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SUPERFICIAL MUSCLES OF
THE BACK
05. 03. 2014
Kaan Yücel
M.D., Ph.D.
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Dr.Kaan Yücel
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Superficial muscles of the back
There are two major groups of muscles in the back:
The extrinsic back muscles include superficial and intermediate muscles that produce and control limb and
respiratory movements, respectively.
The intrinsic (deep) back muscles include muscles that specifically act on the vertebral column, producing its
movements and maintaining posture.
Muscles in the superficial and intermediate groups are extrinsic muscles because they originate embryologically
from locations other than the back. They are innervated by anterior rami of spinal nerves:
•Superficial group consists of muscles related to and involved in movements of the upper limb;
•Intermediate group consists of muscles attached to the ribs and may serve as a respiratory function.
Muscles in the superficial group include:
Trapezius
Latissimus dorsi
Rhomboid major
Rhomboid minor
Levator scapulae
Rhomboid major, rhomboid minor, and levator scapulae are located deep to trapezius in the superior part of
the back. Although located in the back region, for the most part these muscles receive their nerve supply from the
anterior rami of cervical nerves and act on the upper limb. The trapezius receives its motor fibers from a cranial
nerve, the spinal accessory nerve (CN XI).
The trapezius attaches the pectoral girdle to the cranium and vertebral column and assists in suspending the
upper limb.
Descending (superior) fibers elevate the scapula (e.g., when squaring the shoulders).
Middle fibers retract the scapula (i.e., pull it posteriorly).
Ascending (inferior) fibers depress the scapula and lower the shoulder.
The name latissimus dorsi (L. widest of back) was well chosen because the muscle covers a wide area of the
back. Latissimus dorsi is a large, flat triangular muscle that begins in the lower portion of the back and tapers as it
ascends to a narrow tendon that attaches to the humerus anteriorly. Movements associated with this muscle include
extension, adduction, and medial rotation of the upper limb. Latissimus dorsi can also depress the shoulder,
preventing its upward movement. The thoracodorsal nerve of the brachial plexus innervates the latissimus dorsi
muscle.
From the transverse processes of the upper cervical vertebrae, the fibers of the levator of the scapula pass
inferiorly to the superomedial border of the scapula. True to its name, the levator scapulae acts with the descending
part of the trapezius to elevate the scapula, or fix it (resists forces that would depress it, as when carrying a load.
Levator scapulae is innervated by branches from the anterior rami of spinal nerves C3 and C4 and the dorsal
scapular nerve.
The rhomboids (major and minor), which are not always clearly separated from each other, have a rhomboid
appearance. The two rhomboid muscles lie deep to the trapezius, inferior to levator scapulae and form broad parallel
bands that pass inferolaterally from the vertebrae to the medial border of the scapulae. Rhomboid minor is superior
to rhomboid major. The rhomboids retract and rotate the scapula, depressing its glenoid cavity. The dorsal scapular
nerve innervates both rhomboid muscles.
The muscles in the intermediate group of back muscles consist of two thin muscular sheets in the superior and
inferior regions of the back, immediately deep to the muscles in the superficial group; serratus posterior superior
and serratus posterior inferior muscles. These muscles are related to the movements of the thoracic cage, as the
superficial muscles are related to the movements of the shoulder (girdle). These two muscles are innervated by the
anterior rami of upper thoracic nerves.
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Superficial muscles of the back
1. MUSCLES OF THE BACK
Most body weight lies anterior to the vertebral column, especially in obese people; consequently, the
many strong muscles attached to the spinous and transverse processes of the vertebrae are necessary to
support and move the column.
There are two major groups of muscles in the back:
The extrinsic back muscles include superficial and intermediate muscles that produce and control limb and
respiratory movements, respectively.
The intrinsic (deep) back muscles include muscles that specifically act on the vertebral column, producing its
movements and maintaining posture.
Muscles in the superficial and intermediate groups are extrinsic muscles because they originate
embryologically from locations other than the back. They are innervated by anterior rami of spinal nerves:
Muscles of the deep group are intrinsic muscles because they develop in the back.
•Superficial group consists of muscles related to and involved in movements of the upper limb;
•Intermediate group consists of muscles attached to the ribs and may serve as a respiratory function.
Figure 1. Superficial and intermediate groups of back muscles
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Superficial muscles of the back
1. SUPERFICIAL GROUP OF BACK MUSCLES
The muscles in the superficial group are immediately deep to the skin and superficial fascia. They are
connected with the shoulder girdle. They attach the superior part of the appendicular skeleton (clavicle,
scapula, and humerus) to the axial skeleton (skull, ribs, and vertebral column). Because these muscles are
primarily involved with movements of this part of the appendicular skeleton, they are sometimes referred to
as the appendicular group. Accordingly, they are also referred as posterior axioappendicular muscles and
produce and control limb movements.
Muscles in the superficial group include:
Trapezius
Latissimus dorsi
Rhomboid major
Rhomboid minor
Levator scapulae
Deep to the trapezius the scapula is attached to the vertebral column by three muscles-the levator scapulae,
rhomboid minor and rhomboid major. These three muscles work with the trapezius (and with muscles found
anteriorly) to position the scapula on the trunk. Although located in the back region, for the most part these
muscles receive their nerve supply from the anterior rami of cervical nerves and act on the upper limb. The
trapezius receives its motor fibers from a cranial nerve, the spinal accessory nerve (CN XI).
Each trapezius muscle is flat and triangular, with the base of the triangle situated along the vertebral
column (the muscle's origin) and the apex pointing toward the tip of the shoulder (the muscle's insertion).
The trapezius attaches the pectoral girdle to the cranium and vertebral column and assists in
suspending the upper limb. This large, triangular muscle covers the posterior aspect of the neck and the
superior half of the trunk. It was given its name because the muscles of the two sides form a trapezium (G.
irregular four-sided figure). The muscles on both sides together form a trapezoid.
The fibers of the trapezius are divided into three parts, which have different actions at the
physiological scapulothoracic joint between the scapula and the thoracic wall:
Descending (superior) fibers elevate the scapula (e.g., when squaring the shoulders).
Middle fibers retract the scapula (i.e., pull it posteriorly).
Ascending (inferior) fibers depress the scapula and lower the shoulder.
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Superficial muscles of the back
The trapezius muscle is a powerful elevator of the shoulder and also rotates the scapula to extend the
reach superiorly. The superior and inferior fibers work together to rotate the lateral aspect of the scapula
upward, which needs to occur when raising the upper limb above the head.
The trapezius also braces the shoulders by pulling the scapulae posteriorly and superiorly, fixing them
in position on the thoracic wall with tonic contraction; consequently, weakness of this muscle causes drooping
of the shoulders.
Motor innervation of trapezius is by the accessory nerve [XI], which descends from the neck onto the
deep surface of the muscle. Proprioceptive fibers from trapezius pass in the branches of the cervical plexus and
enter the spinal cord at spinal cord levels C3 and C4.
Figure 2. Trapezius muscle
http://www.teachpe.com/anatomy/muscles/trapezius.php
ORIGIN
Trapezius
 Superior nuchal line
 External occipital
protuberance
 Ligamentum nuchae
 Spinous processes of
C7 to T12
INSERTION
 Lateral 1/3 of
clavicle
 Acromion
 Spine of scapula
The name latissimus dorsi (L. widest of back) was well chosen because the muscle covers a wide area
of the back. Latissimus dorsi is a large, flat triangular muscle that begins in the lower portion of the back and
tapers as it ascends to a narrow tendon that attaches to the humerus anteriorly. The posterior axillary fold is
formed by the tendon of latissimus dorsi as it passes around the lower border of the teres major muscle. It
can be easily palpated between the finger and thumb.
This large, fan-shaped muscle passes from the trunk to the humerus and acts directly on the
glenohumeral joint and indirectly on the pectoral girdle. The latissimus dorsi extends, retracts, and rotates
the humerus medially (e.g., when folding the arms behind the back or scratching the skin over the opposite
scapula). As a result, movements associated with this muscle include extension, adduction, and medial
rotation of the upper limb. Latissimus dorsi can also depress the shoulder, preventing its upward movement.
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Superficial muscles of the back
In combination with the pectoralis major, the latissimus dorsi is a powerful adductor of the humerus
and plays a major role in downward rotation of the scapula in association with this movement. In conjunction
with the pectoralis major, the latissimus dorsi raises the trunk to the arm, which occurs when performing
chin-ups (hoisting oneself so the chin touches an overhead bar) or climbing a tree, for example. The latissimus
dorsi is also useful in restoring the upper limb from abduction superior to the shoulder; hence the latissimus
dorsi is important in climbing.
Figure 3. Latissimus dorsi
http://www.becomehealthynow.com/body/muscles/atlas/latissimus.shtml
ORIGIN
Latissimus
dorsi
 Spinous
processes of
T7 to L5
 Sacrum
 Iliac crest
 Ribs 10 to 12
INSERTION
Floor of
intertubercular
sulcus of
humerus
Levator scapulae is a slender muscle that descends from the transverse processes of the upper cervical
vertebrae to the upper portion of the scapula on its medial border at the superior angle The superior third of
the strap-like levator scapulae lies deep to the sternocleidomastoid; the inferior third is deep to the trapezius.
It elevates the scapula and may assist other muscles in rotating the lateral aspect of the scapula inferiorly.
From the transverse processes of the upper cervical vertebrae, the fibers of the levator of the scapula
pass inferiorly to the superomedial border of the scapula. True to its name, the levator scapulae acts with the
descending part of the trapezius to elevate the scapula, or fix it (resists forces that would depress it, as when
carrying a load.
With the rhomboids and pectoralis minor, the levator scapulae rotates the scapula, depressing the
glenoid cavity (rotating the lateral aspect of scapula inferiorly). Acting bilaterally (also with the trapezius), the
levators extend the neck; acting unilaterally, the muscle may contribute to lateral flexion of the neck (toward
the side of the active muscle).
Levator scapulae is innervated by branches from the anterior rami of spinal nerves C3 and C4 and the
dorsal scapular nerve.
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Superficial muscles of the back
Figure 4. Levator scapulae
Figure 5. Levator scapulae and rhomboid muscles
http://en.wikipedia.org/wiki/File:Levator_scapulae.png
http://home.comcast.net/~wnor/lesson1superficialmusclesofback.htm
The two rhomboid muscles are inferior to levator scapulae. Rhomboid minor is superior to rhomboid
major. The rhomboid minor is a small, cylindrical muscle. The rhomboid minor arises from the ligamentum
nuchae of the neck and the spinous processes of vertebrae CVII and TI and attaches to the medial scapular
border opposite the root of the spine of the scapula.
The rhomboids (major and minor), which are not always clearly separated from each other, have a
rhomboid appearance—that is, they form an oblique equilateral parallelogram. The two rhomboid muscles lie
deep to the trapezius, inferior to levator scapulae and form broad parallel bands that pass inferolaterally from
the vertebrae to the medial border of the scapulae.
The rhomboids retract and rotate the scapula, depressing its glenoid cavity. They also assist the
serratus anterior in holding the scapula against the thoracic wall and fixing the scapula during movements of
the upper limb. The rhomboids are used when forcibly lowering the raised upper limbs.
The dorsal scapular nerve, a branch of the brachial plexus, innervates both rhomboid muscles.
Figure 6. Rhomboid major et minor
http://www.rad.washington.edu/academics/academic-sections/msk/muscle-atlas/upper-body/rhomboid-major-and-minor
ORIGIN
INSERTION
Rhomboid
major
Spinous processes of T3 to T5
(Rho-Rhomb)
Medial border of scapula
between spine and inferior
angle
Rhomboid
minor
 Lower portion of
ligamentum nuchae
 Spinous processes of C7
and T1 (RhomboiRhomboid)
Medial border of scapula at
the spine of scapula
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Superficial muscles of the back
2. INTERMEDIATE GROUP OF BACK MUSCLES
The muscles in the intermediate group of back muscles consist of two thin muscular sheets in the
superior and inferior regions of the back; serratus posterior superior and serratus posterior inferior. They lie
immediately deep to the muscles in the superficial group. These muscles are related to the movements ofthe
thoracic cage, as the superficial muscles are related to the movements of the shoulder (girdle).
The intermediate extrinsic back muscles are thin muscles, commonly designated as superficial
respiratory muscles, but are more likely proprioceptive rather than motor in function (Fibers from these two
serratus posterior muscles pass obliquely outward from the vertebral column to attach to the ribs. This
positioning suggests a respiratory function, and at times, these muscles have been referred to as the
respiratory group).
Serratus posterior superior is deep to the rhomboid muscles, whereas serratus posterior inferior is
deep to latissimus dorsi. Both serratus posterior muscles are attached to the vertebral column and associated
structures medially, and either descend fibers of serratus posterior superior) or ascend (fibers of serratus
posterior inferior) to attach to the ribs. These two muscles therefore elevate and depress the ribs.
The serratus posterior muscles are innervated by segmental branches of anterior rami of intercostal
nerves.
Figure 7. Intermediate group of back muscles: serratus posterior superior et inferior
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ORIGIN
Serratus posterior
superior
Serratus posterior
inferior
 Lower portion of
ligamentum nuchae
 Spinous processes of
C7 to T3
 Supraspinous
ligaments
 Spinous processes of
T11 to L3
 Supraspinous
ligaments
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INSERTION
Upper border of ribs
2 to 5 just lateral to
their angles
Lower border of ribs
9 to 12 just lateral to
their angles
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Superficial muscles of the back
Table. Extrinsic back muscles [Superficial (appendicular) group & intermediate (respiratory) group of back muscles]
Muscle
Origin
Insertion
Innervation
Function
Trapezius
Motora powerful elevator of the
 Superior nuchal line
 Lateral 1/3 of
accessory nerve shoulder and rotates the
clavicle
 External occipital
[XI];
scapula to extend the reach
protuberance
proprioception- superiorly.
 Acromion
 Ligamentum nuchae
C3 and C4
Assists in rotating the scapula
 Spinous processes of
during abduction of humerus
C7 to T12
above horizontal plane
 Spine of scapula
when raising the upper limb
above the head.
upper fibers elevate, middle
fibers adduct, lower fibers
depress
scapula
Braces the shoulders by
pulling the scapulae
posteriorly and superiorly,
fixing them in position on the
thoracic wall
Latissimus dorsi
Floor of
Thoracodorsal
Extends, adducts, and
 Spinous processes of
intertubercular
nerve (C6 to C8) medially rotates humerus
T7 to L5
sulcus of humerus
 Sacrum
 Iliac crest
 Ribs 10 to 12
Levator scapulae
Transverse processes of Upper portion
C3 to C4 and
Elevates scapula
C1 to C4
medial border of
dorsal scapular
scapula superior to nerve (C4, C5)
root of scapular
spine
Rhomboid major
Spinous processes of T3 Medial border of
Dorsal scapular Retracts (adducts) and
to T5
scapula between
nerve (C4, C5)
elevates scapula
spine and inferior
angle
Rhomboid minor
Medial border of
Dorsal scapular Retracts (adducts) and
 Lower portion of
scapula
at
the
spine
nerve (C4, C5)
elevates scapula
ligamentum nuchae
of scapula
 Spinous processes of
C7 and T1
Serratus posterior  Lower portion of
Upper border of
Anterior rami of Elevates ribs 2 to 5
superior
ribs
2
to
5
just
upper thoracic
ligamentum nuchae
lateral to their
nerves (T2 to
 Spinous processes of
angles
T5)
C7 to T3
 Supraspinous
ligaments
Serratus posterior  Spinous processes of
Lower border of
Anterior rami of Depresses ribs 9 to 12 and
inferior
ribs 9 to 12 just
lower thoracic
may prevent lower ribs from
T11 to L3
lateral
to
their
nerves
(T9
to
being elevated when the
 Supraspinous
angles
T12)
diaphragm contracts.
ligaments
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