8.29.11+-+Shoulder

Objectives
**1) Define the terms: superior appendicular skeleton, shoulder, arm (brachium), forearm (antebrachium), hand (namus), wrist (carpus) and pectoral girdle.**
 * 1) ** Superior appendicular skeleton ** : Formed by the bones of the upper limb.
 * 2) ** Shoulder ** **:** begins at the base of the neck, overlies the thorax and bac and contains the pectoral girdle.
 * 3) ** Arm (Brachium) ** : lies between glenohumeral and elbow joints and contains the humerus
 * 4) ** Forearm (antebrachium) ** : lies between elbow and wrist joints and contains the radius and ulna.
 * 5) ** Hand (manus) ** : lies distal to the forearm and is divided into wrist (carpus), palm region and digits. Contains metacarpal and phalange bones.
 * 6) ** Wrist (carpus) ** **:** contains the carpal bones.
 * 7) ** Pectoral girdle ** **:** Part of the shoulder - Incomplete bony ring made of clavicle and scapula.

**2) Describe structure and functions(s) of the clavicle, scapula and proximal humerus.**
 * 1) Clavicle:
 * 2) Structure: S shaped long bone. Medial half of the shaft projects anteriorly and the lateral half projects posteriorly. The medial end is large and triangular in shape; it articulates with the manubrium of the sternum at the sternoclavicular (SC) joint. The lateral end is flat and articulates with the acromion of the scapula at the acromioclavicular (AC) joint.
 * 3) Function: The clavicle is a strut that
 * 4) suspends the upper limb at the SC joint,
 * 5) protects underlying neurovascular elements supplying the upper limb,
 * 6) transmits impacts from the upper limb to the axial skeleton and
 * 7) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;"> provides for muscle attachments.
 * 8) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Scapula
 * 9) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Structure: large, triangular flat bone overlying the 2nd-7th ribs. It is divided into head, neck and body.
 * 10) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">The small disc-shaped head is separated from the body by the constricted neck. The scapula has medial, lateral and superior borders and superior, lateral and inferior angles.
 * 11) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;"> A somewhat horizontal superior border has a divot, the suprascapular notch.
 * 12) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;"> The medial border is parallel to the vertebral spinous processes. The lateral border ends at the head and neck.
 * 13) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;"> Superior and medial borders meet at the superior angle. Medial and lateral borders meet at the inferior angle. Lateral and superior borders meet at the lateral angle that is truncated as the head and neck. The dorsum of the scapula is complex.
 * 14) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;"> The scapular spine is a bony strut arising from the posterior surface; its medial end is the root and its lateral end is a flat projection, the acromion. About midway, the spine detaches from the body of the scapula forming the concave spinoglenoidnotch and then ends as the acromion.
 * 15) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">The spine divides the posterior scapula into supraspinous and infraspinous fossae. The anterior or costal surface is concave, forming the subscapular fossa.
 * 16) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">The coracoid process arches from the superior border just lateral to the suprascapular notch. The
 * 17) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">lateral surface consists of head and two tubercles. The ring like head bears a shallow glenoid cavity that articulates with the humeral head at the glenohumeral joint. Supraglenoid and infraglenoid tubercles lie above and below the glenoid cavity.
 * 18) Function: provides muscle attachments, forms the socket of the glenohumeral join and increases the range of motion of the upper limb.
 * 19) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Proximal humerus:
 * 20) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">structure
 * 21) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Largest bone of the upper limb with a ball-shaped head that articulates with the glenoid cavity at the glenohumeral joint.
 * 22) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">The head is attached to flared metaphysis that narrows to the shaft. Two bony knobs jut from the metaphysis: the anterior lesser tubercle and the lateral but larger greater tubercle.
 * 23) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">The anatomical neck divides the head from the metaphysis and its tubercles.
 * 24) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Surgical neck encircles the metaphysis just distal to the tubercles.
 * 25) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Intertubercular (bicipital) groove separates the tubercles.
 * 26) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Deltoid tuberosity projects laterally near the middle of the shaft.
 * 27) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Radial (spiral groove) curves along the posterior surface.
 * 28) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Function: proximal humerus provides muscle attachments and forms the ball part of the glenohumeral joint.

<span style="font-family: Arial,Helvetica,sans-serif;">**3) Discuss the anatomy and movements of sternoclavicular, acromioclavicular and glenohumeral joints.**


 * 1) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Sternoclavicular (SC) joint: Saddle type of synovial joint between the medial clavicle and the sternal notch of the manubrium. Articular disc separates joint cavity. Joint surfaces covered with fibrocartilage.
 * 2) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Movements are elevation, depression, protraction, retraction and rotation.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Sternoclavicular, costoclavicular and interclavicular ligaments reinforce the joint capsule and jointly support most of the weight of the upper limb.
 * 4) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Only site where upper limb articulates with axial skeleton
 * 5) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Acromioclavicular joints: planer type of synovial joint with an articular disc.
 * 6) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Movements are gliding and rotation.
 * 7) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Acromioclavicular ligament forms most of the joint capsule. Strong coracoclavicular (with conoid and trapezoid parts)and coracoacromial ligaments help resist separation of the joint and coordinate movements between clavicle and scapula.
 * 8) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Glenohumeral joints: Synovial joint of ball-and-socket type between the head of humerous and glenoid cavity.
 * 9) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Movements: abduction, adduction, flexion, extension, medial rotation, lateral rotation and cicumduction.
 * 10) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Glenoid labrum deepens small, shallow glenoid cavity. Hyaline cartilage forms the labrum and covers articular surfaces.
 * 11) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Humeral head is much larger than glenoid cavity (1/3 of head in contact with cavity at any given time). Joint is highly mobile but unstable.
 * 12) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Joint capsule joins the anatomical neck of the humerus to just outside the margin of the glenoid cavity. Rotator cuff tendons help reinforce the joint capsule.
 * 13) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;">Tendons of the long head of biceps brachii traverses and helps stabilizes joint cavity.
 * 14) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt; vertical-align: middle;"> 2 fluid filled bursae act as cushions between joint and adjacent muscles. Subacromial (subdeltoid) bursa udnerlies acromion and AC ligament. The subscapularis bursa underlies the subscapularis muscles.

<span style="font-family: Arial,Helvetica,sans-serif;">**4) Name anterior axioappendicular, posterior axioappendicular and scapulohumeral muscles. Describe origins (proximal attachments) insertions (distal attachments), innervation and actions of each muscle.**

<span style="font-family: Arial,Helvetica,sans-serif;">**Anterior Axioappendicular Muscles:** Four muscles that attach the anterior axial skeleton to the superior appendicular skeleton. These include: pectoralis major, pectoralis minor, subclavius and serratus anterior.

<span style="font-family: Arial,Helvetica,sans-serif;">A. Pectoralis Major: A large, fan-shaped muscle that covers the anterior chest wall. It has clavicular and sternocostal heads.


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">Origin (Proximal Attachment): Clavicular head arises from the medial clavicle; sternocostal head from sternum, 1st-6th costal cartilages and aponeurosis of external abdominal oblique muscle.
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">Insertion (Distal Attachment): Lateral lip of intertubercular groove. Note: the tendon folds such that superior fibers insert inferiorly and inferior fibers insert superiorly on the lateral lip of the groove.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">Innervation:Medialandlateralpectoralnerves.
 * 4) <span style="font-family: Arial,Helvetica,sans-serif;">Actions:Actingtogether,bothheadsadductandmediallyrotatehumerus; acting alone, the clavicular head flexes glenohumeral joint; acting alone, the sternocostal head extends (the flexed) glenohumeral joint.

<span style="font-family: Arial,Helvetica,sans-serif;">B. Pectoralis Minor: Small, triangular muscle underlying pectoralis major.


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">Origin: 3rd-5th ribs (near costal cartilages).
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">Insertion: Coracoid process.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">Innervation:Medialpectoralnerve.
 * 4) <span style="font-family: Arial,Helvetica,sans-serif;">Action: Protracts scapula.

<span style="font-family: Arial,Helvetica,sans-serif;">C. Subclavius: Small, strap-like muscle underlying the clavicle.


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">Origin: 1st rib (near costal cartilage).
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">Insertion: Inferior surface of middle clavicle.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">Innervation: Nerve to subclavius.
 * 4) <span style="font-family: Arial,Helvetica,sans-serif;">Action: Depresses the clavicle.

<span style="font-family: Arial,Helvetica,sans-serif;">D. Serratus Anterior: Large, saw-toothed muscle overlying lateral thoracic wall.


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">Origin: Lateral surfaces of 1st – 8th ribs.
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">Insertion: Anterior surface of medial border of scapula.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">Innervation: Long thoracic nerve (of Bell).
 * 4) <span style="font-family: Arial,Helvetica,sans-serif;">Action: Protracts and rotates scapula. Clinical Note: injury to the long thoracic nerve causes paralysis of the serratus anterior. The scapula moves away from the thoracic wall, a condition known as “winged scapula”.

<span style="font-family: Arial,Helvetica,sans-serif;">**Posterior Axioappendicular Muscles:** Five muscles attaching the posterior axial skeleton to the superior appendicular skeleton. Muscles include the superficial trapezius and latissimus dorsi and the deeper levator scapulae, rhomboid major and rhomboid minor.

<span style="font-family: Arial,Helvetica,sans-serif;">A. Trapezius: A large, flat triangular muscle covering neck and superior trunk.


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">Origin: Superior nuchal line, external occipital protuberance, nuchal ligament and spinous processes of C7-T12 vertebrae.
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">Insertion: Lateral 1/3 of clavicle, acromion and spine of scapula.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">Innervation:Accessorynerve(CNXI).
 * 4) <span style="font-family: Arial,Helvetica,sans-serif;">Actions:Superiorfiberselevate,middlefibersretractandinferiorfibers depress the scapula. Acting together, superior and inferior fibers rotate glenoid cavity superiorly.

<span style="font-family: Arial,Helvetica,sans-serif;">B. Latissimus Dorsi: A large fan-shaped muscle covering lower back.


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">Origin: T7-T12 vertebral spines, thoracolumbar fascia, iliac crest, inferior 3 or 4 ribs (inferior angle of scapula).
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">Insertion: Floor of intertubercular groove.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">Innervation: Thoracodorsal nerve.
 * 4) <span style="font-family: Arial,Helvetica,sans-serif;">Actions: Extends, adducts and medially rotates humerus.

<span style="font-family: Arial,Helvetica,sans-serif;">C. Levator Scapulae: A strap-like muscle traversing the posterior neck.


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">Origin:TransverseprocessesofC1-C4vertebrae.
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">Insertion: Medial border of scapula, superior to root of spine.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">Innervation: Dorsal scapular nerve and cervical nerves.
 * 4) <span style="font-family: Arial,Helvetica,sans-serif;">Actions: Elevates and rotates scapula to depress glenoid cavity.

<span style="font-family: Arial,Helvetica,sans-serif;">D. Rhomboides Major and Minor: Two rhomboid-shaped muscles, often not distinct from one another.


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">Origin: Rhomboid minor from nuchal ligament and C7-T1 vertebral spines; rhomboid major from T2-T5 vertebral spines.
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">Insertion: Rhomboid minor to medial border of scapula at root of spine; rhomboid major to medial border of scapula inferior to root of spine.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">Innervation: Dorsal scapular nerve.
 * 4) <span style="font-family: Arial,Helvetica,sans-serif;">Actions:Retractandrotatescapulatodepressglenoidcavity.

<span style="font-family: Arial,Helvetica,sans-serif;">**ScapulohumeralMuscles:** Six muscles that attach the scapula and humerus. Muscles are: deltoid, supraspinatus, infraspinatus, teres minor, teres major and subscapularis.

<span style="font-family: Arial,Helvetica,sans-serif;">A. Deltoid: Muscle shaped the Greek letter, delta (Δ). Divided into anterior, middle and posterior fibers.


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">Origin: Lateral 1/3 of clavicle, acromion and scapular spine.
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">Insertion:Deltoidtuberosity.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">Innervation:Axillarynerve.
 * 4) <span style="font-family: Arial,Helvetica,sans-serif;">Actions: Anterior fibers flex and medially rotate humerus. Middle fibers abduct humerus. Posterior fibers extend and laterally rotate humerus.

<span style="font-family: Arial,Helvetica,sans-serif;">B. Supraspinatus: Small, fan-shaped muscle of posterior scapula.


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">Origin:Supraspinous fossa of scapula.
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">Insertion:Superiorfacetofgreatertubercleofhumerus.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">Innervation:Suprascapularnerve.
 * 4) <span style="font-family: Arial,Helvetica,sans-serif;">Actions: Abducts (first 15 degrees) of humerus. Note: full abduction of the upper limb requires rotation of the scapula by the trapezius.

<span style="font-family: Arial,Helvetica,sans-serif;">C. Infraspinatus: Small, fan-shaped muscle of posterior scapula.


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">Origin:Infraspinousfossaofscapula.
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">Insertion:Middlefacetofgreatertubercleofhumerus.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">Innervation:Suprascapularnerve.
 * 4) <span style="font-family: Arial,Helvetica,sans-serif;">Actions:Laterallyrotateshumerus.

<span style="font-family: Arial,Helvetica,sans-serif;">D. Teres Minor: Small, round muscle of the posterior scapula.


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">Origin:Middlepartoflateralborderofscapula.
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">Insertion:Inferiorfacetofgreatertubercleofhumerus.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">Innervation:Axillarynerve.
 * 4) <span style="font-family: Arial,Helvetica,sans-serif;">Actions:Laterallyrotateshumerus.

<span style="font-family: Arial,Helvetica,sans-serif;">E. Teres Major: Thick, round muscle of the posterior scapula.


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">Origin:Posteriorsurfaceofinferiorangleofscapula.
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">Insertion:Mediallipoftheintertuberculargroove.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">Innervation:Lowersubscapularnerve.
 * 4) <span style="font-family: Arial,Helvetica,sans-serif;">Actions:Adductsandmediallyrotateshumerus.

<span style="font-family: Arial,Helvetica,sans-serif;">F. Subscapularis: Triangular muscle on costal surface of scapula.


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">Origin:Subscapularfossa.
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">Insertion: Lesser tubercle of humerus.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">Innervation:Upperandlowersubscapularnerves.
 * 4) <span style="font-family: Arial,Helvetica,sans-serif;">Actions:Adductsandmediallyrotateshumerus.

<span style="font-family: Arial,Helvetica,sans-serif;">**5) Define the term "rotator cuff". name the SITS muscles and discuss their significance.** <span style="font-family: Arial,Helvetica,sans-serif;">Rotator cuff is a musculotendinous ring formed by muscles that attach to greater and lesser tubercles of the humerus. Their tendons bind and reinforce the joint capsule and secur ethe humeral head in the glenoid cavity. Made up of the SITS muscles or Supraspinatus, Infraspinatus, Teres Minor and Subscapularis. Supraspinatus tendon is most commonly torn.