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Myology

Bony Anatomy of the Vertebral

Column

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Gross Anatomy

Osteology of the Spine

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Spinal Anatomy• Spine is made up of 24 small bones (vertebrae) that are

stacked on top of each other to create the spinal column.• Between each vertebra is a soft, gel-like intervertebral disc

that helps absorb pressure and keeps the bones from rubbing against each other.

• Each vertebra is held to the others by groups of ligaments (connect bones to bones)

• Tendons connect muscles to bones. There are also tendons that fasten muscles to the vertebrae.

• The spinal column also has real joints (just like the knee or elbow or any other joints) called facet joints. The facet joints link the vertebrae together and give them the flexibility to move against each other.

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• The spine itself has three main segments:

– Cervical spine

– Thoracic spine– Lumbar spine

• The cervical is the upper part of the spine, made up of seven vertebrae.

• The thoracic is the center portion of the spine, consisting of 12 vertebrae.

• The lower portion of the spine is called the lumbar spine, consisting of five vertebrae.

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Intervertebral Discs

• Between adjacent vertebrae absorbs vertical shock• Permit various movements of the vertebral column• Fibrocartilagenous ring (Annulus fibrosis) with a pulpy center

(Nucleus pulposus)

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Normal Curves of the Vertebral Column• Curves in vertebral column function to:

– Increase strength– Maintain balance in the upright position– Absorb shock during walking and running– Protect spinal column from fracture

• Primary curves– Thoracic and sacral are formed during fetal development

• Secondary curves– Cervical is formed when infant raises head at 4 months– Lumbar forms when infant sits up & begins to walk at 1

year

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Anatomy of a typical vertebrae• Body:

– Large, round portion of bone– Superior and inferior surfaces are roughened for attachment of

intervertebral disc.• Neural Arch: attached to the vertebral body consists of several

parts– Pedicle: two thick processes which project posteriorly from the

body, uniting with the laminae.• Vertebral notches: upper and lower indentations on the

pedical• Intervertebral Foramen: Opening formed between adjacent

vertebrae (when stacked) for the exiting of a single spinal nerve.

– Laminae: flat pieces of bone forming the posterior portion of the vertebral arch

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– Vertebral Foramen: space between the vertebral arch and body containing the spinal cord, adipose, and areolar connective tissue

– Vertebral (Spinal) Canal: formed by all vertebral foramina of all vertebrae together.

• Processes: a total of 7 processes;– Transverse process (2): extends laterally from the lamina

pedicle junction; functions for muscle attachment– Spinous process (1): extends posteriorly from the junction

of the lamina; functions for muscle attachment– Superior articulating process (2): articular processes that

form joints with the vertebrae above– Inferior articulating process (2): articular processes that

form joints with the vertebrae below• Facet: the articulating surface of the articular process.

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Cervical Spine• The cervical spine is made up of the first seven vertebrae in

the spine. • It starts just below the skull and ends just above the thoracic

spine. • The cervical spine has a lordotic curve (a backward C-shape) • The cervical spine is much more mobile than both of the other

spinal regions.• Unlike the rest of the spine, there are special openings in each

transverse process in the vertebra in the cervical spine for the arteries supplying the brain.

• All of the cervical vertebrae with the exception of C1 and C7 have a bifid spinous process.

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• Atypical Vertebrae: C1, C2, and C7• Two vertebrae in the cervical spine, the atlas and the axis, differ

from the other vertebrae because they are designed specifically for rotation. The 7th cervical vertebrae differs as it is marked by its large spinous process.

• First cervical vertebra (Atlas): – Sits between the skull and the rest of spine. – Arches: atlas does not have a vertebral body, but does have a

thick forward (anterior) arch and a thin back (posterior) arch. – Spinous process: atlas has no spinous process– Lateral masses: in place of a vertebral body, the atlas has two

lateral masses which support the skull.• Superior articular facets: located on superior aspect of the

facet articulating with the occipital condyles. This joint allows for movement as in nodding the head “yes”

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• Second cervical vertebra (Axis):

– Odontoid process: bony projection projecting upward from the body through the front of the ring of the atlas.

• Allows rotation to the left and right

• 7th Cervical vertebra (Vertebra prominens):

– C7 has a large non-bifid spinous process

16Atlas and Axis

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C3 through C6 Vertebrae

• The remaining vertebrae (C3-C7) have the features of a more typical vertebrae (bodies, spinous processes, transverse processes, lamina, and pedicles).

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Thoracic Spine• The thoracic spine is made up of the middle 12 vertebra of the

spine. • These vertebrae connect to the ribs and form part of the back

wall of the thorax (the ribcage area between the neck and the diaphragm).

• The thoracic spine has very narrow, thin intervertebral discs, so there is much less movement allowed between vertebrae than in the lumbar or cervical parts of the spine.

• The thoracic spine's curve is called kyphotic because of its shape, which is a regular "C"-shaped curve with the opening of the "C" in the front.

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• Body:

– Larger and stronger bodies than in the cervical spine

• Processes:

– Longer transverse & spinous processes

– Spinous processes are directed more inferior, so that they overlap

• Facets or demifacets on body: articulating surfaces for the articulation with the head of rib

– Facet: full indentation on the body of the thoracic vertebrae

– Demifacet: half facet on the body of a thoracic vertebrae

• Facets on transverse processes (T1-T10): for articulation with the tubercle of rib

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Lumbar Spine

• The lowest part of the spine

• This area has five vertebrae.

• Strongest & largest vertebrae

• Short thick spinous & transverse processes

– Serves as attachment points for back musculature

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Sacrum• Triangular bone which curves anteriorly, formed by the union of five

sacral vertebrae, serving as a foundation for the pelvic girdle

• Anatomy:

– Sacral foramen: Anterior and posterior sacral foramen, allow passage of the sacral nerves

– Sacral Ala (Wings): upper lateral portion of the sacrum formed by the fusion of transverse processes.

– Median sacral crest: posterior ridge formed by the fusion of sacral spinous processes

– Sacral canal: continuation of the vertebral canal. Ends as the sacral hiatus which is an opening for the last spinal nerve.

– Articular surface: on both lateral surfaces for articulation with the ilium of the pelvis.

– In the female, the sacrum is shorter, wider, and more curved between S2-S3

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Coccyx• Also a triangular bone form by the fusion of four coccygeal

vertebrae.

• In the female the coccyx points inferiorly while in the male is points more anteriorly.

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Palpation of the Spine

Spinous process of the vertebrae (general): Seated; have your partner flex their head and trunk slightly. Place your fingers along the centerline of the back and locate the long line of processes. Slide your fingers slowly up and down the spine noting the different sizes, prominences, and spaces between the processa. Cervical spinous processes: Supine; locate the EOP and then slide your fingers inferior onto the neck. The first palpable spinous process will be C2 (recall, C1 has a posterior tubercle). Continue palpating inferiorly gently until you reach the C7 spinous (the most prominent of the cervical spinous processes). Verify C7 by flexing your partner’s neck, C7 will move superiorly while T1 will remain fixed.

Inferior angle and T7: Prone, locate the inferior angle of the scapula slide your finger medially to the vertebral column. The spinous of T7 is in line with the inferior angle.

Superior angle and T2: Prone, locate the superior angle of the scapula slide your finger medially to the vertebral column. The spinous of T2 is in line with the superior angle.

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Top of iliac crest and L4: Prone; using the “knife edge” portion of your hand place your hands on the tops of the iliac crests. Then slide your thumbs medially meeting at the spine, the spinous process of L4 can be felt as a large knob.

Twelfth rib and T12: Prone; locate the lowest rib (12th) and palpate the shaft of the rib back to the spinal column. The 12th rib may be lost as it passes under the large erector spinae musculature.

Transverse processes of cervical vertebrae: Supine; place your fingers on the side of the neck below the ear lobes. Using the flat thumbpads, slide anteriorly and posteriorly to feel the ridge of the transverse processes. Note, the tips of the individual TP’s are not usually palpable as the pass anterior and inferior.

Thoracic transverse process: Prone; locate a portion of the thoracic spinous processes. Move about 1” laterally and palpate through the thick erector spinae group for the knobby shaped transverse processes.

Lumbar transverse processes: Prone; locate the lumbar spinous processes and slide about 2” laterally. Slowly sink your fingers through the thick erector spinae muscle, directing your pressure at a medial angle. Because of the thick muscle, the individual process may not be palpable, try to sense the solid ridge they form.

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Cervical laminar groove: Supine; support the head with one hand and locate the cervical transverse process with the other hand. Slide posteriorly off the transverse processes, palpating the space between the transverse and the spinous processes which is the laminar groove.

Thoracic and lumbar laminar groove: Prone; locate the spinous processes of the thoracic vertebrae. With the other hand locate the transverse processes of the thoracic vertebrae. Using firm pressure palpate the area between these two landmarks. Work your way down the laminar groove to the lumbar spine. Note the thick muscle of the transversospinalis group.

Sternum: Supine; place your fingers on the center of the chest. Then slide superiorly toward the jugular notch at the top. Then move your fingers slightly lateral and palpate the sternoclavicular joints (confirm by having your partner move their upper extremity). Return to the sternum and palpate inferiorly onto the manubrium and body. Finally, slide your fingers down onto the xiphoid process feeling the tip between the costal cartilages.

Ribs: Supine; slide laterally from the sternum onto the costal cartilages. Roll off the cartilage into the spaces between. Follow the costal cartilages laterally on to the ribs.