Muscles connecting UL to vertebral column
**please refer to pictures in the slides*
Deltoid
Shape : Triangular in shape
Origin ( outer ) : 3 origins : 1- Anteriorly --- Clavicle
2- laterally --- acromion
3- posteriorly --- spine of scapula
Insertion : Deltoid tuberosity ( on the lateral surface of humerus ) ... !
three origins converge !
Action : according to origins and insertion …Its fibers run in three
directions :- Anterior --- assist in flexing shoulder
Middle(horizontal/transvers)--- abduct arm (humerus)
Posterior --- extend shoulder
*** Notice that : the direction of fiber's running ( from origin to
insertion ) is opposite to the direction of action ( from insertion to origin )
.
NV : Axillary N.
**Deltoid abduct the arm from 15 – 90˚
Trapezius
Shape : Single --- Triangular in shape
Double --- Trapezoid in shape
Origin : originated from axil skeleton :
Skull (mid line ) , spines of C1 – T 12 vertebrae ( all servical and all
thoracic vertebrae )
Insertion ( inner) : direction of fibers :Downward / anterior -- Clavicle
Transverse / lateral -- Acromion
Upward / superior -- Spine of scapula
Action :
Upper fibers -- elevate scapula
Middle fibers -- adduct medial
Lower fibers -- pull/depress scapula downward
** Assist in abducting the arm ( humerus) 180˚ above the head (
with the help of Serratus anterior )
NS : Spinal accessory N.
*Note : there are two types of nerves :1- spinal nerves --- from spinal cord
2- cranial nerves (1- 12 nerves) --- from Brain
First : Olfactory nerve
Second : hypoglossal
*** Spinal accessory nerve is the cranial nerve # 11
Latissmus dorsi
Shape : wide muscle
Origin : Vertebral column (T 7-T12 / L1-L5 / sacrum )&
Iliac crest : bone of the lower limp.
Insertion : Floor of biceptal (intertubercular ) groove.
NS : Thoracodorsal N. ( from bracial plexus network )
Action : Extension , adduction and medial rotation of Humerus like
in canoeing .
**Notes :
* We use Latissmus dorsi in climbing …
*It fix humerus with vertebral column (axial skeleton )
latissmus : ‫العريضة‬
dorsi : ‫الظھرية‬
deep to trapezius…
Rhomboid minor
Origin : Vertebral column C7-T1 ( two vertebrae )
Ins : Scapula (upper 1/3 of the medial border of scapula)
Action : adduction and elevation of scapula
NS : Dorsal scapular N.
Rhomboid major
Origin : Vertebral column T2-T5 ( four vertebrae )
Ins : Scapula (lower 2/3 of the medial border of scapula)
Action : adduction and elevation of scapula ( powerful )
NS : Dorsal scapular N.
** Notes :
* Rhomboid major & minor cooperate together to move scapula &
fix medial border of scapula with VC.
* Elevating scapula is a snergestic action between 4 muscles :
Trapezuis,Rhomboid major & minor and Levator scapulae .
Another muscle :
Levator scapulae
Origin : C1-C4
Insertion : scapula ( superior medial angle of scapula )
Action : elevate the scapula
Muscles connecting UL to scapula
Supraspinatus
Origin : supraspinous fossa
Insertion : greater tubercle of humerus
Action : Initiate abduction of the humerus 0-15 ˚
NS : suprascapular N. ( from bracial plexus )
Infraspinatus
Origin : infraspinous fossa
Insertion : greater tubercle of humerus
Action : lateral rotation of arm ( humerus )
NS : suprascapular N. ( from bracial plexus )
** Note : Infraspinatus & supraspinatus share to things :
Insertion and NS .
Teres minor
Shape : rounded ( Teres :: rounded)
Origin : lateral border of scapula ( upper part 2/3)
Insertion : greater tubercle of humerus
Action : lateral rotation of humerus ( like infraspinatus )
NS : a branch of Axillary N. ( n. to Deltoid )
Teres major
Shape : rounded
Origin : lateral border of scapula ( lower part )
Insertion : medial lip of intertubercular groove
Action : medial rotation & adduction of arm (like pectoralis major)
NS : Lower subscapular N. ( share with subscapularis )
Subscapularis
( Anterior part of scapula )
Shape : triangular
Origin : subscapular fossa ( it's fibers run laterally)
Insertion: lesser tubercle
Action : medial rotation of humerus
NS: Upper & lower subscapular Ns.
☺ Note : SIT ---- inserted into greater tubercle.
SITS ---- inserted into tubercles of humerus .
☺
**synergistic ( cooperative) action --Pectoralis major , Teres major and Subscapularis ... → to rotate
arm medially .
Rotator cuff muscles of shoulder
" muscles that stabilize & strengthen the shoulder joint while
moving ( Rotating ) "
-Shoulder joint is the weakest joint in the body .
◊ Consist of 4 muscles : ( SITS)
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
** The Feature >>> their tendons flatten at their insertion and
blend ( merge) with capsule of shoulder joint to strengthen it .
They act as a handcuff that strengthen the shoulder joint :
Superior → by Supraspinatus
Posterior → by Infraspinatus & Teres minor
Anterior → by Subscapularis
BUT NOT Inferior ?!! weak region and commonly Dislocated .
Serratus anterior
Location : on the lateral site of the thorax
Origin : outer surface of the upper 8 ribs ( it is a sheet o muscles
origins from 8 parts (digits) )
Insertion : medial border of scapula ( anteriorly )
Action : protraction of scapula ( pulls the scapula forward over
thoracic wall ) >> when you push .
It assists trapezius to elevate arm 180˚ above shoulder .
NS : Long thoracic N.
** Winging of scapula when serratus anterior paralyze.
*Cooperation >> 4 muscles
˚/ Deltoid : 15 -90
˚Serratus anterior & Trapezius : 180 ˚
Supraspinatus : abduct the arm 0 -15