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Regional Anatomy Canadian College of Massage and Hydrotherapy Term 1

Joints of the Spine and Muscle of the Back

Agenda • • • •

Anterior intervertebral joints Posterior facet joints Craniovertebral joints Intrinsic muscles of the back

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Anterior Intervertebral Joints • Cartilaginous joint (symphyses) between adjacent vertebral bodies of the spine which are designed for strength and weight bearing. • Articular surfaces are covered with hyaline cartilage and are connected by a intervertebral disc (IVD) and ligaments. • The IVDs are the thickest in the lumbar spine; they are also thicker anteriorly (wedge shaped) in the cervical and lumbar regions creating the lordotic curve. • There is no IVD between C1 and C2 (no body). Lecture 5 Joints of the Spine and Back Muscles

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The IVDs consists of 2 major parts: •

•

Annulus Fibrosus: – Fibrous rim of IVD – Composed of concentric lamellae of fibrocartilage run obliquely from one vertebrae to another – Thinner posteriorly Nucleus Pulposus: – Central core of the IVD – More cartilaginous than fibrous, highly elastic – Located more posteriorly – Like a semifluid ball bearing during flex, ext, rot, lat.flex of the spine – Avascular (nourished by diffusion)

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Ligaments supporting the anterior intervertebral joints: • Anterior Longitudinal Ligament (ALL): – Strong broad fibrous band – Connects the bodies of the vertebrae and the IVD – Extends from anterior sacrum to the anterior tubercle of C1 and occipital bone anterior to the foramen magnum – Functions to stabilize joints and prevent hyperextension Lecture 5 Joints of the Spine and Back Muscles

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Ligaments supporting the anterior intervertebral joints • Posterior Longitudinal Ligament (PLL): – Narrow; somewhat weaker than the ALL – Runs along the posterior vertebral bodies inside the vertebral canal – Broadest superiorly where it’s continuous with the tectorial membrane, attaching to the internal aspect of the foramen magnum – Attaching in the spine from C2 to the sacrum – Prevents hyperflexion Lecture 5 Joints of the Spine and Back Muscles

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Ligaments supporting the posterior intervertebral joints • Ligamentum Flavum - also called the Yellow Ligament. It is a broad, elastic band that connects the laminae of adjacent vertebrae. It consists of mostly elastic fibers which appear yellow in color. – main function: preserve the normal curves of the spine and to straighten the spine after it has been flexed.

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Ligaments supporting the posterior intervertebral joints • Interspinous Ligament - This is a weak ligament that attaches adjacent SPs in the thoracic and lumbar regions • Supraspinous Ligament - This is a strong “cord-like” ligament that attaches the tip of the SPs from C7 to the spine of the sacrum. It is thicker and broader in the lumbar region. • Note: the interspinous and supraspinous ligaments thicken and widen in the cervical spine for attachement of muscles and is called the ligamentum nuchae. Lecture 5 Joints of the Spine and Back Muscles

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Ligaments supporting the posterior intervertebral joints • Intertransverse Ligament - thin ligament which connects adjacent TVP’s • Limits lateral flexion

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(a) Ligamentum Flavum (b) Interspinous Ligament (c) Supraspinous Ligament

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Posterior Facet Joints (Zygapophyseal Joints) • Plane type of synovial joints between the inferior articular facet of one vertebrae and the superior articular facet of the vertebrae below. • The facets are covered with hyaline cartilage and each one is surrounded by a thin, loose articular capsule which allows for a greater degree of motion. • These joints are designed for movement and bear only a minimum amount of weight. Lecture 5 Joints of the Spine and Back Muscles

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Posterior Facet Joints (Zygapophyseal Joints) • When these joints move together, they can produce flexion/extension/lateral flexion and rotation • The orientation of the facet change by region: – Cervical spine: horizontal plane (raise the roof) – Thoracic spine: coronal plane (wax on, wax off) – Lumbar spine: sagittal plane (choo choo train) Lecture 5 Joints of the Spine and Back Muscles

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Craniovertebral Joints Joint between the vertebrae and the skull (cranium) • Consists of: 1. Atlantooccipital 2. Atlantoaxial joints. • Both are synovial joints •

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Posterior Skull • Atlanto-occipital Joint: – Condyloid synovial joint between superior articular surface of C1 and the occipital condyles (right and left) – Allows for flexion and extension of the head (nodding) – This joint has a thin, loose capsule – The skull and C1 are connected by the anterior and posterior atlanto-occipital membranes – These membranes join the arches of C1 to the foramen magnum – C1 is also supported by the tectorial membrane which is a superior continuation of the PLL from the body of C2 to the internal surface of the occipital bone

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Posterior skull • Atlanto-axial Joint: – Consists of an articulation between the dens (C2) and C1 • Represents a pivot joint

– And between the superior articular facets of C2 (axis) and the inferior articular facets of C1(atlas) • Represents a plane joint • These joints allow for rotation of the skull

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Ligaments supporting the AtlantoAxial Joint • Transverse Ligament: – Strong band extending between the lateral masses of C1 – Secures the dens to the anterior arch of C1

• Superior/Inferior Bands: – Vertically oriented bands extending from the transverse ligament • Superiorly to the occipital bone • Inferiorly to the body (dens) of C2 NOTE: the transverse ligament and superior/inferior bands are together called the cruciform ligament Lecture 5 Joints of the Spine and Back Muscles

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Ligaments supporting the Atlantoaxial Joint • Alar Ligament: – Extends from the sides of the dens to the lateral margins of the foramen magnum – Checks rotation and side to side movements of the head

• Apical Ligament: – Extends from apex of dens to the anterior margin of the foramen magnum – Weaker ligament Lecture 5 Joints of the Spine and Back Muscles

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Apical Ligament Transverse Lig. Inferior Band

Superior Band

Alar Ligaments

CRUCIFORM LIGAMENT Lecture 5 Joints of the Spine and Back Muscles

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What type of view is this? Lecture 5 Joints of the Spine and Back Muscles

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Muscles of the Back •

The muscles of the back are divided into 3 groups:

1. Superficial (extrinsic) 2. Intermediate (extrinsic) 3. Deep (intrinsic) • •

Extrinsic muscles are concerned with limb movement and respiration Intrinsic muscles are concerned with movement of the spine Lecture 5 Joints of the Spine and Back Muscles

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Label diagram 1. 2. 3. 4. 5. 6. 7. 8.

Occiput Cervical spine (C/S) Thoracic spine (T/S) Lumbar spine (L/S) Sacrum Iliac crest Scapula Ribs

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Superficial Back Muscles (Extrinsic)

• Trapezius • Latissimus Dorsi • Levator Scapula • Rhomboids

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Intermediate Back Muscles (Extrinsic)

• Serratus Posterior Superior • Serratus Posterior Inferior

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Deep Back Muscles (Intrinsic) • The deep layer of back muscles is divided into 3 groups: 1. Superficial 2. Intermediate 3. Deep

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Deep Back Muscles (Intrinsic) Superficial muscles: • Consists of Splenii (bandage-like) muscles • Can be difficult to palpate; located deep to superior trapezius; between superior trapezius and SCM – Splenius capitis – Splenius cervicis Lecture 5 Joints of the Spine and Back Muscles

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Splenius Capitus ORIGIN: • inferior half of ligamentum nuchae • SPs of C7-T3 INSERTION: • Mastoid process • Lateral third of Superior Nuchal line INNERVATION: •

Dorsal division of inferior cervical nerves

ACTION: • Unilaterally: ipsilateral rotation and lateral flexion • Bilaterally: extension of head and neck COMMENTS: • Deep to trapezius • fibers run supralaterally Lecture 5 Joints of the Spine and Back Muscles

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Splenius Cervicis ORIGIN: • SPs of T3-T6 INSERTION: • TVPs of upper cervical vertebrae (C1-C4) INNERVATION: • Dorsal division of inferior cervical nerves ACTION: • Unilaterally: ipsilateral rotation and lateral flexion • Bilaterally: extension of head and neck COMMENTS: • deep to splenius capitis Lecture 5 Joints of the Spine and Back Muscles

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Deep Back Muscles (Intrinsic) Intermediate Muscles • Erector spinae muscles lie within a fascial compartment between posterior and anterior layers of the thoracolumbar fascia • Arranged in 3 vertical columns (from lateral to medial) – Iliocostalis (cervicis, thoracis, lumborum) – Longissimus (capitis, cervicis, thoracis) – Spinalis (capitis, cervicis, thoracis) Most of the erector spinae originate from a common • broad tendon which is attached to the posterior sacrum, iliac crest, and SPs of the lumbar spine and T11-T12 thoracic vertebrae

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ILIOCOSTALIS (lumborum, thoracis, cervicis) ORIGIN: • Common tendon (lumborum) • Posterior surface of ribs 1-12 (thoracis and cervicis) INSERTION: • TVP’s L1-L3, posterior surface of ribs 6-12 (lumborum) • posterior surface of ribs 1-6 (thoracis) • TVP’s of lower cervical vertebrae [C5 – C7] (cervicis) INNERVATION: • Dorsal primary division of spinal nerves ACTION: • Bilaterally: extend the vertebral column • Unilaterally: ipsilateral side flexion Lecture 5 Joints of the Spine and Back Muscles

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LONGISSIMUS (thoracis, cervicis, capitis) ORIGIN: • Common tendon (thoracis) • TVPs of upper T1-T5 (cervicis and capitis) INSERTION: • Ribs 4-12 and the TVP’s of T4-T12 (thoracis) • TVPs of C1-C7 (cervicis) • Mastoid process (capitis) INNERVATION: • Dorsal primary division of spinal nerves ACTION: • Bilaterally: extend the vertebral column • Unilaterally: ipsilateral side flexion Lecture 5 Joints of the Spine and Back Muscles

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SPINALIS (cervicis, thoracis) ORIGIN: • SPs T11-L2 (thoracis) • Ligamentum Nuchae • SP of C7 INSERTION: • SPs T1-T8 (thoracis) • SPs C2-C6 (cervicis) INNERVATION: • Dorsal primary division of spinal nerves ACTION: • Bilaterally: extend the vertebral column • Unilaterally: ipsilateral side flexion Lecture 5 Joints of the Spine and Back Muscles

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ILIOCOSTALIS

LONGISSIMUS

SPINALIS

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Deep Back Muscles (Intrinsic) Deep muscles Found deep to the erector spinae in the • laminar groove between the TVPs and SPs • Collectively known as the Transversospinal muscles: – – – – –

Semispinalis (thoracis, cervicis, capitis) Mulitifidus Rotatores Interspinalis Intertransversarii Lecture 5 Joints of the Spine and Back Muscles

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SEMISPINALIS MUSCLE ORIGIN: • TVPs of thoracic spine • Articular processes of C5-C7 INSERTION: • SPs of upper thoracic spine • SPs of C2-C7 • Superior nuchal line INNERVATION: • Dorsal primary division of spinal nerves ACTION: • Extend the spine and head COMMENTS: • Semispinalis = “half the spine” Lecture 5 Joints of the Spine and Back Muscles

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MULTIFIDUS MUSCLE ORIGIN: • Sacrum • TVPs of the vertebral column (C/S, T/S, L/S) INSERTION: • SPs of vertebral column (C/S, T/S, L/S) – Except C1 •

Span 2 – 4 vertebrae

INNERVATION: • Dorsal primary division of spinal nerves ACTION: • Extend the spine • Contralateral rotation COMMENTS: • only muscles with fibers that lie across the posterior sacrum Lecture 5 Joints of the Spine and Back Muscles

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ROTATORES ORIGIN: • Sacrum • TVPs of the vertebral column (C/S, T/S, L/S) INSERTION: • SPs of vertebral column (C/S, T/S, L/S) • Except C1 • Span 1-2 vertebrae INNERVATION: • Dorsal primary division of spinal nerves ACTION: • Extend the spine • Contralateral rotation COMMENTS: • only difference b/w rotatores and mulitifidi is: Rotatore mm. are shorter Lecture 5 Joints of the Spine and Back Muscles

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INTERSPINOUS MUSCLE ORIGIN: • SPs above (C/S to L/S) INSERTION: • SPs below INNERVATION: • Dorsal rami of spinal nerves ACTION: • assist with extension of the spine COMMENTS: • Well developed in the C/S Lecture 5 Joints of the Spine and Back Muscles

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INTERTRANSVERSARII MUSCLE ORIGIN: • TVP of vertebrae above (C/S to L/S) INSERTION: • TVP of vertebrae below INNERVATION: • Ventral rami of spinal nerves (&, in some cases, dorsal rami of spinal nerves) ACTION: • unilaterally: ipsilateral flexion • bilaterally: assist with extension of spine

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