Podcast
Questions and Answers
Which muscle is NOT part of the superficial layer of extrinsic back muscles?
Which muscle is NOT part of the superficial layer of extrinsic back muscles?
What is the primary function associated with the erector spinae group?
What is the primary function associated with the erector spinae group?
Which of the following muscles is categorized as a minor deep back muscle?
Which of the following muscles is categorized as a minor deep back muscle?
Which muscle is classified as part of the deep layer of back muscles?
Which muscle is classified as part of the deep layer of back muscles?
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Which muscles are part of the intrinsic back muscles but not included in the erector spinae group?
Which muscles are part of the intrinsic back muscles but not included in the erector spinae group?
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Which muscle is primarily innervated by the spinal accessory nerve (CN XI)?
Which muscle is primarily innervated by the spinal accessory nerve (CN XI)?
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Which of the following muscles connects the axial skeleton to the superior appendicular skeleton?
Which of the following muscles connects the axial skeleton to the superior appendicular skeleton?
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Which extrinsic back muscle is NOT part of the superficial layer?
Which extrinsic back muscle is NOT part of the superficial layer?
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Which pair of muscles are classified as posterior axio-appendicular muscles?
Which pair of muscles are classified as posterior axio-appendicular muscles?
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Which statement about the innervation of extrinsic back muscles is true?
Which statement about the innervation of extrinsic back muscles is true?
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What is the primary function of the serratus posterior superior muscle?
What is the primary function of the serratus posterior superior muscle?
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Which nerve roots innervate the serratus posterior inferior muscle?
Which nerve roots innervate the serratus posterior inferior muscle?
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Which statement is true regarding the classifications of the serratus muscles?
Which statement is true regarding the classifications of the serratus muscles?
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Which function is less likely attributed to the serratus posterior muscles?
Which function is less likely attributed to the serratus posterior muscles?
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How are the serratus posterior muscles classified in terms of their role?
How are the serratus posterior muscles classified in terms of their role?
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What structural feature encloses the intrinsic back muscles?
What structural feature encloses the intrinsic back muscles?
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Which group classification does NOT exist for intrinsic back muscles?
Which group classification does NOT exist for intrinsic back muscles?
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From which nerves do the intrinsic back muscles receive their innervation?
From which nerves do the intrinsic back muscles receive their innervation?
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What is the main anatomical connection point of the intrinsic back muscles?
What is the main anatomical connection point of the intrinsic back muscles?
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Which fascia type is specifically mentioned in relation to the intrinsic back muscles?
Which fascia type is specifically mentioned in relation to the intrinsic back muscles?
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What is the primary origin of the splenius muscles?
What is the primary origin of the splenius muscles?
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Which insertion corresponds to the splenius cervicis muscle?
Which insertion corresponds to the splenius cervicis muscle?
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Which action is primarily attributed to the unilateral function of the splenius muscles?
Which action is primarily attributed to the unilateral function of the splenius muscles?
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What is the nerve supply for the splenius muscles?
What is the nerve supply for the splenius muscles?
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Which of the following best describes the appearance of the splenius muscles?
Which of the following best describes the appearance of the splenius muscles?
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What action do the splenius muscles perform bilaterally?
What action do the splenius muscles perform bilaterally?
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What is the primary action of the longissimus muscle?
What is the primary action of the longissimus muscle?
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Which nerve supply innervates the erector spinae group?
Which nerve supply innervates the erector spinae group?
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Which muscle attaches to the lumbar, thoracic, and cervical regions?
Which muscle attaches to the lumbar, thoracic, and cervical regions?
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What is the origin of the erector spinae muscle group?
What is the origin of the erector spinae muscle group?
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Which muscle is primarily responsible for lateral flexion of the vertebral column?
Which muscle is primarily responsible for lateral flexion of the vertebral column?
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Which muscle is situated laterally within the erector spinae group?
Which muscle is situated laterally within the erector spinae group?
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Which muscle is considered the most medial of the erector spinae group?
Which muscle is considered the most medial of the erector spinae group?
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Which of the following muscles is included in the erector spinae group?
Which of the following muscles is included in the erector spinae group?
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The erector spinae group consists of muscles that primarily support which action?
The erector spinae group consists of muscles that primarily support which action?
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Which of the following muscles is NOT a part of the erector spinae group?
Which of the following muscles is NOT a part of the erector spinae group?
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Which of the following muscles is part of the transversospinales group?
Which of the following muscles is part of the transversospinales group?
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What is a function of the minor deep back muscles?
What is a function of the minor deep back muscles?
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Which muscle is categorized as a minor deep back muscle?
Which muscle is categorized as a minor deep back muscle?
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How are the interspinales muscles primarily categorized?
How are the interspinales muscles primarily categorized?
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Which of the following muscles is NOT part of the transversospinales?
Which of the following muscles is NOT part of the transversospinales?
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Which of the following muscles is part of the transversospinales group?
Which of the following muscles is part of the transversospinales group?
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What is the primary role of the minor deep back muscles?
What is the primary role of the minor deep back muscles?
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Which of the following best describes the function of the rotatores muscles?
Which of the following best describes the function of the rotatores muscles?
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Which muscle is NOT categorized as a minor deep back muscle?
Which muscle is NOT categorized as a minor deep back muscle?
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Which structure includes both levator costarum longus and levator costarum brevis?
Which structure includes both levator costarum longus and levator costarum brevis?
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What is a primary role of the multifidus muscle?
What is a primary role of the multifidus muscle?
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Which characteristic distinguishes the semispinalis muscle from other deep back muscles?
Which characteristic distinguishes the semispinalis muscle from other deep back muscles?
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Which of the following muscles is most likely to provide stability to individual vertebrae?
Which of the following muscles is most likely to provide stability to individual vertebrae?
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In which area of the body would you primarily find the semispinalis muscle working?
In which area of the body would you primarily find the semispinalis muscle working?
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What type of muscle action is primarily associated with the multifidus during bilateral contraction?
What type of muscle action is primarily associated with the multifidus during bilateral contraction?
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What is the primary origin point of the rotatores muscles?
What is the primary origin point of the rotatores muscles?
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Which statement accurately describes the insertion points of the rotatores?
Which statement accurately describes the insertion points of the rotatores?
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How do the fibers of the rotatores muscles run?
How do the fibers of the rotatores muscles run?
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What role do the rotatores muscles primarily serve in the vertebral column?
What role do the rotatores muscles primarily serve in the vertebral column?
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Which aspect of proprioception might the rotatores muscles be involved in?
Which aspect of proprioception might the rotatores muscles be involved in?
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What is the primary origin location of the interspinales muscles?
What is the primary origin location of the interspinales muscles?
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Which of the following best describes the insertion of the interspinales muscles?
Which of the following best describes the insertion of the interspinales muscles?
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What primary function do the interspinales muscles serve?
What primary function do the interspinales muscles serve?
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Which regions do the interspinales muscles primarily span?
Which regions do the interspinales muscles primarily span?
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How do the interspinales muscles contribute to movement?
How do the interspinales muscles contribute to movement?
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What is the primary function of the intertransversarii muscles when engaged unilaterally?
What is the primary function of the intertransversarii muscles when engaged unilaterally?
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Which of the following correctly describes the innervation of the intertransversarii?
Which of the following correctly describes the innervation of the intertransversarii?
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Where do the intertransversarii muscles primarily originate?
Where do the intertransversarii muscles primarily originate?
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What is the primary action of the intertransversarii when activated bilaterally?
What is the primary action of the intertransversarii when activated bilaterally?
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Which statement correctly describes the insertion points of the intertransversarii muscles?
Which statement correctly describes the insertion points of the intertransversarii muscles?
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Study Notes
Extrinsic Back Muscles
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Superficial Layer: Comprises major muscles that facilitate shoulder movement and upper limb functions.
- Trapezius: Elevates, retracts, and rotates the scapula, crucial for shoulder stability.
- Latissimus dorsi: Responsible for arm extension, adduction, and internal rotation; participates in actions like swimming.
- Levator scapulae: Elevates the scapula and tilts its glenoid cavity downward.
- Rhomboid Major: Retracts and elevates the scapula, aids in maintaining posture.
- Rhomboid Minor: Similar function to major; assists in scapular retraction.
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Intermediate Layer: Contains muscles that assist in respiration and back stability.
- Serratus Posterior Superior: Elevates upper ribs, aiding in inhalation.
- Serratus Posterior Inferior: Depresses lower ribs, supporting exhalation.
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Suboccipital Triangle: A group of small muscles that stabilize and allow fine movements of the head and neck.
Deep Layer (Intrinsic Muscles)
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Superficial Intrinsic Layer:
- Splenius Capitis: Extends and rotates the head and neck; influences posture and movement.
- Splenius Cervicis: Similar to capitis but focuses on cervical spine mobility.
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Intermediate Intrinsic Layer (Erector Spinae): Key for maintaining erect posture and spinal flexion.
- Iliocostalis: Lateral extension and lateral flexion of the vertebral column.
- Longissimus: Extends the vertebral column and rotates the head; the longest of the erector spinae group.
- Spinalis: Primarily extends the spine, located closest to the vertebrae.
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Deep Intrinsic Layer:
- Transversospinales: Consists of muscles that rotate and extend the spine, stabilizing vertebrae.
- Semispinales: Extend the thoracic and cervical spine, important for posture.
- Multifidus: Provides stability to the spine, particularly during movement and heavy lifting.
- Rotatores: Assist in rotation and stabilization of vertebrae, typically only present in the thoracic region.
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Minor Deep Back Muscles: Small muscles that provide additional stability and movement to the spine.
- Interspinales: Facilitate extension between adjacent vertebrae.
- Intertransversarii: Aid in lateral flexion of the vertebral column.
- Levatores Costarum: Elevate the ribs, assist in breathing and posture.
Superficial Extrinsic Back Muscles
- Extrinsic back muscles link the axial skeleton to the superior appendicular skeleton
- Most notable muscles include:
- Trapezius: This large, triangular muscle covers the upper back and neck
- Latissimus dorsi: A broad muscle of the back that extends, adducts, and rotates the shoulder
- Levator scapulae: Elevates the scapula and assists in neck movement
- Rhomboid major: Retracts and elevates the scapula
- Rhomboid minor: Similar to rhomboid major, aids in scapular retraction and elevation
Innervation
- Most superficial extrinsic back muscles are innervated by anterior rami of cervical nerves
- Trapezius is an exception, receiving motor fibers from the spinal accessory nerve (CN XI)
- Proper nerve supply is crucial for muscle function and coordination during movement
Intermediate Extrinsic Back Muscles
- Include Serratus posterior superior and Serratus posterior inferior.
Description
- Classified as superficial respiratory muscles impacting rib movements.
- Serratus posterior superior functions to elevate ribs during inhalation.
- Serratus posterior inferior functions to depress ribs during exhalation.
- These muscles may play a role in proprioception, enhancing body awareness.
Innervation
- Both muscles are innervated by specific intercostal nerves:
- Serratus posterior superior: innervated by T1-T4 intercostal nerves.
- Serratus posterior inferior: innervated by T8-T12 intercostal nerves.
Intrinsic Back Muscles
- Muscles span from the pelvis to the cranium, supporting movement and stability of the spine.
- Enclosed within deep fascia, contributing to the separation of back muscles from surrounding structures.
- Thoracolumbar fascia plays a crucial role in reinforcing the lower back and serves as attachment sites for muscles.
Muscle Grouping
- Intrinsic back muscles are classified into three groups:
- Superficial muscles focus on movements of the upper body.
- Intermediate muscles assist with posture and movement stabilization.
- Deep muscles are primarily responsible for spinal extension and lateral flexion.
Innervation
- All intrinsic back muscles are primarily innervated by the posterior rami of spinal nerves, which provide motor control and sensory feedback.
Splenius Muscles Overview
- Splenius muscles consist of two main components: Splenius Capitis and Splenius Cervicis.
- Located in the lateral and posterior aspects of the neck, these muscles play crucial roles in neck movement.
Splenius Capitis
- Origin: Nuchal ligament and spinous processes of vertebrae C7 to T6.
- Insertion: Inserts into the lateral half of the superior nuchal line and the mastoid process of the temporal bone.
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Actions:
- Unilateral action: Facilitates lateral flexion and rotation of the head.
- Bilateral action: Contributes to extension of the neck and head.
Splenius Cervicis
- Origin: Shares the same origin as the Splenius Capitis, from the nuchal ligament and C7 to T6 spinous processes.
- Insertion: Attaches to the tubercles of the transverse processes of the first three or four cervical vertebrae (C1-C4).
- Actions: Similar to the Splenius Capitis, allowing for lateral flexion and rotation when acting unilaterally, and neck/head extension bilaterally.
Nerve Supply
- Both muscles are innervated by the posterior rami of the spinal nerves, allowing for motor control and coordination.
Additional Notes
- The term "splenion" implies a bandage-like structure, indicating how these muscles cover deeper vertical muscles in the neck.
- The overall structure of the muscles is thick and flat, adapting well for their functions in neck stabilization and movement.
Erector Spinae Muscle Overview
- Arises from posterior iliac crest and surface of sacrum.
- Origin includes sacroiliac ligaments and sacral vertebrae.
- Responsible for extension and lateral flexion of the spine.
Innervation
- Supplied by dorsal rami of spinal nerves.
- Importance in maintaining posture and supporting spinal health.
Clinical Relevance
- Key muscle group for stabilizing the spine during movements.
- Often targeted in rehabilitation for back pain and injury recovery.
Extrinsic Back Muscles
-
Superficial Layer:
- Composed of trapezius, latissimus dorsi, levator scapulae, rhomboid major, and rhomboid minor.
- Posterior axio-appendicular muscles connect the axial skeleton to the superior appendicular skeleton.
- The trapezius is innervated by motor fibers from the spinal accessory nerve (CN XI); other muscles receive innervation from anterior rami of cervical nerves.
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Intermediate Layer:
- Consists of serratus posterior superior and serratus posterior inferior.
- These muscles are considered superficial respiratory muscles, with the superior muscle elevating ribs and the inferior muscle depressing them.
- Innervation comes from specific intercostal nerves: T1-4 for serratus posterior superior and T8-12 for serratus posterior inferior.
Intrinsic Back Muscles
- Encompass muscles extending from the pelvis to the cranium, surrounded by deep fascia, specifically thoracolumbar fascia.
- Grouped into superficial, intermediate, and deep layers, with innervation supplied by the posterior rami of spinal nerves.
Splenius Muscles
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Splenius Capitis and Splenius Cervicis:
- Origin: Nuchal ligament and spinous processes of C7-T6.
- Cervicis Insertion: Tubercles of transverse processes C1-3/4; action includes lateral neck flexion and head rotation.
- Capitis Insertion: Lateral half of the superior nuchal line and the mastoid process; action includes extension of the neck/head.
- Innervated by posterior rami of spinal nerves; these muscles are thick and flat, covering the vertical muscles of the neck.
Erector Spinae
- Deep intrinsic muscles comprising the iliocostalis, longissimus, and spinalis positioned laterally to medially along the spine.
- Originate from a common tendon attached to the posterior part of the iliac crest, sacral surface, and sacroiliac ligaments.
- Function primarily to extend the vertebral column and assist in maintaining posture.
Deep Muscles of the Back
- Composed of short, obliquely oriented muscles that facilitate spinal movements and stability.
Transversospinales Group
- A key muscle group located along the spine, providing rotational and stabilizing functions.
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Semispinales:
- Encompasses three segments vital for head and neck movements:
- Semispinalis capitis: Extends and rotates the head.
- Semispinalis cervicis: Aids in cervical spine extension and rotation.
- Semispinalis thoracis: Involved in thoracic spine movement.
- Encompasses three segments vital for head and neck movements:
-
Multifidus:
- Runs along the length of the spine, crucial for maintaining posture and stability.
-
Rotatores:
- Small muscles located between adjacent vertebrae, involved in localized rotation of the spine.
Minor Deep Back Muscles
-
Interspinales:
- Located between adjacent spinous processes, aiding in extension of the spine.
-
Intertransversarii:
- Found between transverse processes, assisting in lateral flexion and stabilization.
-
Levatores costarum:
- Connect ribs to the transverse processes of the thoracic vertebrae, facilitating rib elevation and aiding in breathing mechanics.
Deep Layer of Back Muscles
- Comprises short, obliquely orientated muscles that contribute to spinal stability and movement.
Transversospinales Group
- Includes muscles that run between the transverse and spinous processes of the vertebrae.
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Semispinales: Divided into three parts
- Semispinalis capitis: Extends the head and rotates it contralaterally.
- Semispinalis cervicis: Primarily extends and laterally bends the cervical spine.
- Semispinalis thoracis: Extends and rotates the thoracic spine.
Multifidus
- A series of small muscles located along the spine, crucial for maintaining posture and providing stability during movement.
Rotatores
- Paired muscles found along the spine that are primarily responsible for rotation and stabilization of the vertebral column.
Minor Deep Back Muscles
- A group of smaller muscles aiding in finer adjustments to the spinal alignment and movement.
Interspinales
- Small muscles situated between adjacent spinous processes; play a role in extension of the vertebral column.
Intertransversarii
- Located between the transverse processes; assist in lateral flexion and stabilization of the spine.
Levator Costarum
- Muscle group that elevates the ribs during inhalation.
- Levator costarum longis: Longer fibers that connect to the second rib below.
- Levator costarum brevis: Shorter fibers attaching directly to the rib below.
Rotatores Overview
- Originates from the transverse processes of the thoracic vertebrae.
- Fibers are oriented in a superomedial direction, facilitating specific movement mechanics.
Insertion Points
- Inserts at the junction of the lamina and transverse processes of adjacent vertebrae.
- Attaches to the spinous processes of vertebrae:
- Brevis: connects to the spinous process of the immediately superior vertebra.
- Longus: connects to the spinous process of the vertebra two segments superior.
Functions
- Stabilizes the vertebrae during movement.
- Assists in the extension and rotation of the vertebral column, enhancing spinal mobility.
- May serve as organs of proprioception, contributing to the body's sense of position and movement.
Extrinsic Back Muscles
-
Superficial Layer consists of key muscles including:
- Trapezius: Connects axial skeleton to the upper appendicular skeleton
- Latissimus dorsi: Also connects axial skeleton with superior appendicular skeleton
- Levator scapulae
- Rhomboid major
- Rhomboid minor
-
Innervation:
- Most are innervated by anterior rami of cervical nerves
- Exception: Trapezius is innervated by the spinal accessory nerve (CN XI)
-
Intermediate Layer:
- Comprised of Serratus posterior superior and Serratus posterior inferior
- These muscles act as superficial respiratory muscles; superior elevates ribs, while inferior depresses them
- Innervated by intercostal nerves (T1-4 for superior and T8-12 for inferior)
Intrinsic Back Muscles
-
Categories:
- Superficial: Includes Splenius capitis and Splenius cervicis
- Intermediate: Comprised of Erector spinae muscles (Iliocostalis, Longissimus, Spinalis)
- Deep Layer: Contains Transversospinales (Semispinales, Multifidus, Rotatores) and minor deep back muscles (Interspinales, Intertransversarii, Levatores costarum)
-
General Characteristics:
- These muscles extend from the pelvis to the cranium and are enclosed by deep fascia
- Innervation is predominantly by posterior rami of spinal nerves
Splenius Muscles
-
Splenius Capitis & Cervicis:
- Originates from nuchal ligament and spinous processes of C7-T6
-
Inserts:
- Cervicis: Tubercles of transverse processes C1-3/4
- Capitis: Lateral ½ of superior nuchal line & mastoid process
-
Actions:
- Unilateral: Laterally flexes neck and rotates head
- Bilateral: Extends neck/head
Erector Spinae Muscles
- Consists of three primary muscles arranged laterally to medially:
- Iliocostalis
- Longissimus
- Spinalis
- Arises from the posterior part of the iliac crest, sacrum, and related structures
Deep Layer Muscles
-
Transversospinales:
- Short, obliquely oriented muscles include:
- Semispinales: Subdivided into capitis, cervicis, and thoracis
- Multifidus
- Rotatores: Fibers run superomedial to insert on the spinous processes of vertebrae
- Short, obliquely oriented muscles include:
-
Functions of Rotatores:
- Stabilize vertebrae and assist in extending and rotating the vertebral column
- May also function as proprioceptive organs
Minor Deep Back Muscles
- Includes:
- Interspinales
- Intertransversarii
-
Levatores costarum:
- Expands to Levator costarum longis and brevis
Interspinales Muscles
- Origin: Attaches to the superior surface of spinous processes in both cervical (C) and lumbar (L) regions.
- Insertion: Connects to the inferior surface of the spinous process of the vertebra immediately above.
- Function: Plays a role in facilitating extension and rotation of the vertebral column, contributing to spinal stability and movement.
INTERTRANSVERSARII Muscle Overview
- Originates from transverse processes of cervical (C) and lumbar (L) vertebrae.
- Inserts onto the transverse processes of adjacent vertebrae, facilitating vertebral stability.
- Innervated by anterior and posterior rami of spinal nerves, linking it to neurological control and movement.
- Functions unilaterally to assist in lateral flexion of the vertebral column, allowing for side bending.
- Functions bilaterally to stabilize the vertebral column, providing essential support during movement.
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Description
Test your knowledge on the anatomy of back muscles, including both extrinsic and intrinsic layers. This quiz covers key muscles such as the trapezius, latissimus dorsi, erector spinae, and more. Explore the details about their classifications and functions.