Anatomy - Outcome 11 Flashcards by Jayden Bohn

What are muscles composed of?

Each muscle is composed of several small fibers held together by a thin membrane like fascia which allows the muscles to be serparated from other structures in the area

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Each muscle has an origin and an insertion…

the orgin is usually fixed, or the least movable structure

the insertion is usually attached to the more moveable structure

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What percentage do muscles make up of the body’s weight?

40-50%

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There are essentially 3 types of muscle tissue:

cardiac - found in the heart
smooth - located in the stomach, intestinal walls, blood vessels, urinary tract and ducts
skeletal - responsible for bodily movements and breathing

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Skeletal Muscle

Each skeletal muscle consists of a body and two attachments. The body contains muscular tissue. The attachments are fibrous tissue and attach the muscle at both ends to bones, ligaments, tendons, skin, or sometimes to each other

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Depression definition

to lower or closer

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Elevation definition

to lift or close

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Lateral excursion definition

to move side to side

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Mastication definition

to chew and grind

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Protrusion definition

to move forward or extend

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Retrusion definition

to pull backward or inwards

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What is Mastication?

a series of highly coordinated functions that involve the teeth, tongue, muscles of mastication, lips, cheeks, and sailva in the preparation of food for swallowing and digestion

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There are three starges of mastication:

Cutting of food
Crushing of food into smaller particles
Grinding of food

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When the impulse to massticate food..

When the impulse to masticate food is relayed along with the muscles of mastication, the mucle fibers shorten, pulling toward their origin and thus providing joint action. This reflex action allows the muscles of mastication to play a major role in preparing food for swalloing

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The rest position

The teeth are arranged in both arches so that when the muscles of mastication bring the jaws together, the teeth meet in a function relationship known as occlusion, with the upper and lower teeth not quite in contact, but with a space of 2 to 5mm betwween the anterior teeth. This is known as the rest position

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The muscles of mastication have the ability to…

Have the ability to move the lower jaw (mandible) from side to side, as well as the ability to protract or retract the mandible

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The act of mastication consists of…

Placing food between the anterior teeth and closing until the teeth meet with the lower incisors to the lingual of the upper incisors. Then, with a shearing motion, a piece of food is cut free. The portion is then transfered by the tongue to the posterior teeth and is held in position by the cheeks and positerior teeth to reduce the food to “bits”. After the food has been prepared for swallowing, the tongue propels it against the posterior of the palate and into the pharynx, and down into the stomache

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Masseter Muscle - Origin & Insertion

Origin: zygomatic arach (lower boder and medial side) fibers run downard and slightly backward

Insertion: angle of the mandible, lateral side

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Temporal Muscle - Origin & Insertion

Origin: Temporal fossa superior to the suture joining the temporal and paretal bones

Insertion: Coronoid process of the mandible

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The Medial (Internal) Pterygoid - Origin & Insertion

Origin: pterygoid plate and fossa (part of the sphenoid bone) and maxillary tuberosity

Insertion: angle of the mandible (medial side)

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The Lateral (External) Pterygoid - Origin & Insertion

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Origin: has 2 separate origins..
-greater wing of the sphenoid bone
-pterygoid plate of the sphenoid bone

Insertion: temporomandibular joint neck of the condyle

The Masseter Muscle Function

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-probably the most powerful of the muscles of mastication

Function:
1. Elevates the mandible, closing the mouth
2. Clenches the teeth
3. Brings the molars together for crushing and grinding

The Temporal Muscle (Temporalis) Function

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has a wide span and supports the overall action of closing the lower jaw ultimately closing the mouth

Function:
1. Elevation of the mandible, forceful retraction, and retrution of the mandible
2. The final “squeeze” when closing

The Medial (Internal) Pterygoid Function

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This muscle parallels the masseter but iis not as powerful. The masseter and the medial pterygoid form a “sling” for the mandible, with the masseters inserting on the lateral side and the medial pterygoid inserting on the medial side of the angle of the mandible

Function:
1. Elevate the mandible, close the mouth

The Lateral (External) Pterygoid Function

-is a short, thick muscle that extends horizontally, in a posterior direction Function: 1. Protrusion of the mandible 2. Side-to-side movement of the mandible

What muscles accomplish depression of the mandible/opening the mouth?

Muscles in the neck referred to as the hyoid muscles accomplish opening the mouth

The Hyoid Bone

A horshoe-shaped bone suspended beneath the mandible

2 Groups of the Hyoid Muscles

The suprahyoid (above the hyoid) muscles The infrahyoid (below the hyoid) muscles

The suprahyoid muscle group includes

-digastric muscle -stylohyoid muscle -mylohyoid muscle -geniohyoid muscle The muscles form the floor of the mouth. They are responsible for the elevation of the hyoid bone, as well as the depression of the mandible

The infrahyoid muscle groups include

-omohyoid muscle -sternohyoid muscle -stenothyroid muscle -thyrohyoid muscle - these muscles are responsible for depressing the hyoid bone and the larynx. They are located deep within the throat area

The Muscles of Mastication

-Massetter Muscle -Temporal Muscle -The Medial (Internal) Pterygoid -The Lateral (External) Pterygoid

The Muscles of Facial Expression

-Buccinator Muscle -The Orbicuaris Oris -The Mentalis Muscle -The Zygomatic Major -The Zygomatic Minor

Buccinator Muscle Origin & Insertion

Origin: alveolar process, molar area, buccal aspect Insertion: obicularis oris, at the corners of the mouth

The Orbiularis Oris Origin & Insertion

Origin: many layers of fibers surrounding the mouth Insertion: angles of the mouth

The Mentalis Muscle Origin & Insertion

Origin: Anterior surface of the mandible, just below the lateral incisors Insertion: skin of the chin

The Zygomatic Major Origin & Insertion

Origin: zygomatic bone Insertion: into the orbicularis oris at the angle of the mouth

The Zygomatic Minor Origin & Insertion

Origin: Zygomatic bone Insertion: Orbicularis oris, toward the midline

Paired Muscles of Facial Expression

The actions of paired muscles on each side of the face are usually symmetrical. A loss of symmetry may often be an early sign of injury to the facial nerve on one side

Muscles of Facial Expression - Superficial vs. Deeper

it should be noted that some are superficial, while others are located deeper within the body.

The Buccinator Muscle Function

-is the principle cheek muscle. Although it is a muscle of facial expression, it also plays a role in mastication Function: 1. Pulls the corners of the mouth backward 2. Compresses the cheeks 3. Forces food onto occlusal surfaces of teeth 4. Expels air between the lips

The Orbicularis Oris Function

-sometimes called the kissing muscle. It circles the oral cavity in the tissue of the lips Function: 1. Compresses, contracts and protrudes the lips 2. Keeps food in the mouth 3. Assists in facial expression

The Zygomatic Major Function

-is the prominent muscle on the cheek. It elevates the angle of the mouth creating a smile Function: 1. Draws the angles of the mouth upward and backward (laughing)

The Zygomatic Minor Function

-is a smaller muscle of the mouth coming from the area of the zygomatic bone. It is ysyalyl a very poorly developed muscle Function: 1. Raises the upper lip

Muscles of the Neck

-Trapezius -Sternocleoidmastoid -Platysma

The Trapezius

- is a large, flat, triangular-shaped muscle covering the back of the neck, shoulder, and clavicle Origin: occipital bone Insertion: clavicle and shoulder Function: moves the head backwards and sideways - turns the skull

The Sternocleoidmastoid

-also called the "sternomastoid" muscle Origin: The sternum and clavicle Insertion: the mastoid process of the temporal bone Function: Tilting and rotating the head

The Platysma

- is a thin sheet of muscle located just below the skin of the neck Origin: clavicle and shoulder Insertion: lower border of the mandbile, near the angle of the mouth Function: wrinkles the skin of the neck and chin and draws lower lip down and back

Extrinsic Muscles of the Tongue Functions

The extrinsic or external muscles of the tongue allow movement and essentially all functions of the tongue. They facilitate speech, swallowing, and position of the tongue

Extrinsic Muscles of the Tongue

-genioglossus -hypoglossus -styloglossus

Major Muscles of the Soft Palate Functions

The muscles of the soft palate facilitate swallowing by raising the soft palate. The form the tonsillar pillars and include: -Palatoglossus -Palatopharyngeal

Anatomy - Outcome 11 Flashcards

(50 cards)