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– 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

• ACTIONWith 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.

• NERVEspinal portion of accessory nerve (XI cranial nerve) and ventral ramus, C2, 3, 4

LATISSIMUS DORSI

• ORIGIN– 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

• NERVEthoracodorsal 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)

• INSERTIONBy fibrous attachment to medial border of scapula between spine and inferior angle (major)

• ACTIONadduct and elevate the scapula, and rotate it so that glenoid cavity faces caudally

• NERVEdorsal scapular, C4, 5

RHOMBOID MINOR

• ORIGINligamentum nuchae, spinous processes of 7th cervical and 1st thoracic vertebrae (minor)

• INSERTION medial border at root of spine of scapula (minor)

• ACTIONadduct and elevate the scapula, and rotate it so that glenoid cavity faces caudally

• NERVEdorsal scapular, C4, 5

Serratus anterior (the boxer’s muscle)• ORIGIN

outer surface and superior borders of upper eight or nine ribs

• INSERTIONcostal surface of medial border of scapula

• ACTIONWith 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

• NERVELong thoracic, C5, 6, 7, 8 (winging the scapula if damaged)

DELTOID • ORIGIN

– anterior fibers: anterior border, superior surface, lateral one third of claviclemiddle fibers: lateral margin and superior surface of acromion

– posterior fibers: inferior lip and superior border of spine of scapula

• INSERTION– deltoid tuberosity of humerus

• ACTIONAbduction 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. 

• NERVEaxillary nerve, C5, 6

TERES MAJOR • ORIGIN

dorsal surface of inferior angle and lower third of lateral border of scapula

• INSERTIONthe crest of the lesser tubercle of humerus

• ACTIONMedially rotates, adducts, and extends the shoulder

• NERVELower Subscapular Nerve C 5, 6, 7

TERES MINOR • ORIGIN

Upper two thirds, dorsal surface of lateral border of scapular

• INSERTIONthe lowest facet of the greater tubercle of the humerus, and shoulder joint capsule

• ACTIONLaterally rotates shoulder joint, and stabilizes head of humerus in the glenoid cavity during movement of this joint

• NERVEAxillary nerve, C5, 6

INFRASPINATUS

• ORIGINmedial two thirds of infraspinatus fossa of scapula

• INSERTIONthe middle facet of the greater tubercle of the humerus, and shoulder joint capsule

• ACTIONLateral rotates shoulder joint and stabilizes head of humerus in the glenoid cavity during movement of this joint

• NERVEsuprascapular nerve, C(4), 5, 6 

SUPRASPINATUS • ORIGIN

medial two thirds of supraspinous fossa of scapula

• INSERTIONsuperior facet of greater tubercle of humerus, and shoulder joint capsule

• ACTIONAbducts the shoulder joint, and stabilizes head of humerus in the glenoid cavity during movement of this joint

• NERVESuprascapular nerve, C 4, 5, 6

SUBSCAPULARIS

• ORIGINSubscapular fossa of scapula

• INSERTIONlesser tubercle of humerus and shoulder joint capsule

• ACTIONmedially rotates shoulder joint, and stabilizes the head of the humerus in the glenoid cavity during movements of this joint

• NERVEupper and lower subscapular nerve, C5, 6, 7

SERRATUS POSTERIOR SUPERIOR

• ORIGINligamentum nuchea in the neck, spinous processes of C7, and T1 to T3

• INSERTIONsuperior borders of second to forth ribs

• ACTIONelevate first four ribs, aid respiration by increasing diameter of the thorax

• NERVEintercostal nerve

SERRATUS POSTERIOR INFERIOR

• ORIGINspinous processes of the last two thoracic and first two lumbar

• INSERTIONinferior borders of the inferior three or fourth ribs

• ACTIONdepress inferior ribs, preventing them from 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