Trapezius muscle
Encyclopedia
In human anatomy
, the trapezius is a large superficial muscle
that extends longitudinally from the occipital bone to the lower thoracic vertebrae
and laterally to the spine of the scapula
(shoulder blade). Its functions are to move the scapulae and support the arm
.
The trapezius has three functional regions: the superior region (descending part), which supports the weight of the arm; the intermediate region (transverse part), which retracts the scapulae; and the inferior region (ascending part), which medially rotates and depresses the scapulae.
(trapezoid in American English), or diamond-shaped quadrilateral
. The word "spinotrapezius" refers to the human trapezius, although it is not commonly used in modern texts. In other mammals, it refers to a portion of the analogous muscle.
, the medial third of the superior nuchal line of the occipital bone
(both in the back of the head), and the ligamentum nuchae. From this origin they proceed downward and laterally to be inserted into the posterior border of the lateral third of the clavicle
.
The middle fibers of the trapezius arise from the spinous process
of the seventh cervical (both in the back of the neck), and the spinous processes of the first, second and third thoracic vertebrae
. They are inserted into the medial margin of the acromion, and into the superior lip of the posterior border of the spine of the scapula.
The inferior or lower fibers of the trapezius arise from the spinous processes of the remaining thoracic vertebrae (T4-T12). From this origin they proceed upward and laterally to converge near the scapula and end in an aponeurosis
, which glides over the smooth triangular surface on the medial end of the spine, to be inserted into a tubercle at the apex of this smooth triangular surface.
At its occipital origin, the trapezius is connected to the bone by a thin fibrous lamina, firmly adherent to the skin. The superficial and deep epimysia are continuous with an investing deep fascia that encircles the neck and also contains both sternocleidomastoid muscles.
At the middle, the muscle is connected to the spinous processes by a broad semi-elliptical aponeurosis, which reaches from the sixth cervical to the third thoracic vertebræ and forms, with that of the opposite muscle, a tendinous ellipse. The rest of the muscle arises by numerous short tendinous fibers.
(CN XI). Sensation, including pain and proprioception
, travel via the ventral rami of the third (C3)
and fourth (C4)
cervical nerves
. Since it is a muscle of the upper limb, the trapezius is not innervated by dorsal rami despite being placed superficially in the back.
It is possible to feel the muscles of the superior trapezius become active by holding a weight in one hand in front of the body and, with the other hand, touching the area between the shoulder and the neck.
s and upright row
s. Middle fibers are developed by pulling shoulder blades together. The lower part can be developed by drawing the shoulder blades downward while keeping the arms almost straight and stiff.
It is mainly used in throwing, with the deltoid muscle
s.
The upper and lower trapezius fibers also work in tandem with the serratus anterior to upwardly rotate the scapulae, such as during an overhead press. When activating together, the upper and lower fibers also assist the middle fibers (along with other muscles such as the rhomboids
) with scapular retraction/adduction.
and compromise shoulder health, can result if all three sections of the trapezius are not developed equally.
Human anatomy
Human anatomy is primarily the scientific study of the morphology of the human body. Anatomy is subdivided into gross anatomy and microscopic anatomy. Gross anatomy is the study of anatomical structures that can be seen by the naked eye...
, the trapezius is a large superficial muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
that extends longitudinally from the occipital bone to the lower thoracic vertebrae
Thoracic vertebrae
In human anatomy, twelve thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. They are intermediate in size between those of the cervical and lumbar regions; they increase in size as one proceeds down the spine, the upper...
and laterally to the spine of the scapula
Scapula
In anatomy, the scapula , omo, or shoulder blade, is the bone that connects the humerus with the clavicle ....
(shoulder blade). Its functions are to move the scapulae and support the arm
Arm
In human anatomy, the arm is the part of the upper limb between the shoulder and the elbow joints. In other animals, the term arm can also be used for analogous structures, such as one of the paired forelimbs of a four-legged animal or the arms of cephalopods...
.
The trapezius has three functional regions: the superior region (descending part), which supports the weight of the arm; the intermediate region (transverse part), which retracts the scapulae; and the inferior region (ascending part), which medially rotates and depresses the scapulae.
Terminology
The trapezius muscle resembles a trapeziumTrapezium
The word trapezium has several meanings:* - a quadrilateral with one pair of parallel sides ....
(trapezoid in American English), or diamond-shaped quadrilateral
Quadrilateral
In Euclidean plane geometry, a quadrilateral is a polygon with four sides and four vertices or corners. Sometimes, the term quadrangle is used, by analogy with triangle, and sometimes tetragon for consistency with pentagon , hexagon and so on...
. The word "spinotrapezius" refers to the human trapezius, although it is not commonly used in modern texts. In other mammals, it refers to a portion of the analogous muscle.
Anatomy
The superior or upper fibers of the trapezius arise from the external occipital protuberanceExternal occipital protuberance
Near the middle of the occipital squama is the external occipital protuberance, and extending lateralward from it on either side is the superior nuchal line, and above this the faintly marked highest nuchal line.It is less pronounced in females....
, the medial third of the superior nuchal line of the occipital bone
Occipital bone
The occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the cranium, is trapezoidal in shape and curved on itself...
(both in the back of the head), and the ligamentum nuchae. From this origin they proceed downward and laterally to be inserted into the posterior border of the lateral third of the clavicle
Clavicle
In human anatomy, the clavicle or collar bone is a long bone of short length that serves as a strut between the scapula and the sternum. It is the only long bone in body that lies horizontally...
.
The middle fibers of the trapezius arise from the spinous process
Spinous process
The spinous process of a vertebra is directed backward and downward from the junction of the laminae , and serves for the attachment of muscles and ligaments. In animals without an erect stance, the process points upward and may slant forward or backward...
of the seventh cervical (both in the back of the neck), and the spinous processes of the first, second and third thoracic vertebrae
Thoracic vertebrae
In human anatomy, twelve thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. They are intermediate in size between those of the cervical and lumbar regions; they increase in size as one proceeds down the spine, the upper...
. They are inserted into the medial margin of the acromion, and into the superior lip of the posterior border of the spine of the scapula.
The inferior or lower fibers of the trapezius arise from the spinous processes of the remaining thoracic vertebrae (T4-T12). From this origin they proceed upward and laterally to converge near the scapula and end in an aponeurosis
Aponeurosis
Aponeuroses are layers of flat broad tendons. They have a shiny, whitish-silvery color, are histologically similar to tendons, and are very sparingly supplied with blood vessels and nerves. When dissected, aponeuroses are papery, and peel off by sections...
, which glides over the smooth triangular surface on the medial end of the spine, to be inserted into a tubercle at the apex of this smooth triangular surface.
At its occipital origin, the trapezius is connected to the bone by a thin fibrous lamina, firmly adherent to the skin. The superficial and deep epimysia are continuous with an investing deep fascia that encircles the neck and also contains both sternocleidomastoid muscles.
At the middle, the muscle is connected to the spinous processes by a broad semi-elliptical aponeurosis, which reaches from the sixth cervical to the third thoracic vertebræ and forms, with that of the opposite muscle, a tendinous ellipse. The rest of the muscle arises by numerous short tendinous fibers.
Innervation
Motor function is supplied by the accessory nerveAccessory nerve
In anatomy, the accessory nerve is a nerve that controls specific muscles of the shoulder and neck. As part of it was formerly believed to originate in the brain, it is considered a cranial nerve...
(CN XI). Sensation, including pain and proprioception
Proprioception
Proprioception , from Latin proprius, meaning "one's own" and perception, is the sense of the relative position of neighbouring parts of the body and strength of effort being employed in movement...
, travel via the ventral rami of the third (C3)
Cervical spinal nerve 3
The cervical spinal nerve 3 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 3 ....
and fourth (C4)
Cervical spinal nerve 4
The cervical spinal nerve 4 is a spinal nerve of the cervical segment..It originates from the spinal column from above the cervical vertebra 4 .Its control of the thoracic diaphragm has inspired a medical mnemonic: "Cut C4, breathe no more."...
cervical nerves
Cervical nerves
The cervical nerves are the spinal nerves from the cervical vertebrae.Although there are seven cervical vertebrae , there are eight cervical nerves . All nerves except C8 emerge above their corresponding vertebrae, while the C8 nerve emerges below the C7 vertebra...
. Since it is a muscle of the upper limb, the trapezius is not innervated by dorsal rami despite being placed superficially in the back.
It is possible to feel the muscles of the superior trapezius become active by holding a weight in one hand in front of the body and, with the other hand, touching the area between the shoulder and the neck.
Actions and exercises
Contraction of the trapezius muscle can have two effects: movement of the scapulae when the spinal origins are stable, and movement of the spine when the scapulae are stable.Scapular movements
The upper portion of the trapezius can be developed by elevating the shoulders. Common exercises for this movement are shoulder shrugShoulder shrug
The shoulder shrug is an exercise in weight training used to develop the upper trapezius muscle.- Form and execution :...
s and upright row
Upright row
The upright row is a weight training exercise performed by holding a barbell with the overhand grip and lifting it straight up to the collarbone. This is a compound exercise that involves the trapezius, the deltoids and the biceps. The narrower the grip the more the trapezius muscles are exercised,...
s. Middle fibers are developed by pulling shoulder blades together. The lower part can be developed by drawing the shoulder blades downward while keeping the arms almost straight and stiff.
It is mainly used in throwing, with the deltoid muscle
Deltoid muscle
In human anatomy, the deltoid muscle is the muscle forming the rounded contour of the shoulder. Anatomically, it appears to be made up of three distinct sets of fibers though electromyography suggests that it consists of at least seven groups that can be independently coordinated by the central...
s.
The upper and lower trapezius fibers also work in tandem with the serratus anterior to upwardly rotate the scapulae, such as during an overhead press. When activating together, the upper and lower fibers also assist the middle fibers (along with other muscles such as the rhomboids
Rhomboids
Rhomboids can refer to:* Rhomboid muscles** Rhomboid major muscle** Rhomboid minor muscle...
) with scapular retraction/adduction.
Spinal movements
When the scapulae are stable (such as lying on one's back, or using muscles to fix them in space), trapezius contractions can cause spinal movements, particularly the upper fibers on the cervical vertebrae, a co-contraction of both sides can extend the neck.Balance
Muscle imbalances, which can heavily affect postureHuman position
Human positions refers to the different positions that the human body can take.There are several synonyms that refer to the human position, often used interchangeably, but having specific flavors....
and compromise shoulder health, can result if all three sections of the trapezius are not developed equally.