Muscles Flashcards
Define skeletal muscle
- voluntary striated muscle that is usually attached to one or more bones
- Human muscular tissue consists of 40 to 50% of body weight.
What are the five physiological characteristics of muscle?
1-irritability [responsiveness]
- it is a property of all living cells but muscles and nerves cells have developed this property to the highest degree
- It is often referred to as excitability.
- It is the property of receiving stimuli (For example cold, a change in environment) and responding to them.
- muscle response to the stimuli is “contraction”
2-contractility
- it is the property that enables muscles to change their shape and become shorter and thicker
3-elasticity
-When a muscle cell is stretched and then the tension is released, it recoils to its original resting length. Elasticity is often misunderstood as the ability to stretch, refer to this tendency of a muscle cell to return to the original length when tension is released.
4-conductivity
-stimulation of a muscle fibre produces more than a local effect. The local electrical charge triggers a wave of excitation that travels rapidly along the fibre and initiates processes leading to muscle contraction.
5-Extensibility
- in order to contract, a muscle cell must be extensible – able to stretch again between contractions. Most cells rupture if they are stretched even a little, but skeletal muscle fibres can stretch to as much as three times their contracted length.
All muscle in the body is due to which three types of muscle?
- Skeletal or striated
- Smooth
- cardiac
Describe skeletal or striated muscle
- Contraction allows the movement of the entire body and is under voluntary control
- Skeletal muscles are attached to the bones
- make up a large percentage of body mass
- Nerve impulses trigger a reaction from the muscle which contracts, moving its associated bone or joint
Describe smooth muscle, non-striated muscles also known as involuntary or visceral
- Function automatically, without conscious will
- These muscles are found in digestive and circulatory system as well as some internal organs of the body
Describe cardiac muscle
- Involuntary muscle that makes up the heart
- This type of muscle is unique and not found in any other part of the body
- It is striated and has a Crossing, banding pattern that allows contraction and that’s the beating of the heart
- It is under the control of the autonomic nervous system
Describe how muscles are attached to the bone
- Muscles are attached to the bone by cordlike structures of dense connective tissue with the extension of loose fibers… These are called tendons
- Tendons extend into and surround all the muscle tissue forming the whole muscle
Name the three parts of the muscles
- The origin – is the more fixed part of the muscle closest to the skeleton, which flexes but remain stationary
- The belly- the middle part of the muscle
- The insertion – the part of the muscle which is the moveable attachment and farthest from the skeleton.
- insertion of facial muscle is in skin not bone.
Describe pressure of massage in relation to these three muscle parts
- Pressure in massage is usually directed from insertion to the origin
- When many fibres are stimulated together they produce a shortening of the whole muscle and tension between the two ends
- if the stimulus is prolonged or done too frequently, the muscle may become fatigued
Where is the orbicularis oculi located and what action does it perform?
Action:
-close the eyelids.
-Draws lacrimal canal onto the surface of the eye.
-Muscle pulls on lacrimal sac
Origin: frontal bone and maxilla at medial margin of orbit and palpebral ligament
Insertion: same as origin
Where is the levator palpebrae superioris located and what action does it perform?
Action:
Raises upper eyelid or voluntarily open the eye
* Opposes orbicularis oculi
Origin: inferior surface of lesser wing of sphenoid
Insertion: tarsal plate of upper eyelid

Where is the corrugator supercilii located and what action does it perform?
Action: draws eyebrows medially and inferiorly
Origin: arch of frontal bone above nasal bone
Insertion: skin above the middle of the supraorbital margin and above the nasal bone
And where is the procurus located and what action does it perform?
Action: draws down medial angles of eyebrows and produces transverse wrinkles over the bridge of the nose
Origin: fascia over nasal bone and lateral nasal cartilage
Insertion: skin over the lower for head between the eyebrows
Where is the orbicularis Oris located and what action does it perform?
Origin: arises indirectly from the maxilla and mandible; fibres blend with the fibres of other facial muscles associated with the lips
Insertion: encircles mouth and inserts into muscle and skin at angles of mouth
Action: closes and protrudes the lips, Compresses lips against teeth
Where is the nasalis located and what action does it perform?
Origin: maxilla below infraorbital foramen
Insertion: muscle from opposite side over bridge of nose
Action: covers the nose, flares the nostrils, Maintain opening of nares during forceful inspiration
Where is the Levator labii superioris located and what action does it perform?
Origin: zygomatic bone and infraorbital margin of maxilla
Insertion: skin and orbicularis Oris muscle of upper lip
Action: elevates the upper lip
Where is the Lavator anguli Oris [Zygomaticus major synergist] located and what action does it perform?
Origin: canine Fossa of maxilla
Action: elevates corners of the mouth
Insertion: angle of mouth, blending with fibres of zigomaticus major, depressor anguli oris, and orbicularis oris muscles
Where is the zygomaticus major and minor and what action do they perform together?
Action: draws angle of the mouth upward and outward, elevates the lips: as in laughing
Origin Minor: zygomatic bone
Action minor: elevates upper lip and produces nasal labial furrow
Insertion: angle of mouth blending with the levator anguli Oris, orbicularis Oris, and depressor anguli Oris muscles
Origin major: zygomatic bone
Action: draws angle of mouth upward and outward
Insertion: angle of mouth blending with the levator anguli Oris, orbicularis Oris, and depressor anguli Oris muscles
Where is the risorius located in what action does it perform?
Action: draws angles of the mouth out and back {[laterally]
Origin: lateral fascia over masseter muscle and parotid gland
Insertion: skin at angle of the mouth
Where is the depressor labii inferioris located and what action does it perform?
Action: draws lower lip inferiorly and laterally during mastication
Origin: body of the mandible lateral to the midline, between the mandibular symphesis and mental foreman
Insertion: skin and muscle of lower lip blending with fibres of orbicularis Oris
Where is the depressor anguli Oris and what action does it perform?
Action: draws angles of the mouth downward and laterally
Origin: oblique line of mandible
Insertion skin and muscle at angle of mouth below insertion of zygomaticus
Where is the Mentalis located and what action does it perform?
Action: elevates and protrudes lower lip, wrinkling the skin of the chin
Origin: incisive fossa of mandible
Insertion: skin of chin
Where is the frontalis located and what action does it perform?
Action: draws back the scalp and aids in wrinkling the forehead. Also involved in headaches. 
Origin: lateral 2/3 of superior nuchal line of occipital and masturbated process of temporal
Insertion: galea aponeurotica covering skull
Name the muscles of mastication [chewing]
-buccinator
-temporalis
-masseter
(Frontalis)
Where is the Buccinator located and what action does it perform?
Action: chewing, whistling, sucking. Compresses cheek, draws corner of mouth laterally.
Origin: outer surface of alveolar process of maxilla and mandible and Pterygomandibular raphe
Insertion: angle of mouth blending with fibres of the orbicularis Oris muscle
Where is the temporalis located in what action does it perform?
Action: elevating and stabilizing the jaw. Elevates and retracts mandible, assists inside to side movement of the mandible
-synergist in mouth closure
Origin – entire rim of the temporal Fossa of the skull. Temporal fossa and temporal fascia
Insertion – coronoid process of the mandible Via a tendon that passes deep to the Ziggomatic arch
Where is the masseter located in what action does it perform?
Action: elevating the jaw/clenching the teeth. Elevates mandible and slightly protract it
Origin: zygomatic process of maxilla and medial and inferior surfaces of zygomatic arch
Insertion angle and ramus of the mandible
Where is the platysma [Murphy Brown neck] located and what action does it perform?. [Muscles of the neck]
Action: draws down the lower jaw and lower lips, and angle of mouth. Tenses skin of neck; helps depress mandible
Origin- subcutaneous fascia covering the pectoralis major and the deltoid.
Insertion- lower margins of mandible, and subcutaneous fascia and muscles of jaw and mouth
Where is the sternocleidomoastoid located and what action does it perform?
Action: Bends the neck up-and-down, rotates head to opposite sides
Origin - [inferior attachment] sternal head: manubrium of sternum. Clavicular head: superior border of medial third of clavicle.
Insertion – [superior attachment]: mastoid process of temporal and lateral half of superior nuchal line
