Podcast
Questions and Answers
What is the primary innervation for the splenius capitus muscle?
What is the primary innervation for the splenius capitus muscle?
Which of the following muscles is primarily responsible for lateral flexion of the neck?
Which of the following muscles is primarily responsible for lateral flexion of the neck?
Which part of the erector spinae muscle group is most lateral?
Which part of the erector spinae muscle group is most lateral?
What is the common origin for the muscles of the erector spinae?
What is the common origin for the muscles of the erector spinae?
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Which action is associated with the splenius cervicis muscle?
Which action is associated with the splenius cervicis muscle?
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Which intercostal muscles run inferoanteriorly from superior rib to inferior rib?
Which intercostal muscles run inferoanteriorly from superior rib to inferior rib?
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What is the primary neurovascular arrangement found in the costal groove?
What is the primary neurovascular arrangement found in the costal groove?
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Which muscle is continuous with the internal oblique abdominal muscle anteriorly?
Which muscle is continuous with the internal oblique abdominal muscle anteriorly?
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Which intercostal muscle is located deepest and spans 2-3 levels?
Which intercostal muscle is located deepest and spans 2-3 levels?
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What is the main muscle innervated by segmental anterior primary rami (APR)?
What is the main muscle innervated by segmental anterior primary rami (APR)?
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Which muscle is continuous inferiorly with the transverse abdominus muscle?
Which muscle is continuous inferiorly with the transverse abdominus muscle?
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What is the function of the innermost intercostals in relation to the internal intercostals?
What is the function of the innermost intercostals in relation to the internal intercostals?
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Which of the following structures provides arterial supply to intercostal spaces 3-7?
Which of the following structures provides arterial supply to intercostal spaces 3-7?
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What is the primary action of the Semispinalis muscle?
What is the primary action of the Semispinalis muscle?
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Which muscle spans the greatest number of vertebral segments?
Which muscle spans the greatest number of vertebral segments?
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What is the innervation of the Multifidus muscle?
What is the innervation of the Multifidus muscle?
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Which muscle is specifically responsible for stabilizing the spine through proprioception?
Which muscle is specifically responsible for stabilizing the spine through proprioception?
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What is the likely function of the Interspinales muscle?
What is the likely function of the Interspinales muscle?
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Which structure serves as the origin for the Semispinalis muscles?
Which structure serves as the origin for the Semispinalis muscles?
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What anatomical regions are primarily acted upon by the Multifidus muscle?
What anatomical regions are primarily acted upon by the Multifidus muscle?
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Which of the following muscles has the shortest span of vertebral segments?
Which of the following muscles has the shortest span of vertebral segments?
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What is the primary action of the levator costarum muscles?
What is the primary action of the levator costarum muscles?
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Which muscles are primarily involved in stabilizing the spinal column?
Which muscles are primarily involved in stabilizing the spinal column?
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What actions do the deep layer muscles of the back primarily facilitate?
What actions do the deep layer muscles of the back primarily facilitate?
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Which muscle primarily assists with raising the ribs during inspiration?
Which muscle primarily assists with raising the ribs during inspiration?
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What is the role of the intertransverserii muscles?
What is the role of the intertransverserii muscles?
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What characterizes the thoracolumbar fascia?
What characterizes the thoracolumbar fascia?
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Which of the following is NOT a function of back muscles?
Which of the following is NOT a function of back muscles?
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What anatomical structure connects the deep fascia to the thoracolumbar fascia?
What anatomical structure connects the deep fascia to the thoracolumbar fascia?
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What is the primary function of the thoracolumbar fascia?
What is the primary function of the thoracolumbar fascia?
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Which component of the thoracolumbar fascia envelopes the intrinsic muscles of the back?
Which component of the thoracolumbar fascia envelopes the intrinsic muscles of the back?
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What nerves innervate the serratus posterior superior and inferior muscles?
What nerves innervate the serratus posterior superior and inferior muscles?
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Which of the following correctly describes the innervation of most connective tissue structures in the back?
Which of the following correctly describes the innervation of most connective tissue structures in the back?
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The outer portions of the intervertebral discs are innervated by which nerves?
The outer portions of the intervertebral discs are innervated by which nerves?
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Study Notes
Intercostal Muscles
- External intercostals extend from the tubercles of ribs to the costochondral junctions, running inferoanteriorly from a superior rib to an inferior rib.
- Internal intercostals occur deep to the external intercostals at a 90° angle, spanning ribs and costal cartilages to the sternum.
- Innermost intercostals are separated from internal intercostals by the intercostal neurovascular bundle and span the internal surfaces of adjacent ribs.
- Subcostalis muscles span 2-3 levels and originate near the angles of the lower ribs, positioned deep to the innermost intercostals.
- Transverse thoracis is continuous inferiorly with the transverse abdominis muscle.
- Levator costarum is generally categorized with intrinsic back muscles.
Neurovascular Supply to Intercostals
- Neurovascular structures run in the costal groove between internal and innermost intercostal layers, arranged from superior to inferior as vein, artery, nerve (VAN).
- Innervation is provided by segmental anterior primary rami (APRs).
- Arterial supply varies by intercostal space:
- Spaces 1-2 receive blood from the superior/supreme intercostal arteries (from axillary artery).
- Spaces 3-7 are supplied by intercostal arteries.
- Below rib 8, blood supply is via the musculophrenic artery (off the internal thoracic artery).
- Venus drainage is achieved through intercostal veins.
Intrinsic Back Muscles
Superficial Intrinsics
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Splenius Capitis
- Originates at the ligamentum nuchae and spinous processes of C7-T4.
- Inserts at the mastoid process and the lateral third of the superior nuchal line.
- Functions include lateral flexion, ipsilateral rotation, and extension (bilaterally).
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Splenius Cervicis
- Originates at ligamentum nuchae and spinous processes of T3-T6.
- Inserts at the posterior tubercles of transverse processes of C1-C4.
- Similar functions as splenius capitis.
Intermediate Intrinsics: Erector Spinae
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A common aponeurotic origin from the thoracolumbar fascia attaches at the iliac crest, sacrum, and lumbar processes.
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Iliocostalis
- Divided into lumborum, thoracis, and cervicis sections.
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Longissimus
- Divided into thoracis, cervicis, and capitis sections.
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Spinalis
- Divided into thoracis and cervicis, with the added semispinalis spanning 4-6 vertebral segments.
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Multifidus and Rotatores
- Multifidus spans 2-4 vertebral segments.
- Rotatores span 1-2 vertebral segments.
Minor Deep Layer
- Interspinales: Located between the spinous processes of adjacent segments.
- Intertransversarii: Positioned between the transverse processes of adjacent vertebrae, aiding in lateral flexion.
- Levator Costarum: Elevates the rib between the tubercle and angle during respiration and lateral flexion.
Thoracolumbar Fascia
- Composed of superficial and deep layers.
- The superficial layer contains subcutaneous tissue, possibly with adipose tissue.
- The deep layer blends with gluteal fascia and contains multiple laminae enveloping intrinsic back muscles, stabilizing the lumbar spine during muscle contraction.
Innervation to the Back
- Extrinsic Muscles: Innervated by branches of the brachial plexus; serratus muscles innervated by ventral rami (T2-5, T9-12).
- Intrinsic Muscles: Innervated by segmental posterior primary rami (PPRs), with the lateral portion of intertransversarii receiving APRs.
- Most connective tissues are also innervated by segmental PPRs, including outer portions of intervertebral discs via sinuvertebral nerves.
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Description
This quiz covers the anatomy of intercostal muscles, including their origins, insertions, and functions. Additionally, it addresses the neurovascular supply relevant to these muscles, detailing the arrangement of veins, arteries, and nerves. Perfect for anatomy students seeking to solidify their understanding of thoracic muscle structure.
