As with the skeletal system, the muscles are generally named in Greek, Latin or various other old languages based on their location, size, shape or action. Understanding what the words actually mean is a huge advantage in learning them. My own somewhat suspect translations have helped me in exams and when explaining things to my clients. 

You are expected to know the various muscles’ groupings. Much like the skeletal system there are plenty of mnemonics to help and overwhelmingly they are rude! I’m not sure if that is because they are easier to remember or if it’s because people who are obsessed with the human body are generally a little perverted. Maybe we’ll never know but we can become familiar with many of the standard muscles and groupings you’ll come across in your exams or on an anatomy chart.

The Rotator Cuff

Name Meaning
Supraspinatus Supra=superior/above, spina=spine/thorn (referring to the spine of the shoulder blade)
Infraspinatus Infra=inferior, spina=spine/thorn (referring to the spine of the scapula)
Teres minor Teres=cylindrical, minor=small
Subscapularis Sub=under, scapularis=shoulder blade

As the name suggests, the supraspinatus is positioned highest, followed by the infraspinatus then the teres minor with the subscapularis behind the scapula. The order can be remembered with the mnemonic SITS.

The Abdominals

Name Meaning
Transverse abdominals (TVA) Transverse=across (Latin), abdo=to conceal
Internal oblique Internal=inside, oblique=diagonal
Rectus abdominus Rectus=straight, abdo=to conceal
External oblique External=outside, oblique= diagonal

These muscles can be remembered from the deepest to the most superficial with the mnemonic ‘spare TIRE’

Erector spinae or sacrospinalis muscles

Name Meaning
Erector spinae erect=upright (snigger), spinae=spine/thorn
Illiocostalis (lumborum, thoracis, cervicis) Ilio=Flank bone, costalis=rib
Longissimus (thoracis, cervicas, capitis) Longi=long, mus=muscle
Spinalis (thoracis and cervicis) Spina=spine/thorn

These muscles further subdivide by location but can be remembered from lateral to medial with the mnemonics I Love Sex or the more moderate but somehow cruder I Like Shagging.

The hamstrings

Name Meaning
Biceps Femoris Bi=two, ceps=heads, femoris=thigh.

This muscle sub divides into the long head and the short head. The short head has a different insertion and innervation and so some don’t consider it a hamstring.

SemiTendinosus Semi=half, tendere=to stretch
SemiMembranosus (half a thin sheet) Semi=half, membrana=skin

The hamstrings can be remembered lateral to medial using the area of the muscle underlined with the following mnemonic:

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Quadricep Femoris

Name Meaning
Quadriceps Quad=four, ceps=heads
Rectus Femoris Rectus=straight, femoris=thigh (this is the only quadricep that passes the hip and so is also capable of hip flexion)
Vastus Lateralis Vastus=vast/large, lateralis=side
Vastus Medialis Vastus=vast/large, medialis=middle
Vastus Intermedialis Vastus=vast/large, inter=between, medial=middle

Despite quadricep meaning four headed muscle it is actually four separate muscles that are all innerviated from the femoral nerve.

Occasionally the vastus medialis is referred to as the VMO (vastus medialis obliques), suggesting the angle of the muscle is important but this is debated.

You will also hear about a fifth and and even sixth muscle in the group that are rarely mentioned or included in the group. I’ve included them below merely to acknowledge their existence.

Tensor Vastus Intermedialis Tensor= to stretch, vastus=vast/large, inter=between, medial=middle
Articularis Genus Articulus=connecting, genus=birth

The deep external rotators of the hip

Name Meaning
Piriformus Piri=pear, form=shape
Gemellus Inferior Geminus=twin, inferior=lower
Obturator Externus Obturat=to close, externus=outside
Gemellus Superior Geminus=twin, superior=above
Obturator Internus Obturat=to close, internus=inside
Quadratus Femoris Quadratus=square, femoris=thigh

This group can be remembered using the first letter underlined of each muscle with the mnemonic:

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The Adductors of the hip

Name Meaning
Adductor Brevis Ad=towards, duct=move, brevis=brief/short
Adductor Longus Ad=towards, duct=move, longus=long
Adductor Magnus Ad=towards, duct=move, magnus=broad/tall
Pectineus Pecten=comb
Gracilis Slim/ fine

This group can be remembered by taking the three adductors and the first letter underlined of each muscle (as underlined) with the mnemonic:

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Pes anserinus 

Name Meaning
Pes Anserinus Pes=foot, anserine=goose. This is where the sartorius, gracilis and the semitendinosis conjoin making a shape that resembles a gooses foot
Sartorius Sartor=tailor. This refers to the crosslegged position tailors would sit in
Gracilis Slim/ fine
SemiTendonosis Semi=half, tendere=to stretch

Following the area underlined on each muscle you can use the mnemonic 

Say Grace at Tea

Anterior Forearm

Name Meaning
Ponator Teres Pronator=face downwards, teres=cylindrical
Flexor Carpi Radialis Flexor=flexes, carpi=wrist, radialis=spoke
Palmaris Longus Palm=palm, longus=long
Flexor Carpi Ulnaris Flexor=flexes, carpi=wrist, ulnaris=elbow
Flexor Digitorum Superficialis Flexor=flexes, digitorum=fingers/toes, superficialis=close to the surface

The muscles can be remembered thumb to little finger with the mnemonic Pimps F*** Prostitutes For Fun

The Posterior Ankle muscle and tendons

Name Meaning
Tibialis Posterior Tibia=flute/shin, posterior=rear
Flexor Digitorum Lonus Flexor=flexes, digitorum=fingers/toes, longus=long
Flexor Hallucis Longus Flexor=flexes, hallux=big toe, longus=long

Using the letters underlined the order of these muscles can be remembered anterior to posterior using the mnemonic Tom, Dick and Harry

The rest of the muscular system

Name Meaning
Abductor pollicis longus Ab=towards, duct=move, pollics=thumb, longus=long
Anconeus Ankon=elbow (Greek), long glove; the muscle is sometimes referred to as ‘the fourth tricep head’ and situated where a long glove would end.
Anterior deltoid Anterior=front, delta=triangle (third letter of the Greek alphabet), oid=resembles
Biceps brachii Bi=two, ceps=heads, brachii=arm
Brachioradialis Brachii=arm, radial=spoke
Buccinator To blow a trumpet
Corragator Corrigated/wrinkles or wrinkler of the forehead
Diaphram Dia=across (Greek), phram=frame
Extensor carpi radialis Extensor=extends, carpi=wrist, radialis=spoke
Extensor carpi ulnaris Extensor=extends, carpi=wrist, ulnaris=elbow
Extensor digitorum Extensor=extends, digitorum=fingers/toes
Extensor indicis Extensor=extends, indicus=index finger or indicating finger as in to point out something
Gastrocnemius Gastro=belly, knem=leg, anatomically the leg is the area between your knee and ankle
Gluteus maximus Gluteus=rump, maxi=largest, mus=muscle
Gluteus medius Gluteus=rump, medius=middle
Gluteus minimus Gluteus=rump, mini=smallest, mus=muscle
Hallucis flexor longus Hallucis/hallux=big toe, flexor=flexes, longus=long
Iliacus Soft tissue of the flank
Iliopsoas The so called hip flexor, combining the iliacus and psoas
Iliotibial band Attaches between ilium and the tibia
Intercostals Inter=between, costals=ribs
Latissimus dorsi Latis=broadest, mus=muscle, dorsi=back
Levator labii superioris alaeque nasi Levator=lifts, labi=lip, superios=upper, ala=wing, nasi=nose
Levator scapulae Levator=elevate/lifts, scapulae=shoulder blade
Linea aspera Linea=line, aspera=rough
Lubrical Lubric=smooth/slippery
Medial deltoid Medial=middle, delta=triangle (third letter of the Greek alphabet), oid=resembles
Multifidus Multi=many, findere=to split
Orbicularis oris Orbis=circle/encircle, ulis=little, oris=mouth
Orbicularis occuli Orbis=circle/encircle, ulis=little, oculus=eye
Pectoralis major Pectoralis=chest/breast (Latin), major=large
Pectoralis minor Pectoralis=chest/breast (Latin), minor=small
Peronius brevis Perone=pin (Greek), brevis=brief/short
Peronius longus Perone=pin (Greek), longus=longest
Peronius tertius Perone=pin (Greek), tertius=third
Plantaris Plant=on the floor/sole of the foot
Platysma Flat
Posterior deltoid Posterior=rear, delt=triangle (third letter of the Greek alphabet), oid=resembles
Psoas Muscles of the loins
Quadratus lumborum Quadrus=square, lumborum=loin, or ‘quadrant of the lower back’
Quadriceps femoris Quad=four, ceps=heads, femur=thigh
Rhomboid Parelelagram
Sternocleidomastoid Referring to the muscle spaning the sternum, clavicle and mastoid
Serratus anterior Serra=saw, anterior=front
Serratus posterior Serra=saw, posterior=rear 
Soleus Soleus=sole
Temporalis Tempor=time. This area is covered by hair but over time it recedes or goes grey
Tendon Tendere=to stretch
Tensor fasciae latae Tensor=to stretch, fasc=band, latae=side
Teres major Teres=cylindrical, major=large
Thoracolumbar fascia Thora=chest, lumbar=loin, fascia=band
Tibialis Anterior Tibia=flute/shin, anterior=front
Triceps brachii Tri=three, ceps=heads, brachii=arm


Insertions and origins

Some define the muscle origin as the largest or least moveable end. naturally during a contraction this would make the insertion the smaller more moveable area. I don’t find that helpful considering reverse muscle actions create so many exceptions to the rule. 

Rather the aptly named origin is nearest to the centre of the body (the proximal end). hence the distal end (the section furthest from the centre line) is the insertion. I can’t think of any obvious exceptions to this rule so I don’t think it’s worth trying to remember them in any other way. 

Active and passive insufficiency 

A muscle can typically contract to 50% and lengthen to 150% of its original length.

Muscles that pass more than one joint (biarticular muscles) are subject to passive and active insufficiency (defined below), which can limit range of motion that would otherwise be available in the joint.

Passive insufficiency happens when a muscle passing two or more joints cannot lengthen enough to allow full range of the joints it passes e.g. the hamstring. It passes the hip and knee and normally it would stretch when either the knee extends, straightening the leg or the hip flexes. Passive insufficiency describes the limitation that the muscle will not permit simultaneously the hip to extend and the knee to straighten. The same is true if the leg were fully straightened; the hamstring would then not be able to lengthen enough for the hip to fully flex.

Active insufficiency occurs when a muscle passing two joints cannot contract enough to complete the available range of motion with all the joints in question. Again the hamstring is an example. It can flex the knee or extend the hip, but not both at the same time. The muscle cannot shorten enough and usually results in cramp from the muscle that has contracted to its fullest extent and has lost stability. This is should be the limiting factor when performing active stretches.

Muscle tension relationship refers to the ideal length of a muscle to produce maximal force. Optimal exercises will challenge the muscle at this length. Note that a full contraction is not the same as a peak contraction. When a muscle is at its shortest (especially during active insufficiency) it will produce much less tension, making it a weak position. When a muscle is at its longest (especially during passive insufficiency) there will be a lot of passive tension but the muscle will again not be able to produce much force.

This is critical because a muscle’s action cannot always be predicted purely by which joint it passes. They can often flit between roles and not behave as anatomically expected. For example, the psoas is colloquially known as ‘the hip flexor’, but it is very unlikely it would be up to the task just because a strand of it passes the hip joint. But I guess ‘dynamic lumbar stabiliser’ wasn’t going to be as catchy.

If you haven’t already check out what some of the basic anatomic terms mean here and the skeletal system here.