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
|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.
|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
|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.
|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:
Big Females Seem To like S&M
|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
|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:
Pretty Girls Often Get Off Quickly
The Adductors of the hip
|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|
This group can be remembered by taking the three adductors and the first letter underlined of each muscle (as underlined) with the mnemonic:
3 Ducks Pecking Grass
|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|
|SemiTendonosis||Semi=half, tendere=to stretch|
Following the area underlined on each muscle you can use the mnemonic
Say Grace at Tea
|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
|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
|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|
|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|
|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|
|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|
|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|
|Sternocleidomastoid||Referring to the muscle spaning the sternum, clavicle and mastoid|
|Serratus anterior||Serra=saw, anterior=front|
|Serratus posterior||Serra=saw, posterior=rear|
|Temporalis||Tempor=time. This area is covered by hair but over time it recedes or goes grey|
|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.