pattern of the back musculature

Pattern of the Back Musculature:Extrinsic Back Muscles:

muscles associated with upper limb or ribs that migrated to the back, so

are supplied by anterior primary rami (one exception - CNXI)

Superficial group, superficial layer:

• a. Trapezius: diamond-shaped (=trapezoid )

Trapezius

• attachments:

Origin, superior, proximal: from superior nuchalline, external occipital protuberance,

ligamentum nuchae, spinous processes of C7 through T12

Insertion, inferior, distal: to lateral clavicle, acromion & spine of scapula

• innervation: cranial n. XI (spinal accessory) + C3 & C4 (proprioception)

Trapezius

• actions: extension of head; elevation (upper part); depression (lower part) of pectoral girdle; retraction and upward rotation of scapula

Superficial group, superficial layer:

• b. Latissimus dorsi: fan-shaped, covers lower back, widest (= latissimus) muscle of back

Latissimus dorsi

• attachments: Origin, superior, proximal: from spinous processes

of T7-12 + thoracolumbar fascia, crest of ilium, lower ribs

Insertion, inferior, distal: to floor of intertubercularsulcus of humerus

• innervation: thoracodorsal n. (C6 - 8) of posterior cord of brachial plexus

• actions: medial rotation, extension & adduction of humerus

Superficial group, deep layer:

• c. Rhomboids major & minor: rhombus-shaped

Rhomboids major & minor:

• attachments: Origins, superior, proximal: ligamentum nuchae & spinous

processes of C7 & T1 (minor), spinous processes of T2 - 5 (major)

Insertions, inferior, distal: to vertebral border of scapula from root of spine (minor)

to inferior angle (major) • innervation: dorsal scapular n.(C4 - C5) upper root Brachial

Plexus• actions: retraction and downward rotation of scapula;

secure scapula to thoracic wall (with serratus anterior)

Superficial group, deep layer:

• d. Levator scapulae:

Levator scapulae

• attachments:

Origin, superior, proximal: from transverse processes of upper 4 cervical vertebrae

Inserts, inferior, distal: to vertebral border of scapula from superior angle to root of spine

• innervation: dorsal scapular n. (C4-5) from upper root of brachial plexus

• actions: assist rhomboids & elevation of scapula

Intermediate group:

• Serratus posterior muscles: very thin & supplied by intercostal n.,a.,v.’s

Intermediate group:

• - Serratus posterior superior lies deep to rhomboids, fiber orientation parallel to rhomboids

• Attaches:

Origin, superior, proximal: spinous processes

Insertion, inferior, distal: to superior ribs;

• Assists inspiration (breathing in)

Intermediate group:

• - Serratus posterior inferior lies deep to latissimusdorsi,

• Attaches:

Origin, superior, proximal: extending from lower vertebral spinous processes

Insertion, inferior, distal: to lower ribs;

• Assists expiration

Intrinsic muscles: 3 deep layers of muscles

• (only muscles of the body innervated by posterior primary rami of spinal n.)

• - "true" back muscles - fill in hollow between vertebral spinous processes & angles of ribs

• - move the vertebral column and attach to vertebrae, ribs, pelvis and skull

Intrinsic muscles: 3 deep layers of muscles

• - contained in a tube of deep fascia that attaches to the ligamentumnuchae, spinous processes & supraspinous ligament to the medial sacral crest, then to transverse processes and angles of the ribs in the thoracic spine;

inferior to the neck it is called the thoracolumbar fascia of which the lumbar aponeurosis is the thickened inferior portion with anterior & posterior layers to enclose the muscles

• deep 1: splenius capitis & cervicis (superolateral fiber orientation)• deep 2: erector spinae mm. (vertical-superolateral fiber

orientation)• deep 3: transversospinalis mm. (superomedial fiber orientation)

DEEP 1: Splenius capitis & cervicis:

splenion = bandage;

caput = head;

cervix = neck;

• covers deeper muscles like a bandage

DEEP 1: Splenius capitis & cervicis:

• attachments: Origin, superior, proximal: ligamentum nuchae &

spinous processes of C7 -T6

Insertion, inferior, distal: to transverse processes of upper cervical vertebrae (cervicis) & superior nuchal line and mastoid process (capitis)

• innervation: middle & lower cervical nn.• actions: extension of head (both sides); ipsilateral

rotation of head and neck

DEEP 2: Erector spinae mm. (aka "sacrospinalis"):

• three columns of massive muscle extending from sacrum to skull,

• a hand's breadth on each side of spinous processes,

• encased in thoracolumbar fascia,

• Attachments:

Origin, superior, proximal: arise from a common inferior tendon that extends from the iliac crest

Insertion, inferior, distal: to median sacral crest

• actions: extension of vertebral column (both sides), ipsilateralrotation (single side)


• i. lateral column: iliocostalis (attaches to ribs; costa = rib)


• ii. intermediate column: longissimus = longest, from sacrum to skull,

attaches to transverse processes and eventually mastoid process

• iii. medial column: spinalis, spanning spinousprocesses of vertebrae on each side

DEEP 3: Transversospinalis:

• Attaches:Origin, superior, proximal: from lower transverse processes Insertion, inferior, distal: to higher spinous processes ;

• Actions: extension & contralateral rotation of vertebral column, head & neck; three layers… see the following 3 slides

• interspinales, intertransversarii, levatores costarum(transverse processes to ribs between tubercle and angle) are minor deep back muscles


• i. outermost: superior: Semispinalis capitis, cervicis & thoracis (from T10 superiorly); important in holding up head


• ii. intermediate: Multifidus (= many cleavages; spans 2 - 5 vertebrae)

- more prominent on lower spine


• iii. innermost: Rotatores (span 1 to 2 vertebrae); "segmental" mm.

- mainly stabilizing spine

pattern of the back musculature

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