head neck and trunk muscles

Question 1

Rectus abdominis

Answer 1

• Proximal attachment: xiphoid process of
  sternum, costal cartilages of ribs 5-7
• Distal attachment: pubic crest and
  symphysis
• Actions:
• Bilaterally: flexion of the trunk,
  increases intra-abdominal pressure
• Unilaterally: lateral flexion of the trunk

Question 2

External oblique

Answer 2

Proximal attachment: outer border of
lower 8 ribs and costal cartilages
* Distal attachment: iliac crest, linea alba
* Actions:
* Bilaterally: flexion of the trunk,
increases intra-abdominal pressure
* Unilaterally: lateral flexion and
contralateral rotation of the trunk

Question 3

Internal oblique

Answer 3

Proximal attachment: lower border of lower 4
ribs and costal cartilages
* Distal attachment: iliac crest, thoracolumbar
fascia, inguinal ligament, linea alba
* Actions:
* Bilaterally: flexion of the trunk, increases
intra-abdominal pressure
* Unilaterally: lateral flexion and ipsilateral
rotation of the trunk

Question 4

Transversus abdominis

Answer 4

• Proximal attachment: inner surface of costal
  cartilages of lower 6 ribs
• Distal attachment: iliac crest, thoracolumbar
  fascia, inguinal ligament, linea alba
• Actions:
• Bilaterally: increases intra-abdominal
  pressure
• Unilaterally: ipsilateral rotation of the
  trunk

Question 5

Pyramidalis

Answer 5

• Proximal attachment: pubic crest
• Distal attachment: linea alba
• Action: tenses linea alba

Question 6

Quadratus lumborum

Answer 6

• Proximal attachment: medial half of lower
  border of rib 12, transverse processes of
  L1-L5 vertebrae
• Distal attachment: iliac crest, iliolumbar
  ligament
• Actions:
• Bilaterally: extension of the trunk,
  fixes rib 12 during inspiration
• Unilaterally: lateral flexion of the trunk

Question 7

Psoas major

Answer 7

Proximal attachment: bodies and
transverse processes of T12-L5
vertebrae, and intervening IVDs
* Distal attachment: lesser trochanter
of femur
* Actions (in trunk):
* Bilaterally: flexion of the trunk
* Unilaterally: lateral flexion of the
trunk

Question 8

Psoas minor

Answer 8

• Proximal attachment: bodies of
  T12-L1 vertebrae and intervening
  IVD
• Distal attachment: iliopubic
  eminence, iliac fascia
• Action: weak flexion of the trunk

Question 9

Spinalis

Answer 9

Most medial column
* Attaches to spinous processes (SPs) of vertebrae
* Three parts:
* Spinalis thoracis
* From SPs of upper lumbar and lower thoracic vertebrae to SPs of upper
thoracic vertebrae
* Spinalis cervicis
* From SPs of upper thoracic vertebrae to SPs of cervical vertebrae
* Spinalis capitis
* Extensions of medial portion of semispinalis capitis (part of
transversospinalis)
* Actions:
* Bilaterally: extension of the trunk, neck and head
* Unilaterally: lateral flexion of the trunk, neck and head (although not strong)

Question 10

Longissimus

Answer 10

• Intermediate column
• Attaches to transverse processes (TPs) of vertebrae
• Three parts:
• Longissimus thoracis
• From common origin to TPs of thoracic vertebrae and adjacent ribs
• Longissimus cervicis
• From TPs of upper thoracic vertebrae to TPs of middle cervical vertebrae
• Longissimus capitis
• From TPs of upper thoracic and middle cervical vertebrae to skull
  (mastoid process of temporal bone)
• Actions:
• Bilaterally: extension of the trunk, neck and head
• Unilaterally: lateral flexion of the trunk, neck and head (although not strong)

Question 11

Iliocostalis

Answer 11

• Most lateral column
• Attaches to angles of ribs
• Three parts:
• Iliocostalis lumborum
• From common origin to angles of lower ribs
• Iliocostalis thoracis
• From angles of lower ribs to angles of upper ribs
• Iliocostalis cervicis
• From angles of upper ribs to TPs of lower cervical
  vertebrae
• Actions:
• Bilaterally: extension of the trunk and neck
• Unilaterally: lateral flexion of the trunk and neck

Question 12

Semispinalis

Answer 12

Most superficial layer
* Muscle fibres span many (5-7) vertebral segments
* Three parts:
* Semispinalis thoracis
* From TPs of lower thoracic vertebrae to SPs of upper thoracic and
lower cervical vertebrae
* Semispinalis cervicis
* From TPs of upper thoracic vertebrae to SPs of middle cervical
vertebrae
* Semispinalis capitis
* From TPs of upper thoracic and lower cervical vertebrae to skull
(occipital bone)
* Actions:
* Bilaterally: extension of the trunk, head and neck
* Unilaterally: contralateral rotation of the trunk, neck and head

Question 13

Multifidus

Answer 13

Intermediate layer
* Muscle fibres span a few (2-5) vertebral segments
* Found along the entire length of the vertebral column (most
inferior fibres attach to the sacrum, but does not extend as far
superiorly as the skull)
* Most developed in the lumbar region (multifidus
lumborum) of the vertebral column
* Actions:
* Bilaterally: extension of the trunk and neck
* Unilaterally: lateral flexion and contralateral rotation of the
trunk and neck
* Function: stability

Question 14

Rotatores

Answer 14

Deepest layer
* Muscle fibres span 1-2 vertebral segments
* Long and short fibres
* Most developed in the thoracic region
(rotatores thoracis) of the vertebral column
(often absent in cervical and lumbar regions)
* Action: contralateral rotation of the trunk in the
thoracic region
* Function: stability

Question 15

Interspinales

Answer 15

Vertical fibres spanning between adjacent
spinous processes
* Most developed in the cervical and lumbar
regions of the vertebral column (often
absent in thoracic region)
* Action: assists in extension of the trunk
* Function: stability

Question 16

Intertransversarii

Answer 16

Vertical fibres spanning between adjacent
transverse processes
* Most developed in the cervical and lumbar
regions of the vertebral column (often
absent in thoracic region)
* Cervical: anterior and posterior parts
* Lumbar: medial and lateral parts
* Action: assists in lateral flexion of the trunk
* Function: stability