Trunk Muscles

Question 1

External Abdominal Oblique Muscle

Answer 1

1. Origin: Anterior iliac crest, Pubic bone, Linea alba
2. Insertion: Lower 8 ribs
3. Actions: Flexion, lateral flexion and contralateral rotation of trunk @ spinal joints, posterior pelvic tilt and increase abdominal pressure (valsalva maneuver)
4. Nerve: Intercostal nerves (T7-T12 & L1)

Question 2

Internal Abdominal Oblique Muscle

Answer 2

1. Origin: Anterior portion of iliac crest, Inguinal ligament, Thoracolumbar fascia
2. Insertion: Linea alba, lower 3 ribs
3. Actions: Flexion, lateral flexion and ipsilateral rotation of trunk @ spinal joints, posterior pelvic tilt, increases abdominal pressure (valsalva maneuver)
4. Nerve: Intercostal nerves (T7-T12 & L1)

Question 3

Transverse Abdominis Muscle

Answer 3

1. Origin: Iliac crest, thoracolumbar fascia, Cartilage of lower 6 ribs, inguinal ligament
2. Linea alba
3. Compresses abdominal content
4. Intercostal nerve (T7-T12 & L1)

Question 4

Rectus Abdominis

Answer 4

1. Origin: Pubic crest and pubis symphysis
2. Insertion: Xiphoid process and cartilage of ribs 5-7
3. Actions: Flexion of trunk @ spinal joints, posterior pelvic tilt, compresses abdominal contents
4. Intercostal nerves (T5-T12)

Question 5

Quadratus Lumborum

Answer 5

1. Origin: Iliac crest and iliolumbar ligament (between TP of L5 and iliac crest)
2. Insertion: TPs of L1-L4 and rib 12
3. Action: Extension, lateral flexion and ipsilateral rotation of trunk @ spinal joints, anterior pelvic tilt, depression of rib 12 and elevation of pelvis
4. Nerve: Ventral rami of spinal nerves (T12-L3)

Question 6

Anterior Scalene

Answer 6

1. Origin: TPs of C3-C6 (typical cervical vertebrae)
2. Insertion: Scalene tubercle of 1st rib
3. Actions: Lateral flexion of neck @ spinal joints and elevation of 1st rib during forced inhalation @ sternocostal and costospinal joints (accessory respiratory nerve)
4. Nerve: Ventral rami of cervical spinal nerves (C3-C6)

Question 7

Middle Scalene

Answer 7

1. Origin: TPs of C2-C7 (1 above and 1 below typical cervical vertebrae)
2. Insertion: 1st rib
3. Actions: flexion and lateral flexion of neck @ spinal joints and elevation of 1st rib during forced inhalation @ sternocostal and costospinal joints (accessory respiratory muscle)
4. Nerve: Ventral rami of cervical spinal nerves (C2-C7)

Question 8

Posterior Scalene

Answer 8

1. Origin: TPs of C5-C7
2. Insertion: 2nd rib
3. Actions: Lateral flexion of neck @ spinal joints and elevation of 2nd rib during forced inhalation @ sternocostal and costospinal joints (accessory respiratory muscle)
4. Nerve: Ventral rami of cervical spinal nerves (C5-C7)

Question 9

Inguinal Ligament

Answer 9

Inferior free boarder of aponeurosis of external abdominal oblique muscle stretched between ASIS to pubic tubercle. (Bone to bone) *not a real ligament as it does not support a joint

Question 10

Thoracolumbar Fascia

Answer 10

Thick layer of fascia in posterior abdominal wall, forms base for muscle attachment (transverse abdominis and external abdominal oblique muscle)

Question 11

Linea Alba

Answer 11

Connective tissue in anterior abdominal wall that stretches from xiphoid process to pubic crest

Question 12

Rectus Sheath

Answer 12

Sheath that sandwiches the rectus abdominis, formed by aponeurosis of three muscles from either side

Question 13

Infrahyoid Group of Muscles

Answer 13

1. Sternohyoid
2. Omohyoid
3. Sternothyroid
4. Thyrohyoid

(Attach inferiorly to hyoid bone and depress hyoid bone)

Question 14

Suprahyoid Group of Muscles

Answer 14

1. Geniohyoid
2. Mylohyoid
3. Stylohyoid
4. Diagastric

(Attaches superiorly to hyoid bone and elevates hyoid)

Question 15

Hyoid Muscles Nerves

Answer 15

1. CN V (mandibular branch of trigeminal nerve)
2. CN VII (fascia)
3. C1 spinal nerve (runs w/ CN XII) and cervical plexus