Muscles

Question 1

Define skeletal muscle

Answer 1

• voluntary striated muscle that is usually attached to one or more bones
• Human muscular tissue consists of 40 to 50% of body weight.

Question 2

What are the five physiological characteristics of muscle?

Answer 2

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.

Question 3

All muscle in the body is due to which three types of muscle?

Answer 3

• Skeletal or striated
• Smooth
• cardiac

Question 4

Describe skeletal or striated muscle

Answer 4

• 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

Question 5

Describe smooth muscle, non-striated muscles also known as involuntary or visceral

Answer 5

• Function automatically, without conscious will

- These muscles are found in digestive and circulatory system as well as some internal organs of the body

Question 6

Describe cardiac muscle

Answer 6

• 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

Question 7

Describe how muscles are attached to the bone

Answer 7

• 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

Question 8

Name the three parts of the muscles

Answer 8

1. The origin – is the more fixed part of the muscle closest to the skeleton, which flexes but remain stationary
2. The belly- the middle part of the muscle
3. 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.

Question 9

Describe pressure of massage in relation to these three muscle parts

Answer 9

• 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

Question 10

Where is the orbicularis oculi located and what action does it perform?

Answer 10

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

Question 11

Where is the levator palpebrae superioris located and what action does it perform?

Answer 11

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


Question 12

Where is the corrugator supercilii located and what action does it perform?

Answer 12

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

Question 13

And where is the procurus located and what action does it perform?

Answer 13

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

Question 14

Where is the orbicularis Oris located and what action does it perform?

Answer 14

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

Question 15

Where is the nasalis located and what action does it perform?

Answer 15

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

Question 16

Where is the Levator labii superioris located and what action does it perform?

Answer 16

Origin: zygomatic bone and infraorbital margin of maxilla
Insertion: skin and orbicularis Oris muscle of upper lip
Action: elevates the upper lip

Question 17

Where is the Lavator anguli Oris [Zygomaticus major synergist] located and what action does it perform?

Answer 17

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

Question 18

Where is the zygomaticus major and minor and what action do they perform together?

Answer 18

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

Question 19

Where is the risorius located in what action does it perform?

Answer 19

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

Question 20

Where is the depressor labii inferioris located and what action does it perform?

Answer 20

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

Question 21

Where is the depressor anguli Oris and what action does it perform?

Answer 21

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

Question 22

Where is the Mentalis located and what action does it perform?

Answer 22

Action: elevates and protrudes lower lip, wrinkling the skin of the chin
Origin: incisive fossa of mandible
Insertion: skin of chin

Question 23

Where is the frontalis located and what action does it perform?

Answer 23

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

Question 24

Name the muscles of mastication [chewing]

Answer 24

-buccinator
-temporalis
-masseter
(Frontalis)

Question 25

Where is the Buccinator located and what action does it perform?

Answer 25

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

Question 26

Where is the temporalis located in what action does it perform?

Answer 26

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

Question 27

Where is the masseter located in what action does it perform?

Answer 27

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

Question 28

Where is the platysma [Murphy Brown neck] located and what action does it perform?. [Muscles of the neck]

Answer 28

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

Question 29

Where is the sternocleidomoastoid located and what action does it perform?

Answer 29

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

Question 30

What is muscle tone?

Answer 30

- Muscle is always under some degree of contraction and this is referred to as tone - The tone of the striated or skeletal muscle give certain firmness and maintains a slight steady pull on the attachment even when the muscle is at rest

Question 31

What is the zygomaticus major?

Answer 31

Draws angle of the mouth upward and outward

Question 32

What is the zygomaticus minor

Answer 32

Elevates the upper lip and produces nasal labial furrow