Superficial musclesof the back

Kaan Yücel M.D., Ph.D 05.March.2014 Wednesday

MUSCLES OF THE BACKExtrinsic back muscles

Superficial group Movements of the upper limb

Intermediate group Attached to the ribs May serve as a respiratory function.

Intrinsic (deep) back muscles Act on the vertebral columnIts movementsMaintain posture

SUPERFICIAL GROUP OF BACK MUSCLESImmediately deep to the skin and superficial fascia.

Connected with the shoulder girdle.

Attach the superior part of the appendicular skeleton (clavicle, scapula, and humerus) to the axial skeleton (skull, ribs, and vertebral column).

SUPERFICIAL GROUP OF BACK MUSCLESProduce and control limb movements.

Trapezius Latissimus dorsiRhomboid major Rhomboid minor Levator scapulae

TRAPEZIUSCovers posterior aspect of neck & superior half of trunk

trapezium (G. irregular four-sided figure)

TRAPEZIUSmuscle's origin: base of triangle situated along vertebral column muscle's insertion: apex pointing toward tip of shoulder

ScapulaVertebral column

Occipital bone

TRAPEZIUSattaches the pectoral girdle

to cranium & vertebral column

assists in suspending the upper limb.

TRAPEZIUSDescending (superior) fibers elevate the scapula (e.g., when squaring the shoulders).

Middle fibers retract the scapula (i.e., pull it posteriorly).

Ascending (inferior) fibers depress the scapula and lower the shoulder.

TRAPEZIUSSuperior fibers of trapezius

from the skull and upper portion of the vertebral column descend to attach to

lateral 1/3 clavicle & acromion of scapula.

TRAPEZIUS

C7 to T12Lateral 1/3

Spine of scapula

TRAPEZIUSSuperior nuchal line

Spinous processes of C7 to T12

Ligamentum nuchae

External occipital protuberance

Lateral 1/3 of clavicle

Acromion

Spine of scapula

TRAPEZIUSSuperior and inferior fibers work together to rotate the lateral aspect of the scapula upward, which needs to occur when raising the upper limb above the head.

TRAPEZIUSThe trapezius also braces the shoulders by pulling the scapulae posteriorly and superiorly, fixing them in position on the thoracic wall with tonic contraction; consequently, weakness of this muscle causes drooping of the shoulders.

TRAPEZIUSMotor innervation of trapezius accessory nerve [XI]descends from the neck onto the deep surface of the muscle. Proprioceptive fibers from trapezius pass in the branches of the cervical plexus and enter the spinal cord at spinal cord levels C3 &C4.

LATTISIUMUS DORSIL. widest of back

Begins in the lower portion of the back Tapers as it ascends to a narrow tendon that attaches to the humerus anteriorly.

LATTISIUMUS DORSIPosterior axillary fold

LATTISIUMUS DORSI• Spinous processes of T7 to

L5• Sacrum• Iliac crest• Ribs 10 to 12

Floor of intertubercular sulcus of humerus

LATTISIUMUS DORSIPasses from the trunk to the humerus. Acts directly on the glenohumeral joint. Acts indirectly on the pectoral girdle.

LATTISIUMUS DORSIExtendAdduct humerus (arm,upper limb)Medially rotate

can also depress the shoulder, preventing its upward movement

Apley scratch test.

LATTISIUMUS DORSIIn combination with pectoralis major

powerful adductor of the humerus

plays a major role in downward rotation of the scapula in association with this movement.

LATTISIUMUS DORSIalso useful in restoring the upper limb from abduction superior to the shoulder; important in climbing.

In conjunction with pectoralis major, raises the trunk to the arm,

performing chin-ups or climbing a tree

LATTISIUMUS DORSI

LATTISIUMUS DORSIInnervation: thoracodorsal nerve

LEVATOR SCAPULAESuperior 1/3 deep to sternocleidomastoidInferior 1/3 deep to trapezius

LEVATOR SCAPULAE

Upper portion medial

border of scapula

superior to root of spine of scapula

LEVATOR SCAPULAE

LEVATOR SCAPULAEacts with the descending part of the trapezius to elevate the scapula, or fix it! resists forces that would depress it, as when carrying

a load.

LEVATOR SCAPULAEWith rhomboids & pectoralis minor, rotates the scapula, depressing the glenoid cavity

rotating the lateral aspect of scapula inferiorly

LEVATOR SCAPULAEActing bilaterally (also with the trapezius), the levators extend the neck.

Acting unilaterally, may contribute to lateral flexion of the neck

toward the side of the active muscle.

RHOMBOID MAJORRHOMBOID MINOR

Deep to trapezius, inferior to levator scapulae Broad parallel bands Pass inferolaterally from vertebrae to medial border of scapulae

RHOMBOID MINORLower portion of ligamentum nuchae Spinous processes of C7 and T1

Medial border of scapula at the spine of scapula

RHOMBOID MAJORSpinous processes of T3 to T5Medial border of scapula between spine & inferior angle

RHOMBOID MAJOR ET MINORRetract (adduct) and elevate scapula

Assist serratus anterior in holding the scapula against the thoracic wall and fixing the scapula during movements of the upper limb.

Innervation: dorsal scapular nerve branch of brachial plexus

C4 & C5

INTERMEDIATE GROUPOF BACK MUSCLES

SERRATUS POSTERIOR SUPERIORSERRATUS POSTERIOR INFERIOR

.Deep to the muscles in the superficial group

Related to the movements of the thoracic cage

Superficial respiratory muscles

More likely proprioceptive rather than motor in function

.

Serratus posterior superior lies deep to the rhomboids

Serratus posterior inferior lies deep to the latissimus dorsi

SERRATUS POSTERIOR SUPERIORSERRATUS POSTERIOR INFERIOR

.attached to the vertebral column and associated structures mediallyEither descend (fibers of serratus posterior superior) or Ascend (fibers of serratus posterior inferior)

to attach to the ribs. These two muscles therefore elevate and depress the ribs

SERRATUS POSTERIOR SUPERIORSERRATUS POSTERIOR INFERIOR

.

Lower portion of ligamentum nuchaeSpinous processes of C7 to T3Supraspinous ligamentsUpper border of ribs 2 to 5 just lateral to their angles

Spinous processes of T11 to L3Supraspinous ligamentsLower border of ribs 9 to 12 just lateral to their angles

SERRATUS POSTERIOR SUPERIOR

SERRATUS POSTERIOR INFERIOR .first four intercostal spinel nerves

last four intercostal spinel nerves