved in chewing have been discussed previously and then simply those involved in swallowing and back up will be discussed below.

Muscles Involved in Swallowing and Speaking

Located to the anterior of the cervix, these muscles are divide into two based on their location relative to the hyoid bone. The U-shaped hyoid bone sits beneath the mandible and in front end of the esophagus, providing a level of protection and facilitating the wide range of muscle activeness required for speaking and swallowing.

Suprahyoid Muscles

Suprahyoid and infrahyoid muscles of the neck: Suprahyoid and infrahyoid muscle groups are named based on their location relative to the hyoid os. The hyoid bone sits below the mandible and in front of the esophagus, providing a level of protection but also facilitating the wide range of muscle activity required for speaking and swallowing.

The 4 suprahyoid muscles establish above the hyoid bone human activity in concert to drag the hyoid os, profitable with swallowing by widening the esophagus.

• Stylohyoid: The most superior of the suprahyoid muscles, the stylohyoid originates from the skull and attaches to the hyoid bone.
• Digastric: The digastric muscle is split into 2 parts that are connected by a tendon attached to the hyoid bone. The anterior section originates from the mandible and the posterior section from the skull.
• Mylohyoid: The mylohyoid is a wide apartment muscle which forms the floor of the oral cavity. Information technology originates from the mandible and attaches to the hyoid bone.
• Geniohyoid: The deepest of the suprahyoid muscles, the geniohyoid muscle originates from the mandible and attaches to the hyoid os.

Infrahyoid Muscles

The four infrahyoid muscles found below the hyoid bone human action in concert to depress the hyoid bone during swallowing and speaking, compressing the esophagus.

• Sternohyoid: A superficial musculus which originates from the sternum and attaches onto the hyoid bone.
• Omohyoid: Located laterally to the sternohyoid, the omohyoid musculus is split in two parts attached by a tendon. The inferior region originates from the scapula, joins the superior region, and attaches to the hyoid bone.
• Sternothyroid: Sitting deeper than the sternohyoid, the sternothyroid originates from the sternum and attaches to the thyroid cartilage associated with the hyoid os.
• Thyrohyoid: A short continuation of the sternothyroid muscle, the thyrohyoid originates from the thyroid cartilage and attaches to the hyoid bone.

Muscles of the Back and Neck

Muscles of the back and neck: Muscles of the back and neck play an of import role in maintaining posture and the motion of the head and cervix.

The muscles of the back and neck are responsible for maintaining posture and facilitating motility of the caput and neck. They are divided into three layers.

Superficial Layer

Two muscles in the superficial layer are responsible for rotation of the head.

• Splenius Capitis: A thick rectangular musculus, the most superior of the neck muscles.
  • Attachments: Originates from the upper spine and attaches to the skull.
  • Actions: Rotates and extend the head and neck.
• Splenius Cervicis: A small triangular-shaped muscle located immediately beneath the splenius capitis.
  • Attachments: Originates from the spine and attaches several vertebrae higher.
  • Actions: Rotate and extend the head and neck.

Intermediate Layer

3 columnar muscles in the intermediate layer are responsible for flexion and extension of the neck equally well as posture maintenance. All three originate from a mutual tendon associated with the pelvis and can be divided into thoracic, cervicis, and capitis regions.

• Iliocostalis: The about laterally located of the three intermediate muscles.
  • Attachments: Originates from the mutual tendon and attaches to the ribs and lower neck.
  • Deportment: Extends and controls abduction and adduction of the spine and neck.
• Longissimus: Located betwixt the iliocostalis and spinalis muscles, this is the largest of the intermediate layer muscles.
  • Attachments: Originates from the common tendon and attaches to the lower ribs, the spine, and the skull.
  • Deportment:  Extends and controls abduction and adduction of the spine and neck.
• Spinalis: The most medially located and smallest of the 3 intermediate layer muscles.
  • Attachments: Originates from the common tendon and attaches to the upper spine and skull.
  • Deportment:  Extends and flexes to control abduction and adduction of the spine and neck.

Deep Layer

Two muscles in the deep layer are responsible for maintenance of posture and rotation of the neck.

• Semispinalis: The semispinalis is the most superficial of the deep muscles.
  • Attachments: A broad origin on the upper regions of the spine, with each origin attaching several vertebrae higher or to the skull.
  • Actions: Extends and rotates the head and maintains posture.
• Multifidus: The multifidus is located underneath the semispinalis musculus and is key in maintaining posture.
  • Attachments: A broad origin upwards the length of the spine, with each origin attaching several vertebrae higher.
  • Actions: Maintains posture through the spine.

Other Muscles That Act on the Neck

Several other muscles act on the head and neck. Below are three with a larger affect.

• Trapezius: The trapezius is the most superficial muscle of the dorsum and forms a broad flat triangle.
  • Attachments: The trapezius originates from the skull and spine of the upper back and neck. It attaches to the clavicle and scapula.
  • Actions: The superior region supports the arm and elevates and rotates the scapula. Information technology controls adduction, abduction and rotation of the head, the intermediate region retracts the scapula, and the inferior region rotates and depresses the scapula.
• Sternocleidomastoid: A thick rectangular musculus that is responsible for many movements inside the neck.
  • Attachments: Dual-headed, the sternocleidomastoid originates from the clavicle and the sternum and attaches to the mandible.
  • Actions: Abduction, adduction, extension, flexion, and rotation of the neck depending on intra and inter-muscle contractions.
• Platysma: A broad sheet of muscle arising from the fascia covering the pectorals.
  • Attachments: Originates from the fascia covering the pectorals and attaches to various locations inside the mandible and dermis of the face up and neck.
  • Actions: Depresses the mandible and angles the lip and mouth, wrinkling the peel upon the cervix flexing.

Primal Movements

• Extension (tilting head backwards): Produced by the semispinalis, splenus capitis, longissimus, trapezius (superior fibers), and sternocleidomastoid (posterior fibers).
• Flexion (tilting head forwards): Produced by the sternocleidomastoid (anterior fibers).
• Abduction (tilting head towards shoulder): Produced by the sternocleidomastoid, longissimus, splenius capitis, semispinalis, and trapezius (superior fibers)
• Adduction (returning head to midline): Produced past the sternocleidomastoid, longissimus, splenius capitis, semispinalis, and trapezius (superior fibers)
• Rotation (rotation caput to left or correct): Produced by the sternocleidomastoid, longissimus, splenius capitis, semispinalis, and trapezius (superior fibers)

Source: https://courses.lumenlearning.com/boundless-ap/chapter/head-and-neck-muscles/

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