Trunk Dr. Jason Peeler PhD, Certified Athletic Therapist

Objectives

1.Name the main functions of the vertebral column and the body movements that occur at specific parts of the column. 2.Describe the components of a vertebrae and the specific distinguishing features of cervical, thoracic, lumbar and sacral vertebrae. 3.Describe the joints of the vertebral column, and the main structural components that comprise each. 4.Identify the major muscle groups responsible for motion of the spine.

Function of the Vertebral Column

• Support

– upright posture

• Protection

– Spinal cord

• Movement

– flex/ext, side flex, rotation

Vertebral Column

• Comprised of 33 individual Vertebrae

– 7 cervical

– 12 Thoracic

– 5 Lumbar

– 5 Sacral

– 5 Coccyx

Postural influences

• Back extensors contract eccentrically most of the time to keep us upright.

• Abdominal muscles are more quiescent.

• Low back pain is often a result of poor abdominal strength rather than the back muscles.

Abnormal Curvatures

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http://www.healthcentral.com/ency/408/ImagePages/9583.html

Vertebrae - General Structure

• Body – Anterior component of the vertebrae

– Dense bone square in shape

– Serves to bear body weight

• Vertebral Arch – The bony process which comprise the

posterior portion of the vertebrae form a closed circle or arch which surrounds and protects the spinal cord

• Pedicles – Extend posterior from both sides of the

body

• Lamina – Complete the posterior margins of the arch

and join

Vertebrae - General Structure

• Spinous Processes – Bony processes which extend posteriorly

from the junction of the two lamina

• Transverse Processes – Bony processes which extend sideways

from the junction between the pedicle and lamina

– Act as “handle bars” when muscles attach to them and create movement

• Vertebral Foramen – The opening created by the vertebral arch

– With multiple vertebrae it is referred to as the “Vertebral Canal”

Intervertebral Foramen

• Between the body and posterior elements on will be a vertebral notch extending the width of the vertebrae

• When two vertebrae are stacked one on the other, the notch now becomes the intervertebral foramen

• The peripheral nerve root exits from the spinal cord through this foramen

Regional Differences

Special Features of Cervical Region • Small vertebral bodies • Bifid Spinous processes (except C7)

• Foramina in transverse process which accommodates vertebral arteries

• Large vertebral foramen (canal) that accommodates the large brachial plexus of nerves

• Articular processes orientated in horizontal plane which facilitates rotation.

• Uniqueness of C1 & C2 vertebrae • C7 (Vertebra Prominens) - has

the longest spinous process of the cervical vertebrae (not bifid)

Atlas (C1) • Supports the skull

• Does not have a vertebral body

• Has anterior and posterior arches

• Tubercles in the vertebral foramen for transverse atlantal ligament attachment

• Superior articular facets articulate with the occipital Condyle of the skull (facilitates nodding your head)

Axis (C2) • Characterized by the Dens

(Odontoid Process).

• The Dens projects through the vertebral foramen of the atlas to form a pivot for rotation.

• Held in place by the transverse atlantal ligament.

• Together with C1, creates the Atlanto/Axial Joint (junction of C1/C2).

Special Features of Thoracic Vertebrae

• Long pointed spinous vertebrae that overlap each other like shingles on a roof.

• Superior and inferior demifacets on the vertebral body (site of rib attachment).

• Facets on transverse processes also for rib attachment

• Superior and inferior articular facets face in frontal plane and facilitate side flexion.

Special Features of Lumbar Vertebrae

• Large and Heavy vertebral bodies (for weightbearing)

• Large, thick, Square cut spinous process - projects straight back

• “Grasping” articular facets face in sagittal plane - allow flexion and extension movements.

Sacrum • Superior end has a “sacral

promentory” which articulates the body of L5

• Posterior surface is rough for muscle and ligament attachment

• Median crest analagous to spinous processes

• Lateral crests analagous to transverse processes

• Sacral foramina analagous to intervertebral foramen

Coccyx

• Small structure of fused bones

• Attached to the distal end of the sacrum

Joints of Vertebral Column

Segmental Motion of Spine

• Functional unit of the spine is called a motion Segment

• Consists of 2 adjacent vertebrae & soft tissue.

• Results in segmental motion

• Can lead to areas of hyper / hypo mobility

• Anterior portion – Stability

• Posterior portion - Mobility

Anterior Portion - Stability

• Intervertebral Joints: – bear compressive loads

– become progressively larger as you move towards pelvis

– Tremendous ligamentous support (6 in #)

Intervertebral Disc – Structure

• Has a laminated fibrous outer ring (annulus fibrosis

• Inner core of gel like fluid ( Nucleus pulposis)

• Function – Shock Absorbtion – Allows movement

(cartilagenous/amphiarthrotic)

– Gives height to the vertebral column

Vertebral Ligaments

Posterior Portion - Mobility

• Movement controlled by

Facet Joints (Zygoapophyseal)

• Determined by region & orientation of superior & inferior articular processes of adjacent vertebral segments.

Zygoapophyseal (Facet) Joints

• The transverse process will have articular processes which project inferiorly and superiorly

• They are flat surfaces and thus referred to as facet surface

• Each vertebrae will articulate with the one above and below via the superior and inferior articular processes

Facet Joint Orientation and Movement of Spine Lumbar Vertebrae

Function:

ROM in Spine

C spine - Built for mobility - Flex/ext, rotation,

lat flex T spine - Built for stability - Rotation, lat

flexion - Little flex/ext

L spine - Built to flex/ext - Some lat flex - Little rotation

Atlanto-Occipital Joint (C1/C0) • Joint Type: Synovial: Condyloid joint.

• Articular Surfaces:

– Occipital condyles of the skull

– Facets on superior surface of lateral masses of atlas vertebra.

• Motion Possible: Flexion / extension (nodding head “Yes”), slight side flexion.

Atlanto-Axial Joints (C1/C2) • Joint Type: Synovial: Pivot (lateral) & plane (median) joints

• Articular Surfaces:

- Facet on posterior aspect of anterior arch of the atlas

- Facet on anterior aspect of dens of the axis.

• Motion Possible: Rotation (shaking head “No”).

- Accounts for 40% of cervical flexion/60% of cervical rotation

• No inter-vertebral disc between C1/C2

Spinal Stability & Mobility

“Back” muscles function to: 1. protect the spine

2. transfers loads from head and trunk to pelvis

3. permit motion in all 3 planes

Two Main Grouping:

Intrinsic Muscles: - Small muscles that stabilize spine & maintain posture

- Control / guide precise movements between adjacent segments

Extrinsic Muscles: - Large muscles that power global movements of the back

Back Muscles

Divided into 2 groups:

• Superficial: 1. Trapezius

2. Latissimus dorsi

• Deep 1. Levator Scapulae

2. Rhomboids – Major & Minor

3. Erector Spinae

4. Quadratus lumborum

5. Iliopsoas

Trapezius: • GD: Large, superficial, triangular muscle of the upper back and neck region. • Large number of functions, depending on location & direction:

1. Upper fibers: • scapular elevation/rotation ("shrug“) • Neck Side Flexion (unilateral) or Extension (bilateral)

2. Middle fibers:

• scapular retraction

3. Lower fibers: • pull medial end of scapular spine down. • (rotates glenoid fossa upward) • important to facilitate raising the arm over head

Latissimus Dorsi GD: Large, superficial, broad

muscle of back; Diamond shaped Forms posterior wall of

axilla(armpit) Arises from lower back and

inserts prox. humerus Functions:

• Shoulder extension • Adduction • Medial rotation • Composite action: swimming,

paddling

Levator Scapulae:

• Deep to Trapezius

• Functions to elevate scapula

Rhomboid Muscles

• Deep to Trapezius

– from vertebral column to scapula

– run obliquely down and laterally

• Functions to retract scapula

ERECTOR SPINAE MUSCLE GROUP • Large column of

muscle on either side of the vertebral column.

• Often described as a single muscle

• Comprised of three muscles

①

QUADRATUS LUMBORUM • Square muscles on either side of the lumbar spine. • Powers lateral flexion of the lumbar spine. • Stabilizes the twelfth rib against the action of the

diaphragm during inspiration

PSOAS MAJOR AND ILIACUS (ILIOPSOAS)

• The Psoas major and the Iliacus share a common tendon therefore the term Iliopsoas.

• These muscles are deep to the abdominal contents adjacent to the vertebral column and within the pelvic cavity.

ABDOMINAL MUSCLES

• 2 MAIN GROUPS : ANTERIOR ABDOMINAL WALL

- In front of vertebral column (FLEXION) POSTERIOR ABDOMINAL WALL

- Behind vertebral column (EXTENSION)

ANTERIOR ABDOMINAL MUSCLES

• The abdominal muscles form the anterolateral wall of the abdominal cavity.

• Unlike the thoracic cavity, there is no bony protection.

• The muscles serve a protective function; cause movement of the trunk; and allow for changes in size of the cavity.

• The abdominal muscles are a lamination of four muscles each covered by two layers of fascia.

Anterior Abdominal Wall

• The Anterior abdominal wall is comprised of three pairs of muscles that run transversely and one pair that runs in a proximal/distally. The three pair of transverse muscles from superficial to deep are:

• External Oblique

• Internal Oblique

• Transverse Abdominus

• Rectus Abdominus

EXTERNAL OBLIQUE

• Outermost muscle fibers run from back to front in a downward ("Hands In Pocket") direction.

INTERNAL OBLIQUE • LOCATED DEEP TO EXTERNAL OBLIQUE • FIBRES PERPENDICULAR TO EXTERNAL OBLIQUES (UP AND MEDIALLY) • FROM PELVIS TO RIBS • USUALLY THICKEST OF THE THREE MUSCLES • Called the “same side rotators”

TRANSVERSUS ABDOMINUS (TRANSVERSE)

• DEEPEST AND THINNEST OF ABDOMINALS, FIBRES PARALLEL TO FLOOR; RUNS FROM BOTH RIBS AND PELVIS TO CENTRE

Function of Transverse Abdominus

Rectus Abdominus The fourth, the most superficial pair of muscles run up

on either side of the Mid-line of the abdomen and are called the Rectus Abdominus Muscles. The rectus abdominus are classically identified by their bulging segments. The segments are created by connective tissue divisions called Tendinous Intersections (inscriptions).

ACTIONS AND FUNCTIONS OF ABDOMINALS

• ACT LIKE A DYNAMIC CORSET

• PROTECT ABDOMINAL CONTENTS

• COMPRESS CONTENTS TO RAISE ABDOMINAL PRESSURE

• ASSIST WITH EXPULSIVE ACTS

• CONTRACT VIGOROUSLY AGAINST BLOWS TO THE ABDOMEN

• FORCED EXPIRATION (FORCE LIVER AGAINST DIAPHRAGM)

Functions of Abdominal Muscles

• TRUNK/HIP FLEXION AGAINST GRAVITY (SIT-UPS)

• LUMBAR STABILITY

• PELVIC STABILIZATION

MOVEMENTS of ABDOMINALS

• ROTATION (OR SIDE BENDING) – contraction of External Oblique on

one side and – internal oblique on the opposite

side

– Example if rotating to the left, the left internal oblique and the right external oblique will contract together to perform this action

What have we learned today?

1.What are the main functions of the vertebral column. 2. What movements occur in each region/ Why? 3. What are the main components of a typical vertebrae. 4. Be able to distinguish between cervical, thoracic, lumbar and sacral vertebrae. 5. Describe main joints of the vertebral column, and their structural composition. 6. What are the main muscle groups of the spine (back), and abdominal region. Distinguish between their functions.