"Neuroanatomy" 3: Muscles of the back and neck

Question 1

What is the name of the large dorsal ligament that supports the weight of the head?

Answer 1

Nuchal ligament

Question 2

Where does the nuchal ligament have its origin in the dog, horse, and ruminant?

Answer 2

Nuchal ligament origin

• Dog: Caudal aspect of C2 (axis)
• Horse, ruminant: Occiput (nuchal crest)

Question 3

In what common species is the nuchal ligament absent?

Answer 3

Cat, pig

Question 4

What ligament forms the caudal continuation of the nuchal ligament?

Answer 4

supraspinous ligament

Question 5

What are the names of the two parts of the nuchal ligament?

Answer 5

Funicular part, lamellar part

Question 6

What is the origin and insertion of the funicular part of the nuchal ligament in the dog?

Answer 6

Funicular part of the nuchal ligament in the dog (paired)

• Origin: Caudal aspect of C2 (axis)
• Inserion: Spinous process of 1st thoracic vertebra

Question 7

Where does the lamellar part of the nuchal ligament extend in horses and cattle?

Answer 7

From funicular part in a sheet-like manner to C2-C7 (horse) and C2-C4 (cattle)

Question 8

The superficial layer of the thoracic muscle group is innervated by which nerve(s)?

Answer 8

Innervated by ventral branches of the spinal nerves

Question 9

The deep layer of the thoracic muscle group is innervated by which nerve(s)?

Answer 9

Innervated by dorsal branches of the spinal nerves

Question 10

As a group, what is the term for the muscles that are found dorsal to the transverse process?

Answer 10

Epaxial

Question 11

As a group, what is the term for the muscles that are found ventral to the transverse process?

Answer 11

hypaxial

Question 12

What are the three main groups of the epaxial muscles (four in the horse)?

Answer 12

Lateral

• Iliocostalis System
  
  • Thoracic and lumbar parts
• Longissimus System
  
  • Cervical, thoracic and lumbar parts

Medial (blended in the dog so one group, distinct in horses)

• Spinalis System
  
  • Between spinous process
• Transversospinalis System
  
  • From spinous process to the transverse process of adjacent vertebrae

= Erector spinae muscles

• carnivores

Question 13

What is the origin, insertion, and action of Iliocostalis lumborum?

To what muscle system does it belong?

Answer 13

Origin: Wing of ilium, iliac crest, intermuscular septa

Insertion: Ribs 13-10 (caudal border)

Action: Unilaterally = lateral flexion of vertebral column; Bilaterally = fixation of vertebral column (as a unit in the system)

Group: Iliocostalis System

Question 14

What is the origin, insertion, and action of Iliocostalis thoracis?

To what muscle system does it belong?

Answer 14

Origin: Ribs 12-2 (cranial border)

Insertion: Transverse process of C7

Action: Unilaterally = lateral flexion of vertebral column; Bilaterally = fixation of vertebral column (as a unit in the system)

Group: Iliocostalis System

Question 15

What is the other name for longissimus lumborum et thoracis?

Answer 15

Longissimus lumborum et thoracis = Longissimus dorsi

Question 16

What is the origin and fibre direction of longissimus lumborum et thoracis (longissimus dorsi)?

Answer 16

Origin: Iliac crest, ventral surface of ilium, via aponeurosis from the supraspinous ligament and lateral to the spinous processes of lumbar and thoracic vertebrae

Fibre direction: Fibres run craniolaterally

Question 17

What is the insertion of longissimus lumborum et thoracis (longissimus dorsi)?

Answer 17

Longissimus lumborum et thoracis insertion:

• Thoracic vertebrae
  
  • Accessory processes of T13 –T6
  • Caudal ends of transverse processes of T5-T1
• Ribs
  
  • 13 – 6 medial to iliocostalis
  • 5 –1 costal tubercles

Question 18

What is the action of longissimus lumborum et thoracis?

Answer 18

extension of the vertebral column

Question 19

What is the origin, insertion, and action of Longissimus cervicis? To what system does it belong?

Answer 19

Longissimus cervicis

Origin: transverse processes of the first 5 thoracic vertebrae (T1-T5) - cranial continuity of thoracic part

Insertion: Transverse processes C7-C4

Action: Bilaterally = Extension of the neck; Unilaterally = turns head and raises neck obliquely

System: Longissimus System

Question 20

What is the origin, insertion, and action of longissimus capitis? To what system does it belong?

Answer 20

Longissimus capitis

Origin: T3-T1

Insertion: mastoid process of temporal bone - medial to longissimus cervicis

Action: Bilaterally = Extension of atlanto-occiptialjoint; fixation of this joint; Unilaterally = rotation of the atlantoaxialjoint

System: Longissimus System

Question 21

What two muscles make up the spinalis system within the medial system?

Answer 21

Spinalis thoracis & spinalis cervicis

Question 22

What muscles make up the transversospinalis system within the medial system?

Answer 22

• Semispinalis thoracis
• Semispinalis capitis (biventer; complexus)
• Multifidus lumborumet thoracis, cervicis (+ Sacrocaudalis dorsalis medialis)
• Rotatores longi et breves

This system includes the spinalis system in the dog as they are difficult to differentiate

Question 23

What muscles make up the interspinalis system within the medial system?

Answer 23

• Interspinales lumborum, thoracis, cervicis
• Intertransversariicaudalis, lumborumet thoracis, cervicis

Question 24

*What is the Latin term for the combination of the spinalis cervicis, spinalis thoracis, and semispinalis combined musculature in the carnivore model (e.g. dog)?

Answer 24

Spinalis et Semispinalis thoracis et cervicis

Question 25

What is the origin and insertion of **semispinalis thoracis**?

Answer 25

Semispinalis thoracis **Origin**: Deep fascia of longissimus thoracis, mamillary processes of thoracic vertebrae; spinous process of thoracic vertebrae T11-T7 **Insertion**: Spinous processes of T6-C6

Question 26

What is the origin and insertion of **spinalis thoracis**? In carnivores, this muscle is closely related to and difficult to separate from what other muscle?

Answer 26

Spinalis thoracis **Origin**: spinous processes of thoracic and cervical vertebrae **Insertion**: extends forward as spinalis cervicis (T1) closely related and difficult to separate in carnivores: **Semispinalis thoracis**

Question 27

What is the origin and insertion of **Spinalis cervicis?**

Answer 27

Spinalis cervicis **Origin**: Cranial border of T1 **Insertion**: Spinous processes of C5 to C2

Question 28

What is the origin and insertion of **Semispinalis cervicis**?

Answer 28

Semispinalis cervicis **Origin**: continuation of semispinalis thoracis **Insertion**: fused medially with spinalis cervicis

Question 29

What is the action of the combined Spinalis et Semispinalis thoracis et cervicis?

Answer 29

Spinalis et Semispinalis thoracis et cervicis **Action**: Bilaterally = Fixes the vertebral column. Raise (elevate) the neck. Unilaterally = flex the back and neck

Question 30

What are the origin, insertion, action, and two parts of the **Semispinalis capitis** muscle?

Answer 30

Continuation of Spinalis et Semispinalis thoracis et cervicis **Origin**: Spinocostotransverse fascia,transverse process of T5-C7, articular processes of C2-C7 **Insertion**: Occipital Bone (Nuchal ligament runs between the left and right semispinalis capitis) **Parts**: Biventer cervicis (dorsal and medial) and Complexus (ventral and lateral) **Action**: Bilaterally raises the head; Unilaterally flexes thehead and neck

Question 31

What is the origin, insertion, and action of **multifidus lumborum**?

Answer 31

Multifidus lumborum **Origin**: Sacrum **Insertion**: Spinous process vertebrae ending at T8 or T9 (divided into 11 individual portions) **Action**: working as a whole, mulitifidus fixes the vertebral column

Question 32

What is the origin and insertion of **multifidus thoracis**? Into the tail what muscle does it extens into?

Answer 32

Multifidus thoracis **Origin**: Mamillary and transverse processes of T11–T3 **Insertion**: Spinous process of T8 – C7 **Extends into:** Sacrocaudalis dorsalis medialis (= coccygeus)

Question 33

What is the origin, insertion, and action of the **multifidus cervicis**?

Answer 33

Multifidus cervicis **Origin**: Articular process of T2 **Insertion**: Spinous process of axis (C2) **Action**: Elevates the neck

Question 34

Where do the **interspinales lumborum, thoracis et cervicis** run?

Answer 34

Run between spinous processes of adjacent vertebrae

Question 35

What is the origin and insertion of the **capitis** part of the **splenius** muscle?

Answer 35

Splenius (capitis) **Origin**: Spinocostotransverse fascia, nuchal ligament **Insertion**: Occipital bone + Mastoid process (horse)

Question 36

What is the origin and insertion of the **cervicis** part of the **splenius** muscle? What animals is it absent in?

Answer 36

**cervicis** part of the **splenius** muscle **Origin**: continuation of capitis **Insertion**: Transverse process of C3-C5 **Absent in**: carnivores

Question 37

What is the action of the **splenius** muscle?

Answer 37

Extend and raise head and neck. Laterally flex head and neck on one side

Question 38

What are the names, origins, insertions, and action of the parts of the **scalenus** muscle in the dog?

Answer 38

Scalenus * **dorsalis** (superficial) * **Origin**: ribs 7-9, 3, 1 * **Insertion**: transverse processes of C3-C5 * **medius** (deep) * **Origin:** dorsal portion of 1st rib * **Insertion**: transverse processes of C6, C7 **Action**: Fixes the neck; Flexes the neck; Laterally flexes the neck on one side; Superficial part is also a muscle of inspiration

Question 39

What are the three parts of the **scalenus** muscle that are present in some species? Which species have all parts present, and what parts are horses and carnivores missing?

Answer 39

1. Ventralis 2. Medius 3. Dorsalis Variable between species * All parts present in **pigs, ruminants** * **Dorsal** absent in **horses** * **Ventral** absent in **carnivore**

Question 40

What is the origin, insertion, and action of the **longus colli**?

Answer 40

longus colli **Origin**: T6 **Insertion**: C1 (atlas) **Action**: Flexes the neck or draws neck downwards

Question 41

What is the origin, insertion, and action of the **longus capitus**?

Answer 41

Longus capitis (Lies lateral to Longus colli) **Origin**: transverse processes of C6 –C2 **Insertion**: Base of skull **Action**: Flexes atlanto-occipital joint; Draws neck downwards (bilaterally) (= flexion); and head sideways (unilaterally) (= lateral flexion)

Question 42

What are the names of the three parts of the rectus capitus muscle?

Answer 42

Rectus capitis 1. ventralis 2. lateralis 3. dorsalis (three distinct parts)

Question 43

What is the origin and insertion of the **rectus capitis ventralis**?

Answer 43

Rectus capitis ventralis **Origin**: C1 (atlas) (ventral arch) **Insertion**: Basioccipital bone of skull

Question 44

What is the origin, insertion, and action of the **rectus capitis lateralis** muscle?

Answer 44

Rectus capitis lateralis **Origin**: C1 (atlas: ventral surface of caudal half of the wing) **Insertion**: paracondylarprocess of the skull **Action**: Flexion at atlanto-occipital joint

Question 45

What is the origin, insertion, and action of the rectus capitis dorsalis muscle? How many parts does it have?

Answer 45

rectus capitis dorsalis **Origin**: C1 and C2 **Insertion**: medial aspect of occipital bone **Action**: extension of atlanto-occipital joint **Parts**: three

Question 46

What is the origin, insertion, and action of the **obliquus capitis caudalis** muscle?

Answer 46

Obliquus capitis caudalis **Origin**: spinous process of C2 (axis) **Insertion**: border of wing of C1 (atlas) **Action**: Unilaterally –rotation of C1 (atlas) (& head); Bilaterally –fixation of atlanto-axial joint.

Question 47

What is the origin, insertion, and action of the **obliquus capitis cranialis** muscle?

Answer 47

obliquus capitis cranialis **Origin**: ventrolateral surface and border of wing of C1 (atlas) **Insertion**: Mastoid process of temporal bone and then onto to nuchal line **Action**: Extension of atlanto-axial joint.