Serratus Posterior Muscles: Location and Action

The Serratus posterior muscles consist of a superior and inferior (upper and lower) which are located on each side of the upper and lower part of the thoracic region of the back. They are thin quadrilateral muscles which are deep to the true back muscles such as the rhomboids, and in the case of the … Read more

Brachialis Muscle: Location and Actions

The brachialis muscle is located on the front part of the upper arm, nearest the elbow. Along with the biceps brachii and the brachioradialis, it is one of the primary flexors of the elbow. It gets its name from the Greek words brachialis and brachion, pertaining to the (upper) arm. It is important not to confuse these words with the Greek brachy which … Read more

Digastric Muscle: Location and Actions

The digastric is a double muscle of the throat which is located under the chin, behind and below the corner of the jaw, immediately in front of the top of the sternocleidomastoid, one for each side of the jaw and neck. It gets its name from the Greek word for “two bellies”. The Greek word … Read more

Biceps Brachii Location and Actions

The biceps brachii is a two-headed muscle located on the front of the arm and makes up the largest part of its bulk. The name biceps is derived from the Greek word bi, meaning “two” and the Latin caput, meaning “head.” The name brachii is a form of the Latin and Greek words brachialis and brachion, which describe something that pertains to the arm. Thus, biceps brachii means … Read more

Rhomboid Major and Minor Muscles: Location and Actions

The proper names for the muscles we call the rhomboids are Rhomboideus Major and Minor or the Rhomboidei. Although two different muscles, they are very difficult to distinguish from one another and perform the same actions together. They run obliquely downward from the spine to the inner edge of the scapula, on each side of the middle back … Read more

Infraspinatus Muscle: Location and Actions

The infraspinatus muscle is a thick, triangular muscle which occupies most of the concave, dorsal surface of the scapula, a part of the scapula called the infraspinatus fossa. In other words, this muscle covers almost the entire scapula (shoulder blade) below the scapular spine. See infraspinatus Trigger Points The muscle gets its name from its … Read more

Teres Major Muscle: Location and Actions

The teres major muscle is a small, round muscle lying along the lateral border of the scapula. It forms the inferior border of both the triangular space and quadrangular space. The muscle gets its name from its shape and size. Teres means “round” in Latin, and the term major refers to it being the larger of two muscles, the teres minor muscle … Read more

Deltoid Muscle: Location and Actions

The deltoid muscle is a large, triangular, course, and thick muscle which gives the shoulder its shape and contour. Its name is often reported to have derived from the Greek letter Delta (Δ) but it actually derives from the Latin word deltoides which means “triangular in shape or form” and was taken from the shape of the letter delta … Read more

Splenius Capitis and Cervicis Muscles: Location and Actions

The splenius muscles are broad and thin, getting their name from the Greek word splenium, meaning bandage. Capitis comes from the Latin word for head, caput which refers to the origin of the splenius capitis on the mastoid process and adjacent occipital bone of the skull, underneath the sternocleidomastoid. Cervicus derives from the Latin word cervix which … Read more

Extensor Digitorum Muscle: Location and Actions

The extensor digitorum [pronounced ex-TEN-sur dih-ji-TAW-rum] muscle gets its name from the Greek and Latin ex which means “out of”, and the Latin tendere, which means “to stretch”. So an extensor is a muscle that stretches out or straightens out a joint. The word digitorum is from Latin, indicating the digits or fingers. Communis is Latin for “common” and it … Read more