Muscle Practical Lab

Key guide: O- origin and I-Insertion

Origin

portion of the muscle attached to an immovable structure (usually bone)

Insertion

portion of muscle attached to the movable structure (usually bone)

Agonist (brachii)

(Prime mover) the main muscle responsible for a given movement

Synergist (biceps brachii)

muscles that assist and stabilize the prime mover

Antagonist (triceps brachii)

muscle that resists the prime mover; responsible for the opposite motion

Occipitofrontalis (epicranius)

O: occipital; I: muscles around eye; top of cranium

raises eyebrows, pulls scalp posteriorly

Frontalis

Occipitalis

Epicranial aponeurosis

Orbicularis oculi

O: frontal bone & maxilla, orbit ligament; I: eyelid

closes eye; the "squinting muscle"

Sphincter

(muscle which decreases the size of an opening) surrounding eye

Orbicularis oris

O: maxilla & mandible, orbit ligament; I: muscle & skin encircling lips and mouth

sphincter muscle surrounding mouth;

purses lips, the "kissing muscle"

Buccinator

O: alveolar processes of maxilla & mandible; I: orbicularis oris

parallels body of mandible and forms the wall of cheek;

compresses cheek (as in blowing or sucking), holds food between teeth

Zygomaticus

O: zygomatic; I: orbicularis oris

muscles between cheek & mouth; the "smiling muscle" - raises lateral corner of mouth

Risorius

o: fascia of masseter; I: lateral mouth

parallel to mouth beneath zygomaticus, The “laughter muscle”

Platysma

O: fascia of upper chest; I: lower mandible

large sheet like muscle; pulls lower lip downward, "pouting muscle"

Mastication

Chewing Muscles

Masseter

O: zygomatic arch & maxilla, I: ramus & body of mandible

thick and powerful muscle anterior to the ear

closes the jaw and elevates mandible

Temporalis

O: temporal; I: coronoid process & ramus of mandible

broad muscle in the temple region

closes the jaw, elevates mandible, aids in grinding movements

Pterygoids

O: sphenoid, I: mandible

wing-like muscle (pterygoid = "wings") deep to masseter, synergist of masseter & temporalis

Medial pterygoids

Lateral pterygoids

Sternocleidomastoid

O: sternum & clavicle, I: mastoid process

long oblique muscles of lateral neck

flexes neck when both contract, rotate head when acting

Capitis group

extend, bend & rotate head

Splenius capitis

O: C7 - T3 spinous processes; I: mastoid process & occipital

oblique-band-like (= "splenium") muscle in back of head (=capit) most superficial of capitis group

Semispinalis capitis

deeper capitis muscle “along the spine” part of erector spinae group (below)

Longissimus capitis

Erector spinae group

O: lower spine, ribs & pelvis; I: ribs, C & T vertebrae

semispinalis, longissimus, & iliocostalis muscles

important group, muscle which lie along either side of the vertebral column

all extend and laterally bend the vertebral column, etc.

Semispinalis

Longissimus

liocostalis

Scalene group

O: transverse processes of c vertebrae; I: ribs 1 and 2

no need to distinguish – just know as a group 3 very deep muscles of lateral neck flex and slightly rotate the neck

External oblique

O: ribs 5-12, I: iliac crest & linea alba (center "line" of abdominal aponeurosis)

largest and most superficial abdominal muscle

Internal oblique

O: iliac crest, I: cartilage of ribs 10-12, linea alba deep to external oblique

Transversus abdominis

O: iliac crest, cartilage of ribs 6-12, I: linea alba, pubis, xiphoid process

deepest of the abdominal muscles

the obliques & transversus abdominis all compress the abdomen

Obliques

also bend the vertebral column laterally when the R or L contracts independently

Rectus abdominis

O: pubis; I: xiphoid process, ribs 5-7

straight (= rectus) large, superficial muscle separated by horizontal bands of CT

compresses abdominal contents, flexes vertebral column

Diaphragm

Separates abdominal and thoracic cavity; not on models. involuntary skeletal muscle for inhalation

External Intercostals

O: superior border of rib below; I: inferior border of rib above

11 pairs of muscles on the external rib cage

pull the rib cage up and out and aid in inhalation

Internal Intercostals

O: inferior border of rib; I: superior border of rib below

11 pairs of muscles on the internal rig cage–pull the rib cage down and in and aid in exhalation

Trapezius

(Scapula spine)

Serratus anterior

O: ribs 1-8, I: ventral scapula

large saw-like ("serratus") muscle along upper lateral thoracic cage, pulls shoulder anteriorly and inferiorly ("pushing / boxing muscle"), stabilizes shoulder

Rhomboideus

O: spinous process of T2-T5; I, vertebral border of scapula

large oblique (rhomboid: parallelogram) muscles between vertebral column & scapula;

steadies, elevates and retracts scapula

Pectoralis minor

O: anterior ends of rib 3-5; I: I: coracoid process

tripartite oblique muscle deep to the pectoralis major draws scapula anterior and inferior (with ribs fixed), draws ribs upward

Levator scapulae

O: transverse processes of C1 - C4, I: vertebral border of scapula

narrow muscle adjacent to capitis group elevates ("levator") scapula and bends neck laterally

Coracobrachialis (flexor)

O: coracoid process, I: medial surface of shaft of humerus

small muscle from scapula to medial upper arm toward the axillary region flexes and adducts

Pectoralis major (flexor)

O: clavicle, sternum, cartilage of ribs 2-6; I: greater tubercle

complex thick fan-shaped muscle of upper chest flexes, adducts (as in swimming) & rotates medially; pulls body up when arm is fixed (as in climbing)

Teres major (extensors)

O: inferior posterior scapula, I: lesser tubercle

thick round (= teres) muscle inferior to teres minor

extends, adducts and rotates medially

Latissimus dorsi (extensors)

O: spinous processes of T6-L5, sacrum, iliac crest, ribs 10-12,

I: intertubercular groove;

broad flat complex superficial muscle of lower back and sides

extends, adducts (climbing) and rotates arm medially

Supraspinatus (Abductors)

O: supraspinous fossa, I: greater tubercle

deep to deltoid & trapezius

abducts arm – very important stabilizer of the shoulder

Subscapularis (Rotators)

O: anterior scapula, I: lesser tubercle

large muscle covering the entire anterior surface of scapula

medial / internal rotation of arm

Infraspinatus (Rotators)

O: posterior scapula below spine, I: greater tubercle of humerus

superior to teres major & minor

lateral / external rotation of arm

Teres minor (Rotators)

O: axillary border of scapula, I: greater tubercle of humerus

inferior to infraspinatus and superior/deep to teres major

lateral / external rotation of arm

Rotator cuff

all 3 rotators and supraspinatus

“SITS” (supraspinatus, infraspinatus, teres minor, subscapularis)

it encircles most of the shoulder joint and holds the head of the humerus in the glenoid fossa

very common sight of muscle and tendon tearing in athletic injuries

Biceps brachii (flexor)

O: coracoid process (short head); above glenoid cavity of scapula (long head)

I: radial tuberosity

long two-headed superficial muscle of anterior upper arm

flexes and supinates forearm; weakly flexes upper arm

Brachialis (flexor)

O: distal anterior humerus, I: coronoid process of ulna

muscle deep to biceps brachii

most powerful forearm flexor

Brachioradialis (flexor)

O: proximal to lateral epicondyle of humerus, I: distal radius

flexes forearm

Triceps brachii (extensor)

O: 3 separate – proximal humerus and glenoid area I: olecranon

the main powerful extensor of posterior humerus

Supinator (rotators)

O: lateral epicondyle & proximal ulna, I: lateral proximal radius

deep oblique muscle in lateral elbow/forearm region

important supinator!!!

Pronator teres (rotators)

O: medial epicondyle of humerus, coronoid process of ulna, I: lateral mid-radius

muscle that is medial to brachioradialis

pronates forearm

Pronator quadratus (rotators)

O: distal anterior ulna, I: distal anterior radius

deep and transverse/oblique muscle of anterior wrist

pronates forearm

Flexor carpi radialis (flexor)

O: medial epicondyle humerus; I: 2nd & 3rd metacarpal

Located on the anterior forearm

medial to pronator teres, crosses forearm / toward lateral side (along the radius)

flexes hand (also abducts)

Palmaris longus (flexor)

O: medial epicondyle humerus; I: fascia / aponeurosis of palm

medial to flexor carpi radialis

flexer wrist (& tenses the palmar fascia)

Flexor carpi ulnaris (flexor)

O: medial epicondyle humerus, olecranon of ulna;

I: carpals metacarpals

Located on the anterior forearm

most medial of the flexor group

flexes the hand (also adducts)

Extensor carpi radialis: Longus and Brevis (Extensors)

know as the pair, no need to distingish

O: distal humerus; I: 2nd & 3rd metacarpals

Located on the posterior forearm

next to brachioradialis along the lateral posterior forearm – along the radius

extends hand (also abducts)

Extensor digitorum (extensors)

O: lateral epicondyle of humerus; I: tendons to phalanges 2-5

Located on the posterior forearm

multipart muscle on center of posterior forearm

extends fingers (also flares fingers)

Extensor carpi ulnaris (extensors)

O: distal humerus; I: 3rd metacarpal

most medial of the posterior group – along the ulna

extends hand (also abducts)

liopsoas

both (psoas major and iliacus ) flex the thigh

("walking muscles")

Psoas major (anterior)

O: L vertebrae, I: lesser trochanter

long thick muscle which passes through pelvis to the superior medial thigh

Iliacus (anterior)

O: ilium, I: lesser trochanter

large fan shaped muscle in the iliac fossa; lateral to the lower psoas major

Tensor fasciae latae (lateral)

O: iliac crest, I: iliotibial tract to tibia

superficial lateral hip muscle at the top of the iliotibial tractlateral leg fascia) tenses iliotibial tract (hence name), abducts, medially rotates and flexes thigh

Gluteus maximus (posterior)

O: sacrum, coccyx, & iliac crest, I: mid-iliotibial tract

largest most superficial gluteal muscle, oblique, forms

buttock mass extends and rotates thigh laterally

Gluteus medius (posterior)

O: lateral ilium, I: greater trochanter

thick muscle on back of hip, smaller & partially covered by gluteus maximus abducts and medially rotates thigb

Adductor longus (adductors)

O: anterior pubis, I: linea aspera

long medial thigh muscle

adducts, flexes and medially rotates thigh

Adductor magnus (adductors)

O: pubis & ischial tuberosity, I:linea aspera & medial epicondyle

slightly deeper and has more inferior boundary than adductor longus adducts, also extends, medially rotates and stabilizes thigh

Gracilis (adductors)

O: pubis, I: medial proximal tibia

strap-like (gracilis = slender), superficial muscle of medial thigh; adducts leg, also flexes knee and medially rotates thigh a “pulled groin” muscle is usually an adductor muscle

Hamstrings

Contains: biceps femoris, semitendinosus, semimembransus (BSS)

fleshy muscles of posterior thigh; flex knee and extend thigh

Biceps femoris (Flexors)

O: ischial tuberosity (long head) & linea aspera of femur (short head)

I: head of fibula & lateral condyle of tibia

the most lateral hamstring, the anterior portion deep to

gluteus maximus

Semitendinosus (Flexors)

O: ischial tuberosity, I: medial proximal tibia

medial to biceps femoris, has a long tendon at its distal end ("half tendon")

Semimembranosus (flexors)

O: ischial tuberosity, I: medial proximal tibia

deepest and flattest hamstring; partially more medial to

semitendinosus

Sartorius (flexors)

O: anterior superior iliac spine; medial proximal tibia

strap-like, superficial and oblique muscle;

flexes thigh & knee, abducts & lateral rotation of thigh;

"tailors (= sartor) muscle"

Quadriceps femoris

large and fleshy muscle group that covers the front and sides of the thigh

all have a common insertion: a tendon which continues as the patellar ligament to the tibial tuberosity

all 4 (rectus femoris, vestus lateralis, vastius medialia, vastus intermedius) extend the leg at the knee

rectus also flexes the thigh

Rectus femoris (extensors)

O: anterior inferior iliac spine, I: tibial tuberosity

runs straight (= "rectus") down center of thigh

Vastus lateralis (extensors)

O: greater trochanter & linea aspera, I: tibial tuberosity

forms lateral thigh and is lateral to the rectus femoris

Vastus medialis (extensors)

O: linea aspera, I: tibial tuberosity

forms the medial thigh & is medial to the rectus femoris

Vastus intermedius (extensors)

O: anterior/superior femur, I: tibial tuberosity

deep to the rectus femoris; between (= "intermedius") vastus (lateralis & medialis)

Tibialis anterior (dorsal flexor)

O: lateral condyle & lateral proximal tibia, I: tarsal (first cuneiform)

dorsiflexes and inverts foot

Extensor digitorum longus (dorsal flexor)

O: distal tibia; I: phalanges of toes 2-5

extends toes, dorsiflexes foot

Gastrocnemius (plantar flexor)

O: lateral & medial condyles of femur, O: calcaneus (Achilles / calcaneal tendon)

two headed superficial calf muscle, forms a prominent

bulge in the upper calf; plantar flexes foot and flexes knee

Soleus (plantar flexor)

O: superior fibula & medial tibia,

I: calcaneus via Achilles tendon;

broad calf muscle deep to gastrocnemius; plantar flexes foot

Tibialis posterior (inverter)

O: proximal fibula & tibia, I: tarsals & metatarsals

runs along the lateral tibia, deep to soleus

inversion & plantar flexion of foot

Peroneus / fibularis longus (everter)

O: superior fibula; #1 metatarsal; superficial lateral muscle eversion and plantar flexion of the foot