SHOULDER REGION MUSCLES
Feb 25, 2016
SHOULDER REGION MUSCLES
Coracobrachialis
Adduction of the shoulder & flexion.
Pectoralis Major
The first action is flexion of the humerus, Secondly, it adducts the humerus. Thirdly, it rotates the humerus medially. Finally it aids in deep inspiration
Subscapularis
Internal rotation of the shoulder
Deltoid
Abduction of shoulder
Infraspinatus
External rotation
Teres Major Adduction of scapula
Teres MinorThe infraspinatus and teres minor attach to head of the humerus; as part of the rotator cuff they help hold the humeral head in the glenoid cavity of the scapula. They work in tandem with the posterior deltoid to externally (laterally) rotate the humerus, as well as perform transverse abduction, extension and transverse extension.
Supraspinatus
Abduction of the shoulder
Coracobrachialis
Pect. Major
Subscapularis Deltoid
Supraspinatus Teres Major
InfraspinatusTeres Minor
PracticeList the muscles that
do flexion of the shoulder
CoracobrachialisPectoralis major
(upper to part)Anterior DeltoidBiceps
• List the muscles that do extension of the shoulder
• Latissimus dorsi• Teres major• Posterior deltoid• Pectoralis major (lower
fibers to neutral)
PracticeList the muscles that
do adduction of the shoulder
Pectoralis major (lower and upper below 90°)
CoracobrachialisLatissimus dorsiTeres major
List the muscles that do abduction of the shoulder
• Deltoid (all sections)• Supraspinatus• Pectoralis major (upper
past 90°)
PracticeList the muscles that
do internal rotation of the shoulder
SubscapularisLatissimus dorsiTeres majorAnterior deltoidPect. major
• List the muscles that do external rotation of the shoulder
• Infraspinatus• Teres minor• Posterior deltoid
Questions What muscle works closely with the anterior deltoid? Pectoralis major What muscle is involved in any lifting movements? Deltoid What is the major (strongest) extensor muscle? Latissimus Dorsi Name the four rotator cuff muscles. Subscapularis, Supraspinatus, Infraspinatus, and Teres minor. What muscle works closely with the infraspinatus? Teres minor
AXILLARY REGION
The axilla, or armpit, is a pyramidshaped space between the
upper part of the arm and the side of the chest.
Realize that the upper end, or apex, is directed into the root of the
neck and is bounded anteriorly by the clavicle, posteriorly by the
upper border of the scapula, and medially by the outer border of
the first rib. The lower end, or base, is bounded anteriorly by the
anterior axillary fold (formed by the lower border of the
pectoralis major muscle), behind by the posterior axillary fold
(formed by the tend of latissimus dorsi and the teres major
muscle), and medially by the chest wall.
Walls of the Axilla.
Identify the structures forming the walls of the �axilla:
Anterior wall. This is formed by the pectoralis major, pectoralis minor, clavipectoral fascia, and subclavius muscle
Posterior wall.
From above downward this wall is
formed by the subscapularis,
latissimus dorsi, and the teres major
muscles.
Medial wall. This is formed by the upper four or
five ribs and the intercostal spaces
covered by the serratus anterior
muscle.
Lateral wall.
This is formed by the
coracobrachialis and biceps
muscles in the bicipital groove of
the humerus.
Axillary Sheath.
The axillary artery (but not the vein) and the
brachial plexus are enclosed in a fascial
sheath derived from the prevertebral layer of
deep cervical fascia in the neck.
Axillary Artery. This commences at the outer border of the first rib as a continuation of the subclavian artery. Having passed through the axilla, it becomes the brachial artery at the lower border of the
teres major muscle. It is arbitrarily divided into three parts by the pectoralis minor muscle
that crosses it anteriorly.
Brachial Plexus.
Brachial plexus The brachial plexus is divided into Roots,
Trunks, Divisions, Cords, and Branches. There are five "terminal" branches and numerous other "pre-terminal" or "collateral" branches that leave the plexus at various points along its length.
The five roots are the five anterior rami of the spinal nerves, after they have given off their segmental supply to the muscles of the neck.
These roots merge to form three trunks:– "superior" or "upper" (C5-C6)– "middle" (C7)– "inferior" or "lower" (C8-T1)
Brachial plexus Each trunk then splits in two, to form six divisions:
– anterior divisions of the upper, middle, and lower trunks– posterior divisions of the upper, middle, and lower trunks
These six divisions will regroup to become the three cords. The cords are named by their position with respect to the axillary artery.– The posterior cord is formed from the three posterior
divisions of the trunks (C5-T1)– The lateral cord is the anterior divisions from the upper
and middle trunks (C5-C7)– The medial cord is simply a continuation of the anterior
division of the lower trunk (C8-T1) The branches are shown in the following diagram
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