Unit 6 Myology Bryce LaRoche

How many muscles are in the body?

There are 650 skeletal muscles

What are the characteristics of muscles?

Excitability and Contractility

What does excitability mean?

The capacity to generate electrical impulses (Action Potentials)

What does Contractility mean?

The capacity to shorten in length

What are the only two cells in the body that exhibit excitability?

Muscle and nervous cells

What are the three functions of muscles?

Voluntary movement, maintenance and of body posture, and heat production.

What is the tendon of origin commonly called?

The head or “ceps”

What does the tendon of origin connect to?

The less movable structures

What is the tendon of insertion commonly called?

The “tail” of the muscle

What does the tendon of insertion connect to?

More movable structures

What are the three layers of the fascia?

Epimysium, Perimysium, and endomysium

What does a Somatic Motor unit consist of?

A motor neuron and all the muscle fibers it stimulates.

What are proprioceptors?

sensory neurons that supply muscles

What is an agonist?

Is a muscle that causes a desired action

What is a synergist muscle?

A muscle that acts with an agonist

What is an antagonist muscle?

A muscle that causes the opposite action for the agonist

What is a fixator or stabilizer?

The muscle that stabilizes body position and decreases unnecessary movement

What are the characteristics of muscles used in maximal training?

White in color due to low myoglobin content.

What are the characteristics of muscles used in sub-maximal training?

Smaller in diameter and darker in color because of high myoglobin content.

Frontalis

The Muscle above the Frontal bone

Orbicularis Oculi

The muscle that closes the eyelids

Orbicularis Oris

Puckers the lips

Buccinator

Compresses the cheek, as when blowing

Platysma

Pulls lower lip and jaw downwards

Zygomaticus

Does smiling

Superior Rectus

Elevates eye

Inferior Rectus

Depresses eye

Medial Rectus

Rotates the eye medially

Lateral Rectus

Rotates the eye laterally

Temporalis

Elevates the mandible and thus closes the jaw

Masseter

Synergist with the Temporalis; ie elevates mandible

Genioglossus

Sticks the tongue out

Styloglossus

Pulls the tongue back in

What are general characteristics of facial muscles?

They are superficial, insert into he overlying skin, develop from the branchial arches, and they are innervated by the facial nerve (VII)

What nerve innervates the facial muscles?

The Facial Nerve (VII)

What is the action of the frontalis?

Raises the eyebrows and wrinkles the forehead

What muscle closes the eyelids?

The Orbicularis Oculi

What muscle is responsible for squinting, blinking, and winking?

The Orbicularis Oculi

What muscle puckers the lips?

THe Orbicularis Oris

What muscle compresses the cheeks?

The Buccinator

What muscle pulls the lower lip downward?

Platysma

What is Bell’s Palsy?

Unilateral paralysis of the facial nerve often from inflammation

How many muscles move the eye?

Four

What muscle elevates the mandible?

Masseter

What nerve innervates the tongue?

Glossopharyngeal Nerve (IX)

What are the two characteristics of the muscles of the vertebral column?

Permits movement of the spine and stabilizes the spine when moving limbs

What are prevertebral muscles responsible for?

Flexing the spine and pulling the spine to one side

Sterniocleidomastoid

Flexes the neck

External Oblique

Flexes the waist left to right

Internal oblique

Flexes the waist back and forth

Transverse abdominus

Goes across the abdomen, flexes the waist

Rectus Abdominus

Goes upright across the abdomen, flexes the waist

Quadratus Lumborum

Below the abs

Iliopsoas

Extends waist

Why is iliopsoas called the “Switch Hitter” muscle?

It can flex and extend the waist

What are post vertebral muscles responsible for?

Extension of the spine and pulls the spine to one side

Splenius

Extends the neck

What are the three muscles of the erector spinae?

Spinalis dorsi, longissimus dorsi, and iliocostalis dorsi

Trapezius

Pulls the shoulders towards the midline; can also elevate the shoulders

What are the three parts of the trapezius

Clavotrapezius, spinotrapezius, and acromiotrapezius.

Rhomboideus

Pulls shoulders towards the midline

Serratus Anterior

Pulls the shoulders downwards toward the ribs

What does abduct mean?

To pull

Deltoid

Abducts the arm

Supraspinatus

Abducts the arm

What does it supinate?

The Deltoid

Biceps Brachii

Both heads originate on the scapula, insert at the radial tuberosity of the radius, flexes the forearm, and supinates the hand.

Brachialis

Originates on the distal end of the humerus, inserts on the coronoid process of the ulna, flexes the forearm and synergizes with the biceps Brachii

Brachioradialis

Originates on the distal end of the humerus, inserts on the styloid process of the radius, flexes the forearm and synergizes with the biceps brachii

Triceps Brachii

Originates on the long head of the scapula, land lateral and medial heads of the humerus, inserts on the olecranon process of the unla, extended the forearm and synergizes with the antagonist of the biceps brachii)

Flexor carpi radialis

Originates in the medial epicondyle of the humerus, inserts on the metacarpal bones and phalanges, and flexes and abducts the hand (the thumb)

Palmaris Longus

Originates in the medial epicondyle of the humerus, inserts on the metacarpal bones and phalanges, and flexes the hand (the middle three fingers)

Flexor Carpi Ulnaris

Originates in the medial epicondyle of the humerus, inserts on the metacarpal bones and phalanges, flexes and adducts the hand (Pinky finger)

Pronator Teres

Originates in the medial epicondyle of the humerus, inserts on the metacarpal bones and phalanges, pronates the hand (makes it palm down), antagonist of the biceps brachii

Extensor Carpi Radialis

Originates in the lateral epicondyle of the humerus and inserts in the metacarpal bones and phalanges, extends and abducts the hand (thumbs up).

Extensor Carpi Ulnaris

Originates in the lateral epicondyle of the humerus and inserts in the metacarpal bones and phalanges, extends and abducts the hand (the Pinky)

Thennar Eminence

Permits movement of the thumb, makes it opposable

Levator Ani

Origin: pubic arches, Insertion: coccyx bone, Action: supports the pelvic organs

Bulbocavernosus

Constricts vaginal opening and contracts during orgasm

Tensor Fascia Lata

Origin: Iliac crests via a broad sheet of fascia called the fascia lata (“broad fascia”), Insertion: Lateral condyle of the tibia via broad sheet of fascia called the iliotibial band, Action: Abducts the thigh

Gluteus Maximus

Forms the mass of th ebuttocks, extends and rotates the thigh laterally (antagonist of the tensor fascia lata), the upper lateral quadrant of this muscle is a commonly used site for intra-muscular (IM) injections

Quadriceps Femoris

Extends the lower leg, originates in the femur, inserts in the tibial tuberosity via the patellar tendon, and is innervated by branches of the femoral nerve.

Rectus Femoris

Located on the mid portion of the thigh

Vastus Lateralis

This muscle is a commonly used site for intra-muscular (IM)

Vastus Medialis

On the front inner thigh

Vastus intermedius

Located just below the Rectus femoris but is often difficult to separate from the other 3 parts of the quadriceps

Sartorius

A strap like muscle that extends diagonally across the anterior aspect of the thigh (the longest muscle in the body but not very strong). Originates in the anterior iliac spine, inserts in the tibia, and pulls the entire thigh up towards the hip, thus it flexes the thigh like the anterior muscles of the thigh

Gracilis

Appears as a very broad muscle in the cat, that almost crosses with the sartorius muscle (Dancers muscle)

Biceps femoris

This muscle is broader in the cat than it is in men, middle right back leg muscle of the hamstring

Semitendinosus

Inner muscle of the hamstring

Semimembranosus

2nd most inner muscle of the hamstring

Plantar Flexion

Moves the ankle downward

Dorsiflexion

Moves the ankle up

Tibialis Anterior

Located just lateral to the anterior crest, shin splints tendinitis of the tibialis anterior.

Extensor Digitorum Longus

Located int eh lateral aspect of the leg and extends the hallucis longus

Gastrocnemius

Calf muscles, originates in the tibia, inserts int eh calcaneus bone via the Achilles tendon, action plantar flexes the foot, innervated by branches of the tibial nerve

Soleus

Located in the calf below the gastrocnemius

Flexor Digitum longus

A deep muscle located on the postero-medial aspect of the leg that flexes the hallucis longus

Peroneus Longus

Everts the foot; plantarflexes the foot

Superficial posterior crural group (“calf muscles”) characteristics

Originate in the tibia, inserts int eh calcaneus bone via the Achilles tendon, plantarflexes the foot