Muscles of the Back Quiz

Correct answer: E

7. Inward rotation of the humerus is controlled by the contraction of which of the following muscles? A. Rhomboids minor B. Subcostal C. Trapezius D. Rhomboids major E. Latissimus dorsi

CORRECT AMSWER: A The answer is spinalis cervicis. The erector spinae is a fused muscle mass that passes superiorly and divides into iliocostalis, longissimus, and spinalis, each of which has regional subdivisions, including the spinalis in the cervical region (spinalis cervicis). I love Sex mnemonic

9. The erector spinae muscle group includes ________________. A. spinalis cervicis. B. Levator costarum. C. multifidus. D. splenius capitis. E. semispinalis capitis.

A suboccipital puncture or cisternal puncture is a diagnostic procedure that can be performed in order to collect a sample of cerebrospinal fluid. When CSF cannot be obtained from the lumbar space, a cisternal tap may be required. If the needle is advanced too far it can enter the medulla, sometimes causing sudden respiratory arrest and death.

Clinical Relevance of Suboccpital Triangle

Is a procedure used for treatment of back pain caused by disease of these joints Denervation is directed at articular branches of two adjacent posterior rami of spinal nerves because each joint receives innervation from both nerve exiting at that level & superjacent nerve

Denervation of Lumbar Zygapophysial Joints

Zygapophysial joints are of clinical interest because they are close to IV foramina through which spinal nerves emerge from vertebral canal When these joints are injured or develop osteophytes - osteoarthritis spinal nerves are often affected This causes pain along distribution patterns of dermatomes & spasm in muscles derived from associated myotomes

Injury & Disease of Zygapophysial Joints

* Control Respiratory movements 1. Serratus Posterior Superior 2. Serratus Posterior Inferior 3. Splenius Capitis 4. Splenius Cervicis * all muscles endining in -itis extend the head

Intermediate Extrinsic Back Muscles of the Back

1. Levator Scapulae 2. Semispinalis 3. Multifidus 4. Rotatores 5. Intertransversarii 6. Levatore Costarum

Muscles of the back that attach to Transverse processes

Pain in lower back & hip radiating down back of thigh into leg Often caused by a herniated lumbar IV disc that compresses & compromises L5 or S1 component of sciatic nerve Bone spurs - osteophytes developing around zygapophysial joints (!!) or posterolateral margins during aging may narrow foramina even more, causing shooting pains down lower limbs Any maneuver that stretches sciatic nerve, such as flexing thigh with knee extended - straight leg raising test - may produce or exacerbate sciatic pain

Sciatica

Failure or fracture of interarticular parts of vertebral laminae of L5 -spondylolysis of L5 especially may result in spondylolisthesis of L5 vertebral body relative to sacrum - S1 vertebra due to downward tilt of L5/S1 IV joint Spondylolisthesis at L5-S1 IV joint may result in pressure on spinal nerves of cauda equina as they pass into superior part of sacrum, causing lower back & lower limb pain

Spondylolisthesis

* Dog sign - Stress fracture of interarticularis Fracture of column of bones connecting superior & inferior articular processes - pars interarticularis / interarticular part —occurs, interlocking mechanism is broken

Spondylolysis

Inferior lumbar (Petit's) triangle The margins of the are composed of the iliac crest inferiorly and the margins of two muscles - latissimus dorsi (posteriorly) and external abdominal oblique (anteriorly). The floor of the inferior lumbar triangle is the internal abdominal oblique muscle. The fact that herniations occasionally occur here is of clinical importance.[ Superior lumbar (Grynfeltt-Lesshaft) triangle is formed medially by the quadratus lumborum muscle, laterally by the internal abdominal oblique muscle, and superiorly by the 12th rib. The floor of the superior lumbar triangle is the transversalis fascia and its roof is the external abdominal oblique muscle. Triangle of auscultation It has the following boundaries: Superiorly and medially, by the inferior portion of the trapezius Inferiorly, by the latissimus dorsi Laterally, by the medial border of the scapula

Triangles in the back

The splenius capitis is innervated by dorsal primary rami of the middle and lower cervical nerves. The suboccipital nerve (dorsal primary ramus of C1) supplies the muscles of the suboccipital area including the rectus capitis posterior major, obliquus capitis superior and inferior, and the semispinalis capitis.

1. In a freak hunting accident, a 17 year-old boy was shot with an arrow that penetrated into his suboccipital triangle, injuring the suboccipital nerve between the vertebral artery and the posterior arch of the atlas. Which of the following muscles would be unaffected by such a lesion? (A) Rectus capitis posterior major (B) Semispinalis capitis (C) Splenius capitis (D) Obliquus capitis superior (E) Obliquus capitis inferior

Correct answer: B Muscles that attatch to Transverse processes 1. Levator Scapulae 2. Semispinalis 3. Multifidus 4. Rotatores 5. Intertransversarii 6. Levatore Costarum

2. After his car was broad-sided by a large truck, a 26-year-old man is brought to the emergency department with multiple fractures of the transverse processes of the cervical and upper thoracic vertebrae. Which of the following muscles might be affected? (A) Trapezius (B) Levator scapulae (C) Rhomboid major (D) Serratus posterior superior (E) Rectus capitis posterior major

The answer is the longissimus. The longissimus muscle, one of the deep muscles of the back and a component of the erector spinae musculature, has extensive attachments to the ribs via its thoracic portion. Thus, spastic contractions of this muscle could directly affect fractured ribs. Rhomboidsis incorrect. The rhomboid muscles do not attach onto the ribs. They run from vertebral spinous processes onto the scapula. Semispinalis is incorrect. The semispinalis muscle is part of the transversospinalis group of deep muscles of the back. It runs from transverse processes of cervical and thoracic vertebrae to spinous processes of cervical and thoracic vertebrae and to the occipital bone. Splenius is incorrect. The splenius is another deep muscle of the back. It courses from the ligamentum nuchae and upper vertebral spines to the base of the skull and cervical transverse processes. Trapezius is incorrect. The trapezius runs from the base of the skull and cervical and thoracic spines to the clavicle and scapula.

3. A 70-year-old woman falls down the stairs in her home and suffers multiple rib fractures. Subsequent spastic contractions of which of the following muscles could displace fragments of the broken ribs? A.Longissimus B. Rhomboids C. Semispinalis D. Splenius E. Trapezius

the answer is splenius capitis. The posterior (dorsal) primary rami of spinal nerves innervate the embryonic epimere and all the skeletal muscles derived from it. The derivatives of the epimere constitute the deep (intrinsic) muscles of the back (or epaxial muscles), including the splenius capitis and cervicis muscles, suboccipital muscles, transversospinales muscles (including the semispinalis, multifidus, and rotatores muscles), and several other small muscles. Thus, damage to the cervical posterior (dorsal) primary rami, SPECIFICALLY C2-6, would result in paralysis of the splenius capitis muscle. Trapezius is incorrect. The trapezius is a member of the superficial extrinsic layer of back muscles, which connect the upper limbs to the trunk. When these muscles contract, movements result in the upper limb. However, the trapezius muscle does not originate from either the epimere or hypomere, as evidenced by its innervation via the spinal accessory nerve (CN XI). Instead, it is likely related to postbranchial origins, along with the sternocleidomastoid. Thus, destruction of the cervical posterior (dorsal) primary rami will not directly affect the innervation of the trapezius muscle. Latissimus dorsi is incorrect. The latissimus dorsi (L: widest muscle of back) is a member of the superficial extrinsic layer of back muscles, which connect the upper limbs to the trunk. When these muscles contract, movements result in the upper limb. The latissimus dorsi muscle is derived from hypomeres, which develop lateral and anterior to the vertebral axis. All of the muscles derived from hypomeres are innervated by the anterior (ventral) primary rami of spinal nerves. The latissimus dorsi muscle acts on the upper limb, and it migrates secondarily into the back. Due to being innervated by the anterior (ventral) primary rami, the latissimus dorsi muscle would not be affected by destruction of the cervical posterior (dorsal) primary rami seen in this patient. Levator scapulae is incorrect. The levator scapulae muscle is a member of the superficial extrinsic layer of back muscles, which connect the upper limbs to the trunk. When these muscles contract, movements result in the upper limb. The levator scapulae muscle is derived from hypomeres, which develop lateral and anterior to the vertebral axis. All of the muscles derived from hypomeres are innervated by the anterior (ventral) primary rami of spinal nerves. Due to being innervated by the anterior (ventral) primary rami, the levator scapulae muscle would not be affected by destruction of the cervical posterior (dorsal) primary rami seen in this patient. Rhomboid major is incorrect. The rhomboid major muscle is a member of the superficial extrinsic layer of back muscles, which connect the upper limbs to the trunk. When these muscles contract, movements result in the upper limb. The rhomboid major muscle is derived from hypomeres, which develop lateral and anterior to the vertebral axis. All of the muscles derived from hypomeres are innervated by the anterior (ventral) primary rami of spinal nerves. Due to being innervated by the anterior (ventral) primary rami, the levator scapulae muscle would not be affected by destruction of the cervical posterior (dorsal) primary rami seen in this patient.

4. As a result of multiple vertebral fractures incurred in an automobile crash, an 8-year-old girl suffers a series of torn posterior primary rami of spinal nerves C2-6. Which of the following muscles will be paralyzed as a result? A.Trapezius B. Latissimus dorsi C. Levator scapulae D. Rhomboid major E. Splenius capitus

CORRECT ANSWER: B

5. A 25-year-old man with congenital abnormalities at birth has a lesion of the dorsal scapular nerve, making him unable to adduct his scapula. Which of the following muscles is most likely paralyzed? (A) Semispinalis capitis (B) Rhomboid major (C) Multifidus (D) Rotator longus (E) Iliocostalis

The answer is latissimus dorsi. The latissimus dorsi forms boundaries of the auscultation and lumbar triangles and receives blood from the thoracodorsal artery. The levator scapulae, rhomboid minor, and splenius capitis muscles do not form boundaries of these two triangles. The trapezius muscle forms a boundary of the auscultation triangle but not the lumbar triangle. The levator scapulae, rhomboid minor, and trapezius muscles receive blood from the transverse cervical artery. The splenius capitis muscle receives blood from the occipital and transverse cervical arteries.

6. After an automobile accident, a back muscle that forms the boundaries of the triangle of auscultation and the lumbar triangle, receives no blood. Which of the following muscles might be ischemic? (A) Levator scapulae (B) Rhomboid minor (C) Latissimus dorsi (D) Trapezius (E) Splenius capitis

The answer is the splenius capitis. All the deep (intrinsic) muscles in the back, including splenius capitis, are supplied by the posterior primary rami of spinal nerves. The brachial plexus is formed from ventral primary rami of spinal nerves. Therefore, the deep muscles of the back retain intact motor supplies when the brachial plexus is damaged. The latissimus dorsi is one of the superficial extrinsic muscles of the back. All the members of this group, except the trapezius muscle, are innervated by ventral primary rami of spinal nerves via the brachial plexus. Thus, the latissimus dorsi could be paralyzed following a brachial plexus injury. The levator scapulae is another member of the superficial extrinsic group of back muscles, and receives its motor supply from the brachial plexus. The rhomboid major muscle is another component of the superficial extrinsic muscles of the back, with motor innervation from the brachial plexus. The rhomboid minor is a small subportion of the rhomboid muscle sheet. As with the larger rhomboid major, it is supplied by ventral primary rami via the brachial plexus.

8. A 25-year-old woman suffers several lesions of her right side brachial plexus as a result of multiple stab wounds in the neck and axilla. Which of the following muscles will retain its intact motor supply? A. Latissimus dorsi B. Levator scapulae C. Rhomboid major D. Rhomboid minor E. Splenius capitis