Muscular System

Anterior forearm muscles: superficial group

There are five, like five digits of your hand.

Place your thumb into your palm, then lay that hand palm down on your other arm, as shown in diagram.

Your 4 fingers now show distribution: spells PFPF [pass/fail, pass/fail]:

  • Pronator teres
  • Flexor carpi radialis
  • Palmaris longus
  • Flexor carpi ulnaris

Your thumb below your 4 fingers shows the muscle which is deep to the other four: Flexor digitorum superficialis.

Anterior forearm muscles: superficial group

Pimps F*ck Prostitutes For Fun”:

  • Pronator teres
  • Flexor carpi radialis
  • Palmaris longous
  • Flexor carpi ulnaris
  • Flexor digitorum superficialis

Biceps brachii muscle: origins

“You walk shorter to a street corner. You ride longer on a superhighway.”:

Short head originates from coracoid process.

Long head originates from the supraglenoid cavity.

Bicipital groove: attachments of muscles near it

“The lady between two majors“:

Teres major attaches to medial lip of groove.

Pectoralis major to lateral lip of groove.

Latissimus (Lady) is on floor of groove, between the 2 majors.

Brachioradialis: function, innervation, one relation, one attachment


Function: Its the Beer Raising muscle, flexes elbow, strongest when wrist is oriented like holding a beer.

Innervation: Breaks Rule: it’s a flexor muscle, But Radial. (Radial nerve usually is for extensors: Recall BEST rule: B was for brachioradialis).

Important relation: Behind it is the Radial nerve in the cubital fossa.

Attachment: Attaches to Bottom of Radius.

Elbow: muscles that flex it

Three B‘s Bend the elBow:

  • Brachialis
  • Biceps
  • Brachioradialis

Elbow: which side has common flexor origin

FM (as in FM Radio):

Flexor Medial, so Common Flexor Origin is on the medial side.

Extensor expansion location in the hand

The eXtensor eXpansion is on the proXimal phalynX.

Flexor digitorum muscles: how they insert onto fingers

A little rhyme:

Superficialis Splits in two,

To Permit Profundus Passing through.

Interossei muscles: actions of dorsal vs. palmar in hand

PAd and DAb“:

The Palmar Adduct and the Dorsal Abduct.

Use your hand to dab with a pad.

Interossei muscles: number of palmars vs. dorsals

3 on the P, 4 on the Dor“:

There are 3 Palmar, and 4 Dorsal interossei.

Intrinsic muscles of hand (palmar surface)


Thenar, lateral to medial:

  • Abductor pollicis longus
  • Opponens pollicis
  • Flexor pollicis brevis
  • Adductor pollicis.
  • Hypothenar, lateral to medial:
  • Opponens digiti minimi
  • Flexor digiti minimi
  • Abductor digiti minimi

Lumbricals action

Lumbrical action is to hold a pea, that is to flex the metacarpophalangeal joint and extend the interphalangeal joints. When look at hand in this position, can see this makes an “L” shape, since L is for Lumbrical.

Muscles: potentially absent ones

Muscles which may be absent but may be important:

5 P’s:

  • Palmaris longus [upper limb]
  • Plantaris [lower limb]
  • Peroneus tertius [lower limb]
  • Pyramidalis [anterior abdominal wall]
  • Psoas minor [posterior abdominal wall]

Oblique muscles: direction of externals vs. internals

“Hands in your pockets”:

When put hands in your pockets, fingers now lie on top of external obliques and fingers point their direction of fibers: down and towards midline.

Note: “oblique” tells that must be going at an angle.

Internal obliques are at right angles to external.

Rotator cuff muscles

“The SITS muscles”:

Clockwise from top:

  • Supraspinatus
  • Infraspinatus
  • Teres minor
  • Subscapularis

A pro baseball pitcher has injured his rotator cuff muscles. As a result, he SITS out for the rest of the game, and then gets sent to the minor leagues.

Serratus anterior: innervation


Serratus Anterior = Long Thoracic.

Serratus anterior: innervation and action

“C5-6-7 raise your arms up to heaven“:

Long thoracic nerve roots (567) innervate Serratus anterior.

Test C567 roots clinically by ability to raise arm past 90 degrees.

Supination vs. pronation

SOUPination”: Supination is to turn your arm palm up, as if you are holding a bowl of soup.

POUR-nation”: Pronation is to turn your arm with the palm down, as if you are pouring out whatever is your bowl.

Alternatively, Pronation donation: Pronation is palm facing downward, as if making a donation.

Supination vs. pronation: which is more powerful

Screws were designed to be tightened well by majority of people.

“Righty tighty”: to tighten screws you turn to the right.

Majority of people are right-handed.

Turning right-hand to the right is supination.

Palmaris longus: location, relative to wrist nerves

“The Palmaris between two Palmars“:

Palmaris longus is between the Palmar cutaneous branch of Ulnar nerve and Palmar cutaneous branch of Median nerve.

 You can suggest more mnemonics …

Warm regards,

Dr. Indrajit Rana


6 responses to “Muscular System

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