L3 The Back and Neck muscles

Question 1

What’s the difference between an extrinsic and intrinsic back muscles?

Answer 1

• Extrinsic muscles are superficial muscle (more distal)

Primary function doesn’t concern the back (movement of upper limbs), only secondary functions involve back

• Intrinsic muscles are more internal

Attachment sites on vertebrae or ribs

Primary function is the movement/support of V.C

Innervated by the posterior rami of spinal nerves

Question 2

What extrinsic muscles compose the first superficial layer of the back?

Answer 2

• Trapezius
  
  • Fixed scapula
  • Bilateral function: extension of the neck (skull to shoulders)
  • Unilateral function: ipsilateral lateral flexion, contralateral rotation of the cervical spine
• Latissimus dorsi
  
  • Origin: Midline Insertion: Arm
  • Bilateral function : Extension of v.c
  • Unilateral function : Ipsilateral lateral flexion of lumbar spine

Question 3

What extrinsic muscles compose the 2nd superificial layer of the back?

Answer 3

• Levator scapulae
  
  • O: Cervical spine I: Scapula
  • Elevation of the scapula
• Rhomboid major/minor
  
  • O: Cervical/Thoracic spine I: Scapula
  • Retraction of the scapula
  • Major on bottom (bigger), minor on top (smaller)

Question 4

What are the muscles of the 3rd superficial layer of the back?

Answer 4

• Serratus posterior superior
  
  • O: Ligamentum nuchae/SPs CVII-TIV I: Upper ribs
  • Elevation of the ribs
• Serratus posterior inferior
  
  • O: Thoracolumbar fascia and SPs of lower thor. I:Lower ribs
  • Depression of lower ribs
• Serratus (serrated look, sharp) makes a diamond shape in middle of back
• Used to breathe (not resting)

Question 5

What is this space called?

Answer 5

• Triangle of Auscultation
  
  • Bordered by: Trapezius – Latissimus dorsi – Rhomboid Major
  • Triangle where the back is thinnest (used to listen to longs via stethoscope)

Question 6

What intrinsic back muscles are responsible for posture and standing up?

Answer 6

• Erector Spinae (back)
  
  • Stand up, posture
  • ‘I Like Standing’
  • Iliocostali
    
    • O: Ilium (lower back) I: Ribs (-costalis)
  • Longissimus
    
    • Longest
  • Spinalis
    
    • Closest to the midline
• Erector spinae is covered by thick layer of fascia (Thoracolumbar fascia) for additional support
• Bilateral: Extension of the spine
• Unilateral: Lateral flexion of the spine (iliocostalis)

Question 7

What is the deepest layer of intrinsic back muscles?

Answer 7

Transversospinal (Deep group)

1. All originate at TPs and inserts on SPs

• Semispinalis
  
  • Span 4-6 vertebrae levels
  • Contralateral rotation of the spine, extension of the head
  • Capitis – Cervicis – Thoracis
  • Bilateral function: Extension and rotation (muscles are oblique, TP to SP)
• Multifidus
  
  • Span 2-4 vertebral levels
  • Prominent in lumbar region
  • Lower back strength
• Rotatores
  
  • Deepest, span 1-2 vertebral levels
  • Contralateral rotation of the spine
  • Longus, Brevis (wavy)

Question 8

What muscles compose the minor deep group of intrinsic back muscles?

Answer 8

• Interspinalis
  
  • Stretch between (inter-) SPs
  • Extension of the spine
• Intertransversari
  
  • Prominent in cervical/lumbar regions
  • Stretch between TPs
  • Ipsilateral, lateral flexion (because they’re on the sides)
• Levatores costarum
  
  • Between TPs of thoracic region and rib (costa-)
  • Elevation of the ribs (levatores) and ipsilateral lateral flexion

Question 9

What is the name of this muscle and what are its functions?

Answer 9

• Sterno-cleido-mastoid
  
  • O – Sternum (sterno), Clavicle(cleido) I – Mastoid process (mastoid)
  • Bilateral: Extension of the head
  • Unilateral: Contralateral rotation, ipsilateral lateral flexion

Question 10

What are these deep muscles of the neck?

Answer 10

Posterior:

• Rectus capitis posterior minor
  
  • O: Posterior tubercle on the atlas I: Occiput
  • Extension of the head
• Rectus capitis posterior major
  
  • O: SP of axis I: Occiput
  • Extension and ipsilateral rotation of the head
• Obliquus capitis superior
  
  • O: TP of atlas I: Occiput
  • Extension and ipisilateral, lateral flexion of head
• Obliquus Capitis inferior
  
  • O: SP of axis I: TP of atlas
  • Ipsilateral rotation of the head

Question 11

What is this space called? What are its borders?

Answer 11

• Suboccipital triangle
  
  • Borders: RCPMaj – OCS – OCI
  • Vertebral artery (C1 spinal nerve) which innervates all suboccipital muscles (for numbing pain)

Question 12

What are the anterior deep muscles of the neck?

Answer 12

• Rectus capitis lateralis
  
  • O: TP of atlas I: Occiput
  • Lateral flexion of the head
• Rectus capitis anterior
  
  • Flexion and ipsilateral rotation of the head
• Longus capitis
  
  • O: TP of cervical vertebrae I: Occiput
  • Flexion of the head
• Longus colli
  
  • O: Vertebral bodies I: TP of cervical vertebrae
  • Superior oblique – Vertical – Inferior oblique
• Scalenes
  
  • O: TP I: Rib
  • Anterior, middle (rib 1), posterior (rib 2)
  • Elevation of ribs during inspiration, flexion of the cervical spine