BIO 201 MUSCLE SYSTEM LAB GUIDE

Abbreviation key

L= Location

A= Action

O= Origin

I= Insertion

Occipitalis

L: Covers occipital bone

A: Retracts scalp/pulls backward

Frontalis

L: Covers frontal bone

A: Elelevates eyebrows/wrinkles forehead

Temporalis

L: Covers squamous portion of temporal bone & attached to mandible.

A: Elevates and retracts mandible, agonist (prime mover) of mandible elevation.

Masseter

L: Covers ramus of mandible.

A: Elevates mandible, clenches teeth (aids chewing).

Zygomaticus

L: Zygomatic bone to corners of mouth

A: Lifts corner of mouth in a smile

Buccinator

L: Fleshy part of the cheek - between mandible & maxillae

A: Compresses cheek; holds food between teeth during chewing, contracted when blowing (i.e., balloon, trumpet)

Orbicularis oculi

L: Around eye.

A: Winking, blinking, closing eyelid.

Orbicularis oris

L: Around mouth

A: Puckering

Nasalis

L: Sides of nose

A: Twitch nose, flaring nostrils

Sternocleidomastoid

L: Sides of neck extending to chest

A: Bilateral action: flexes neck. Unilateral action: lateral flexion of neck and rotation of head to opposite side. Elevates sternum upon forceful inhale.

O: Two heads, one on sternum (sterno-), one on clavicle (cleido-).

I: Mastoid process of the temporal bone

Platysma

L: Superficial neck muscle

A: Pulls outer edges of lower lip down; tense skin of neck

O: Fascia of deltoid and pectoralis major muscles, and acromion of scapula.

I: Skin of cheek and mandible

Trapezius

L: Upper back & neck (2 peices, together = diamond-shaped)

A: Elevates, retracts, and depresses scapula; also, rotates scapula superiorly; adducts scapulae together; shrugs shoulders

Latissimus dorsi

L: Lower back to humerus, forms posterior armpit

A: Extends, adducts, and medially rotates arms, i.e. as in the downward stroke of the butterfly when swimming. Antagonistic to pectoralis major (arm extension); synergistic to pectoralis major (adduction and medial rotation of humerus).

Pectoralis major

L: Upper chest, sternum to humerus, forms anterior armpit

A: Flexes arm (agonist), adducts and medially totates arm, Antagonistic to latissimus dorsi.

Pectoralis minor

L: Deep muscle under pectoralis major (ribs to coracoid process of scapula).

A: Abducts and depresses scapula (hunched shoulders), can aid in inhalation.

Intercostals

L: Between ribs (external & internal layers on opposite bias).

A: External intercostals aid in quiet and forced inspiration. Internal intercostals depress ribs in forced expiration.

Serratus anterior

L: Under arms and below pectoralis minor (from ribs to scapula)

A: Abducts scapulae and pulls them forward. Antagonisitc to trapezius.

Rectus abdominis

L: "6 pack" in front of abdomen (2 longitudinal strips, from ribs &sternum to pubis bones).

A: Flexes trunk, sit ups ,crunch compresses abdominal wall.

External oblique

L: Superficial muscle along lateral abdominal wall.

A: Flexion, twisting, turning of the trunk, compression of abdomen

Internal oblique

L: Deep to external oblique and superior to transversalis

A: Compression of abdomen

Transversalis

L: Inner wall

A: flexion, twisting, turning of the trunk, compression of abdomen.

Levator ani

L: Floor of pelvic cavity; group of muscles forming anterior and lateral pelvic diaphragm.

A: Support pelvic organs, elevates anus

Diaphragm

L: Dome-shaped muscle between thoracic and abdominal cavities

A: Contraction expands the thoracic cavity causing inspiration

Deltoid

L: Top of shoulder

A: Too long to say

O: Clavicle and scapula

I: Deltoid tuberosity of humerus

Biceps brachii

L: Anterior arm

A: Flexes forearm (biceps curl with supine palm). Antagonistic to triceps brachii.

Triceps brachii

L: Posterior arm

A: Extends forearm . Antagonistic to biceps

Brachialis

L: Anterior arm, deep to biceps brachii

A: Prime flexor of arm (elbow flexion)

Brachioradialis

L: Anterolateral surface of foreman

A: flexes arm (elbow flexion)

O: distal, lateral humerus

I: Styloid process of radius bone

Pronator teres

L: Proximal, anterior surface of forearm.

A: Pronates palm, Antagonistic to supinator

Flexor carpi radialis

L: Anterior forearm

A: Abduction; Antagonistic to extensor carpi muscles

Flexor carpi ulnaris

L: Anterior forearm

A: Adduction; Antagonistic to extensor carpi muscles

Extensor carpi radialis longus

L: Posterior forearm

A: Abducts the hand; Antagonistic to flexor carpi muscles.

Extensor carpi radialis brevis

L: Posterior forearm

A: Abducts the hand; Antagonistic to flexor carpi muscles.

Extensor carpi ulnaris

L: Posterior forearm

A: Adducts the hand; Antagonistic to flexor carpi muscles.

Flexor digitorum

L: Anterior forearm

A: Flexes fingers; Antagonist to extensor digitorum

Extensor digitorum

L: Posterior forearm

A: Extend fingers; Antagonist to flexor digitorum

Gluteus maximus

L: Posterior leg muscle in gluteal region

A: Extends thigh; laterally rotates thigh

Gluteus medius

L: Upper thigh

A: Abducts thigh; medially rotates thigh

O: Lateral surface of ilium

I: Greater trochanter of femur

Gluteus minimus

L: Deep muscle under gluteus medius

A: Abducts thigh; medially rotates thigh; synergistic to gluteus medius.

Rectus femoris

L: Middle, anterior thigh

A: Flexes thigh, extends leg (straightens knee)

Vastus lateralis

L: Just above knee, lateral thigh

A: Extends leg; synergist with rectus femoris

Vastus medialis

L: Just above knee, medial thigh

A: Extends leg; synergist with rectus femoris

Vastus intermedius

L: Deep muscle, under rectus femoris

A: Works synergistically with the other quads to help extend leg.

Biceps femoris

L: Posterior, lateral thigh

A: Flexes knee, extends hip and laterally rotates leg

Semitendinosus

L: Posterior, medial thigh

A: Flexes knee, extends hip and medially rotates leg

Semimembranosus

L: Deep muscle, under semitendinosus

A: Flexes knee, extends hip, medially rotates leg

Tensor fasciae latae

L: Lateral hip (from the iliac crest to the fascia of thigh)

A: Abducts and medially rotates the thigh (elevates leg at 45 degree angle). Antagonistic to gracilis and adductors; synergistic to gluteus medius

Sartorius

L: Strap-like muscle crossing the thigh

A: Flexes hip when lifting and everting knee (sit crisscross)

O: Anterior, superior iliac spine

I: Medial, proximal tibia

Adductors

L: Medial, anterior upper thigh

A: Adduct thigh (gripping with knees when riding horseback, "Thigh Master"). Synergistic to gracilis

Gracilis

L: Medial most thigh muscle, (pubic bone to medial proximal tibia)

A: Adducts and flexes thih, flexes leg. Antahonistic to tensor fasciae latae; synergistic to adductors

Gastrocnemius

L: Posterior aspect of leg

A: Flexes leg; plantar flexion (agonist)

O: Distal femur

I: Calcaneus via canaeal (Achilies) tendon

Tibialis anterior

L: Anterior, lateral lower leg (fills gap between tibia & fibula)

A: Flexes ankle (dorisflexion). Antagonistic to gastrocnemius

Fibularis longus

L: Lateral aspect of leg, overlies fibula

A: Eversion of the sole of the foot, also aids plantar flexion. Antagonistic to tibialis anterior (inversion and eversion and dorsi and plantar flexion), synergistic with soleus (plantar flexion)

Soleus

L: Deep muscle to the body of gastrocnemius

A: Plantar flexion. Synergist to gastrocnemius and fibularis longus.