TOPIC TOPIC
Musculoskeletal
L/1
System:
Vertebrae & Back L/1
Muscles
Musculoskeletal System: Vertebrae & Back Muscles
Include spinal physiology in this notes section so that you
can apply
RED=Important
BLUE= Clinical
T1/t2 images must found out what those are
Overview of the Back and Vertebral Column
Back
• Formed by the posterior part of the trunk (torso: is the part
of the body where limbs attach), the back is inferior to the
neck and superior to the buttox
• It includes the vertebral column and spinal cord (the cord
extends from the cranium to the tip of the coccyx)
• The column supports the bodies weight and disperses to
the pelvis and lower limbs
• The back is the region where head, neck and limbs are attached
Back consists of:
1. Skin and subcutaneous tissue
2. Muscles (superficial back muscles, and true back muscles)
3. Vertebral column: vertebrae, IV discs, and ligaments
4. Ribs: in thoracic region
5. Spinal cord and meninges
6. Nerves and vessels (blood vessels and spinal nerves)
Axial skeleton: skull, vertebral column and thoracic cage (sternum
and ribs)
Appendicular skeleton: shoulder, upper limbs and pelvic girdle
Vertebrae Column
• The vertebrae and IV disks collectively make up the
vertebral column also called spine or backbone
• The vertebral column extends from cranium to the apex of
the coccyx
• Because most of the weight is anterior to the column, the
column is supported posteriorly by numerous and
powerful muscles attached to strong levers
• The vertebral column is flexible because it consists of
many relatively small bones, called vertebrae (singular =
vertebra), that are separated by resilient IV discs
Vertebral column has 4 functions
,PROPERTY OF HIGHYIELD HUB DO NOT COPY
1. Protects the spinal cord and spinal nerves
2. Supports the weight of the body superior to the level of the pelvis
3. Provides partly rigid and flexible axis for the body and an extended base on which the head is placed and pivots
4. Plays important role in posture and locomotion (the movement from one place to another)
• In a typical adult, there are 33 vertebrae arranged in 5 regions:
o 7 cervical (Fxn of cervical is to support and move the head)
• 8 cervical nerves so the cervical spinal nerves exit above its vertebrae
• Example 1: so C1 exit between the Skull and C1
• Example 2: C2 spinal nerve will exit between C1-C2
o 12 thoracic (12 thoracic nerves) (Fxn of thoracic is to provide attachment of ribs)
• Thoracic nerve is named after the vertebrae below it
• For example T 1 will exit between T1 and T2
o 5 lumbar (5 lumbar nerves) (Fxn of lumbar is to bear the weight of entire upper body
• Lumbar nerve is named after vertebrae below it
• For example L1 spinal nerve is between L1 and L2
o 5 sacral (5 sacral nerves) Fxn of sacrum is that top half transmits weight to pelvic girdle, bottom half is non-weight bearing
o 4 coccyxgeal ( Fxn of coccyx: remnant of tail bone, helps with defecation)
Way to remember this: you eat breakfast at 7AM, lunch at 12PM, dinner at 5 PM and 5AM you eat a snack and then 4PM you have to exercise
your butt after all that eating
5 sacral vertebrae are fused in adults to form the sacrum, and after approximately age 30, the 4 coccygeal vertebrae fuse to form the coccyx.
• Significant motion occurs only between the 25 superior vertebrae.
• The vertebrae gradually become larger as the column descends to the sacrum and then become progressively smaller toward the apex of
the coccyx
The change in size is related to the fact that successive vertebrae bear increasing amounts of the body’s weight as the column descends. The
vertebrae reach maximum size immediately superior to the sacrum, which transfers the weight to the pelvic girdle at the sacro-iliac joints.
• The 25 cervical, thoracic, lumbar, and first sacral vertebrae also articulate at synovial zygapophysial (facet) joints), which facilitate and
control the vertebral column’s flexibility.
• Although the movement between two adjacent vertebrae is small, in aggregate the vertebrae and IV discs uniting them form a remarkably
flexible yet rigid column that protects the spinal cord it surrounds.
Typical Vertebrae (Structure & Function)
Think of tranverse process and spinous process as spokes on a boat help with movement*
, PROPERTY OF HIGHYIELD HUB DO NOT COPY
Important Joints
1. Zygapophysial Joint
- Bone-bone *there is little movement, very slight!
- Synovial facet joints between the articular processes of adjacent vertebrae
- Surrounded by a joint capsule
- Maintain alignment of the vertebral column by restricting movement
Movements of Vertebral Column
- Cervical à flexion and extension, forward and lateral and rotation
- Thoracicà rotation
- Lumbarà flexion/extension (forward and lateral)
2. Symphysis Joint
Formed by an intervertebral disc and adjacent vertebral bodies
From C2/C3 – L5/S1
In thoracic and lumbar regions IV discs form the inferior half of the anterior border of IV foramen
Assist in weight bearing
Acts as a fulcrum during flexion and extension