SHOULDER Kaan Yücel M.D., Ph.D 12.March.2014 Wednesday

shoulder Region of upper limb attachment to the trunk Proximal segment of limb overlaps parts of the trunk (thorax and back) and lower lateral neck. includes Pectoral Scapular Deltoid regions of the upper limb lateral part (greater supraclavicular fossa) of lateral cervical region. Overlies half of the pectoral girdle.

The pectoral (shoulder) girdle formed by: Scapulae and clavicles completed anteriorly by the manubrium of the sternum (part of the axial skeleton).

Bone framework of the shoulder Clavicle & scapula [pectoral girdle-shoulder girdle] Proximal end of humerus

The superficial muscles of the shoulder trapezius & deltoid muscles together form the smooth muscular contour over the lateral part of the shoulder. Connect scapula to trunk & clavicle to arm. .

Joints The 3 joints in the shoulder complex : Sternoclavicular joint Acromioclavicular joint Glenohumeral joint

Muscles

The two most superficial muscles of the shoulder trapezius and deltoid muscles. Trapezius attaches scapula & clavicle to the trunk Deltoid attaches scapula & clavicle to the humerus

POSTERIOR AXIOAPPENDICULAR MUSCLES EXTRINSIC SHOULDER MUSCLES SUPERFICIAL POSTERIOR AXIOAPPENDICULAR MUSCLES EXTRINSIC SHOULDER MUSCLES Trapezius & latissimus dorsi DEEP POSTERIOR AXIOAPPENDICULAR MUSCLES EXTRINSIC SHOULDER MUSCLES Levator scapulae & rhomboids

(INSTRINSIC SHOULDER) MUSCLES SCAPULOHUMERAL (INSTRINSIC SHOULDER) MUSCLES 6 scapulohumeral muscles Deltoid, teres major, supraspinatus, infraspinatus, subscapularis, and teres minor pass from scapula to humerus Act on the glenohumeral joint. All the intrinsic muscles but the deltoid and the subscapularis are muscles of the posterior scapular region.

Deltoid Large and triangular in shape Base attached to the scapula and clavicle Apex attached to the humerus

Deltoid Lateral 1/3 of clavicle Acromion Spine of scapula Deltoid tuberosity of humerus

Deltoid Major function: Abduction of the arm beyond the initial 15° accomplished by supraspinatus Clavicular: flexes and medially rotates arm Acromial: abduction of arm Spinal: extends and laterally rotates arm

branch of the posterior cord of the brachial plexus Deltoid Innervation: Axillary nerve branch of the posterior cord of the brachial plexus

Subscapularis Thick, triangular muscle Lies on the costal surface of the scapula Subscapular fossa Lesser tubercle of humerus

Subscapularis Primary medial rotator of the arm Adducts the arm. Joins the other rotator cuff muscles in holding the head of the humerus in the glenoid cavity during all movements of the glenohumeral joint! Innervation: Superior and inferior subscapular nerves

POSTERIOR SCAPULAR REGION 4 muscles pass between the scapula and proximal end of humerus: POSTERIOR SCAPULAR REGION Supraspinatus Infraspinatus Teres minor Teres major

+ part of long head of the triceps brachii, passes between the scapula and the proximal end of the forearm.

Supraspinatus & Infraspinatus Originate from 2 large fossae, 1 above and 1 below the spine, on the posterior surface of the scapula. Insert on greater tubercle of the humerus. Supraspinatus initiates abduction of the arm. Infraspinatus laterally rotates the humerus.

Supraspinatus & Infraspinatus

Teres minor A cord-like muscle Laterally rotates the humerus Component of the rotator cuff. Middle part of lateral border of scapula Inferior facet of greater tubercle of humerus

Teres major Posterior surface of inferior angle of scapula Medial lip of intertubercular sulcus of humerus Medially rotates and extends the humerus.

ROTATOR CUFF MUSCLES (SITS muscles) 4 intrinsic shoulder muscles Supraspinatus Infraspinatus Teres minor Subscapularis (SITS muscles) Form a musculotendinous rotator cuff around the glenohumeral joint.

ROTATOR CUFF MUSCLES Insertion exception: Supraspinatus Infraspinatus Teres minor greater tubercle Subscapularis lesser tubercle

ROTATOR CUFF MUSCLES Functional exception: All except supraspinatus are rotators of the humerus Supraspinatus, besides being part of the rotator cuff, initiates and assists the deltoid in the first 15° of abduction of the arm.

Gateways to the posterior scapular region Suprascapular foramen The route through which structures pass between the base of the neck and the posterior scapular region. Formed by suprascapular notch of scapula & superior transverse scapular (suprascapular) ligament, which converts the notch into a foramen.

Gateways to the posterior scapular region The suprascapular nerve passes through the suprascapular foramen; Suprascapular artery & suprascapular vein follow the same course as the nerve, but normally pass immediately superior to the superior transverse scapular ligament and not through the foramen.

Gateways to the posterior scapular region Quadrangular space axillary nerve & posterior circumflex humeral artery and vein

Gateways to the posterior scapular region Triangular space circumflex scapular artery and vein

Gateways to the posterior scapular region Triangular interval radial nerve ,profunda brachii artery (deep artery of arm)

Nerves The two major nerves of the posterior scapular region: Suprascapular & Axillary nerves originate from the brachial plexus in the axilla.

Suprascapular nerve Originates where? Base of the neck from superior trunk of brachial plexus Reach where through which space? Posterior scapular region through suprascapular foramen Which muscles innervates ? Supraspinatus muscle & infraspinatus

Axillary nerve Originates where? Posterior cord of brachial plexus Reach where through which space? From the posterior wall of axilla to posterior scapular region through quadrangular space Which muscles innervates ? Deltoid & teres minor

Axillary nerve Cutaneous branch? Superior lateral cutaneous nerve of the arm carries general sensation from the skin over the inferior part of the deltoid muscle.

3 major arteries in the posterior scapular region Suprascapular artery Posterior circumflex humeral artery Circumflex scapular artery These arteries contribute to an interconnected vascular network around the scapula.

Formation of anastomosis around the surgical neck of humerus Posterior circumflex humeral artery anastomoses with anterior circumflex humeral artery and also with branches from: profunda brachii (brachial artery) suprascapular (subclavian artery) thoracoacromial (axillary artery) arteries .

Movements of the shoulder girdle Abduction of the shoulder is initiated by the supraspinatus; the deltoid can then abduct to 90 degrees. Further movement to 180 degrees (elevation) is brought about by rotation of the scapula upwards by the trapezius and serratus anterior. As soon as abduction commences at the shoulder joint, so the rotation of the scapula begins.  

Principal muscles acting on the shoulder joint Abductors Supraspinatus Deltoid Adductors Pectoralis major Lattisimus dorsi Extensors Teres major Deltoid (posterior fibres) Flexors Coracobrachialis Deltoid (anterior fibres)   Medial rotators Pectoralis major Lattisimus dorsi Teres major Deltoid (anterior fibres) Subscapularis Lateral rotators Infraspinatus Teres minor Deltoid (posterior fibres)