Podcast
Questions and Answers
What is the primary function of the splenius cervicis and splenius capitis muscles?
What is the primary function of the splenius cervicis and splenius capitis muscles?
Which muscle is NOT part of the erector spinae group?
Which muscle is NOT part of the erector spinae group?
Where do the deep intrinsic back muscles primarily attach?
Where do the deep intrinsic back muscles primarily attach?
Which of the following is the correct sequence for distinguishing between the three muscles of the erector spinae?
Which of the following is the correct sequence for distinguishing between the three muscles of the erector spinae?
Signup and view all the answers
Which intrinsic back muscle originates from the ligamentum nuchae?
Which intrinsic back muscle originates from the ligamentum nuchae?
Signup and view all the answers
What type of muscle action do the erector spinae muscles primarily perform?
What type of muscle action do the erector spinae muscles primarily perform?
Signup and view all the answers
Which muscle is known as the longest in the transversospinales group?
Which muscle is known as the longest in the transversospinales group?
Signup and view all the answers
What is the innervation for all back muscles discussed?
What is the innervation for all back muscles discussed?
Signup and view all the answers
What type of rotation is performed by the deep intrinsic back muscles?
What type of rotation is performed by the deep intrinsic back muscles?
Signup and view all the answers
What does the pneumonic 'I Luv Spaghetti' help to remember?
What does the pneumonic 'I Luv Spaghetti' help to remember?
Signup and view all the answers
What is the primary action of the rotatores muscle group?
What is the primary action of the rotatores muscle group?
Signup and view all the answers
Which muscle group aids in stabilizing the spine and maintaining posture isometrically?
Which muscle group aids in stabilizing the spine and maintaining posture isometrically?
Signup and view all the answers
What structure envelopes the erector spinae and aids in lumbar stability?
What structure envelopes the erector spinae and aids in lumbar stability?
Signup and view all the answers
Which of the following does NOT originate from the transverse processes in the thoracic region?
Which of the following does NOT originate from the transverse processes in the thoracic region?
Signup and view all the answers
What are the two components of the rotatores muscle group?
What are the two components of the rotatores muscle group?
Signup and view all the answers
Which muscles fill in the gap between two consecutive transverse processes?
Which muscles fill in the gap between two consecutive transverse processes?
Signup and view all the answers
What type of innervation do intrinsic back muscles primarily receive?
What type of innervation do intrinsic back muscles primarily receive?
Signup and view all the answers
Which back muscle assists in the trunk returning to an erect posture from a flexed position?
Which back muscle assists in the trunk returning to an erect posture from a flexed position?
Signup and view all the answers
Which statements describe the thoracolumbar fascia?
Which statements describe the thoracolumbar fascia?
Signup and view all the answers
Which action is NOT commonly performed by the intrinsic back muscles?
Which action is NOT commonly performed by the intrinsic back muscles?
Signup and view all the answers
Study Notes
Intrinsic Back Muscles
- Muscles with attachments only within the trunk, solely acting on the trunk.
-
Superficial intrinsics: Muscles closest to the surface, acting on the trunk.
- Innervated by segmental Posterior Primary Ramus
- Splenius cervicis: Connects to transverse process of C1, originates from ligamentum nuchae of upper thoracic spine.
- Splenius capitis: Connects to the skull, originates from C7/upper thoracic and inserts on the mastoid, temporal bone, and occipital bone.
- Splenius cervicis/capitis fibers run obliquely.
- Both contribute to rotation, extension, and lateral flexion, acting as ipsilateral rotators.
-
Intermediate intrinsics: Erector spinae (composed of 3 muscles)
- Iliocostalis: Lateral-most muscle. Originates from sacrum and lumbar fascia, attaching to the ribs and cervical transverse processes.
- Longissimus: Middle muscle. Originates from sacral and pelvic fascia, attaching to the ribs, thoracic and cervical transverse processes, and mastoid process.
- Spinalis: Medial-most muscle. Originates from a fascial band, attaching to the spinous processes of the thoracic and cervical regions and cranium.
- Pneumonic: “I Luv Spaghetti.”
- All attach to the posterior iliac crest, posterior surface of the sacrum, and spinous processes of the sacrum and lumbar vertebrae.
- All erector spinae muscles are innervated by segmental posterior primary rami of spinal nerves.
-
Inferior attachment of erector spinae:
- Posterior iliac crest
- Posterior SI ligament
- Posterior surface of the sacrum
- Lumbar and sacral spinous processes
- Supraspinous ligament
- Function: Primarily work isometrically and eccentrically, eccentrically for bending to touch toes, and concentrically for postural support.
-
Deep Intrinsic Back Muscles: Deepest layer, attaching to the spine and moving it.
-
Transversospinales: Group of three muscles running longitudinally in the spine with slight oblique angulation, involved in back rotation.
- Semispinalis: Longest muscle, extending from the thorax and cervical region to the head.
-
Multifidus: Shorter fibers spanning 2-4 vertebral levels, crucial for back pain prevention.
- Originates from the sacrum, near the PSIS of the ilium, and the lumbar vertebrae's mammillary processes.
-
Rotatores: Shortest muscle fibers with oblique angles, spanning one and two levels, evident in the thoracic spine.
- Rotatores longus: Extend across two vertebral segments.
- Rotatores brevis: Cross a single vertebral segment.
- All originate from thoracic transverse processes and insert on the vertebral segment's lamina.
- Function as contralateral rotators and spinal stabilizers.
-
Transversospinales: Group of three muscles running longitudinally in the spine with slight oblique angulation, involved in back rotation.
-
Deep minor intrinsics: Maintain space between vertebral segments, provide proprioception, and stabilize.
- Interspinales: Between spinous processes.
- Intertransversarii: Fill the gap between consecutive transverse processes.
- Levatores costarum: Extend from transverse processes to the same numbered rib in the thoracic region, stabilizing the ribs.
-
Actions of the back muscles:
- Return the trunk to an erect posture from flexion.
- Maintain posture isometrically.
- Perform side bending and rotation.
Thoracolumbar Fascia
- Superficial layer: Most superficial, subcutaneous, adipose.
- Deep layer: Splits into 2-3 lamina attaching to the spinous and transverse processes.
- Envelopes the erector spinae and transversospinales.
- Connects to transversus abdominus, internal oblique, and psoas, providing continuous stabilization across lumbar areas.
Innervation of Back Muscles
- Motor and sensory innervation: Posterior primary rami of spinal nerves for most intrinsic back muscles.
- Extrinsic back muscles: Innervated by anterior primary rami corresponding to the upper extremity.
- Sinuvertebral nerves: Innervate the outer parts of intervertebral discs and their connective tissue.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Explore the anatomy and functions of the intrinsic back muscles. This quiz covers superficial and intermediate intrinsics, their attachments, innervation, and actions on the trunk. Test your knowledge on the splenius and erector spinae muscles.
