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Home , Levator scapulae muscle, Limb (anatomy)

Muscles of the back Musculoskeletal Block - Lecture 4

Objective:

✓ Distinguish between the different groups of back muscles. ✓ Compare between groups of back muscles as regard their supply and action. ✓ List the back muscles of each group. ✓ Describe the attachments of each muscle of the superficial group, as well as, its nerve supply and action. ✓ Describe the triangles of back and their clinical significance

Color index: Important In male’s slides only In female’s slides only Extra information, explanation

Editing file

Contact us: [email protected] Back muscles they are organized into 3 groups:

deep group intermediate group superficial group development intrinsic muscle (Develop In extrinsic muscles (not extrinsic muscles (not the back) developed in the back) developed in the back)

attachment attached to the vertebral attached to attached to column and head ()

function Moves - May serve in involved in the movement and head respiratory functions of the upper limb - Associated with (shoulder) thoracic cage movment

supplied by posterior rami supplied by anterior supplied by anterior rami nerve supply of spinal rami of spinal nerves of spinal nerves

● ● Serratus posterior ● superior ● Levator Scapulae ● ● Rhomboid Minor ● ● Serratus posterior Rhomboid Major ● inferior Latissimus Dorsi ●

muscles Deep group of back muscles:

they include extensors their tone is responsible they extend from sacrum and rotators of the head for the maintenance of to the skull. and vertebral column. normal curvature of the vertebral column. set of muscles that straighten and rotate the back.

the largest muscle of this group is Erector spinae, which is formed of 3 vertical columns (from lateral to medial. iliocostalis, longissimus,spinalis )

extensor: a muscle whose contraction extends or straightens a limb or other part of the body

rotator: a muscle whose contraction cause or assists in rotation of a part of the body

Intermediate Group Of Back muscles:

Intermediate group is separated from the deep group by thoracolumbar (a sheet of connective tissue covering or binding together body structures)

Intermediate group includes 2 muscles:

Serratus posterior Serratus posterior muscle: superior inferior

( elevator)(= raise up) (rib depressor)(= pull Action : down)

deep inspiration forced expiration Contributes in :

anterior rami of thoracic spinal nerves Nerve supply (intercostal nerve). (innervation): Superficial group of back muscles:

They originate from the vertebral column and attach to the of the shoulder (the , and humerus). To test the , trapezius function can be assessed by shrug

Muscles connecting vertebral column to Muscles connecting vertebral column to scapula (move scapula through shoulder humerus (move girdle joints) humerus through shoulder joint)

Levator Rhomboid Trapezius Latissimus Dorsi Scapulae Minor Major

- spinous processes of skull, ligamentum thoracic T6-T12 cervical spinous nuchae, spinous spinous - iliac crest transverse processes of origin processes of cervical processes of - thoracolumbar processes C7-T1 and thoracic T2-T5 fascia (C1-C4) vertebrae vertebrae (C7-T12) vertebrae - inferior 3 or 4 ribs (9th-12th)

medial border medial border tendon attaches to of scapula at of the scapula, lateral ⅓ of the medial border the intertubercular the level of between the insertion clavicle, acromion & of scapula sulcus (groove) of the the spine of scapula spine spine of the scapula (posteriorly) humerus scapula. and inferior

angle

- upper fibers: extension, adduction, elevate the scapula medial rotation of and rotate it during upper limb abduction of the action elevates the (arm;humerus) (movemen (humerus) retract and rotate the scapula scapula (shoulder joint) t) - middle fibers: It is also called the retract scapula climbing muscle. - lower fibers:

depress scapula

- motor innervation: spinal root of accessory (11th thoracodorsal nerve nerve cranial) nerve (C6,7,8) from supply - proprioceptor posterior cord of (sensory): fibers from C3 & C4 spinal nerves

pictures Muscular triangles of back:

Auscultatory Triangle Lumbar Triangle: Triangle of Petit Boundaries: Boundaries: - latissimus dorsi - latissimus dorsi - trapezius - posterior border of external - medial border of scapula. oblique muscle of the - iliac crest. Site: Site: where breath sounds are or ;(ﻓﺗق)of an abdominal hernia most easily heard with where pus may emerge from the a stethoscope. abdominal wall in extra-abdominal lumbar abscess

Summary : Back muscles

Deep group Intermediate group Superficial group

- attached to & moves - attached to & moves ribs. - origin: vertebral column. vertebral column. - supplied by anterior rami - Insertion: scapula EXCEPT - supplied by posterior of spinal nerves. latissimus dorsi : humerus rami of spinal nerves. - Action: moves scapula EXCEPT latissimus dorsi : moves humerus - Nerve supply: anterior rami of spinal nerves through brachial plexus EXCEPT trapezius : 11th cranial nerve.

MCQs

Q1: Which of the following muscles is Q2: which of the following involved in Q3: What is the medial muscle supplied by anterior rami of spinal the movement of the upper limb? of the erector spinae? nerves? A.spinalis A.intermediate muscles B.serratus posterior superior A. Spinalis B.deep muscles C.trapezius B.longissimus C.superficial muscles D.levator scapulae C.iliocostalis D. A and C D.trapezius

Q4: How many muscles is erector Q5: which muscle responsible of Q6: which one of the following is not a spinae formed of? rib elevator border to Auscultatory Triangle?

A. latissimus dorsi A.1 A. serratus posterior superior B. Trapezius B.2 B. serratus posterior inferior C. Medial border of scapula C.3 C. Trapezius D. Lateral border of scapula D.4 D. Latissimus Dorsi

Q7: All superficial muscles of the back Q8: A patient was asked to shrug his Q9: which of the following nerve supplies insert in the scapula except for which shoulders to evaluate the accessory is shared by the Levator scapulae and muscle? nerve. Which muscle’s function is Rhomboid major and minor muscles? being tested here? A.Levator scapulae A. Erector spinae muscle A.thoracodorsal nerve B.Trapezius B. Levator scapulae muscle B.dorsal scapular nerve C.Latissimus Dorsi C. Serrated posterior muscle C.accessory nerve D.intercostal nerve D.Rhomboid major D. Trapezius muscle

Q10: what action does Rhomboid Q11: all superficial muscles of the back Q12: trapezius muscle originate from? minor and major muscles produce? are supplied by anterior rami of spinal nerves except for? A.spinous process of thoracic and cervical A.retract and rotate scapula vertebrae B.elevate the scapula A.latissimus dorsi B.transverse process of thoracic C.depress the scapula B.trapezius vertebrae D.extension of the upper limb C.levator scapulae C.foramen transversarium of

D.spinalis

D.sacrum

6)D 12)A

5)A 11)B

4)C 10)A

3)A 9)B

2)C 8)D

1)D 7)C SAQs

Q1: where does the deep back muscles group attach?

Q2:from where to where does the deep muscles group extend?

Q3: intermediate group It is separated from the deep group by ? Q4:Serratus posterior superior contributes in ………?

Q5:Serratus posterior inferior contributes in ………?

Q6: The site of Auscultatory Triangle muscle?

Q7: list the actions of the .

Q8: compare between superficial and deep group of back muscles in terms of development and

nerve supply. in the back. Supplied by posterior rami of spinal nerves. spinal of rami posterior by Supplied back. the in

Deep back muscles: intrinsic muscles which develop embryologically embryologically develop which muscles intrinsic muscles: back Deep

embryologically in the back. Supplied by anterior rami of spinal nerves. spinal of rami anterior by Supplied back. the in embryologically

Q8: superficial back muscles: extrinsic muscles which do not develop develop not do which muscles extrinsic muscles: back superficial Q8:

Q7: extension, adduction, medial rotation of upper limb (humerus) limb upper of rotation medial adduction, extension, Q7:

Q6: where breath sounds are most easily heard with a stethoscope. a with heard easily most are sounds breath where Q6:

Q5: forced expiration. forced Q5:

Q4: deep inspiration. deep Q4:

Q3: . thoracolumbar Q3:

Q2: they extend from sacrum to skull to sacrum from extend they Q2:

Q1: they attach to the vertebral column and head and column vertebral the to attach they Q1:

This lecture is done by:

Mansour Aldossari Shahd Almezel Shaden Alsaiedan

Team leaders: Mayasem Alhazmi Fahad Alajmi

SPECIAL THANKS TO THE AMAZING #MED438 TEAM