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Lecture One
Superficial back
Bony marks
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spine
supraspinous fossa
infraspinous fossa
acromion process
coracoid process
glenoid cavity
Bony marks
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Greater & Lesser turbercle
Intertubercular groove
Lateral & Medial epicondyle
Anatomical & Surgical neck
Deltoid tuberosity
Olecranon fossa
triangle of auscultation
• a triangle located below the inferior angle
of the scapula bounded by the trapezius
muscle medially, rhomboideus major
muscle superiorly and the latissimus dorsi
muscle inferiorly; its floor is the posterior
thoracic wall, used to hear lungs by
stethoscope
Back muscles
• The skin and superficial fascia of the back can
be divided into three groups organized in layers:
superficial, intermediate, and deep. Muscles of
the superficial and intermediate groups are
called extrinsic back muscles because they are
involved in respiration and movements of the
upper extremity. Muscles of the deep group are
called intrinsic back muscles because they are
involved in movement and stabilization of the
vertebral column.
Superficial back muscles
• trapezius and latissimus dorsi muscle
TRAPEZIUS
• ORIGIN
– Upper fibers: external occipital protuberance,
medial one third of superior nuchal line,
ligamentum nuchae, and spinous process of
7th cervical vertebra
– Middle fibers: spinous processes of first to
fifth thoracic vertebrae
– Lower fibers: spinous processes of sixth to
12th thoracic vertebrae
• INSERTION
– Upper fibers: lateral one third of clavicle and
acromion process of the scapula
– Middle fibers: medial margin of acromion and
superior lip of spine of scapula
– Lower fibers: tubercle at apex of spine of
scapula
TRAPEZIUS
• ACTION
With origin fixed, adduction of the scapula,
performed chiefly by the middle fibers with
stabilization by the upper and lower fibers.
Rotating of the scapula so the glenoid cavity
faces cranially, performed chiefly by the upper
and lower fibers with stabilization by the middle
fibers. In addition, the upper fibers elevate and
the lower fibers depress the scapula.
With the insertion fixed, and acting unilaterally,
the upper fibers extend, laterally flex, and rotate
the head and joints of the cervical vertebrae so
that the face turns toward the opposite side; and
acting bilaterally, the upper Trapezius extends
the neck. The Trapezius also acts as an
accessory muscle of respiration.
• NERVE
spinal portion of accessory nerve (XI cranial
nerve) and ventral ramus, C2, 3, 4
LATISSIMUS DORSI
• ORIGIN
– spinous processes of last six
thoracic vertebrae, last three or
four ribs, through the
thoracolumbar fascia from the
lumbar and sacral vertebrae and
posterior one third of external lip
of iliac crest, a slip from the
inferior angle of the scapula
• INSERTION
– intertubercular groove of
humerus
LATISSIMUS DORSI
• ACTION
With the origin fixed, medially rotates, adducts, and
extends the shoulder joint. By continued action,
depresses the shoulder girdle, and assists in lateral
flexion of the trunk.
With the insertion fixed, assists in tilting the pelvis
anteriorly and laterally. Acting bilaterally, this muscle
assists in hyperextending the spine and anteriorly tilting
the pelvis, or in flexion the spine, depending upon its
relation to the axes of motion. This muscle is important in
ralation to movements such as climbing, walking with
crutches, or hoisting the body up on parallel bars, in
which the muscles act to lift the body toward the fixed
arms. The strength of the latissimus dorsi is a factor in
such forceful arm movements as swimming, rowing, and
chopping. All adductors and medial rotators act in these
strong movements but the latissimus dorsi may be of
major importance. The latissimus dorsi may act as an
accessory muscle for respiration
• NERVE
thoracodorsal nerve, C6, 7, 8
Intermediate Back Muscles
• Levator scapulae - later, rhomboids, serratus
anterior (deep extrinsic muscles)
• Scapular (intrinsic shoulder) muscles (deltoid,
supraspinatus, infraspinatus, teres major, minor
and subcapularis)
Four of these (supraspinatus, infraspinatus,
teres minor and subscapularis) are referred as
rotator cuff muscle
• Serratus posterior superior & Inferior (Muscles of
thorax proper)
RHOMBOID MAJOR
• ORIGIN
spinous processes of 2nd to 5th
thoracic vertebrae (major)
• INSERTION
By fibrous attachment to medial
border of scapula between
spine and inferior angle (major)
• ACTION
adduct and elevate the scapula,
and rotate it so that glenoid
cavity faces caudally
• NERVE
dorsal scapular, C4, 5
RHOMBOID MINOR
• ORIGIN
ligamentum nuchae, spinous
processes of 7th cervical and 1st
thoracic vertebrae (minor)
• INSERTION
medial border at root of spine of
scapula (minor)
• ACTION
adduct and elevate the scapula,
and rotate it so that glenoid cavity
faces caudally
• NERVE
dorsal scapular, C4, 5
Serratus anterior (the boxer’s muscle)
• ORIGIN
outer surface and superior borders of upper eight or
nine ribs
• INSERTION
costal surface of medial border of scapula
• ACTION
With the origin fixed, abducts the scapula, rotates the
inferior angle laterally and the glenoid cavity cranially,
and holds the medial border of the scapula firmly
against the rib cage. In addiction, the lower fibers may
depress the scapula, and the upper fibers may elevate
it slightly. Starting from a position with the humerus
fixed in flexion and the hands against a wall, the
serratus acts to displace the thorax posteriorly as the
effort is made to push the body away from the wall.
Another example of this type of action is in a properly
executed push-up.
With the scapula stabilized in addition by the
rhomboids, thereby fixing the insertion, the serratus
may act in forced inspiration
• NERVE
Long thoracic, C5, 6, 7, 8 (winging the scapula if
damaged)
DELTOID
• ORIGIN
– anterior fibers: anterior border, superior surface,
lateral one third of clavicle
middle fibers: lateral margin and superior
surface of acromion
– posterior fibers: inferior lip and superior border
of spine of scapula
• INSERTION
– deltoid tuberosity of humerus
• ACTION
Abduction of the shoulder joint, performed
chiefly by the middle fibers with
stabilization by the anterior and posterior
fibers. In addition, the anterior fibers flex
and, in the supine position, medially rotate
the shoulder joint; the posterior fibers
extend and, in the prone position, laterally
rotate.
• NERVE
axillary nerve, C5, 6
TERES MAJOR
• ORIGIN
dorsal surface of inferior angle
and lower third of lateral border
of scapula
• INSERTION
the crest of the lesser tubercle of
humerus
• ACTION
Medially rotates, adducts, and
extends the shoulder
• NERVE
Lower Subscapular Nerve C 5, 6,
7
TERES MINOR
• ORIGIN
Upper two thirds, dorsal surface of
lateral border of scapular
• INSERTION
the lowest facet of the greater
tubercle of the humerus, and
shoulder joint capsule
• ACTION
Laterally rotates shoulder joint, and
stabilizes head of humerus in the
glenoid cavity during movement of
this joint
• NERVE
Axillary nerve, C5, 6
INFRASPINATUS
• ORIGIN
medial two thirds of infraspinatus
fossa of scapula
• INSERTION
the middle facet of the greater
tubercle of the humerus, and
shoulder joint capsule
• ACTION
Lateral rotates shoulder joint and
stabilizes head of humerus in the
glenoid cavity during movement of
this joint
• NERVE
suprascapular nerve, C(4), 5, 6
SUPRASPINATUS
• ORIGIN
medial two thirds of supraspinous
fossa of scapula
• INSERTION
superior facet of greater tubercle of
humerus, and shoulder joint
capsule
• ACTION
Abducts the shoulder joint, and
stabilizes head of humerus in the
glenoid cavity during movement of
this joint
• NERVE
Suprascapular nerve, C 4, 5, 6
SUBSCAPULARIS
• ORIGIN
Subscapular fossa of scapula
• INSERTION
lesser tubercle of humerus and
shoulder joint capsule
• ACTION
medially rotates shoulder joint, and
stabilizes the head of the humerus in
the glenoid cavity during movements
of this joint
• NERVE
upper and lower subscapular nerve,
C5, 6, 7
SERRATUS POSTERIOR SUPERIOR
• ORIGIN
ligamentum nuchea in the neck, spinous
processes of C7, and T1 to T3
• INSERTION
superior borders of second to forth ribs
• ACTION
elevate first four ribs, aid respiration by
increasing diameter of the thorax
• NERVE
intercostal nerve
SERRATUS POSTERIOR INFERIOR
• ORIGIN
spinous processes of the last two
thoracic and first two lumbar
• INSERTION
inferior borders of the inferior three or
fourth ribs
• ACTION
depress inferior ribs, preventing them
from being pulled up by diaphragm
• NERVE
intercostal nerve
Rotator Cuff Tear
• Cause
– Over use, aging (middle aged man)
• Symptoms
– Pain, unable to raise arm
• Treatment
– Conservative
– Surgical