Date post: | 11-Jul-2015 |
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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)
DEEP 2: Erector spinae mm. (aka "sacrospinalis"):
• i. lateral column: iliocostalis (attaches to ribs; costa = rib)
DEEP 2: Erector spinae mm. (aka "sacrospinalis"):
• 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
DEEP 3: Transversospinalis:
• i. outermost: superior: Semispinalis capitis, cervicis & thoracis (from T10 superiorly); important in holding up head
DEEP 3: Transversospinalis:
• ii. intermediate: Multifidus (= many cleavages; spans 2 - 5 vertebrae)
- more prominent on lower spine
DEEP 3: Transversospinalis:
• iii. innermost: Rotatores (span 1 to 2 vertebrae); "segmental" mm.
- mainly stabilizing spine