There are over 600 m uscles in the hum an body. Identifying these six hundred m uscles is a daunting task. Furtherm ore, the nam es of these m uscles seem foreign to m ost of us. Most of our m odern anatom ical term s were developed throughout the m id- to late-1500s when m any anatom ists were perform ing dissections of the hum an body. As a result of the influence of the early Greek and Rom an anatom ists, m uscles were nam ed using Latin and Greek roots. Thus, if you have som e appreciation for Latin or Greek roots, you would have an advantage in knowing the function and/or location of a m uscle in the body as a result of its nam e.
Muscles can be nam ed according to the direction their fibers run, their size, where they are found in the body, what bones they attach to, what the m uscle looks like, where it is in relation to certain bones, and their function within the body. Often the nam e of a m uscle contains com binations of each of the above.
Direction of M uscle Fibers
W hen looking at a m uscle, you can often see that it appears to have lines running within it. These lines are com posed of m uscle fibers and the direction that these fibers run in relation to the m idline of the body has been used to provide partial nam es to m any different m uscles.
If the fibers of the m uscle are running with or parallel to the m idline of the body, the term rectus is often used to describe that m uscle. Rectus is of Latin origin and literally m eans "straight." Som e exam ples of m uscles that have the term rectus in their nam e include the rectus femoris and rectus abdominis. If the fibers of the m uscle run at an angle to the m idline of the body, they are said to run obliquely. The term oblique is also of Latin origin. Som e exam ples of m uscles that have the term oblique associated with their nam e include the internal and external oblique m uscles of the thorax.
M uscle Size
Early anatom ists often included the nam e of the m uscle som ething about its size or length. If a m uscle were long, its nam e would likely include the term longus, while if the m uscle were short, its nam e would contain the term brevis (Latin for "short"). Muscles that were large would have the term maximus (Latin for "largest" or "greatest"), major (Latin for "larger"), or vastus (Latin for "huge") in their nam es, while sm all m uscles would contain term s such as minimus (Latin for "least" or "sm allest") or minor (Latin for "sm aller").
Another com ponent of m any m uscle nam es is the association of the m uscle with a particular area of the body. The rectus abdominis is a straight m uscle located in the abdom inal region. The palmaris longus is a long m uscle that attaches to connective tissue in the palm of the hand. Below are m ore exam ples of the Greek and Latin term s for the various regions of the body.
oris (L: "m outh") oculi (L: "eye")
palmaris (L: "palm of the hand") abdominis (L: "abdom en") brachii (G : "arm ")
femoris (L: "thigh") tibialis (L: "shin bone") peroneus (G : "fibula") digitorum (L: "finger or toe") pollicis (L: "thum b")
hallicus (L: "great toe") costals (L: "rib") carpi (G : "wrist") spinalis (L: "spine")
scapularis (L: "shoulder blade")
W here in the body would you expect to find the following: biceps brachii, rectus femoris, adductor pollicis
longus, orbicularis oculi, external intercostals, tibialis anterior, spinalis thoracis, peroneus longus?
Location of the M uscle Attachm ent (Association w ith Bone)
Many m uscles are nam ed as a result of their association with a particular bone. The temporalis m uscle is found covering the tem poral bone while the frontalis m uscle is found covering the frontal bone of the skull.
Location of M uscle's Origin and Insertion on Bones
All m uscles have an origin and insertion. The origin is the part of the body, usually a bone, where the m uscle attaches, and does not m ove when the m uscle contracts. The insertion is the part of the body where the m uscle attaches, and m oves when the m uscle contracts. Som e m uscles are nam ed based upon their origin and insertion. The first part of the m uscle nam e indicates the origin while the second part indicates the insertion. For exam ple, the m uscle that has its origin on the breast bone and clavicle (collar bone) and that inserts on a breast shaped process of the skull is term ed the sternocleidomastoid: sterno (G : "breast bone"), cleido (G: "clavicle"), and mastoid (G: "breast shape").
Num ber of Origins
Som e m uscles have m ultiple origins. As a result, the num ber of origins is often used in the m uscle's nam e. Som e com m on nam es: the biceps brachii and triceps brachii. The term bi is of Latin origin and refers to "two" while ceps, also of Latin origin, refers to "head." Thus this m uscle has two heads that attach to two different origins. How m any heads and origins would thetriceps brachii have?
Not only is a m uscle som etim es nam ed because of the bone to which it attaches, but the nam e m ay be even m ore detailed to describe where its position is in relation to the bone or body part. Below are given som e Latin term s and prefixes that describe position.
supra (L: above or over) infra (L: below or beneath) sub (L: below or under) lateralis (L: the side) medialis (L: the m iddle) inter (L: between or am ong) external (L: outer)
internal (L: inner)
superior (L: above or over) inferior (L: underneath) dorsi (L: the back) anterior (L: in front of)
Exam ples of m uscles that contain som e of the above term s include: supraspinatus, infraspinatus,
subscapularis, vastus lateralis, vastus medialis, intercostals, external and internal obliques, superior and inferior rectus muscles of the eye.
