Thoracic Spine
Thoracic Spine…..
T2-8 are typical and T1 (cervical features) & T9-12 are a-typical (lumbar features).
Bodies are heart shaped and get larger as you descend through the T-sp. Deeper ant-post than med-lat. Left side may be slightly flattened or depressed due to the aorta. Articulate with the ribs at the Costoveretbral joints (Plane synovial joints at T1-12 allowing sliding and gliding. Head of rib articulates with demi-facets of 2 adjacent vertebral bodies’ and the IVD. T1, 11 and 12 [occ. 10] only connected to own vertebral body. Stabilised by capsule, intra-articular lig. and radiate lig.
Facets are orientated in the coronal plane primarily allowing side bending and axial rotation.
TPs extend postero-laterally (extend more posteriorly as you go down the T-sp) with the ribs passing anteriorly. Articulate with ribs on there antero-lateral surface at the Costotranverse joints (synovial joints at T1-10. Tubercle of rib articulates with TP. Stabilised by capsule, ant & post costotransverse ligs, lig of neck of rib and lig of tubercle of rib. Work in association with costovertebral joints to restrain movement and ensure ribs work parallel to each other during breathing). T1 has largest TP’s and T12 the smallest.
SPs are long and slender, and angled downwards so they overlap the neural arch of the vertebrae below. Slope in antero-superior direction and serve as attachment points for segmental muscles and TLF (along with lamina).
Ribs 1-7 are true as they articulate with the sternum directly at the Sternocostal Joints (First is a synchondroses and joints 2-7 are synovial. Thin, weak capsule reinforced by Ant. & Post. Radiate Sternocostal Ligs.) , 8-10 are false as the articulate with the costal cartilages of the ribs above at the Costochondral Joints (Hyaline cartilaginous synchondoses. Ribs have cup-shaped depressions that articulate with costal cartilage. Bound by periosteum of rib and perichondrium of cartilage. No movement at these joints), 11&12 are floating as they do not articulate with anything at there distal ends. Costal cartilages articulate with one another at Interchondral Joints (6th, 7th, 8th and 9th costocartilages. Plane synovial joints enclosed in capsules strengthen by interchondral ligs. 9th & 10th articulation is a fibrous synchondroses joint.
Ligaments same as in L-sp
ALL - covers anterior surfaces of lumbar vertebral bodies and discs. The ligament has three layers: superficial, intermediate and deep. The superficial layer traverses three or four vertebrae, the intermediate layer covers two or three and the deep layer is only between individual vertebrae. The deep layers of the ligament, as it crosses the vertebral body, blend with the periosteum. The ALL maintains the stability of the joints and limits extension.
PLL – in the vertebral canal over the posterior surface of the vertebral bodies and discs, wider over discs than bodies (Not attached to discs). It arises from the posterior aspect of the basiocciput, is continuous with the membrana tectoria, and runs down to the coccyx. It functions to limit flexion of the vertebral column. Fibres are denser than the ALL, superficial layers cover 3-4 segments with deeper layers only extending to adjacent segments.
Supraspinous ligament - Tip of SP to tip of SP from L1-L3. Weakly resists flexion & vertebral separation. Largely of tendinous fibres derived from the back muscles and is closely blended with the neighboring fascia. Superficial layers cover 3-4 segments with deeper layers only extending to adjacent segments. Between the SP’s it is continuous with the interspinous ligament.
Interspinous ligament – Connects SP to SP from root to apex. Weakly resists flexion & vertebral separation. Runs obliquely from the anterior inferior aspect of the SP above to the posterior superior aspect of the SP below. Thin and membranous, and narrow and elongated in the thoracic region.
Ligamentum flavum (LF) – Runs from C2-S1 & connects lamina of adjacent vertebrae, attaching to the interspinous ligament medially and the facet capsule laterally (forming the posterior wall of the vertebral canal). Normally, the ligament is taut, stretching for flexion and contracting its elastin fibers in neutral or extension. It maintains constant disc tension. There are small gaps for the passage of small vessels. The ligamentum flavum is thicker in the thoracic region. Hypertrophy of this ligament is one of the major reasons of spinal stenosis.
Intertransverse Ligaments - Situated between the TP’s. In the thoracic region, they are rounded cords, and closely connected with the deep muscles of the back.
Muscles
There are two major groups of muscles in the back. The extrinsic back muscles produce and control limb and respiratory movements. The intrinsic (deep) back muscles act on the vertebral column, maintaining posture and producing its movements.
Extrinsic
Superficial – Connect U.ex to trunk, produce & control limb movements.
Traps – Occiput, Ligamentum Nuchae, Med. Sup. Nuchal line, SP’s C7-T12 → Lat. 1/3 of Clavicle, Acromium & Spine of Scap. Accessory N CN XI (motor) & C3/4 (sensory).
Lats. – SP’s T7-L5, TLF, Iliac Crest, lower ¾ ribs & Inf. Angle of Scap. → Floor of Bicepital groove. Thoracodorsal N C6-8.
Lev. Scap. – TP’s (post.) C1-4 → Superior angle of medial border of scap. Dorsal Scap. N C5 & C3/4.
Rhomboids – SP’s T2-5 (major). SP’s C7 – T1 & Ligmentum Nuchae (minor)→ Medial border Scap. Dorsal Scap. N C4-5
Intermediate – Superficial respiratory muscle of thoracic wall.
Serratus Post. Sup. – Ligamentum Nuchae & SP’s C7-T3 → Upper borders ribs 2-5. Intercostal N 2-5. (deep to Rhomboids)
Serratus Post. Inf.- SP’s T11-L2 → Inf. Borders ribs 9-12. Intercostal N 9-12
Intrinsic
Maintain posture & control vertebral movements.
The deep muscles of the back are separated from the overlying muscles by fascia. That fascia attaches medially to the nuchal ligament, the tips of the SP’s, the supraspinous ligament, and the median crest of the sacrum. It attaches laterally to the C-Sp and L-Sp TP’s and to the angles of the ribs. The thoracic and lumbar parts of the deep fascia constitute the TLF. In the T-Sp the fascia over the muscles is thin, attached in the midline to the SP’s and laterally at the edge of the muscles to the ribs and fascia covering the intercostal muscles.
Superficial – Hold deep neck muscles in place.
Splenius Capitis - Ligamentum nuchae & SP’s C7-T3/4 → Superior nuchal line & mastoid process. Dorsal rami C3-4.
Splenius Cervicis – SP’s T3-6 → TP’s C1-3. Dorsal rami C6-8
Intermediate – Chief extensor of spine.
Spinalis (medial), Longissimus (intermediate) & Iliocostalis (lateral).
Insertion
Iliocostalis
Longissimus
Spinalis
Lower thoracic vertebrae and ribs
I. lumborum
Upper thoracic vertebrae and ribs
I. thoracis
L. thoracis
S. thoracis
Longissimus Thoracis
Extension, lateral flexion of vertebral column, rib rotation
Dorsal primary divisions of spinal nerves
Iliocostalis Thoracis
Extension, lateral flexion of vertebral column, rib rotation
Dorsal primary divisions of spinal nerves
Spinalis Thoracis
Extends vertebral column
Dorsal primary divisions of spinal nerves
Semispinalis Thoracis
Extends & rotates vertebral column
Dorsal primary divisions of spinal nerves
Rotatores Thoracis
Extends & rotates vertebral column
Dorsal primary divisions of spinal nerves
Deep – AKA Transversospinal.
All have common origins and insertions, the muscle layers are difficult to accurately separate from each other. Originate from TP’s of vertebrae and pass to SP’s of sup. vertebrae. They occupy the valley between the TP’s & SP’s.
Semispinalis (Superficial. 3 parts capitis, cervicis & thoracis)
Multifidus (middle) short, triangular muscular bundles thickest in L-Sp.
Rotatores (deep) best developed in the T-Sp.
Intercostal
External – Elevate ribs and expand chest cavity (quiet & forced inhalation)
Ribs 1-11 → ribs 2-12. Intercostal N’s.
Fibres are orientated obliquely downward and laterally posteriorly and downward and medially anteriorly.
Internal – Depress ribs and decrease size of chest cavity (force exhalation)
Ribs 2-12 → ribs 1-11. Intercostal N’s.
Fibres are orientated obliquely upwards and laterally posteriorly and upwards and medially anteriorly.
Inner most – Deep to internal, separated by neurovascular bundle.
Same fibre orientation as the internal intercostals.
http://www.scientificspine.com/spinal-anatomy/thoracic-spine-anatomy.html
T2-8 are typical and T1 (cervical features) & T9-12 are a-typical (lumbar features).
Bodies are heart shaped and get larger as you descend through the T-sp. Deeper ant-post than med-lat. Left side may be slightly flattened or depressed due to the aorta. Articulate with the ribs at the Costoveretbral joints (Plane synovial joints at T1-12 allowing sliding and gliding. Head of rib articulates with demi-facets of 2 adjacent vertebral bodies’ and the IVD. T1, 11 and 12 [occ. 10] only connected to own vertebral body. Stabilised by capsule, intra-articular lig. and radiate lig.
Facets are orientated in the coronal plane primarily allowing side bending and axial rotation.
TPs extend postero-laterally (extend more posteriorly as you go down the T-sp) with the ribs passing anteriorly. Articulate with ribs on there antero-lateral surface at the Costotranverse joints (synovial joints at T1-10. Tubercle of rib articulates with TP. Stabilised by capsule, ant & post costotransverse ligs, lig of neck of rib and lig of tubercle of rib. Work in association with costovertebral joints to restrain movement and ensure ribs work parallel to each other during breathing). T1 has largest TP’s and T12 the smallest.
SPs are long and slender, and angled downwards so they overlap the neural arch of the vertebrae below. Slope in antero-superior direction and serve as attachment points for segmental muscles and TLF (along with lamina).
Ribs 1-7 are true as they articulate with the sternum directly at the Sternocostal Joints (First is a synchondroses and joints 2-7 are synovial. Thin, weak capsule reinforced by Ant. & Post. Radiate Sternocostal Ligs.) , 8-10 are false as the articulate with the costal cartilages of the ribs above at the Costochondral Joints (Hyaline cartilaginous synchondoses. Ribs have cup-shaped depressions that articulate with costal cartilage. Bound by periosteum of rib and perichondrium of cartilage. No movement at these joints), 11&12 are floating as they do not articulate with anything at there distal ends. Costal cartilages articulate with one another at Interchondral Joints (6th, 7th, 8th and 9th costocartilages. Plane synovial joints enclosed in capsules strengthen by interchondral ligs. 9th & 10th articulation is a fibrous synchondroses joint.
Ligaments same as in L-sp
ALL - covers anterior surfaces of lumbar vertebral bodies and discs. The ligament has three layers: superficial, intermediate and deep. The superficial layer traverses three or four vertebrae, the intermediate layer covers two or three and the deep layer is only between individual vertebrae. The deep layers of the ligament, as it crosses the vertebral body, blend with the periosteum. The ALL maintains the stability of the joints and limits extension.
PLL – in the vertebral canal over the posterior surface of the vertebral bodies and discs, wider over discs than bodies (Not attached to discs). It arises from the posterior aspect of the basiocciput, is continuous with the membrana tectoria, and runs down to the coccyx. It functions to limit flexion of the vertebral column. Fibres are denser than the ALL, superficial layers cover 3-4 segments with deeper layers only extending to adjacent segments.
Supraspinous ligament - Tip of SP to tip of SP from L1-L3. Weakly resists flexion & vertebral separation. Largely of tendinous fibres derived from the back muscles and is closely blended with the neighboring fascia. Superficial layers cover 3-4 segments with deeper layers only extending to adjacent segments. Between the SP’s it is continuous with the interspinous ligament.
Interspinous ligament – Connects SP to SP from root to apex. Weakly resists flexion & vertebral separation. Runs obliquely from the anterior inferior aspect of the SP above to the posterior superior aspect of the SP below. Thin and membranous, and narrow and elongated in the thoracic region.
Ligamentum flavum (LF) – Runs from C2-S1 & connects lamina of adjacent vertebrae, attaching to the interspinous ligament medially and the facet capsule laterally (forming the posterior wall of the vertebral canal). Normally, the ligament is taut, stretching for flexion and contracting its elastin fibers in neutral or extension. It maintains constant disc tension. There are small gaps for the passage of small vessels. The ligamentum flavum is thicker in the thoracic region. Hypertrophy of this ligament is one of the major reasons of spinal stenosis.
Intertransverse Ligaments - Situated between the TP’s. In the thoracic region, they are rounded cords, and closely connected with the deep muscles of the back.
Muscles
There are two major groups of muscles in the back. The extrinsic back muscles produce and control limb and respiratory movements. The intrinsic (deep) back muscles act on the vertebral column, maintaining posture and producing its movements.
Extrinsic
Superficial – Connect U.ex to trunk, produce & control limb movements.
Traps – Occiput, Ligamentum Nuchae, Med. Sup. Nuchal line, SP’s C7-T12 → Lat. 1/3 of Clavicle, Acromium & Spine of Scap. Accessory N CN XI (motor) & C3/4 (sensory).
Lats. – SP’s T7-L5, TLF, Iliac Crest, lower ¾ ribs & Inf. Angle of Scap. → Floor of Bicepital groove. Thoracodorsal N C6-8.
Lev. Scap. – TP’s (post.) C1-4 → Superior angle of medial border of scap. Dorsal Scap. N C5 & C3/4.
Rhomboids – SP’s T2-5 (major). SP’s C7 – T1 & Ligmentum Nuchae (minor)→ Medial border Scap. Dorsal Scap. N C4-5
Intermediate – Superficial respiratory muscle of thoracic wall.
Serratus Post. Sup. – Ligamentum Nuchae & SP’s C7-T3 → Upper borders ribs 2-5. Intercostal N 2-5. (deep to Rhomboids)
Serratus Post. Inf.- SP’s T11-L2 → Inf. Borders ribs 9-12. Intercostal N 9-12
Intrinsic
Maintain posture & control vertebral movements.
The deep muscles of the back are separated from the overlying muscles by fascia. That fascia attaches medially to the nuchal ligament, the tips of the SP’s, the supraspinous ligament, and the median crest of the sacrum. It attaches laterally to the C-Sp and L-Sp TP’s and to the angles of the ribs. The thoracic and lumbar parts of the deep fascia constitute the TLF. In the T-Sp the fascia over the muscles is thin, attached in the midline to the SP’s and laterally at the edge of the muscles to the ribs and fascia covering the intercostal muscles.
Superficial – Hold deep neck muscles in place.
Splenius Capitis - Ligamentum nuchae & SP’s C7-T3/4 → Superior nuchal line & mastoid process. Dorsal rami C3-4.
Splenius Cervicis – SP’s T3-6 → TP’s C1-3. Dorsal rami C6-8
Intermediate – Chief extensor of spine.
Spinalis (medial), Longissimus (intermediate) & Iliocostalis (lateral).
Insertion
Iliocostalis
Longissimus
Spinalis
Lower thoracic vertebrae and ribs
I. lumborum
Upper thoracic vertebrae and ribs
I. thoracis
L. thoracis
S. thoracis
Longissimus Thoracis
Extension, lateral flexion of vertebral column, rib rotation
Dorsal primary divisions of spinal nerves
Iliocostalis Thoracis
Extension, lateral flexion of vertebral column, rib rotation
Dorsal primary divisions of spinal nerves
Spinalis Thoracis
Extends vertebral column
Dorsal primary divisions of spinal nerves
Semispinalis Thoracis
Extends & rotates vertebral column
Dorsal primary divisions of spinal nerves
Rotatores Thoracis
Extends & rotates vertebral column
Dorsal primary divisions of spinal nerves
Deep – AKA Transversospinal.
All have common origins and insertions, the muscle layers are difficult to accurately separate from each other. Originate from TP’s of vertebrae and pass to SP’s of sup. vertebrae. They occupy the valley between the TP’s & SP’s.
Semispinalis (Superficial. 3 parts capitis, cervicis & thoracis)
Multifidus (middle) short, triangular muscular bundles thickest in L-Sp.
Rotatores (deep) best developed in the T-Sp.
Intercostal
External – Elevate ribs and expand chest cavity (quiet & forced inhalation)
Ribs 1-11 → ribs 2-12. Intercostal N’s.
Fibres are orientated obliquely downward and laterally posteriorly and downward and medially anteriorly.
Internal – Depress ribs and decrease size of chest cavity (force exhalation)
Ribs 2-12 → ribs 1-11. Intercostal N’s.
Fibres are orientated obliquely upwards and laterally posteriorly and upwards and medially anteriorly.
Inner most – Deep to internal, separated by neurovascular bundle.
Same fibre orientation as the internal intercostals.
http://www.scientificspine.com/spinal-anatomy/thoracic-spine-anatomy.html