Shoulder region
Muscle
Deltoid
Forms rounded
contour of shoulder
Supraspinatus
Infraspinatus
Teres minor
Teres major
Subscapularis
Origin
Insertion
Deltoid tuberosity at
Anterior fibers:
anterior border of lateral
middle of lateral surface
1/3 of clavicle
of humerus
Middle fibers:
lateral border of acromial
process
Posterior fibers:
lower lip of the crest of
spine of scapula
Medial 2/3 of the supraspinous Highest impression on the
fossa of the scapula
greater tuberosity of the
humerus
Medial 2/3 of the infra-spinous Middle impression on
fossa of the scapula
posterior surface of the
greater tuberosity of the
humerus
Upper 2/3 of posterior surface Inferior impression on the
of the the lateral border of the posterior surface of the
scapula
greater tuberosity of the
humerus.
Lower 1/3 of posterior surface Medial lip of the biciptal
of the lateral border of scapula . groove .
Medial 2/3 of subscapular fossa Lesser tuberosity of
.
humerus
Innervation
Action
Axillary nerve (C5, 6)
Anterior fibers:
Flexion & medial rotation
Middle fibers:
Abduction of arm from
15-90
Posterior fibers:
Extension & lateral rota
Tion
Suprascapular nerve (C5, -Stability of shoulder joint;
C6)
-Initiation of abduction of
arm to 15o at shoulder joint
Suprascapular nerve (C5, -Stability of shoulder joint
C6)
- Lateral rotation of arm .
Axillary nerve (C5, 6)
-Stability of shoulder joint
-Adduction
and
lateral
rotation of arm
Lower subscapular nerve -Stability of shoulder joint
(C5 ,C6)
-Medial rotation ,adduction
and extension of the arm.
Upper
and
lower -Stability of shoulder joint
subscapular nerves (C5, -Adduction;&
medial
C6)
rotation of the arm .
Deltoid muscle
Teres major
Muscles of the back
1. Superficial layer : trapezius and latissimus dorsi
2. Deep layer: levator scapulae , rhomboids minor and rhomboids major
Muscle
Trapezius
Latissimus dorsi
Levator scapulae
Rhomboid minor
Rhomboid major
Origin
Skull:
External
occipital
protuberance & medial 1/3 of
superior nuchal line.
.
Neck:
Ligamentum nuchae & spine
of C 7.
Thorax :
All thoracic spines and
supraspinous ligament.
*Posterior 1/ 3 of outer lip
of iliac crest
*Thoracolumbar fascia
*Spine of lower six
thoracic vertebrae
* Lower 3-4 ribs and
*Back of inferior angle of
scapula.
Transverse processes of C 1
to C 4
Insertion
Upper fibers:
Back of lateral one-third of
clavicle.
Middle fibers:
Medial border of acromion
process & upper lip of crest
of spine of scapula
Lower fibers:
Tubercle of crest of spine
of scapula
Nerve supply
Motor:
Spinal root of
accessory nerve (XI).
Sensory
(Proprioception):
C3 and C4
Floor of bicipital groove.
Thoracodorsal nerve
NB. It tendon has triple
(C6, C7, 8)
relation with teres major;
behind then below then in
front.
Dorsal surface of medial
border of scapula between
spine and superior angle
Lower portion of ligamentum Dorsal surface of medial
nuchae, spinous processes of border of scapula at the
C7 and T1
root of spine of scapula
Spinous processes of T 2 to T Dorsal surface of medial
5.
border of scapula between
spine and inferior angle
Action
Upper fibers elevates tip of
shoulder
Middle fibers
Retraction of scapula
Lower fibers depress
scapula & with the upper
fibers assist in rotating the
scapula upward
during
abduction from90 -180
-Adduction,
medial
rotation, and extension of
the arm
-Deep expiration.
-Helps
climbing
with
pectoralis major by acting
from insertion
C3 to C4 and dorsal -Elevates scapula with
scapular nerve (C5)
upper fibers of trapezius.
-Rotates scapula downward
Dorsal scapular nerve Retracts
with
middle
(C5)
fibers of trapezius .
Rotates scapula downward
Dorsal scapular nerve -like minor
(C5)
Quadrangular and Triangular Spaces
They are inter-muscular spaces lying just below the shoulder joint.
A. Quadrangular space :
- Boundaries:




Above: by the teres minor (seen from behind), the subscapularis (seen from in front) and the capsule of the
shoulder joint.
Below: by teres major.
Medially: by long head of triceps.
Laterally: by surgical neck of humerus.
- Contents:


Posterior circumflex humeral vessels.
Axillary (circumflex) nerve.
B. Upper triangular space (medially) :
- Boundaries:



Above: by teres minor (seen from behind) and subscapularis (seen from in front).
Below: by teres major.
Laterally: by long head of triceps.
- Contents: it transmits only the circumflex scapular artery.
C. Lower triangular space (triangular interval) :
- Boundaries:



Above by: teres major.
Medially by: long head of triceps.
Laterally by: lateral head of triceps and the shaft of humerus.
- Contents: radial nerve and profunda brachii vessels.