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 angle of the scapula bounded by the trapezius muscle medially, rhomboideus major muscle superiorly and the latissimus dorsi muscle inferiorly; its floor is the posterior thoracic wall, used to hear lungs by stethoscope

Back muscles The skin and superficial fascia of the back can be divided into three groups organized in layers: superficial, intermediate, and deep. Muscles of the superficial and intermediate groups are called extrinsic back muscles because they are involved in respiration and movements of the upper extremity. Muscles of the deep group are called intrinsic back muscles because they are involved in movement and stabilization of the vertebral column.

Superficial back muscles trapezius and latissimus dorsi muscle

TRAPEZIUS ORIGIN INSERTION Upper fibers: external occipital protuberance, medial one third of superior nuchal line, ligamentum nuchae, and spinous process of 7th cervical vertebra  Middle fibers: spinous processes of first to fifth thoracic vertebrae  Lower fibers: spinous processes of sixth to 12th thoracic vertebrae  INSERTION Upper fibers: lateral one third of clavicle and acromion process of the scapula Middle fibers: medial margin of acromion and superior lip of spine of scapula  Lower fibers: tubercle at apex of spine of scapula

TRAPEZIUS ACTION With origin fixed, adduction of the scapula, performed chiefly by the middle fibers with stabilization by the upper and lower fibers. Rotating of the scapula so the glenoid cavity faces cranially, performed chiefly by the upper and lower fibers with stabilization by the middle fibers. In addition, the upper fibers elevate and the lower fibers depress the scapula. With the insertion fixed, and acting unilaterally, the upper fibers extend, laterally flex, and rotate the head and joints of the cervical vertebrae so that the face turns toward the opposite side; and acting bilaterally, the upper Trapezius extends the neck. The Trapezius also acts as an accessory muscle of respiration. NERVE spinal portion of accessory nerve (XI cranial nerve) and ventral ramus, C2, 3, 4

LATISSIMUS DORSI ORIGIN INSERTION spinous processes of last six thoracic vertebrae, last three or four ribs, through the thoracolumbar fascia from the lumbar and sacral vertebrae and posterior one third of external lip of iliac crest, a slip from the inferior angle of the scapula INSERTION intertubercular groove of humerus

LATISSIMUS DORSI ACTION With the origin fixed, medially rotates, adducts, and extends the shoulder joint. By continued action, depresses the shoulder girdle, and assists in lateral flexion of the trunk.  With the insertion fixed, assists in tilting the pelvis anteriorly and laterally. Acting bilaterally, this muscle assists in hyperextending the spine and anteriorly tilting the pelvis, or in flexion the spine, depending upon its relation to the axes of motion. This muscle is important in ralation to movements such as climbing, walking with crutches, or hoisting the body up on parallel bars, in which the muscles act to lift the body toward the fixed arms. The strength of the latissimus dorsi is a factor in such forceful arm movements as swimming, rowing, and chopping. All adductors and medial rotators act in these strong movements but the latissimus dorsi may be of major importance. The latissimus dorsi may act as an accessory muscle for respiration NERVE thoracodorsal nerve, C6, 7, 8

Intermediate Back Muscles Levator scapulae - later, rhomboids, serratus anterior (deep extrinsic muscles) Scapular (intrinsic shoulder) muscles (deltoid, supraspinatus, infraspinatus, teres major, minor and subcapularis) Four of these (supraspinatus, infraspinatus, teres minor and subscapularis) are referred as rotator cuff muscle Serratus posterior superior & Inferior (Muscles of thorax proper)

RHOMBOID MAJOR ORIGIN spinous processes of 2nd to 5th thoracic vertebrae (major) INSERTION By fibrous attachment to medial border of scapula between spine and inferior angle (major) ACTION adduct and elevate the scapula, and rotate it so that glenoid cavity faces caudally NERVE dorsal scapular, C4, 5

RHOMBOID MINOR ORIGIN ligamentum nuchae, spinous processes of 7th cervical and 1st thoracic vertebrae (minor) INSERTION medial border at root of spine of scapula (minor) ACTION adduct and elevate the scapula, and rotate it so that glenoid cavity faces caudally NERVE dorsal scapular, C4, 5

Serratus anterior (the boxer’s muscle) ORIGIN outer surface and superior borders of upper eight or nine ribs INSERTION costal surface of medial border of scapula ACTION With the origin fixed, abducts the scapula, rotates the inferior angle laterally and the glenoid cavity cranially, and holds the medial border of the scapula firmly against the rib cage. In addiction, the lower fibers may depress the scapula, and the upper fibers may elevate it slightly. Starting from a position with the humerus fixed in flexion and the hands against a wall, the serratus acts to displace the thorax posteriorly as the effort is made to push the body away from the wall. Another example of this type of action is in a properly executed push-up. With the scapula stabilized in addition by the rhomboids, thereby fixing the insertion, the serratus may act in forced inspiration NERVE Long thoracic, C5, 6, 7, 8 (winging the scapula if damaged)

DELTOID ORIGIN INSERTION anterior fibers: anterior border, superior surface, lateral one third of clavicle middle fibers: lateral margin and superior surface of acromion posterior fibers: inferior lip and superior border of spine of scapula INSERTION deltoid tuberosity of humerus ACTION Abduction of the shoulder joint, performed chiefly by the middle fibers with stabilization by the anterior and posterior fibers. In addition, the anterior fibers flex and, in the supine position, medially rotate the shoulder joint; the posterior fibers extend and, in the prone position, laterally rotate.  NERVE axillary nerve, C5, 6

TERES MAJOR ORIGIN dorsal surface of inferior angle and lower third of lateral border of scapula INSERTION the crest of the lesser tubercle of humerus ACTION Medially rotates, adducts, and extends the shoulder NERVE Lower Subscapular Nerve C 5, 6, 7

TERES MINOR ORIGIN Upper two thirds, dorsal surface of lateral border of scapular INSERTION the lowest facet of the greater tubercle of the humerus, and shoulder joint capsule ACTION Laterally rotates shoulder joint, and stabilizes head of humerus in the glenoid cavity during movement of this joint NERVE Axillary nerve, C5, 6

INFRASPINATUS ORIGIN medial two thirds of infraspinatus fossa of scapula INSERTION the middle facet of the greater tubercle of the humerus, and shoulder joint capsule ACTION Lateral rotates shoulder joint and stabilizes head of humerus in the glenoid cavity during movement of this joint NERVE suprascapular nerve, C(4), 5, 6 

SUPRASPINATUS ORIGIN medial two thirds of supraspinous fossa of scapula INSERTION superior facet of greater tubercle of humerus, and shoulder joint capsule ACTION Abducts the shoulder joint, and stabilizes head of humerus in the glenoid cavity during movement of this joint NERVE Suprascapular nerve, C 4, 5, 6

SUBSCAPULARIS ORIGIN Subscapular fossa of scapula INSERTION lesser tubercle of humerus and shoulder joint capsule ACTION medially rotates shoulder joint, and stabilizes the head of the humerus in the glenoid cavity during movements of this joint NERVE upper and lower subscapular nerve, C5, 6, 7

SERRATUS POSTERIOR SUPERIOR ORIGIN ligamentum nuchea in the neck, spinous processes of C7, and T1 to T3 INSERTION superior borders of second to forth ribs ACTION elevate first four ribs, aid respiration by increasing diameter of the thorax NERVE intercostal nerve

SERRATUS POSTERIOR INFERIOR ORIGIN spinous processes of the last two thoracic and first two lumbar INSERTION inferior borders of the inferior three or fourth ribs ACTION depress inferior ribs, preventing them from being pulled up by diaphragm NERVE intercostal nerve

Rotator Cuff Tear Cause Symptoms Treatment Over use, aging (middle aged man) Symptoms Pain, unable to raise arm Treatment Conservative Surgical