Anatomy 1 - Back, spine and spinal cord

Question 1

What are the functions of the back ?

Answer 1

• Maintenance of posture
• Movements of limbs & trunk

Question 2

Label the surface anatomy of the back indicated

Answer 2

Question 3

Another pic to label the some of the other surface anatomy of the back indicated

Answer 3

Question 4

What is the appendicular skeleton ?

Answer 4

6 regions; shoulder girdle/ pectoral, arm, hand, pelvic girdle, leg and foot

Question 5

Where do the extrinsic back muscles attach between and what is their function ?

Answer 5

• The extrinsic back muscles attach the back to the pectoral girdle (the set of bones in the appendicular skeleton which connects to the arm on each side)
• Their function is to move the upper limb

Question 6

What are the 4 extrinsic back muscles?

Answer 6

1. Levator scapulae
2. Rhomboids
3. Trapezius
4. Latissimus dorsi

Look ruaridh tasha left (LRTL)

Question 7

Label the extrinsic back muscles indicated

Answer 7

Question 8

Where are the intrinsic back muscles located and what is their function ?

Answer 8

• These muscles are located entirely within the back (their attachments are all within the back region)
• Their function is to maintain back posture & move the spine

Question 9

What are the 2 main groups of intrinsic back muscles ?

Answer 9

1. Erector spinae (superficial)
2. Transversospinalis (deep)

Question 10

Where are the erector spinae muscles specifically located and describe their attachments and what is the overall function of the erector spinae ?

Answer 10

There is 3 groups of erector spinae muscles (dont need to know exact details of each) - they are located lateral to the spine

Inferiorly each of the 3 groups of erector spinae have a common tendon which attaches to the sarcum & iliac crests

Superiorly each of the 3 groups individually attach (via tendons) to either:

1. A rib (between rib angles and tubercles)
2. A trasverse process of a vertebra
3. A spinous process of a vertebra

These muscles straighten and rotate the back

Question 11

Where are the transversospinalis muscles located and describe their attachements

Answer 11

They are located within the grooves between the transverse & spinous processes

Individual muscle fibres attach between:

1. A vertebra & the skull
2. A vertebra & a rib
3. Between 2 vertebra
4. The sacrum & a vertebra

Question 12

What is the function of the transversospinalis muscles ?

Answer 12

Rotation and extension of the vertebral column

Question 13

Describe the nerve supply of the intrinsic back muscles

Answer 13

Nerve supply is segmental as per dermatome/ myotome pattern

The posterior rami of spinal nerves supply the muscles & supply sensation to the back

Question 14

Label the following axial image of the back

Answer 14

Question 15

Describe the different movements of the spine and the corresponding muscles involved

Answer 15

• The erector spinae & transversospinalis both help to maintain posture & support the spine
• The erector spinae muscles when acting bilaterally (remember there is a R&L bundle) extends the vertebral column (going from hunched to straight or more extended)
• When the erector spinae muscles act unilaterally (i.e. either the R or L contracts not both) they act to flex the vertebral column laterally
• The transversospinalis muscles main actions is rotation & extension of the vertebral column
• Flexion of the spine is carried out by the psoas major & the rectus abdominus

Note in the pic Flexion and extension are shown starting from a extended or flexed position

Question 16

How many vertebrae are there ?

Answer 16

33 vertebrae in total:

• 7 cervical (C1-C7)
• 12 thoracic (T1-T12
• 5 lumbar (L1-L5)
• 5 sacral (fused to form 1 sacrum)
• 4 coccygeal (fused to form 1 coccyx)

Question 17

How do vertebrae change in shape going from superior to inferior ?

Answer 17

Initially become larger as they bear more weight and then become smaller again once weight has transferred to hip bones

Question 18

What are the functions of vertebrae ?

Answer 18

1. support head and trunk when upright
2. protect the spinal cord (& spinal nerves)
3. allow movements of the head on the neck & movements of the trunk

Question 19

What are the 4 main curvatures of the spine ?

Answer 19

1. Cervical lordosis
2. Thoracic kyphosis
3. Lumbar lordosis
4. Sacral kyphosis

Question 20

Label the key parts of a typical vertebrae

Answer 20

Question 21

Label the structures indicated and describe them

Answer 21

Question 22

Intervertebral discs exist between most of the vertebrae in the spinal column what vertebrae do they not exist between?

Answer 22

C1-2 & the fused sacrum/coccyx

Question 23

What is the function of intervertebral discs ?

Answer 23

• They act as weight bearing shock absorbers between each vertebrae
• They also allow a small degree of movement - these small amounts of movement at each disc summate & allow for larger range of movement

Question 24

Describe the structure of an intervertebral disc

Answer 24

1. Has an outer fibrous ring called the annulus fibrosus - this provides strong bond
2. Has an inner soft pulp called the nucleus pulposus - it is up to 90% water in newborns and provides flexibility and protection

Question 25

What are the 5 main ligaments involved in vertebrae and describe their attachments and function

Answer 25

1. Ligamentum flavum - it connects adjacent laminae vertically (i.e. conencts a laminae from a level above to the one below)
2. Posterior longitudinal ligament - situated in the vertebral canal, extending along the posterior aspect of the bodies of the vertebrae - prevents over flexion of the spine
3. Anterior longitudinal ligament - runs down the anterior surface of the spine, it transverses all of the vertebral bodies & intervertberal discs - it prevents over-extnesion of the spine
4. Supraspinous ligament - connects the tips of spinous processes vertically (same idea as the ligamentum flavum) (I stress just the tips)
5. Interspinous ligament - connects superior and inferior surfaces of adjacent spinous processes (but not the tips)

Question 26

Label the ligaments of the spine indicated

Answer 26

Question 27

Label the ligaments of the spine indicated

Answer 27

Question 28

What are the common features typical of a cervical vertebrae ?

Answer 28

Common typical features:

1. transverse foramen
2. bifid spinous process
3. triangular shaped vertebral foramen (this is the big foramen)

Question 29

What is special about each of the following cervical vertebrae:

1. C1
2. C2
3. C7

Answer 29

C1 called the Atlas:

• It does not have a body or spinous process, it has a posterior arch and an anterior arch instead

C2 called the Axis:

• has an odontoid process which projects superiorly from the vertebral body of C2

C7:

• Vertebrae prominens - the first palpable spinous process in ~70% of people

Question 30

Describe the atlanto-occipital joints and what movements do these joints allow for ?

Answer 30

• These are the joints between the occipital condyles & the superior articular facets of the atlas vertebrae
• These joints allow for flexion, extension and a little lateral flexion & rotation

Question 31

Label the structure of the cervical spine indicated

Answer 31

Question 32

Describe the Atlanto-axial Joints and the movements they allow for

Answer 32

They are formed by 3 articulations:

• 2 between the inferior articular facets of the atlas atlas and the superior articular facets of the axis
• 1 between the anterior arch of the atlas & the odontoid process of thr axis

The main movement facilitated by this joint is rotation

Question 33

Label the structures of the sacrum indicated

Answer 33

Question 34

Describe the key anatomical points of the spinal cord

Answer 34

It begins at the foramen magnum, it is continuous with the medulla

It ends around vertebral level L1/2 in a structre called the conus medullaris

Cauda equina then forms from all the spinal nerve roots from L2 to C0 that have to descend to their numbered vertebrae where their spinal nerve is located within the intervertebral foramen