lab practical 3 - muscles

standard anatomical position

arms and hands at sides with palms facing forward

how is movement of the body achieved?

by shortening or contracting skeletal muscles - muscles can only pull and never push a bone

• as muscles contract the insertion is pulled toward the origin

origin

the immovable point of attachment

insertion

the attachment on the bone that is moveable during an action

• as muscles contract the insertion is pulled toward the origin

agonist

also called a prime mover, a muscle group that is primarily responsible for producing a movement

antagonists

groups of muscle that are located on the opposite side of the joint and reverse the movement of the agonist

synergist

a muscle that aids an agonist in performing a movement

• this may be accomplished by enhancing the agonists movement or by reducing unwanted or interfering movement

Flexion vs. extension (spine)

Flexion bends the spine forward; extension brings it back upright. Ex: bending to touch toes (flexion), standing back up (extension). Flexion = into fetal position; extension = out of it

Elevation vs. depression

Elevation raises the shoulders superiorly; depression returns them inferiorly

Ex: shrugging toward ears (elevation), dropping them (depression)

Protraction vs. retraction

Protraction moves the shoulders anteriorly; retraction pulls them posteriorly

Ex: bringing arms forward until elbows touch (protraction), pulling them back to your sides (retraction)

Flexion vs. extension (shoulder)

Flexion raises the arm anteriorly; extension lowers it and moves it posterior to the body's long axis

Ex: raising arm straight in front of you (flexion), swinging it behind you (extension/hyperextension)

Lateral vs. medial rotation

Lateral rotation turns the anterior humerus outward; medial rotation turns it inward. Ex: elbow bent at 90°, swing hand away from belly (lateral) or toward it (medial). Elbow must be flexed to show shoulder rotation

Abduction vs. adduction

Abduction moves a limb away from the midline; adduction brings it back toward the midline

Ex: raising arm out to the side (abduction), lowering it to your side (adduction). Take away vs. add back

Flexion vs. extension (elbow)

Flexion bends the forearm toward the arm, decreasing the angle; extension straightens it

Ex: bringing a fork to your mouth (flexion), reaching for a shelf (extension)

Supination vs. pronation

Supination turns the forearm into anatomical position (palm anterior); pronation turns the palm posterior

Ex: palm up holding soup (supination), palm down on a keyboard (pronation)

Opposition vs. reposition

Opposition moves the thumb across the palm to touch any fingertip; reposition returns it

Ex: touching thumb to pinky tip (opposition), moving it back out (reposition)

Inversion vs. eversion

Inversion turns the sole of the foot medially; eversion turns it laterally

Ex: rolling your ankle so the sole faces the other foot (inversion; most ankle sprains), turning the sole outward (eversion)

Dorsiflexion vs. plantar flexion

Dorsiflexion points the toes superiorly, decreasing the foot-leg angle; plantar flexion points the toes inferiorly

Ex: walking on heels (dorsiflexion), standing on tiptoes (plantar flexion)

Flexion vs. extension (hip and knee)

Hip flexion raises the thigh anteriorly; knee flexion bends the leg posteriorly; extension straightens each

Ex: marching with knee lifted (hip and knee flexion), standing straight (extension)

Triangle of auscultation

Area on the back not covered by superficial muscles. Bounded by trapezius medially, scapula laterally, latissimus dorsi inferiorly. Stethoscope placed here to hear lung sounds.

Antecubital fossa

Hollow in front of the elbow. Superior border: line between the humeral epicondyles. Lateral border: brachioradialis. Pronator teres felt here when pronating against resistance. Contains the median cubital vein, used for drawing blood.

Muscle that bulges over the scapula when the arm is abducted to 90°

Trapezius

Muscle palpated between the trapezius and SCM when shrugging

Levator scapulae

Muscle felt along the medial borders of the scapulae

Rhomboids

Muscle felt extending from the inferior angle of the scapula when the arm is medially rotated and extended

Teres major (latissimus is just inferior to it)

Muscle felt in the infraspinous fossa when the arm is laterally rotated

Infraspinatus

Muscle felt in the posterior medial axilla when the humerus is medially rotated

Subscapularis

Large muscle forming the fold anterior to the axilla

Pectoralis major

Muscle covering the greater tubercle of the humerus

Deltoid

Muscle that bulges on the lateral forearm when the forearm is flexed

Brachioradialis

Sternocleidomastoid origin and insertion

O: manubrium of sternum; I: mastoid process

Sternocleidomastoid action

A: flexion and lateral rotation of neck; Ex: tucking chin to chest moves the head anteriorly (flexion); turning head to look over shoulder (rotation)

on a human it is the sternocleidomastoid, what muscles would this be in a rat?

sternomastoid and cleidomastoid

in a human it is pectoralis major, what is this muscle in a rat?

pectoralis superficialis

what are the superficial head, shoulder, chest, and neck muscles of a rat?

1. sternomastoid

2. cleidomastoid

3. pectoralis superficialis

4. trap group - clavotrapezius, acromiotrapezius, and spinotrapezius

5. deltoid group - acromiodeltoid and spinodeltoid

in a human it is the deltoid, what is this muscle in a rat?

the acromiodeltoid and spinodeltoid

in a human it is serratus anterior what is this muscle in a rat?

serratus ventralis

what are the trap group muscles of the rat?

clavotrapeizius

acromiotrapezius

spinotrapezius

what muscles are in the deltoid muscle group in a rat?

acromiodeltoid and spinodeltoid - called just the deltoid in a human

what are the superficial back muscles of a rat?

• trap group - clavotrapezius, acromiotrapezius, and spinotrapezius

• deltoid group - acroiodeltoid and spinodeltoid

• latissimus dorsi

what are deep shoulder and back muscles in a rat?

• serratus ventralis

• rhomboids

• teres major

• supraspinatus

• infraspinatus

• subscapularis

• (teres minor)

what muscles are in the brachium muscle group in a rat?

biceps brachii and triceps brachii

what muscles are in the antebrachium muscle group in a rat?

brachioradialis - lateral

pronator teres - medial

Pectoralis major origin and insertion

O: sternum; I: intertubercular groove of humerus

Pectoralis major action

A: flexion, adduction, medial rotation of humerus

Ex: ample: hugging someone pulls the arms anteriorly (flexion) and medially toward the midline (adduction))

Trapezius origin and insertion

O: occipital bone; I: spine of scapula

Trapezius action

A: elevation, depression, retraction, lateral (upward) rotation of scapula; Ex: shrugging shoulders superiorly toward ears (elevation); squeezing shoulder blades medially together (retraction)

Deltoid origin and insertion

O: acromion of scapula; I: deltoid tuberosity of humerus

Deltoid action

A: abduction of humerus; aids flexion, extension, rotation of arm; Ex: raising arm out to the side away from the midline, like a jumping jack (abduction)

Latissimus dorsi origin and insertion

O: spinous processes of T7 to posterior third of iliac crest; I: intertubercular groove of humerus

Latissimus dorsi action

A: extension, adduction, medial rotation of humerus

Ex: on the way down in a jumping jack, the arms move inferiorly and medially from overhead back to the sides of the body (adduction)

Serratus anterior origin and insertion

O: outer anterior surface of upper 8 ribs; I: medial (vertebral) border of scapula

Serratus anterior action

A: lateral (upward) rotation and protraction of scapula; holds scapula against chest; Ex: throwing a punch moves the scapula anteriorly (protraction)

Rhomboids origin and insertion

O: spinous processes of C7–T5; I: vertebral border of scapula

Rhomboids action

A: retraction and downward rotation of scapula; Ex: rowing pulls shoulder blades posteriorly and medially toward the spine (retraction)

Teres major origin and insertion

O: inferior angle of scapula; I: intertubercular groove of humerus

Teres major action

A: medial rotation and adduction of humerus; Ex: reaching your hand behind your back turns the anterior humerus inward (medial rotation)

Supraspinatus origin and insertion

O: supraspinous fossa of scapula; I: greater tubercle of humerus

Supraspinatus action

A: aids abduction of humerus; stabilizes shoulder joint; Ex: the start of a jumping jack

Infraspinatus origin and insertion

O: infraspinous fossa of scapula; I: greater tubercle of humerus

Infraspinatus action

A: lateral rotation of humerus; stabilizes shoulder joint;

Ex: with the elbow bent at the side, the humerus rotates so the forearm moves laterally away from the body, like cocking the arm back to throw

Teres minor origin and insertion

O: lateral border of scapula; I: greater tubercle of humerus

Teres minor action

A: lateral rotation of humerus; stabilizes shoulder joint; Ex: setting up for a tennis backhand turns the anterior humerus outward (lateral rotation)

Subscapularis origin and insertion

O: subscapular fossa of scapula; I: lesser tubercle of humerus

Subscapularis action

A: medial rotation of humerus; stabilizes shoulder joint

Ex: in arm wrestling, the humerus rotates so the forearm moves medially toward the body and pins the opponent’s arm to the table

Biceps brachii origin and insertion

O: coracoid process of scapula (short head); I: radial tuberosity

Biceps brachii action

A: flexion of elbow; supination of forearm; Ex: bicep curl moves forearm anteriorly toward arm (flexion); turning palm up to hold soup (supination)

Triceps brachii origin and insertion

O: posterior shaft of humerus below radial groove (medial head); I: olecranon process of ulna

Triceps brachii action

A: extension of elbow; aids adduction of humerus; long head extends humerus; Ex: pushing up from a push-up straightens the elbow (extension)

Brachioradialis origin and insertion

O: lateral supracondylar ridge of humerus; I: styloid process of radius; Tip: the more lateral one; lateral border of antecubital fossa

Brachioradialis action

A: flexes the forearm at the elbow; Ex: lifting a mug with thumb up moves forearm anteriorly toward arm (flexion)

aids in pronation and supination

Pronator teres origin and insertion

O: medial epicondyle of humerus; I: lateral shaft of radius; Tip: medial partner to brachioradialis

Pronator teres action

A: pronation of forearm; flexes elbow; Ex: turning palm down to dribble a basketball (pronation)

Muscle felt in the antecubital fossa when you pronate your forearm against resistance

Pronator teres

Muscle felt contracting when you flex your forearm and tighten your arm muscles

Biceps brachii

Muscle felt on the posterior arm when you extend your forearm against your other hand

Triceps brachii

What muscles make up the rotator cuff?

supraspinatus, infraspinatus, teres minor, subscapularis

How to feel the rectus abdominis

Lean back in your chair then bend forward with your hand over your abdomen just superior to your navel

Linea semilunaris

Groove made by the lateral margins of the rectus abdominis

Where the gallbladder is located (surface landmark)

On the right side where the linea semilunaris crosses the costal margin

How to palpate the external obliques

Put your hands lateral to the rectus abdominis and cough

Where to feel the gluteus medius

Between the greater trochanter and the iliac crest, just superior to the gluteus maximus, while abducting your thigh

Why intramuscular injections are given in the gluteus medius instead of the gluteus maximus

To avoid piercing the sciatic nerve

Location of the sciatic nerve

Just deep to the gluteus maximus

Muscles of the hamstrings

Biceps femoris, semitendinosus, and semimembranosus

How to find the biceps femoris

Flex your leg and run your hand over the posterior thigh

Cordlike muscle felt on the posterior surface of the knee

Semitendinosus

Location of the semimembranosus (surface anatomy)

Just medial to the semitendinosus

Popliteal fossa

Depression on the back of the knee

Contents of the popliteal fossa

Popliteal artery and vein

Where to feel the popliteal pulse

By pressing your fingers into the popliteal fossa on the back of the knee

Muscle that forms the inferior border of the popliteal fossa

Gastrocnemius

Location of the adductor muscles

Anterior medial surface of the thigh; felt contracting along the inner thigh when you adduct

How to palpate the tensor fasciae latae

Abduct your thigh with your femur medially rotated and feel just anterior to the greater trochanter

Femoral triangle

Depression on the anterior, superior, medial portion of the thigh

Contents of the femoral triangle

Femoral artery and vein

Where to feel the femoral pulse

By pressing hard into the femoral triangle

How to lessen or stop intense bleeding from the lower leg

Press very hard on the femoral artery to occlude the blood supply

Internal Abdominal Oblique action

A: flexion and rotation of trunk; Ex: a bicycle crunch bends the vertebral column anteriorly and twists it to one side (flexion and rotation)

Transverse Abdominis action

A: compression of abdominal cavity; Ex: sucking your belly in pulls the abdominal wall posteriorly toward the vertebral column (compression)