Anatomy-Lec: LE 2 | Trans 2 PDF

ANATOMY-LEC: LE 2 | TRANS 2 Deep Back ZORBA BNN R. BAUTISTA, MD, DPBS & STEVE HK T. NG, MD | Lecture Date (SEPT/16/2024) OUTLINE → Spinal cord and meninges I. Vertebra...

ANATOMY-LEC: LE 2 | TRANS 2 Deep Back ZORBA BNN R. BAUTISTA, MD, DPBS & STEVE HK T. NG, MD | Lecture Date (SEPT/16/2024) OUTLINE → Spinal cord and meninges I. Vertebra IV. Joints → Nerves and vessels A. Back A.Joints of Vertebral B. VERTEBRAL COLUMN / SPINE B. Vertebral Column Bodies or Spine C. Vertebral Structure B.Joints of Vertebral Arches The main part of the axial skeleton It extends from the cranium to the apex of the coccyx 📖 II. Regional Characteristics of the C.Craniovertebral Joints the IV discs 📖 72-75 cms long (in adults); approximately ¼ is formed by Has 5 distinct regions and a total of 33 vertebrae: Vertebrae V. Muscles of the Back → Cervical (7) A. Cervical Vertebra A.Extrinsic Back → Thoracic (12) B. Thoracic Vertebra Muscles → Lumbar (5) C. Lumbar Vertebra B.Intrinsic Back → Sacrum (5 segments) - fused together D. Sacrum Muscles → Coccyx (4 segments) - fused together E. Coccyx C.Suboccipital Region F. Intervertebral VI. Neurovasculature Discs A.Blood Supply III. Ligaments B.Venous Drainage A. Intersegmental C.Nerve Supply Ligaments VII. Review Questions B. Intrasegmental VIII. References Ligaments IX. Appendix SUMMARY OF ABBREVIATIONS IV Intervertebral ALL Anterior Longitudinal Ligaments PLL Posterior longitudinal Ligaments ❗️ Must know 📣 Lecturer 📖 Book 📋 Previous Trans LEARNING OBJECTIVES ✔ Describe the general structure of the vertebral column ✔ Distinguish the representative vertebra from the cervical, thoracic, lumbar, and sacral regions ✔ Identify the deep back musculature, including the muscles in the suboccipital region as to their general Figure 1. Vertebral column and its five regions. [Moore] attachments, innervations, actions, blood supply and lymphatic drainage CURVATURES OF VERTEBRAL COLUMN I. VERTEBRA A. BACK Composed of the following (from superficial to deep): → Skin and subcutaneous tissue → Muscles ▪ Superficial layer group 📣 − Muscles of the posterior axioappendicular muscle − Movement and positioning of the upper limbs 📖 ▪ Deeper layers − “True back muscles” 📖 − Movement and maintaining position of the axial skeleton (posture) → Vertebral column ▪ Vertebrae − Each vertebra is connected to an adjacent vertebra via zygapophysial (facet) joints 📣 Figure 2. Curvatures of the vertebral column. [Moore] ▪ Intervertebral (IV) discs − More flexible aspects of the vertebral column 📣 These curvatures provide additional flexibility ▪ Ligaments (for stability) → Ribs in thoracic region the IV discs 📖 (shock-absorbing resilience) aside from that provided by LE 2 TRANS 2 TG-C10: G. Romero, *C. Rosales, M. Rosell, A. Roxas, C. TE: G. Romero, L. Sabico, L. AVPAA: A. Villanueva Page 1 of 21 Ruben, L. Sabico, L. Sagun, J. Salayo, R. Salazar Sagun  PRIMARY CURVATURE (KYPHOSIS) − Have (articular surface) facets at its tips which Anterior concavity Kyphosis = concave/bending inwards/hunchbacking 📣 above or below 📣 forms joints with the skull above or the vertebrae − With these joints, the processes determine the In the thoracic and sacral regions 📣 Evident throughout life; due to differences in height of types of movements between the adjacent vertebrae vertebrae of each region Develops during fetal period → Only the primary curvature exists during the fetal life Thoracic and Sacral Kyphosis SECONDARY CURVATURE (LORDOSIS) Posterior concavity Lordosis = “convex”📣 In the cervical and lumbar regions 📣 Obvious in the beginning of infancy; due to differences in height of IV discs Cervical lordosis → starts when an infant gains control of their necks📣 (to 📖 raise the head while pronated and to hold the head Figure 3. Functional components of the vertebra. [Moore] erect while sitting ) Vertebral foramen Lumbar lordosis → Formed by the posterior surface of vertebral body and sacrum 📖 → Ends at lumbosacral angle at the junction of L5 with the vertebral arch → Spinal cord & nerves pass through here begins to stand and walk 📣 → Evident within the first year; starts when an infant Vertebral canal → Formed by the succession of vertebral foramina in the FUNCTIONS OF VERTEBRAL COLUMN articulated vertebral column Protects spinal cord and spinal nerves → Contains the spinal cord, roots of spinal nerves, Supports the weight of the body superior to the level of meninges, vessels the pelvis Vertebral notches Provides a partly rigid yet flexible axis for the body where → Superior vertebral notch and inferior vertebral notch the appendicular skeleton will be attached → Two notches form the IV foramen (lateral view) Plays an important role in posture and locomotion → Anteriorly: corresponding projection of the vertebral body stable, flexible, and movable 📣 To perform all these functions, the vertebral column must be → Posteriorly: between the superior and inferior articular processes C. VERTEBRAL STRUCTURE PARTS OF A TYPICAL VERTEBRAE Vertebral body → large, thick, and ovoid structure 📣 → carries most of the weight of each segment 📣 Vertebral arch → 2 components: pedicles and lamina ▪ Pedicles (“feet”) − Short, cylindrical processes − Project posteriorly from the vertebral body ▪ Laminae (“roof”) − 2 broad, flat plates of bone that unite in the midline − Where the protrusions or processes emerge − Mainly for muscle attachment 7 Processes → 3 for muscle attachments ▪ Serve as levers, facilitating the muscles that fix or Figure 4. Lateral view of vertebrae showing IV change the position of the vertebrae foramen. [Moore] ▪ Spinous process (1) Intervertebral foramina junction of the laminae 📣 − Projects posteriorly from the vertebral arch at the → Formed by the superior and inferior vertebral notches of adjacent vertebrae and the IV discs connecting them ❗️ ▪ Transverse processes (2) → Where the spinal nerves emerge from the vertebral − Projects posterolaterally from the junctions of the column pedicles and laminae → Location of the spinal (posterior root) ganglia → 4 for formation of articular joints Intervertebral discs ▪ Superior articulating processes (2) → Attached to the vertebral bodies through the inferior ▪ Inferior articulating processes (2) vertebral “end plate” and the superior vertebral “end 📣 ▪ AKA zygapophyses plate” of the posterior and inferior vertebral bodies, − Also arise from the junctions of the pedicles and respectively laminae → End plates are composed of hyaline cartilage ANATOMY Deep Back Page 2 of 21  → Composed of: Greatest range and variety of movement (among all the ▪ Annulus fibrosus: fibrous outer covering vertebral regions) ▪ Nucleus pulposus: pulpy gel-like core → Flexion → Extension → Lateral flexion → Limited rotation → Circumduction 7 cervical vertebrae Figure 5. Medial view of internal aspects of vertebral bodies and vertebral canal [Moore] NICE TO KNOW: NEUROANATOMY 📣 At the spinal cord level, there is a dorsal horn (purely sensory) and ventral horn (purely motor) As the roots come out, they would eventually merge to form the spinal root As it emerges from the IV foramen, it would divide into the dorsal and ventral rami Figure 7. Cervical vertebra [Moore] TYPICAL CERVICAL VERTEBRAE Note: In Moore, C3-C7 are classified as typical vertebrae but Doc Bautista mentioned in the recorded lecture that C7 has characteristics which sets it apart from the typical ones. C3-C6 VERTEBRA Vertebral End plates → brim around the body where IV discs will be seated/attached → flat, slightly concave surfaces on the superior and 📖 inferior aspects of the vertebral bodies Have uncinate processes (Uncus) Figure 6. Spinal cord cross-section through lumbar (unique to the cervical vertebra) 📣 → It is a brim around the bodies that tend to arch upwards. Transverse foramina (foramen transversarium) vertebra. [Netter] → Hole on either side of the transverse processes II. REGIONAL CHARACTERISTICS OF THE → Present in C1-C7 vertebra VERTEBRAE Spinous process: short and bifid tip → Due to the tension created by the muscle attachments 📣 A. CERVICAL VERTEBRA to the posterior neck (e.g. trapezius) Skeleton of the neck → Less common in black individuals Seem to be very flimsy, especially C1 Superior articular facets are directed supero-posteriorly Vertebral body: small but wide and inferior articular facets are directed infero-anteriorly 📣 Vertebral foramen: large and triangular to ensure that the cervical vertebrae has the most amount → It is large since the thick brainstem courses through the of movements vertebral foramen, coming out of the foramen magnum, Vertebral foramen: larger than usual, triangular and connecting the spinal cord and the brain. 📖 → To accommodate cervical enlargement of spinal cord facing forward from the superior aspect 📣 The articulating facets have a nearly horizontal orientation, → Facets in nearly horizontal orientation + small body + small amount of surrounding body mass (only neck muscles and neurovascular structures coming up and down) = greatest range of motion IV discs are at their thickest ANATOMY Deep Back Page 3 of 21  Figure 8. Typical cervical vertebrae [Lecturer’s PPT] ATYPICAL CERVICAL VERTEBRAE C1 VERTEBRA (ATLAS) NO body and spinous process Anterior and posterior tubercle → Anterior: shorter arches → Posterior: longer arches and noticeable grooves where vertebral artery passes through Figure 9. C1 vertebrae [Netter] Ring-shaped with paired lateral masses and has the C2 VERTEBRA (AXIS) transverse processes on the either side The axis of the atlas Facets in superior view: 📖 Has a large bifid spinous process that can be felt deep in → Form the joint with the occipital condyles of the skull the nuchal groove → Posterior to each of these superior facets, there are Strongest of all cervical vertebrae because of the most grooves for the vertebral artery obvious structure which is the dens (odontoid process) Facets in inferior view: → Inserts into the ring of the atlas in the formation of the → Each of these facets are involved in the attachment to atlantoaxial joint (ONLY synovial pivot joint in the the C2 vertebrae vertebral column) Weakest of all cervical vertebrae → This joint is also found in between the articulating facets → The bone that fractures during hanging compresses the brainstem, which eventually causes the demise Widest of the cervical vertebrae (from tip to tip of its 📣 on either side → Dens: Superiorly protruding part of the vertebral body, transverse processes) Superior articular surface articulates with the occipital facet.📣 articulates with the axis at the posterior articular ▪ It protrudes upwards, allowing the atlas to articulate condyles articulating to the base of the cranium. → It is a condylar joint (atlanto-occipital joint); aids in around which the atlas rotates. 📣 with its posterior surface; the dens acts as the axis the head (“YES” joint) 📣 nodding movement particularly flexion and extension of ▪ Leaves a wide area for the brainstem Inferior Articular Surface articulate with C2 or axis which forms a part of the atlantoaxial joint. 📣 ▪ “NO” joint enabling head rotation to the left and right. ▪ To maintain its position, several ligaments secure the dens: − The apical ligament of the dens and alar 📣 ligament are the deepest ligaments, keeping the dens close to the base of the skull. head overturning. 📣 − The alar ligament specifically prevents excessive − The cruciform ligament further secures the atlantoaxial joint, consisting of the superior and transverse ligament of the atlas. 📣 longitudinal band, inferior longitudinal band, − Cruciate ligament (located posteriorly when viewed superiorly) and alar ligaments support the atlantoaxial joint at the odontoid process ANATOMY Deep Back Page 4 of 21  → Sloping or angled inferiorly like the thoracic spinous processes Smaller or absent transverse foramen →Transmit only small accessory veins 📖 Figure 10. C2 vertebrae [Netter] Figure 11. C7 vertebrae [Netter] Table 1. Summary of the major characteristics of Cervical vertebrae Part Characteristics Vertebral Small and wider from side to side than body anteroposteriorly Superior surface concave with uncus of body (uncinate process) Inferior surface convex Vertebral Large and triangular foramen Transverse Foramina transversarii and anterior and Processes posterior tubercles; Vertebral arteries, accompanying venous and sympathetic plexuses pass through foramina transversarii of all cervical vertebrae except C7 C7 transmits only small accessory vertebral veins Articular Superior facets directed Processes superioposteriorly Inferior facets directed inferio-anteriorly Obliquely placed facets are most nearly horizontal Spinous Short (C3-C5) and bifid (C3-C6); Process process of C6 long, that of C7 is longer (thus called “vertebra prominens”) Movement Greatest range and variety of movement: flexion, extension, lateral flexion, limited rotation, circumduction [Lecturer’s PPT] Figure 10.1. C1 to C4 Vertebrae C7 VERTEBRA (VERTEBRA PROMINENS) Transitions from cervical to thoracic The spinous process is the longest of all cervical spinous processes name vertebra prominens 📣 → The first bone that you feel on your nape, hence the → Almost as long as thoracic spinous process ANATOMY Deep Back Page 5 of 21  B. THORACIC VERTEBRA → Rotation ❗️ ▪ Only allowed movement in thoracic vertebrae ▪ Allows rotation of thorax up to 45 degrees → Limited due to zygapophyseal joint and ribs: ▪ Flexion ▪ Extension ▪ Lateral flexion ATYPICAL THORACIC VERTEBRAE T1 - T4 VERTEBRA T1 vertebra 📋 Have some features of cervical vertebrae → Spinous process: long, almost horizontal; may be as prominent as the vertebra prominens → Superior edge: has a demifacet that contributes Figure 12. T6 vertebra: lateral view[Netter] articular surface of the second rib Located in the upper back and provides attachment for the T9 - T12 VERTEBRA ribs associated with it. Spinous process angulation is oriented inferiorly 📣📣 Have some features of lumbar vertebrae (transitional Articulating facets are almost completely vertical areas) T12 vertebra 📋 Costal facets 📖❗️ → Limits the movement of the thoracic vertebrae → Primary characteristics features of thoracic vertebrae → Shortest spinous process among the thoracic vertebrae → Massive body → Thick pedicles and laminae → For articulation with the ribs → Solitary costal facets ▪ 2 for the head → Superior articulating facet: vertical and pointing ▪ 1 for the tubercle posteriorly → Superior and Inferior costal facets articulate each single → Inferior articulating process oriented laterally (lumbar head of the rib vertebrae characteristic) structures 📋 Location may be approximated by the level of the → T2: at the level of the sternal notch, which is at the superior or proximal end of the sternum → T9: at the level of the xiphoid process, which is at the inferior or distal end of the sternum TYPICAL THORACIC VERTEBRAE Figure 13. T2 vertebrae[Netter] Figure 13. T6 vertebrae superior[Netter] and lateral view[Lecture PPT]] Table 2. Summary of the major characteristics of Thoracic vertebrae Part Characteristics T5 - T8 VERTEBRA Vertebral Heart-shaped and larger than cervical The body has one or two costal facets for articulation with body vertebrae head of rib Vertebral Circular and smaller than cervical and Transverse processes no longer have the transverse Foramen lumbar vertebrae foramina instead they’re much longer. They also have Transverse Long and strong; extends another facet called costal facets. Processes posterolaterally → Articular facets: vertically oriented Length diminishes from T1-T12 Articular processes tend to face anteriorly and T1-T10 have facets for articulation with posteriorly. tubercle of rib → Flexion and extension is limited in the thoracic section. Articular Nearly vertical articular facets and extending in this area. 📣 → Bones and muscles are actually in the way from flexing Processes Almost limits the movement of the thoracic vertebrae → Rotating in the thoracic area aids along with the rotation of the cervical area to look behind the neck and back. Spinous processes: long, downward sloping, 📣 Superior facets: directed posteriorly and slightly laterally Inferior facets: directed anteriorly and posteroinferiorly overlapping. Sometimes it reaches all the slightly medially way down to the vertebral body of the next vertebrae. Planes of facets lie on an arc centered in → Helps in limiting the extension of the thoracic vertebrae the vertebral body Attachment of ribs Movement permitted: ANATOMY Deep Back Page 6 of 21  Spinous Long, slope posteroinferiorly Processes (remarkably inferior) Tips extend to vertebral body below (overlapping) Movement Only rotation (of the thorax) Limited flexion, extension, and lateral flexion due to: →Presence of ribs and sternum anteriorly →Vertical orientation →Overlapping spinous processes C. LUMBAR VERTEBRA Figure 15. Mammillary and Accessory processes[Netter] L5 VERTEBRA Figure 14. Lumbar vertebra [Netter] Massive body and transverse processes Largest of all movable vertebrae other regions 📋 Largest and heaviest vertebrae in terms of mass than the Bigger as you go down the vertebral column to Carries the weight of whole upper body Body markedly deeper anteriorly Markedly taller anteriorly compared to the posterior side accommodate the weight of the rest of the body above it → Responsible for the lumbosacral angle between the Denser and thicker than the rest of the vertebral column. lumbar and sacral region of vertebral column Vertebral foramen: triangular Site of lumbar puncture → Bigger, it accommodates the lumbar section of the → During flexion, spaces widen allowing the procedure to spinal cord that tends to be thicker because it has more be done (extraction of synovial fluid and injection of sections and nerves which supply the muscles of the anesthesia) lower extremities → It also houses the cauda equina. 📣 ▪ Spinal cord ends around the L1 or L2 region in adults, and then continues as cauda equina, giving nerves that are extending downward. Spinous process: 📣📋 off spinal nerves up to S5. It is only the spinal → Short and sturdy. Looks like hatches or axes. → Thick, broad → Hatchet-shaped Articular processes tend to face inward and outwards respectively. Movements: → Facilitates: flexion, extension, lateral flexion → Prohibits: rotation Figure 16. L5 vertebrae[Netter]; Medial view of bisected column ▪ Most of the rotation occurs in the thoracic and cervical from left with ribs, cranium, and pelvis[Lecture PPT] vertebrae. Table 3. Summary of the major characteristics of Lumbar vertebrae Presence of additional processes for attachment of Part Characteristics muscles to support upper body Vertebral Massive → Mammillary process body Kidney-shaped (when viewed ▪ Provide attachment to multifidus muscle and superiorly) intertransversarii muscle Vertebral Triangular ▪ Located at the posterior surface of the superior Foramen Larger than in thoracic vertebrae but articular process smaller than in cervical vertebrae → Accessory process Transverse Long and slender ▪ Provide attachment to intertransversarii muscles only Processes Accessory process on posterior surface ▪ Located at the posterior surface of the base of each of base of each process transverse process Articular Extend vertically Processes Superior facets: oriented posteromedially Inferior facets: oriented anterolaterally Spinous Short and sturdy Processes Thick, broad Hatchet-shaped ANATOMY Deep Back Page 7 of 21  Movement Facilitates: Flexion, extension, lateral E. COCCYX flexion (at the waist) Prohibits: Rotation 4-5 segments of small triangular bone Fused rudimentary coccygeal vertebrae 📖 D. SACRUM eminence 📖 Skeletal remnant of the embryonic tail-like caudal Very limited movement → When sitting, it may flex anteriorly, indicating that it is receiving some weight Attachment for pelvic muscles and levator ani muscles Pelvic surface → concave and relatively smooth Posterior surface → rudimentary articular processes Transverse processes → short, connected to the sacrum F. INTERVERTEBRAL DISCS Figure 18. Intervertebral discs[Netter] Provide strong attachment between vertebral bodies Figure 17. Anterior and posterior view of the sacrum and 20-25% of length (height) of the vertebral column coccyx[Netter] Absorb shock, supports movement, and allow for some S1-S5 bones, including the transverse and spinous flexibility of the vertebral column processes, are fused together to form one huge bony Composed of 2 layers plate → Annulus Fibrosus Sacral Promontory Ring of concentric lamellae → Important obstetrical landmark. Anterior (Pelvic) Surface: smooth 📣 → Anterior projecting edge of the body of the S1 vertebra Oblique direction of fibers in each lamellae that run perpendicular to each other. This gives the tensile and elastic properties for the rest of the vertebrae. Sacral foramina → 4 pairs 📖 → Houses the spinal nerves for the sacral region 📣 Outer dense fibrous connective tissue covering Envelops nucleus pulposus Weakened areas in annulus fibrosus cause nucleus 📖 → For the exit of the posterior and anterior rami of the pulposus to herniate - Herniated discs spinal nerves → Nucleus Pulposus Posterior Surface: Rough, convex, and marked by five Central core; Pulpy center prominent longitudinal ridges or crests serve as muscle Almost 88% water in adults but eventually dries up attachment for lower back and lower extremities. and hardens with age. → Median sacral crest: Fused portion of the spinous Act as a semifluid fulcrum on vertebral movement processes of the sacral vertebrae where weight is distributed. → Lateral sacral crest: Fused portion transverse Gel-like substance that allows shock absorption processes III. LIGAMENTS → Intermediate sacral crest: Fused portion of the Structures that support the vertebral column articular processes Vertebral Body Ligament: → Sacral Hiatus: Inverted U-shaped, Lack of laminae in → Longitudinal as it goes from the very top to the bottom. S4 and S5, leads into sacral canal → Anterior Longitudinal: prevents hyperextension → Sacral canal → Posterior Longitudinal: prevents hyperflexion ▪ It is the continuation of the vertebral canal. Posterior Ligaments ▪ It contains the bundle of spinal nerve roots arising → Supraspinous inferior to the L1 vertebra called cauda equina. → Interspinous ▪ Note: Spinal cord ends at L1-L2 → Ligamentum Flavum → Sacral cornua: Inferior articulating processes of S5 vertebrae ANATOMY Deep Back Page 8 of 21  A. INTERSEGMENTAL / LONGITUDINAL LIGAMENTS → Bridging fat and vessels between the ligament and \ bony surfaces ANTERIOR LONGITUDINAL LIGAMENTS Table 4. ALL vs PLL ALL PLL Characteristic Largest Narrower Widest Weaker Function ❗️ Strongest Prevents hyperextension Weakly resists hyperflexion (Only ligament that Helps prevent limits extension) herniation of the nucleus pulposus Attachment Anterolateral Posterior to aspect of vertebral vertebral bodies bodies IV discs Location C1- sacrum Within vertebral canal Figure 19. Anterior Longitudinal Ligaments[Netter] C2-sacrum Additional Only ligament that (+) nociceptive Largest, widest, and strongest ligament in the vertebral Information encompasses the nerve endings column whole spinal (+) lateral aspects of the vertebral bodies and IV discs Extends from the cervical area to the sacrum 📖 Fibrous band that covers and connects the anterolateral r column transverse projections → Anterior Atlantoocipital membrane B. INTRASEGMENTAL / ACCESSORY LIGAMENTS Functions: \ 📖 LIGAMENTUM FLAVUM → Prevents hyperextension of the vertebral column → The only ligament that limits extension Broad, pale yellow bands of elastic tissue First structure that tears when the back is Thickest in lumbar region because it gets the most work Begins at C3 hyperextended Functions: → Maintain stability of the joints between vertebral bodies → Resist separation of vertebral lamina by limiting abrupt POSTERIOR LONGITUDINAL LIGAMENTS flexion of vertebral column → Help preserve normal curvatures of vertebral column → Assist with straightening of column after flexing Figure 21. Ligamentum Flavum[Netter] INTERSPINOUS LIGAMENT Thin Connects adjacent spinous processes, attaching from root to apex of each process spinous process ❗️ Location: in between superior and inferior borders of Function: Inhibits flexion Figure 20. Posterior Longitudinal Ligaments[Netter] SUPRASPINOUS LIGAMENT Much narrower, somewhat weaker than ALL Runs within the vertebral canal along the posterior aspect Most superficial; Cord-like of the vertebral bodies Connects tips of spinous processes from C7 to sacrum Mainly attached to the IV discs Merges superiorly with the nuchal ligament at the back of Weakly attached to posterior aspect of C2 to sacrum the neck Well-provided with nociceptive (pain) nerve endings Function: Inhibits hyperflexion and excessive lateral Functions: flexion → Weakly resists hyperflexion of the vertebral column ❗️ INTERTRANSVERSE LIGAMENT → Prevents or redirects posterior herniation of the nucleus Connects adjacent transverse processes pulposus Characteristics per region: → Cervical: scattered fibers ANATOMY Deep Back Page 9 of 21  → Thoracic: fibrous cords vertebral foramen or between the internal surface of the → Lumbar: thins and membranous lamina is the Ligamentum Flavum. To pass through the Function: Limits contralateral lateral flexion structures, order is also important. → These structures need to be pierced in order to have access to the vertebral canal for multiple reasons such as spinal anesthesia and diagnostic samples from the spinal fluid. IV. JOINTS The joints of the vertebral column include: → Joints of vertebral bodies 📖 → Joints of vertebral arches → Craniovertebral joints (atlanto-axial and atlanto-occipital) → Costovertebral joints → Sacro-iliac joints A. JOINTS OF VERTEBRAL BODIES weight-bearing and strength → Fibrocartilaginous fusion ❗️ Symphyses (secondary cartilaginous joints) designed for ▪Remember: IV discs are representative of fibrocartilage → Intervertebral discs act as a shock absorber Figure 22. Red: Interspinous ligament; Blue: supraspinous Articulating surfaces connected by intervertebral discs ligament; Green: intertransverse ligament [Moore] B. JOINTS OF VERTEBRAL ARCHES LIGAMENTUM NUCHAE/ NUCHAL LIGAMENT Zygapophysial joints (facet joints) Strong, broad; fibroelastic tissue from the midline base of the skull to the spinous processes of cervical vertebrae. movement they allow 📣 → Orientation of facet joint dictates what type of Plane synovial joints (gliding-type) between the Extends as a median band from the external occipital protuberance at the back of the skull and posterior border superior and inferior articular processes of adjacent vertebrae surrounded by a thin joint capsule cervical vertebrae Functions: ❗️ of the foramen magnum to the spinous processes of the Permits gliding movements between articular processes NOTES →Provides attachment for muscles that attach to the Shape and disposition of articular surfaces: spinous processes of vertebrae at other levels determines the types of movement possible → Inhibits hyperflexion of the neck → Remember facet joint orientation of each spinal ▪ Flexion of the neck causes palpation of the ligamentum segment nuchae from the external occipital protuberance down to the C7 vertebral prominence Size of IV disc: determines range of motion → Large IV disc in cervical and lumbar segments ❗️ C. CRANIOVERTEBRAL JOINTS ATLANTO-OCCIPITAL JOINT 📖 Formed between the atlas (C1 vertebrae) and occipital bone of the cranium “YES” joint ❗️ Synovial joint of the condyloid type → Allows you to nod your head 📣 → Allows flexion and extension of the neck, and also permits lateral flexion, rotation as a condyloid joint Anterior and posterior atlanto-occipital membranes 📋 📋 stabilize or prevent excessive movement of the atlanto-occipital joints. Anterior Atlanto occipital membrane → Extension of the anterior longitudinal ligament. It covers anteriorly a portion of the atlantoaxial joint space Posterior Atlanto occipital membrane → Extension of the Ligamentum Flavum. → This is where the vertebral body pierces. → Vertebral artery passes through the transverse foramina all the way to C1, in order to have access to the cranium, supplying blood to posterior side of brain Figure 23. Ligamentum nuchae on right lateral view [Netter] NOTE Supraspinous ligament runs along the tips of the spinous processes. In between the spinous processes, is the interspinous ligament. Then, right before the ANATOMY Deep Back Page 10 of 21  Figure 24. Atlanto-occipital Joint [Lecture PPT] Figure 27. Atlanto-axial articulations [Lecture PPT] ATLANTO-AXIAL JOINT vertebra)📖 Formed between the atlas (C1 vertebrae) and axis (C2 Synovial joint with NO IV disc → Atlas has no vertebral body Alar ligament and Cruciate ligament supports this joint at the odontoid process Posterior longitudinal ligament extends to tectorial membrane ❗️ → Acts as covering of cruciate ligament 📣 “NO” Joint 📖 → Pivot joint that allows you to shake your head “no” → Allows rotation 📣 Figure 28. Associated ligaments that stabilize joints [Netter] V. MUSCLES OF THE BACK Most body weight lies anterior to the vertebral column; consequently many strong muscles attached to the necessary to support and move the column 2 Major Groups of Back Muscles 📖 spinous and transverse process of the vertebrae are → Extrinsic Back Muscles Superficial (Limb) Intermediate (Respiration) → Intrinsic (Deep) Back Muscles (Vertebral Column) Figure 25. Movement of Atlanto-axial joints [Moore] Superficial Intermediate Deep A. EXTRINSIC BACK MUSCLES Separated from the intrinsic muscles via the thoracolumbar fascia 📖 Extrinsic back muscles produce and control limb and respiratory movements ❗️ → Superficial (posterior axio-appendicular): produce and control movement of limbs ❗️ → Intermediate (serratus posterior): for respiration and proprioception SUPERFICIAL EXTRINSIC LAYER Figure 26. Atlanto-axial joint [Lecture PPT] Three atlanto-axial articulations 📖 → Permits the head to move from side to side → Lateral atlanto-axial joints (2) ▪ Left and right atlanto-axial joints ▪ Gliding-type synovial joints ▪ Between the inferior facets and lateral masses of C1 and the superior facets of C2 ▪ Two facet joints at the articulating processes of vertebral arch → Median atlanto-axial joint (1) ▪ Pivot joint ▪ Between the dens of C2 and anterior arch of the atlas Figure 29. Superficial Extrinsic Back Muscles [Netter’s] ▪ At odontoid process and the anterior arch of atlas ANATOMY Deep Back Page 11 of 21  Includes the posterior axioappendicular muscles (trapezius, latissimus dorsi, levator scapulae, and rhomboids) →These muscles connect the axial skeleton (vertebral column) with the superior appendicular skeleton (pectoral girdle and humerus) →Innervated by the anterior rami of cervical nerves which act on the upper limb → Produce and control limb movements Table 5. Superficial Extrinsic Back Muscles. Muscle Description Trapezius Shape: Large and triangular Innervation: Spinal accessory nerve (CN XI) Action: → Superior fibers: elevate scapula → Middle fibers: retract scapula → Inferior fibers: depress scapula Latissimus Shape: Large and fan-shaped dorsi Innervation: Thoracodorsal nerve Action: Elevate and rotates scapula Rhomboid Shape: Quadrate major and → Rhomboid major is thin, flat, and wider minor Innervation: Dorsal scapular nerve Action: retracts scapula and rotates glenoid fossa INTERMEDIATE EXTRINSIC LAYER For respiration and proprioception 📋📋 SERRATUS POSTERIOR Figure 30. Intermediate Extrinsic Back Muscles [Netter] Wing-like, long, and thin muscles Action: proprioception and respiration Found in different part of the thoracic wall 📋 “True back muscles” 📣 B. INTRINSIC (DEEP) BACK MUSCLES 📣📋 Thoracolumbar fascia - found underneath the serratus SERRATUS POSTERIOR SUPERIOR posterior muscles and it covers the entire back Located deep in relation to the rhomboid muscles Everything deep to your thoracolumbar fascia Innervated by the intercostal nerves SERRATUS POSTERIOR INFERIOR Located deep in relation to the latissimus dorsi Table 6. OINA of Serratus Posterior Serratus posterior Serratus posterior superior inferior Superior Nuchal ligament, Spinous processes Attachment spinous process of of T11-L2 vertebrae C7-T3 vertebrae Inferior Superior borders of Inferior borders of Attachment 2nd-4th ribs 8th-12th ribs near their angles Innervation 2nd-5th intercostal Anterior rami to Figure 31. Thoracolumbar Fascia [Netter] nerves T9-T12 thoracic SUPERFICIAL INTRINSIC LAYER spinal nerves Main action Proprioception Proprioception (elevates the ribs) (depresses the ribs) Figure 32. Muscles of the superficial intrinsic layer [Moore] ANATOMY Deep Back Page 12 of 21  SPLENIUS Most superficial back muscle ❗️ Thick and flat muscle at the upper portion 📖 LONGISSIMUS Forms the intermediate column From the iliac crest all the way up to the mastoid process Lies on the lateral and posterior aspect of the neck, 📋 covering the vertical muscles somewhat like a bandage One muscle with two leaves (bipennate): 📖 or the base of the skull 📋 Only muscle that extends from the pelvis to the area of mastoid process in the skull → Splenius cervicis: ends at C1-C3/C4 SPINALIS cervical vertebrae 📣 ▪ Inserts to the transverse processes of the upper Forms the medial column → Splenius capitis: extends to the mastoid process of skull Several short muscles that transverse three to four segments of the vertebral spine, upward and downward In between the spinous process from lumbar to thoracic 📋 of the skull going to the mastoid processes The splenius leaves are NOT EXCLUSIVE TO ONE SIDE. 📣 ▪ Inserts in the more lateral aspect of inferior nuchal line and within cervical region 📣❗️ It is one whole muscle that has a splenius cervicis and splenius capitis parts on each side. Table 7. OINA of Splenius Muscle Proximal Nuchal ligament and spinous Attachment processes of C7 to T3 or T4 vertebrae Distal Splenius capitis: Fibers run Attachment superolaterally to mastoid process of temporal bone and lateral third of superior nuchal line of occipital bone Splenius cervicis: Tubercles of transverse processes of C1-C3 or C4 Nerve Supply Main action vertebrae Posterior rami of spinal nerves ❗️ Acting alone: laterally flex neck and Figure 34. Erector Spinae Muscles [Moore] rotates head to side of active muscles Table 8. OINA of Erector Spinae Muscle Acting together: extend neck and Proximal Arises by a broad tendon from head Attachment posterior part of iliac crest, posterior surface of sacrum, sacro-iliac INTERMEDIATE INTRINSIC LAYER ligaments, sacral and inferior lumbar spinous processes, and supraspinous ligament Distal Iliocostalis: lumborum, thoracis, Attachment cervicis; fibers run superiorly to angles of lower ribs and cervical transverse processes Longissimus: thoracis, cervicis, capitis; fibers run superiorly to ribs between tubercles and angles to transverse processes in thoracic and cervical regions and to mastoid process of temporal bone Spinalis: thoracis, cervicis, capitis; fibers run superiorly to spinous processes in the upper thoracic region Nerve Supply Main action and to cranium Posterior rami of spinal nerves ❗️ Acting bilaterally: extend vertebral Figure 33. Erector Spinae Muscles [Netter] column and head; as back is flexed, ERECTOR SPINAE MUSCLES control movement via eccentric At the back, there is a narrow furrow at the median or the contraction, “small of the back” and on each side of it, there is a Acting unilaterally: laterally flex 📣 “muscular hump” which is ideally where the erector spinae vertebral column muscles are Chief extensors of the vertebral column ❗️ 📋 column ❗ Chief extensors of the vertebral Often referred to as the “long muscles” of the back DEEP INTRINSIC LAYER: MAJOR LAYER Dynamic (motion-producing) muscles Combination of three muscles: iliocostalis, longissimus, spinalis Collective muscles ❗️called transversospinalis group of Forms the lateral column ILIOCOSTALIS adjacent vertebrae 📣 → Called “transversospinalis” because it transverses → From the transverse processes to the spinous “Ilio” from iliac crest and “costalis” to the ribs processes ANATOMY Deep Back Page 13 of 21  Attachment Fibers pass obliquely superomedially to entire length of spinous processes ❗️ located 2-4 segments superior to proximal attachment Nerve Supply Main action Extension ❗️ Posterior rami of spinal nerves Stabilizes the vertebrae during local movements of vertebral column ROTATORES Smallest of the 3 muscles in the deep intrinsic major layer From the transverse process below to the spinous process above Will allow for a little bit of rotation of the vertebral column Table 11. OINA of Rotatores Muscle Figure 35. Deep Intrinsic Muscle Layer [Lecturer’s PPT] Arises from transverse processes of Proximal vertebrae; best developed in thoracic SEMISPINALIS Attachment region 📋 Most superficial of the deep intrinsic major layer muscles Fibers pass superomedially to attach to junction of lamina and transverse cervical area and to the base of the skull 📣 Upper thoracic transverse processes all the way up to the Distal Attachment process or spinous process of vertebra immediately (brevis) or 2 segments From transverse processes of C4-T12 vertebrae Supports the cervical vertebrae 📣 Considered part of the intermediate group 📣 attachment ❗️ (longus) superior to vertebra of Three part muscle named based on superior attachments SEMISPINALIS CAPITIS Nerve Supply Extension ❗️ Posterior rami of spinal nerves Stabilizes the vertebrae and assists Superomedial occipital bone Becomes the roof of the suboccipital triangle ❗️ Main action with local extension and rotary movements of vertebral column; may 📖 Forms a palpable longitudinal bulge at the back near the median plane function as organs of proprioception SEMISPINALIS CERVICIS Spinous process of the cervical vertebrae SEMISPINALIS THORACIS Spinous process of the thoracic vertebrae Note: Be specific when naming the semispinalis (ex. semispinalis cervicis, capitis, or thoracis) Table 9. OINA of Semispinalis Muscle Proximal Attachment Distal the C4-T12 vertebrae ❗️ Arises from transverse processes of Thoracis, cervicis, capitis; fibers run Attachment superomedially to occipital bone and spinous processes in thoracic and cervical regions, spanning 4-6 segments Nerve Supply Main action Extension ❗️ Posterior rami of spinal nerves Extends head and thoracic and Figure 36. Rotatores Muscles [Netter] cervical regions of vertebral column and rotates them contralaterally MULTIFIDUS Thickest at the lumbosacral area of support → Because it has to support the area there ❗️ Come from the transverse process below to a spinous process 1 or 2 spaces above Table 10. OINA of Multifidus Muscle Proximal Arises from posterior sacrum, PSIS of Attachment ilium, aponeurosis of erector spinae, sacro-iliac ligaments, mammillary processes of lumbar vertebrae, transverse processes of T1-T3, Distal articular processes of C4-C7 Thickest in lumbar region ❗️ ANATOMY Deep Back Page 14 of 21  DEEP INTRINSIC LAYER: MINOR LAYER Aid in lateral flexion of vertebral Main action column; acting bilaterally, stabilizes vertebral column LEVATORES COSTARUM 📋 Serve as connections between the medial portions of the ribs and spinal column Table 14. OINA of Levator costarum Muscle Proximal Tips of transverse processes of C7 and Attachment T1-T11 vertebrae Distal Pass inferolaterally and insert on rib Attachment between tubercle and angle Posterior rami of C8-T11 spinal Nerve Supply nerves Elevate ribs; assisting respiration; Main action assist with lateral flexion of vertebral column C. SUBOCCIPITAL REGION Figure 37. Deep intrinsic muscle layer: minor layer [Netter] Note: These are not part of the back, but still considered as part of the minor deep layer. INTERSPINALES 📋 Serve as connections between the spinous processes of each vertebra 📣 Aids in extension and rotation of the vertebral column In between spinous processes Table 12. OINA of Interspinales Muscle Proximal Superior surfaces of spinous process Attachment of cervical and lumbar vertebrae Inferior surface of spinous processes Distal of vertebra superior to vertebra of Attachment proximal attachment Nerve Supply Posterior rami of spinal nerves Aid in extension and rotation of Main action vertebral column INTERTRANSVERSARII In between transverse processes 📣 📋 Serve as connections between the transverse processes of each vertebra 📋 Posterior intertransversarii muscles of the neck are Figure 38. Suboccipital Triangle [Netter] elevators of the ribs A muscle “compartment” deep to the superior part of the Innervated by both posterior and anterior rami of spinal posterior cervical region, underlying the trapezius, nerves (exception since ALL deep back muscles are innervated by the posterior rami of spinal nerves only) ❗ sternocleidomastoid, splenius, and semispinalis → Splenius ends up on top of the semispinalis capitis 📣 Table 13. OINA of Intertransversarii Muscle Proximal Transverse processes of cervical and line 📣 → Semispinalis capitis is attached to the superior nuchal Attachment Distal lumbar vertebrae Transverse processes of adjacent suboccipital triangle 📣❗️ ▪ Removal of semispinalis capitis exposes the Pyramidal or triangular in space inferior to the external Attachment vertebrae Nerve Supply ❗️ Posterior and anterior rami of spinal nerves posterior aspect of the C1 and C2 vertebrae 📖 occipital prominence of the head that includes the ANATOMY Deep Back Page 15 of 21  SUBOCCIPITAL MUSCLES Innervated by the posterior rami of C1 or suboccipital Periosteal branches: Outside of arteries 📣 Sacral area: Iliolumbar, lateral, and medial sacral 📣 nerve Among the four suboccipital muscles, the obliquus Nutrient branches 📣 Equatorial branches: Feed deeper into vertebral bodies attachment to the cranium 📖❗️ capitis inferior is the ONLY capitis muscle with no vertebral foramen and the structures inside 📣 Spinal branches: From segmental arteries that supply the When you remove the splenius and semispinalis muscle, BLOOD SUPPLY OF THE BACK you will reveal the suboccipital muscle Similar to the blood supply of vertebrae Table 15. OINA of Suboccipital Muscles Origin Insertion Table 17. Blood supply to the back muscles ❗️ Border Structure Rectus capitis Spinous process Lateral part of Cervical Occipital, vertebral, and deep cervical posterior major of vertebra C2 inferior nuchal arteries line of occipital Thoracic Posterior intercostal bone Lumbar Subcostal and lumbar Rectus capitis Posterior tubercle Medial part of Sacral Iliolumbar and lateral sacral posterior minor of posterior arch inferior nuchal of vertebra C1 line of occipital B. VENOUS DRAINAGE (atlas) bone The venous drainage in the back has a lot of networks and Obliquus Transverse Occipital bone is very rich capitis superior process of C1 between → Anterior and posterior external vertebral venous superior plexus & inferior nuchal lines Surrounds the entire vertebral column 📣 → Anterior and posterior internal venous plexus Obliquus capitis inferior Posterior tubercle of posterior arch Transverse process of C1 Plexuses communicate through IV foramina and are densest on the anterior and posterior sides 📋 of vertebra C2 (axis) (atlas) Intervertebral veins → These are veins going through the vertebral bodies → Drain into vertebral, intercostal, lumbar, and lateral 📣 SUBOCCIPITAL TRIANGLE Filled with loose connective tissue to accommodate the sacral veins Basivertebral veins 📋 passage of: → Suboccipital nerve (C1) ❗️ → Form within the vertebral bodies → Drain into the anterior external and especially the → Vertebral artery ❗️ ▪ Nerve supply to the suboccipital muscles ▪ Pierces through the posterior atlanto-occipital anterior internal venous plexuses Venous drainage is very rich in the back, thus spinal anesthesia in the region requires the thinnest needle 📣 membrane possible to avoid hemorrhaging into the subarachnoid ▪ Branch of the 1st part of the subclavian artery space Table 16. Borders of suboccipital triangle ❗️ Aspect of Structure Triangle Superomedial Rectus capitis posterior major Superolateral Obliquus capitis superior Inferolateral Obliquus capitis inferior Floor Posterior atlanto-occipital membrane and posterior arch of vertebra C1 Roof Semispinalis capitis Contents Vertebral artery and suboccipital nerve VI. NEUROVASCULATURE A. BLOOD SUPPLY Figure 39. Venous drainage of vertebral column [Moore] C. NERVE SUPPLY ❗️ BLOOD SUPPLY OF THE VERTEBRAE Blood supply are mainly branches from the aorta Spinal nerves will distribute according to their levels → Aorta courses anterior to the vertebral body so it will be Posterior rami → Supplies cutaneous and motor innervation of back column 📋 giving off branches that would supply the vertebral muscles Intertransversarii muscle, which is not part of the back MAJOR CERVICAL ARTERIES muscles but considered to be part of the minor deep layer, Supplies the cervical areas is innervated by BOTH posterior and anterior rami Vertebral and ascending cervical arteries → Includes the occipital artery from the external carotid, 📋 vertebral artery from the subclavian artery, and deep cervical artery from the costocervical trunk MAJOR SEGMENTAL ARTERIES Thoracic area: Posterior intercostal Lumbar area: Subcostal and lumbar ANATOMY Deep Back Page 16 of 21  b. Multifidus c. Semispinalis d. Splenius 9. At which region of the vertebral column is rotation most restricted? a. Lumbar b. Thoracic c. Cervical ANSWER KEY 1. B The erector spinae muscles are the chief extensors of the vertebral column and are divided into three columns: the iliocostalis forms the lateral column, the longissimus forms the 2. A medial column. 📖 intermediate column, and the spinalis forms the The obliquus capitis inferior is indeed a Figure 40. Nerves of posterior cervical region [Moore] D. LYMPHATIC DRAINAGE misnomer because it does not attach to the skull, despite the name "capitis" suggesting ❗️→ Everything above this point will drain into the Posterior Iliac crest: Point of reference for the lymphatic drainage otherwise, as it is only attached to the cervical vertebrae (C1 and C2). axillary lymph nodes 3. C The atlantoaxial joint is a pivot joint, allowing → Everything below this point will drain into the Inguinal for the rotational movement of the head, which is crucial for turning the head from side to side. lymph nodes (drains anteriorly) Skin and neck lymph drain into cervical nodes 📋 4. B. False In order to access the vertebral canal from the back (posterior approach), you need to go VII. REVIEW QUESTIONS through the posterior ligaments, including the 1. They are considered as the chief extensors of the supraspinous, interspinous, and ligamentum vertebral column. flavum. This is done to perform spinal a. Transversospinalis muscles anesthesia or for taking a sample from the spinal b. Erector Spinae muscles fluid. c. Suboccipital muscles 5. A. The transverse ligament primarily maintains the 2. Which of the following structures is considered as a stability of the atlantoaxial joint, allowing for misnomer? controlled head movement while preventing a. Obliquus capitis inferior