BIOMECHANICS OF THORACIC SPINE DR. FATIMA ZEHRA (Physical Therapist) School of Physiotherapy, IPMR Dow University of Health Sciences

Anatomy of spine Spine has 33 vertebrae; 7 Cervical 12 Thoracic 5 Lumbar 5 SACRAL 4 Coccygeal

Thoracic Spine

Thoracic Vertebrae Characteristics 1.Presence of articular facets on vertebral bodies for Ribs’ attachment 2.Long/thin Spinal Processes directed backward/downward in relation to motion segment & overlap each other 3.Tip of SP lies posterior & inferior to the body of the vertebra Act as lever to rotate the vertebral body Results in gliding of facets joints during flex / ext

Thoracic Spine The SPs of T1, T2, T3 – Project directly backward & the tip is on the same line as the Transverse Process The SPs of T4 to T6 – Located half a vertebra below the one to which they are attached

Thoracic Spine The SPs of T7 to T9 – Located a full vertebra lower than the vertebra to which they are attached The SPs of T10 to T12 – Palpable at the same level as the vertebral body to which they are attached

Thoracic Spine Thoracic Vertebral Bodies – Roughly equal in transverse / AP diameter Facet joints – Vertical & at 60˚ angle from horizontal plane – Superior faces upward / backward – Inferior facet faces downward / forward Atypical thoracic vertebrae – T1 and T12

Thoracic Spine Atypical Thoracic Vertebrae (T1) – The midway b/w cervical & thoracic spine – Inferior facet surface orientation is typically thoracic and superior facet surface is cervical – T1-Dysfunction greatly affects the functional capacity of thoracic outlet( blood vessels or nerves in the space between your collarbone and your first rib) & related structures

Thoracic Spine Atypical Thoracic Vertebrae (T12) – Superior facet surface is usually typically thoracic and inferior facet is lumber – Location of change b/w thoracic Kyphosis & lumber Lordosis – A location of change in mobility of 2 areas of spine – A point of frequent dysfunction T3 … the axis of rotation for the shoulder girdle T6 … the axis of rotation for entire thoracic spine

Thoracic Spine Thoracic Kyphosis – Smooth posterior convexity – Flat spots without the thoracic kyphosis shows vertebral dysfunction( due to malalignment between the lumbar vertebrae at the facet joints or intervertebral discs) – Fracture of Anterior part is common because of considerable load on anterior spine – Intra-diskal pressure is high resulting in disk degeneration earlier in middle & lower thoracic spine Note: Symptoms from thoracic spine are less than from cervical & lumber spines

Thoracic Spine Spinal Canal – Narrower with only a small epidural space b/w spinal cord & bony arch – Narrowest between T4 & T5 IV Foramina … Quite larger Clinical Thoracic Spine – Begins at T3 – T1 & T2 with their nerve root should be considered with cervical spine

Ribs & their attachments Must be consider in physical examination Movement during respiration Moves with a complex combination of; – Pump-handle Motion (Flex. / Ext. ) – Bucket-handle Motion (Abd. / Add.) – Caliper-like Motion (Int. / Ext. Rotation)

 Upper Ribs (Pump-handle + bucket-handle motion)  Middle Ribs (Primarily bucket-handle motion)  Lower Ribs (Mainly Caliper-like Motion)  Rib-1 moves during inhalation by ant., post., & middle scalene muscles Ribs & their attachments

Biomechanics Thoracic spine & rib cage work as a single unit Provide capacity for respiration and circulation Divided into 4 region according to biomechanical differences – Vertebromanubrial Region (C7-T2) – Vertebrosternal Region (T3-T7) – Vertebrochondral Region (T8-T10) – Thoracolumber region (T11-T12)

Vertebromanubrial Region (C7-T2) Transitional zone b/w cervical lordosis & thoracic kyphosis All ranges are diminished but Flex.-Ext. are more than in lower thoracic spine Sup. articular facet lies in coronal body plane Inf. articular facet presents a curve in both transverse & sagittal planes First 2 ribs are less mobile than T1 or T2

Vertebromanubrial Region (C7-T2) Lateral Bending (In mobile thorax) – Same pattern as in the mid cervical spine i.e. side flexion is coupled with ipsilateral rotation of the spine – During right side flexion of head - neck Inf. Glide of transverse process relative to right rib Sup. Glide of transverse process relative to left rib

Rotation (In mobile thorax) Same pattern as in the mid cervical spine During unilateral arm elevation, facet joints side flex & extend resulting in rotation of T1 & T2 (Same side) Vertebromanubrial Region (C7-T2)

Vertebrosternal Region (T3 – C7) Flexion In mobile thoracic spine flexion is coupled with; Ant. Rot. & Sup. glide of the rib neck & tubercle In stiff thoracic spine flexion is coupled with; Inf. movement of Ant. aspect of Rib & Sup. movement of Post. Aspect of Rib In same flexibility of spinal column & rib cage Quantity of movt. b/w Ribs & thoracic vertebrae is reduced Some AS Gliding occurs at facet joints

Vertebrosternal Region (T3 – C7) Extension … Occurs during bilateral elevation of arms & backward bending of the trunk In mobile thoracic spine extension is coupled with; Post. Rot. of Rib neck & an inf. glide of the tubercle In stiff thoracic spine extension is coupled with; Sup. Movt. of Ant. aspect of Rib & Inf. Movt. of Post. aspect of Rib Once Rib Movt. is stopped, thoracic spine extends on stationary ribs

Vertebrosternal Region (T3 – C7) Extension … In same flexibility of spinal column & rib cage Quantity of Movt. b/w ribs & thoracic vertebrae is reduced Some PI Gliding occurs at the thoracic facet joints Rotation In mobile spine Rt. Rot. is coupled with; Lt. translation of Sup. Facet, pulling of Lt. Rib neck forward at Costo-sternal joint, Ant. Rot. of Lt. rib neck & Sup. Glide at Costo-transverse joint

Vertebrosternal Region (T3 – C7) Lateral Bending In mobile spine Right side flexion is coupled with; – Left side convexity – Right ribs approximation at lateral margins – Left ribs separation at lateral margins – Costal motion stops but vertebral side flexion continue to right

Vertebrochondral Region (T8- T10) Flexion is coupled with; – Sagittal motion of ribs with slight articular motion of costovertebral joints of 8 th & 9 th ribs – Superior glide of facet joint – SMP glide of rib tubercle (in mobile thoracic spine) – ILA glide VC & CT Joints (in stiff thoracic spine) Extension is coupled with; – Inferior glide of facet joints

Vertebrochondral Region (T8-T10) Lateral Bending is coup[led with; – Compression of ribs at one side and separation of the ribs on the other side Rotation is coupled with; – Ipsilateral side flexion or contra-lateral side flexion – Rotate with minimal restriction from costal elements

Thoracolumber Region (T11-L1) The Facets are In the Sagittal Plane to match with L1 Freer Rotation with minimal restriction Rotation at this region is coupled with contralateral side flexion or ipsilateral side flexion

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