Back Muscles Lecture Review

A comprehensive set of Q&A flashcards covering origins, insertions, functions, and innervations of superficial, intermediate, intrinsic, and suboccipital back muscles as outlined in the lecture notes.

Which nerve innervates the trapezius muscle?

Spinal accessory nerve (CN XI) with contributions from C3–C4 ventral rami.

Name the origins of the upper fibers of the trapezius.

Medial part of the superior nuchal line, ligamentum nuchae, and the spinous process of C7.

Where do the middle fibers of the trapezius insert?

On the spine of the scapula and the medial margin of the acromion.

What is the primary action of the lower trapezius fibers?

Depress and upwardly rotate the scapula.

Which spinal roots form the thoracodorsal nerve that supplies latissimus dorsi?

C6–C8.

List two key functions of the latissimus dorsi.

Extension, adduction, and internal rotation of the humerus; also assists in climbing and coughing.

From which bony landmark does the levator scapulae originate?

The transverse processes of C1–C4.

What action do the rhomboid major and minor share?

Retraction (adduction), elevation, and downward rotation of the scapula.

Which nerve innervates both rhomboid muscles and levator scapulae?

Dorsal scapular nerve (C5).

What is the function of the serratus posterior superior muscle?

Elevates ribs 2–5 to aid inspiration.

Which intercostal nerves supply serratus posterior inferior?

T9–T12.

Name the two splenius muscles in the superficial intrinsic layer.

Splenius capitis and splenius cervicis.

What common action is produced by the splenius muscles when acting unilaterally?

Rotation and lateral bending of the head/neck to the same side.

Which muscle group is remembered by the mnemonic "I Love Spaghetti"?

The erector spinae: Iliocostalis, Longissimus, Spinalis.

Give the general function of the erector spinae muscles.

Extension and lateral flexion of the vertebral column; longissimus capitis also extends the head.

Where does the iliocostalis lumborum originate?

Iliac crest, sacrum, and thoracolumbar fascia.

What is the insertion of iliocostalis cervicis?

Transverse processes of C4–C6.

Which part of longissimus inserts on the mastoid process?

Longissimus capitis.

What is the primary action of the spinalis muscles?

Extension of the spine.

Which intrinsic back muscle group lies deepest: erector spinae or transversospinalis?

Transversospinalis group (semispinalis, multifidus, rotatores).

Describe the insertion pattern of multifidus.

Spinous processes two to four vertebral levels above their origins.

Which transversospinalis muscle is best developed in the thoracic region and crosses 4–6 segments?

Semispinalis.

What is the main stabilizing muscle of the lumbar spine within the transversospinalis group?

Multifidus.

How many vertebral levels do rotatores brevis and longus span, respectively?

Rotatores brevis span 1 level; rotatores longus span 2 levels.

Name the three minor deep back muscles.

Interspinales, intertransversarii, and levatores costarum.

What is the chief action of the levatores costarum muscles?

Elevate the ribs and assist lateral flexion of the spine.

Which dorsal ramus exclusively supplies all four suboccipital muscles?

The suboccipital nerve (C1 dorsal ramus).

Where does the rectus capitis posterior major originate and insert?

Origin: spinous process of C2; Insertion: inferior nuchal line of the occiput.

Which suboccipital muscle only extends but does not rotate the head?

Rectus capitis posterior minor.

What is the action of obliquus capitis superior?

Extends and laterally bends the head.

Which suboccipital muscle rotates the atlas on the axis (head to same side)?

Obliquus capitis inferior.

Identify the insertion of the latissimus dorsi.

The floor of the intertubercular groove of the humerus.

Which ligament provides an attachment for both trapezius and splenius capitis?

Ligamentum nuchae.

From which ribs does iliocostalis thoracis originate and where does it insert?

Origin: ribs 7–12; Insertion: ribs 1–6.

What common innervation do all intrinsic back muscles share?

Dorsal rami of spinal nerves.

Which intermediate back muscle assists with expiration?

Serratus posterior inferior (depresses ribs 9–12).

What movement results when the upper trapezius and serratus anterior act together?

Upward rotation of the scapula.

Which muscle group helps maintain posture by linking adjacent spinous processes?

Interspinales.