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59 Cards in this Set

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Intersegmental muscles (of the deep back)
Short muscles that span a single intervertebral joint (segment).

Contribute to fine control of vertebral movement.

Important for proprioception (sense of position) because of high proportion of muscle spindles—specialized sensory fibers that register muscle length and velocity
Clinical Correlation Intersegmental muscles:
Because their fibers are very short, intersegmental muscles are
susceptible to strain and are implicated in many cases of back and neck pain.
Multisegmental muscles (of the deep back)
Span multiple intervertebral joints (segments).

Formed by the fusion of intersegmental muscles during embryonic development.

Multisegmental muscles provide forceful extension of the vertebral column, maintain posture, and contribute to rotation and lateral flexion of the torso, head, and neck.
Bilateral contraction (of the deep back)
Right and left side muscles contract simultaneously.

Lateral flexion and rotational actions cancel out, resulting in pure extension.
Unilateral contraction (of the deep back)
Muscle contracts on one side only.

Primarily lateral flexion and rotation result.
Splenius capitis and cervicis mm Origin:
Origin: Ligamentum nuchae and T1–T4 spinous processes
Splenius capitis and cervicis mm Insertion:
Insertion: Mastoid process and superior nuchal line (capitis portion)
C1–C4 transverse processes (cervicis portion)
Splenius capitis and cervicis mm Actions:
Actions: Unilateral: lateral flexion and ipsilateral rotation of head/neck
Bilateral: extension of head/neck
Erector spinae muscle group (major postural muscle group) Origin:
Origin: Common tendon of origin from posterior iliac crest, dorsal sacrum, and
lumbar spinous processes; additional slips originate along the axial
skeleton.
Iliocostalis m. (Erector Spinae group) Insertion:
Insertion: angles of ribs (lumborum and thoracis) and cervical
transverse processes (cervicis)
Longissimus m. (Erector Spinae group) Insertion:
Insertion: thoracic transverse processes and adjacent ribs
(thoracis), cervical transverse processes (cervicis), mastoid process
(capitis).
Spinalis m. (Erector Spinae group) Insertion:
Insertion: upper thoracic spinous processes (thoracis); cervical
spinous processes and ligamentum nuchae (cervicis); occipital bone
between nuchal lines (capitis, usually fused with semispinalis capitis)
Erector spinae muscle group Actions:
Actions: Unilateral: lateral flexion and ipsilateral rotation of trunk and head/neck
Bilateral: extension of trunk and head/neck
Transversospinalis group Origin:
Dorsal sacrum and posterior iliac crest, lumbar mamillary processes,
cervical and thoracic transverse processes.
Transversospinalis group Insertion:
Insertion: Spinous processes and occipital bone.
Semispinalis cervicis (Transversospinalis group):
From upper thoracic transverse processes to
upper cervical spinous processes as far as C2 (axis).

Spans 4–6 segments, best defined in cervical region.
Semispinalis capitis (Transversospinalis group):
From cervical transverse processes to
occipital bone; a major extensor of the head.

Spans 4–6 segments, best defined in cervical region.
Multifidus lumborum
(Transversospinalis group):
2–4 segments, best defined in lumbar region.

Dorsal sacrum and lumbar mamillary
processes to lumbar and lower thoracic spinous processes.
Rotatores longus
(Transversospinalis group):
Span 2 segments.

Best defined in thoracic region.
Rotatores brevis
(Transversospinalis group):
Span 1 segment.


Best defined in thoracic region.
Transversospinalis group Actions:
Unilateral: lateral flexion, contralateral rotation of trunk, head/neck.
Bilateral: extension of trunk and head/neck
Levatores costarum m. Origin:
Origin: Transverse processes of thoracic vertebrae
Levatores costarum m. Insertion:
Insertion: Superior borders of ribs (1 or 2 segments inferior)
Levatores costarum m. Actions:
Actions: Elevate ribs, assist lateral flexion
Interspinalis m. (pl. interspinales)
(Intersegmental muscle):
between adjacent spinous processes in the cervical and lumbar regions.
Intertransverse m. (pl. intertransversarii)
(Intersegmental muscle):
between adjacent transverse processes in the cervical and lumbar regions. Note: in the cervical region, anterior and posterior intertransversarii attach to the anterior and posterior tubercles and are separated by the cervical spinal nerves.
Clinical correlation Intersegmental mm.
Clinical Correlation: Automobile collisions can cause flexion-extension syndrome, or
whiplash. Rapid movement of the head from hyperextension to hyperflexion can tear cervical
intersegmental muscles and sprain cervical ligaments. This produces the characteristic syndrome of tenderness (due to inflammation), stiffness (due to sustained recruitment of uninjured muscles), and radiating pain.
Thoracolumbar fascia
the investing fascia of the intrinsic back muscles in lower thoracic
and lumbar regions.
Posterior layer (Thoracolumbar fascia):
attaches to the vertebral spinous processes. This layer is thin in the
thoracic region but forms a dense aponeurosis in the lumbar region.
Middle layer (Thoracolumbar fascia):
Middle layer: attaches to lumbar transverse processes, iliac crest, and rib 12;
continuous laterally with the aponeurosis of transversus abdominis m.
Anterior layer (Thoracolumbar fascia):
Anterior layer: the anterior fascia of quadratus lumborum m.
Rectus capitis posterior major m. (Suboccipital m.) Origin:
Origin: Spinous process of axis (C2)
Rectus capitis posterior major m. (Suboccipital m.) Insertion:
Insertion: Medial inferior nuchal line
Rectus capitis posterior major m. (Suboccipital m.) Actions:
Actions: Extension (bilateral) and ipsilateral rotation (unilateral) of head.

Principal functions are postural (fine adjustments) and proprioceptive.
Rectus capitis posterior major m. (Suboccipital m.) Innervation:
Innervation: dorsal ramus of C1, the
suboccipital n.
Rectus capitis posterior minor m.
(Suboccipital m.) Origin:
Origin: Posterior tubercle of atlas (C1)
Rectus capitis posterior minor m.
(Suboccipital m.) Insertion:
Insertion: Inferior nuchal line medial to rectus capitis posterior major m.
Rectus capitis posterior minor m.
(Suboccipital m.) Actions:
Actions: Extension of head (bilateral)
Rectus capitis posterior minor m.
(Suboccipital m.) Innervation:
Innervation: dorsal ramus of C1, the
suboccipital n.
Obliquus capitis superior m.
(Suboccipital m.) Origin:
Origin: Transverse process of atlas (C1)
Obliquus capitis superior m.
(Suboccipital m.) Insertion:
Insertion: Occipital bone between nuchal lines
Obliquus capitis superior m.
(Suboccipital m.) Actions:
Actions: Extension of head (bilateral); lateral flexion of head (unilateral)
Obliquus capitis superior m.
(Suboccipital m.) Innervation:
Innervation: dorsal ramus of C1, the suboccipital n.
Obliquus capitis inferior m.
(Suboccipital m.) Origin:
Origin: Spinous process of axis (C2)
Obliquus capitis inferior m.
(Suboccipital m.) Insertion:
Insertion: Transverse process of atlas (C1)
Obliquus capitis inferior m.
(Suboccipital m.) Actions:
Actions: Ipsilateral rotation of head (unilateral)
Obliquus capitis inferior m.
(Suboccipital m.) Innervation:
Innervation: dorsal ramus of C1, the suboccipital n.
Suboccipital triangle Borders:
Rectus capitis posterior major m.

Obliquus capitis superior m.

Obliquus capitis inferior m.
Suboccipital triangle floor:
Posterior atlanto-occipital membrane and posterior arch of atlas.
Suboccipital triangle roof:
semispinalis capitis m.
Suboccipital Triangle - Vertebral a.
Exits transverse foramen of C1.

Curves medially around posterior aspect of lateral mass of atlas.

Pierces posterior atlanto-occipital membrane to enter foramen magnum.
Suboccipital Triangle - Suboccipital n. (dorsal ramus of C1)
Emerges from center of suboccipital triangle.

Gives muscular branches to suboccipital muscles.

The suboccipital n. has few (if any) sensory fibers and no cutaneous distribution.
Occipital a. (branch of external carotid a.):
NOT PART OF THE SUBOCCIPITAL TRIANGLE

emerges lateral to obliquus capitis
superior m. and courses superiorly to supply posterior scalp.
Greater occipital n. (dorsal ramus of C2):
NOT PART OF THE SUBOCCIPITAL TRIANGLE

emerges inferior to obliquus capitis
inferior m. and pierces semispinalis capitis m. (to which it gives some motor fibers) to innervate skin of posterior scalp.
Cutaneous innervation of the central back:
innervated segmentally by
posterior cutaneous nerves, branches of dorsal primary rami.
Cutaneous innervation of the lateral back:
Skin of the lateral back is innervated segmentally by lateral cutaneous nerves, branches of ventral primary rami.
Intrinsic muscles of the back Blood Supply:
Segmental arteries accompanying the dorsal primary rami.

Deep cervical a.: courses deep to semispinalis capitis m.

Vertebral a.: muscular branches to cervical muscles
Skin overlying the intrinsic muscles Blood Supply
posterior cutaneous arteries, branches of segmental aa.
Skin of the lateral back Blood supply
lateral cutaneous arteries, branches of the posterior intercostal aa.