Lecture One
Superficial back
Bony marks
•spine
•supraspinous fossa
•infraspinous fossa
•acromion process
•coracoid process
•glenoid cavity
Bony marks
•Greater & Lesser turbercle
•Intertubercular groove
•Lateral & Medial epicondyle
•Anatomical & Surgical neck
•Deltoid tuberosity
•Olecranon fossa
triangle of auscultation
•a triangle located below the inferior angleof the scapula bounded by the trapeziusmuscle medially, rhomboideus majormuscle superiorly and the latissimus dorsimuscle inferiorly; its floor is the posteriorthoracic wall, used to hear lungs bystethoscope
Back muscles
•The skin and superficial fascia of the back canbe divided into three groups organized in layers:superficial, intermediate, and deep. Muscles ofthe superficial and intermediate groups arecalled extrinsic back muscles because they areinvolved in respiration and movements of theupper extremity. Muscles of the deep group arecalled intrinsic back muscles because they areinvolved in movement and stabilization of thevertebral column.
Superficial back muscles
•trapezius and latissimus dorsi muscle
TRAPEZIUS
•ORIGIN
–Upper fibers: external occipital protuberance,medial one third of superior nuchal line,ligamentum nuchae, and spinous process of7th cervical vertebra
–Middle fibers: spinous processes of first tofifth thoracic vertebrae
–Lower fibers: spinous processes of sixth to12th thoracic vertebrae
•INSERTION
–Upper fibers: lateral one third of clavicle andacromion process of the scapula
–Middle fibers: medial margin of acromion andsuperior lip of spine of scapula
–Lower fibers: tubercle at apex of spine ofscapula
TRAPEZIUS
•ACTIONWith origin fixed, adduction of the scapula,performed chiefly by the middle fibers withstabilization by the upper and lower fibers.Rotating of the scapula so the glenoid cavityfaces cranially, performed chiefly by the upperand lower fibers with stabilization by the middlefibers. In addition, the upper fibers elevate andthe lower fibers depress the scapula.With the insertion fixed, and acting unilaterally,the upper fibers extend, laterally flex, and rotatethe head and joints of the cervical vertebrae sothat the face turns toward the opposite side; andacting bilaterally, the upper Trapezius extendsthe neck. The Trapezius also acts as anaccessory muscle of respiration.
•NERVEspinal portion of accessory nerve (XI cranialnerve) and ventral ramus, C2, 3, 4
LATISSIMUS DORSI
•ORIGIN
–spinous processes of last sixthoracic vertebrae, last three orfour ribs, through thethoracolumbar fascia from thelumbar and sacral vertebrae andposterior one third of external lipof iliac crest, a slip from theinferior angle of the scapula
•INSERTION
–intertubercular groove ofhumerus
LATISSIMUS DORSI
•ACTIONWith the origin fixed, medially rotates, adducts, andextends the shoulder joint. By continued action,depresses the shoulder girdle, and assists in lateralflexion of the trunk. With the insertion fixed, assists in tilting the pelvisanteriorly and laterally. Acting bilaterally, this muscleassists in hyperextending the spine and anteriorly tiltingthe pelvis, or in flexion the spine, depending upon itsrelation to the axes of motion. This muscle is important inralation to movements such as climbing, walking withcrutches, or hoisting the body up on parallel bars, inwhich the muscles act to lift the body toward the fixedarms. The strength of the latissimus dorsi is a factor insuch forceful arm movements as swimming, rowing, andchopping. All adductors and medial rotators act in thesestrong movements but the latissimus dorsi may be ofmajor importance. The latissimus dorsi may act as anaccessory muscle for respiration
•NERVEthoracodorsal nerve, C6, 7, 8
Intermediate Back Muscles
•Levator scapulae - later, rhomboids, serratusanterior (deep extrinsic muscles)
•Scapular (intrinsic shoulder) muscles (deltoid,supraspinatus, infraspinatus, teres major, minorand subcapularis)Four of these (supraspinatus, infraspinatus,teres minor and subscapularis) are referred asrotator cuff muscle
•Serratus posterior superior & Inferior (Muscles ofthorax proper)
RHOMBOID MAJOR
•ORIGINspinous processes of 2nd to 5ththoracic vertebrae (major)
•INSERTIONBy fibrous attachment to medialborder of scapula betweenspine and inferior angle (major)
•ACTIONadduct and elevate the scapula,and rotate it so that glenoidcavity faces caudally
•NERVEdorsal scapular, C4, 5
RHOMBOID MINOR
•ORIGINligamentum nuchae, spinousprocesses of 7th cervical and 1stthoracic vertebrae (minor)
•INSERTIONmedial border at root of spine ofscapula (minor)
•ACTIONadduct and elevate the scapula,and rotate it so that glenoid cavityfaces caudally
•NERVEdorsal scapular, C4, 5
Serratus anterior (the boxer’s muscle)
•ORIGINouter surface and superior borders of upper eight ornine ribs
•INSERTIONcostal surface of medial border of scapula
•ACTIONWith the origin fixed, abducts the scapula, rotates theinferior angle laterally and the glenoid cavity cranially,and holds the medial border of the scapula firmlyagainst the rib cage. In addiction, the lower fibers maydepress the scapula, and the upper fibers may elevateit slightly. Starting from a position with the humerusfixed in flexion and the hands against a wall, theserratus acts to displace the thorax posteriorly as theeffort is made to push the body away from the wall.Another example of this type of action is in a properlyexecuted push-up.With the scapula stabilized in addition by therhomboids, thereby fixing the insertion, the serratusmay act in forced inspiration
•NERVELong thoracic, C5, 6, 7, 8 (winging the scapula ifdamaged)
DELTOID
•ORIGIN
–anterior fibers: anterior border, superior surface,lateral one third of claviclemiddle fibers: lateral margin and superiorsurface of acromion
–posterior fibers: inferior lip and superior borderof spine of scapula
•INSERTION
–deltoid tuberosity of humerus
•ACTIONAbduction of the shoulder joint, performedchiefly by the middle fibers withstabilization by the anterior and posteriorfibers. In addition, the anterior fibers flexand, in the supine position, medially rotatethe shoulder joint; the posterior fibersextend and, in the prone position, laterallyrotate.
•NERVEaxillary nerve, C5, 6
TERES MAJOR
•ORIGINdorsal surface of inferior angleand lower third of lateral borderof scapula
•INSERTIONthe crest of the lesser tubercle ofhumerus
•ACTIONMedially rotates, adducts, andextends the shoulder
•NERVELower Subscapular Nerve C 5, 6,7
TERES MINOR
•ORIGINUpper two thirds, dorsal surface oflateral border of scapular
•INSERTIONthe lowest facet of the greatertubercle of the humerus, andshoulder joint capsule
•ACTIONLaterally rotates shoulder joint, andstabilizes head of humerus in theglenoid cavity during movement ofthis joint
•NERVEAxillary nerve, C5, 6
INFRASPINATUS
•ORIGINmedial two thirds of infraspinatusfossa of scapula
•INSERTIONthe middle facet of the greatertubercle of the humerus, andshoulder joint capsule
•ACTIONLateral rotates shoulder joint andstabilizes head of humerus in theglenoid cavity during movement ofthis joint
•NERVEsuprascapular nerve, C(4), 5, 6
SUPRASPINATUS
•ORIGINmedial two thirds of supraspinousfossa of scapula
•INSERTIONsuperior facet of greater tubercle ofhumerus, and shoulder jointcapsule
•ACTIONAbducts the shoulder joint, andstabilizes head of humerus in theglenoid cavity during movement ofthis joint
•NERVESuprascapular nerve, C 4, 5, 6
SUBSCAPULARIS
•ORIGINSubscapular fossa of scapula
•INSERTIONlesser tubercle of humerus andshoulder joint capsule
•ACTIONmedially rotates shoulder joint, andstabilizes the head of the humerus inthe glenoid cavity during movementsof this joint
•NERVEupper and lower subscapular nerve,C5, 6, 7
SERRATUS POSTERIOR SUPERIOR
•ORIGINligamentum nuchea in the neck, spinousprocesses of C7, and T1 to T3
•INSERTIONsuperior borders of second to forth ribs
•ACTIONelevate first four ribs, aid respiration byincreasing diameter of the thorax
•NERVEintercostal nerve
SERRATUS POSTERIOR INFERIOR
•ORIGINspinous processes of the last twothoracic and first two lumbar
•INSERTIONinferior borders of the inferior three orfourth ribs
•ACTIONdepress inferior ribs, preventing themfrom being pulled up by diaphragm
•NERVEintercostal nerve
Rotator Cuff Tear
•Cause
–Over use, aging (middle aged man)
•Symptoms
–Pain, unable to raise arm
•Treatment
–Conservative
–Surgical