OT Abdominal Region 2.12 & 2.13 PDF

OT Abdominal Region 2.12 & 2.13 OT Anatomy Lecture Units 2.12 & 2.13 Instructor: Julie Meachen, Ph.D. SUGGESTED READING: Clinically Oriented Anatomy, 7th Edition Moore, Agur, and Dalley, pp. 187-193; 311-312....

OT Abdominal Region 2.12 & 2.13 OT Anatomy Lecture Units 2.12 & 2.13 Instructor: Julie Meachen, Ph.D. SUGGESTED READING: Clinically Oriented Anatomy, 7th Edition Moore, Agur, and Dalley, pp. 187-193; 311-312. ABDOMINAL REGION STUDENT OBJECTIVES: At the end of this section you will be able to: 1. Identify and understand the muscular layers of the abdominal wall, including origins, insertions, innervations, and actions. 2. Describe and understand the rectus sheath and its components. 3. Identify the posterior muscles of the abdominal wall, including the origins, insertions, innervations and actions. OUTLINE: I. MUSCULAR LAYERS OF THE ANTERIOR ABDOMINAL WALL 1. External oblique Origin: External surfaces of ribs 5-12 Insertion: Linea alba, pubic tubercle, and anterior half of iliac crest Action: compress and support abdominal viscera; flex and rotate trunk Innervation: thoraco-abdominal nerves (anterior rami of T7-T11) and subcostal nerve (T12) 2. Internal oblique Origin: Thoracolumbar fascia, anterior 2/3 of iliac crest, and connective tissue deep to inguinal ligament Insertion: Inferior borders of ribs 10-12, linea alba and pubis via conjoint tendon Action: compress and support abdominal viscera; flex and rotate trunk Innervation: Thoraco-abdominal nerves (anterior rami of T7-T11) and first lumbar nerve (L1) 3. Rectus abdominus Origin: Pubic symphysis and pubic crest Insertion: Xiphoid process and costal cartilages 5-7 Action: Flexes trunk (lumbar vertebrae) and compresses abdominal viscera (can act as an antagonist to the diaphragm. Stabilizes and controls pelvic tilt (antilordosis) Innervation: Thoraco-abdominal nerves (anterior rami of inferior six thoracic nerves) 1  OT Abdominal Region 2.12 & 2.13 Important differences: Above the arcuate line the internal oblique tendons split, and muscles wrap anteriorly (external oblique & half internal oblique) and posteriorly (transversus abdominus & half internal oblique) equally around the rectus abdominus. Below the arcuate line the tendons fuse and muscles wrap only anteriorly around the rectus abdominus leaving only the transversalis fascia and the parietal peritoneum holding in the viscera. This makes this area weaker and prone to hernias. 4. Transversus abdominus Origin: Internal surfaces of ribs 7-12 costal cartilages, thoracolumbar fascia, iliac crest, and connective tissue deep to inguinal ligament. Insertion: Linea alba with aponeurosis of internal oblique, pubic crest and pectin pubis via conjoint tendon. Action: Compresses and supports abdominal viscera Innervation: Thoraco-abdominal nerves (anterior rami of T7-T11) and first lumbar nerve (L1) IV. POSTERIOR ABDOMINAL WALL MUSCULATURE 1. Psoas major Origin: transverse processes of lumbar vertebrae; sides of vertebral bodies of T12-S1 Insertion: lesser trochanter of femur Innervation: anterior rami of lumbar nerves L1-L3 Action: Acting inferiorly – flexes thigh; acting superiorly – flexes vertebral column laterally to balance trunk; when sitting acts inferiorly to flex trunk 2. Psoas minor Origin: sides of vertebral bodies of T12-L1 Insertion: Pectineal line and iliopubic eminence Innervation: L1 Action: weak trunk flexor 3. Iliacus Origin: superior two thirds of iliac fossa, ala of sacrum and anterior sacro-iliac ligaments Insertion: lesser trochanter of femur and shaft inferior to it. Innervation: femoral nerve (L2-L4) Action: flexes thigh and stabilizes hip joint; acts with psoas major 4. Quadratus lumborum Origin: medial half of inferior border of 12th rib and tips of lumbar transverse processes Insertion: iliolumbar ligament and internal lip of iliac crest Innervation: anterior branches of T12 and L1-L4 nerves Action: extends and laterally flexes vertebral column. Fixes 12th rib during inspiration. 2  OT Abdominal Region 2.12 & 2.13 Formative Assessment & Practice Exam Questions: 1. What is the action of the rectus abdominus muscle? A. Rotates trunk B. Flexes trunk & compress abdominal viscera C. Compresses diaphragm D. Tense the linea alba E. Lateral trunk flexion 2. You have a patient come in with pain in their left side after a bad bicycle accident. After running some diagnostic tests, you decide that they are having pain at the origin of their external oblique muscle. Where is this pain located, specifically? A. anterior 2/3 of the iliac crest B. Internal surfaces of ribs 7-12 costal cartilages C. Pubic symphysis and pubic crest D. Linea alba and pubic tubercle E. External surfaces of ribs 5-12 3. A patient comes into your office complaining of pain when they flex their left thigh, but not when they flex their trunk or when they bend to the left or right side. They also have some pain in the left hip when they are walking and standing. These symptoms tell you that your patient has likely injured their _________________ muscle. A. Quadratus lumborum B. iliacus C. psoas major D. psoas minor E. diaphragm Answers: 1) B; 2) E; 3) B 3 SUGGESTED READING: Clinically Oriented Anatomy 7th Ed (or more recent edition). Moore, Dalley, and Agur, LWW. 2014. pp. 482-496. OBJECTIVES 1. Describe the attachments and actions of the intrinsic back muscles as described in this handout. 2. Describe the muscles, boundaries and contents of the suboccipital triangle. 3. Identify the nerves, arteries, and muscles in the suboccipital region. 4. List the actions and attachments of the muscles of the suboccipital region. 5. Describe the development of the intrinsic back muscles. INTRINSIC BACK MUSCLES—primary action is on the axial skeleton Innervated by regional dorsal primary rami of spinal nerves Review axial movements (Fig. I.5, pp. 7–11) Can act unilaterally or bilaterally o bilateral action of all intrinsic back muscles is extension of the vertebral column and/or head and neck depending on attachments Superficial Group (Table 4.4, p. 485) o splenius capitis & cervicis ▪ origin: spinous processes of C7–T6 and nuchal ligament ▪ insertion: splenius capitis: mastoid process of temporal bone splenius cervicis: transverse processes of C1–3 ▪ unilateral action: laterally flex and rotate head ipsilaterally Intermediate Group (Table 4.5, p. 486) o erector spinae ▪ all share an origin, insertions differ ▪ fibers run superolaterally ▪ all share a unilateral action: laterally flex vertebral column ipsilaterally ▪ origin: iliac crest, sacrum, lumbar spinous processes, & ligaments in region ▪ iliocostalis insertion: angle of ribs and cervical transverse processes divided into three parts (lumborum, thoracis, cervicis) depending on location/attachments o lumborum: lower ribs o thoracis: upper ribs o cervicis: cervical transverse processes ▪ longissimus insertion: ribs between tubercles & angles, transverse processes of thoracic and cervical vertebrae, mastoid process of temporal bone  divided into three parts (thoracis, cervicis, capitis) depending on location/attachments o thoracis: transverse processes of thoracic vertebrae o cervicis: transverse processes of cervical vertebrae o capitis: mastoid process of temporal bone ▪ spinalis insertion: spinous processes of superior thoracic and cervical vertebrae, occipital bone divided into three parts (thoracis, cervicis, capitis) depending on location/attachments o thoracis: spinous processes of thoracic vertebrae o cervicis: spinous processes of cervical vertebrae o capitis: indistinct; usually blends with the semispinalis capitis Deep Group (Table 4.6, p. 489) o transversospinalis group ▪ all share a unilateral action: rotate axial skeleton contralaterally ▪ in general, fibers run superomedially from transverse to spinous processes ▪ semispinalis capitis & cervicis (and thoracis) unilateral action: rotates head/neck contralaterally origin: transverse processes of thoracic and lower cervical vertebrae insertion: occipital bone (semispinalis capitis); spinous processes of thoracic and cervical vertebrae (semispinalis cervicis) o semispinalis cervicis terminates at the spinous process of C2 o span 4–6 vertebral segments semispinalis thoracis is poorly developed ▪ multifidus action: assists in stabilization of vertebrae during locomotion origin: sacrum, ilium (PSIS), mammillary processes of lumbar vertebrae insertion: spinous processes of thoracic and lumbar vertebrae o span 2–4 vertebral segments o best developed in the lumbar region, but also present in thoracic and cervical regions ▪ rotatores longi & breves action: assists in stabilization and rotation of vertebrae origin: transverse processes insertion: spinous process or lamina o rotatores longi span 2 vertebral segments (singular: rotator longus) o rotatores breves attach to the vertebra immediately superior (1 segment) (singular: rotator brevis) o best developed in the thoracic region deep accessory muscles o assist other muscles in extension, rotation, lateral flexion, & stabilization of vert column ▪ interspinales  assist in extension ▪ intertransversarii assist in lateral flexion, stabilization ▪ levatores costarum elevate ribs and assist in respiration assist in lateral flexion Group Actions (Tables 4.7 & 4.8 pp. 490–1) – Just another way of categorizing info from above… flexion [will be covered later] other muscles not associated with the back assist in extension, lateral flexion, and rotation; these will be covered at a later date extension o cervical and cranial ▪ trapezius ▪ levator scapulae ▪ splenius capitis & cervicis ▪ longissimus capitis ▪ iliocostalis cervicis ▪ semispinalis capitis and cervicis ▪ multifidus o thoracic and lumbar ▪ erector spinae ▪ multifidus lateral flexion o cervical and cranial ▪ splenius capitis & cervicis ▪ longissimus capitis & cervicis ▪ iliocostalis cervicis ▪ intertransversarii o thoracic and lumbar ▪ longissimus thoracis ▪ iliocostalis thoracis & lumborum ▪ multifidus rotation o cervical and cranial ▪ splenius cervicis (ipsilateral) ▪ semispinalis capitis & cervicis (contralateral) ▪ multifidus (contralateral) ▪ rotatores (contralateral) o thoracic and lumbar ▪ iliocostalis (ipsilateral) ▪ longissimus (ipsilateral) ▪ multifidus (contralateral) ▪ rotatores (contralateral) DEVELOPMENT  derived from myotomes [for review of myotome development review Early Development and Vertebral Column lectures] o myotome divides into a dorsal and ventral mass ▪ dorsal—epimere becomes intrinsic back muscles ▪ ventral—hypomere becomes hypaxial muscles (e.g., abdominals, intercostals, etc.) SUBOCCIPITAL REGION Pyramidal region inferior to external occipital protuberance Muscles assist in rotation and extension of the head, maintenance of posture, & proprioception Muscles (Table 4.9, p. 493) o rectus capitis posterior major ▪ origin: spinous process of C2 ▪ insertion: inferior nuchal line of occipital bone ▪ actions: extension and ipsilateral rotation o rectus capitis posterior minor ▪ origin: posterior tubercle of C1 ▪ insertion: inferior nuchal line of occipital bone ▪ action: extension and ipsilateral rotation o obliquus capitis inferior ▪ origin: spinous process of C2 ▪ insertion: transverse process of C1 ▪ action: ipsilateral rotation of head o obliquus capitis superior ▪ origin: transverse process of C1 ▪ insertion: occipital bone ▪ action: extension and lateral flexion of head Nerves ** DO NOT confuse these nerves with roots simply because they are primarily cutaneous or motor! These nerves are rami of spinal nerves, so they all contain autonomics (motor) and proprioceptive components (sensory). o greater occipital nerve (dorsal ramus of C2) ▪ skin over posterior neck and head ▪ primarily cutaneous o suboccipital nerve (dorsal ramus of C1) ▪ muscles of suboccipital region ▪ primarily somatic motor o dorsal ramus of C3 (sometimes called “least occipital nerve” or “third occipital nerve)) ▪ motor to intrinsic back muscles and sensory to overlying skin o lesser occipital nerve (branch of the ventral ramus of C2 from cervical plexus) ▪ scalp posterior to the ear and skin of postero-lateral neck (primarily cutaneous) **this nerve is not technically within the suboccipital region, however we will probably see it in lab Arteries  o vertebral artery branch of subclavian ▪ pierces atlanto-occipital membrane to ultimately supply brain and spinal cord o occipital artery branch of external carotid Suboccipital triangle o borders: ▪ superomedial: rectus capitis posterior major ▪ superolateral: obliquus capitis superior ▪ inferolateral: obliquus capitis inferior ▪ floor: atlanto-occipital membrane and posterior arch of C1 ▪ roof: semispinalis capitis o contents: vertebral artery and suboccipital nerve (dorsal ramus of C1) Quiz Yourself 1. The suboccipital nerve is formed by a. ventral ramus C1 b. dorsal ramus C1 c. ventral ramus C2 d. dorsal ramus C2 e. dorsal ramus C3 2. Which of the following muscles is not part of the erector spinae group? a. iliocostalis b. longissimus c. splenius d. spinalis 3. Which of the following muscles is not innervated by a dorsal rami? a. iliocostalis b. longissimus c. splenius d. spinalis e. rhomboid minor 4. What makes up the inferolateral border of the suboccipital triangle? a.rectus capitis posterior major b. obliquus capitis superior c. obliquus capitis inferior d. semispinalis capitis e. trapezius 5. Which artery accompanies the suboccipital nerve in the suboccipital triangle? a. vertebral artery b. thoracodorsal artery c. dorsal scapular artery d. subclavian artery e. posterior intercostal artery ANS: 1-b, 2-c, 3-e, 4-c, 5-a SUGGESTED READING: Relevant chapters from Clinically Oriented Anatomy. Moore, Dalley, and Agur, LWW. OBJECTIVES 1. Describe the surface anatomy of the back in relation to the muscles and bony prominences. 2. Understand the shape of the main shoulder joints and movement at those joints. 3. Describe movements of the scapula and the extrinsic back muscles responsible for those movements. 4. Describe the origins, insertions, innervation, and actions of the extrinsic back muscles. 5. Identify arteries present in the superficial back and describe their spatial relationship to other structures. OSTEOLOGY Review vertebrae from previous lecture. The extrinsic back muscles attach to the humerus, scapula, clavicle, vertebrae, and cranium. You should be able to identify the attachments sites noted in the muscles section below, otherwise more detailed osteology of those bones will be covered in subsequent sections. JOINTS Glenohumeral joint o Movement of the arm o Ball-in-socket, multiaxial o Extremely mobile, weak and not very stable Acromioclavicular joint o Relatively weak planar joint with limited mobility o Some rotation occurs with scapular movements Sternoclavicular join o Mobile, saddle joint surrounded by strong ligaments o Movement occurs with all scapular motions FASCIA superficial fascia (subcutaneous tissue) o deep to skin, primarily adipose tissue o varies in thickness throughout the body; often very thick in lower back deep fascia o dense connective tissue lying deep to superficial fascia investing fascia o extensions of deep fascia that surround muscles and neurovascular bundles EXTRINSIC BACK MUSCLES—primary action is on the upper limb and rib cage Many extrinsic back muscles insert onto the scapula which has slightly different movements than the rest of the upper limb (Table 6.5, Fig. 6.25, p. 702) o elevation vs. depression o protraction vs. retraction o superior vs. inferior rotation Superficial group (Table 6.4, pp. 700–701) o trapezius ▪ ORIGIN: external occipital protuberance, nuchal ligament, spinous processes of lower cervical and thoracic vertebrae (C7–T12) ▪ INSERTION: lateral 1/3 of clavicle, scapular spine, acromion process ▪ ACTIONS: different segments of the muscle produce different actions descending fibers: elevate scapula (extend and laterally flex neck when shoulders are fixed) middle fibers: retracts scapula ascending fibers: depress scapula ascending and descending fibers work together to superiorly rotate the scapula ▪ INNERVATION: CN XI (accessory n.) ▪ Clinical Correlate: injury to spinal accessory nerve (CN XI) vulnerable to injury in the neck proximal to innervation of trapezius results in paralysis of the trapezius and possibly sternocleidomastoid mm shoulder noticeably lower at rest due to unresisted pull of gravity patient will be unable to abduct upper limb above the shoulder due to severely weakened superior scapular rotation o latissimus dorsi ▪ ORIGIN: spinous processes of lower thoracic vertebrae (T7–12), thoracolumbar fascia ▪ INSERTION: anterior humerus (floor of intertubercular sulcus), [sometimes angle of scapula] ▪ ACTIONS: adducts, extends, and medially (internally) rotates humerus ▪ INNERVATION: thoracodorsal n. o levator scapulae ▪ ORIGIN: transverse processes of cervical vertebrae (C1–4) ▪ INSERTION: medial border of the scapula superior to scapular spine ▪ ACTIONS: elevates and inferiorly rotates scapula; assists in extension of neck ▪ INNERVATION: dorsal scapular n. o rhomboid major ▪ ORIGIN: spinous processes of upper thoracic vertebrae (T2–5) ▪ INSERTION: medial border of scapula inferior to scapular spine ▪ ACTIONS: retract and elevate scapula ▪ INNERVATION: dorsal scapular n. o rhomboid minor ▪ ORIGIN: spinous processes of lower cervical and upper thoracic vertebrae (C7–T1)  ▪ INSERTION: medial border of scapula at root of scapular spine ▪ ACTIONS: retract and elevate scapula ▪ INNERVATION: dorsal scapular n. Deep group (Table 1.2, p. 88) o serratus posterior superior ▪ ORIGIN: spinous processes of lower cervical & upper thoracic vertebrae (C7–T3) ▪ INSERTION: superior borders of upper ribs (ribs 2–4) ▪ ACTIONS: elevate ribs (superior), proprioception ▪ INNERVATION: local intercostal nerves (ventral primary rami) o serratus posterior inferior ▪ ORIGIN: spinous processes of lower thoracic & upper lumbar vertebrae (T11–L2) ▪ INSERTION: inferior border of lower ribs (ribs 8–12) ▪ ACTIONS: depress ribs (inferior), proprioception ▪ INNERVATION: local intercostal nerves (ventral primary rami) Clinical Correlate: triangle of auscultation triangular space deep to which is devoid of large muscles making it an ideal place to listen to posterior lungs overlies the 6th intercostal space borders: o inferior: latissimus dorsi o medial: trapezius o lateral: medial border of scapula o Clinical Correlate: lumbar triangle triangular space between latissimus dorsi and external abdominal oblique, lacks muscular reinforcement making it prone to lumbar hernias borders: o inferior: iliac crest o medial: latissimus dorsi o lateral: external abdominal oblique INNERVATIONS Motor/Muscular superficial extrinsic back muscles (except trapezius!!) receive innervation from the brachial plexus, which supplies the upper limb o dorsal scapular and thoracodorsal nerves are branches of the brachial plexus o trapezius is innervated by a cranial nerve (CN XI—accessory nerve) deep extrinsic back muscles receive innervation from local intercostal nerves from ventral primary rami of spinal nerves Sensory/Cutaneous Innervation to skin of back primarily from posterior cutaneous branches of dorsal rami of spinal nerves o develop from dermatomes = area of skin supplied by a single spinal nerve /cord segment  o overlap, but can be used to test for neurologic deficits VASCULATURE primary blood supply to extrinsic back muscles is from branches of subclavian and axillary aa o transverse cervical and dorsal scapular from subclavian ▪ note that sometimes dorsal scapular a comes off transverse cervical a, and can be considered the deep branch of the transverse cervical o thoracodorsal from axillary blood is also supplied by regional intercostal arteries veins accompany arteries and go by the same names Quiz Yourself 1. Which of the following is NOT a primary action of trapezius? a. scapula elevation b. scapula depression c. superior rotation of scapula d. inferior rotation of scapula e. extend the neck 2. Which of the following arteries accompanies the accessory nerve? a. thoracodorsal a b. dorsal scapular a c. transverse cervical a d. subclavian a e. axillary a 3. An injury to the thoracodorsal nerve would affect all of the following, except: a. adduction of the arm b. extension of the arm c. medial rotation of the arm d. protraction of the scapula 4. The deep extrinsic muscles of the back are innervated by what nerve? a. ventral rami of intercostal nerves b. dorsal rami of intercostal nerves c. accessory nerve d. thoracodorsal nerve e. dorsal scapular nerve 5. What is the primary action of the deep extrinsic back muscles? a. scapula rotation b. scapula retraction c. erection of the back d. rotation of the arm e. assist with respiration ANS: 1-d, 2-c, 3-d, 4-a, 5-e SUGGESTED READING: Clinically Oriented Anatomy 7th Ed. Moore, Dalley, and Agur, LWW. 2014. pp. 46-57, 496-501 OBJECTIVES 1. Understand some key terms related to nervous system. 2. Understand that a spinal nerve exits at each vertebral level, carrying sensory and motor fibers, and divides into dorsal and ventral rami. 3. Be able to describe the anatomical concept of dermatomes and myotomes. INTRODUCTION TO NERVOUS SYSTEM Plexus = a collection of nerve fibers Central Nervous System (CNS) o Brain & Spinal Cord Peripheral Nervous System (PNS) o Connects the CNS to limbs & organs via spinal nerves and cranial nerves (including both somatic and autonomic fibers) SPINAL CORD – CENTRAL NERVOUS SYSTEM Extends from cranium (brain) exiting via foramen magnum to L1/L2 vertebra SPINAL NERVES – PERIPHERAL NERVOUS SYSTEM 31 pairs of spinal nerves – exit vertebral column via intervertebral foramina o 8 cervical: C1`-C8 ▪ Cervical spinal nerve exits above the vertebra of the same number until C8, then spinal nerves exit below vertebra of same number o 12 thoracic: T1-T12 o 5 lumbar: L1-L5 o 5 sacral: S1-S5 o 1 coccygeal (Co1) Dermatomes o Strip of skin innervated by a single spinal nerve level o Individual dermatomes overlap, but there are several key dermatomes used as landmarks to test for neurological damage. Myotomes o Muscle mass receiving motor innervation from a single spinal nerve o Individual myotomes control certain actions Note – spinal nerves are a single spinal level, while named peripheral nerves (e.g., femoral nerve) can be composed of nerve fibers from multiple spinal levels (femoral n = L2-L4).  Clinical Correlate: Herpes zoster (Shingles) infection o Can lie dormant in dorsal root ganglia of spinal nerves, but when becomes active manifest as rash and pain in the dermatome of the affected spinal nerve ANATOMY OF A TYPICAL SPINAL NERVE o Spinal nerves carry both efferent (motor) & afferent (sensory) fibers o Spinal nerves immediately divide into ventral and dorsal rami o Dorsal rami provide motor and sensory innervation to intrinsic back muscles, overlying skin, and joints o Ventral rami – everything else. ▪ Form nerve plexuses (networks) at places to create new multisegmental peripheral nerves (i.e., named nerves that carry fibers from multiple spinal levels – e.g., femoral nerve arises from lumbar plexus and contains fibers from L2-L4). o Dorsal and ventral rami also contain BOTH motor & sensory fibers Quiz Yourself 1. The spinal cord ends at what vertebral level? a. T12 b. L1/L2 c. L4/L5 d. S1 e. S4/S5 2. Which of the following terms describes a strip of skin innervated by a single spinal level? a. Dorsal ramus b. Ventral ramus c. Myotome d. Dermatome e. Plexus ANS: 1-b, 2-d Associated Reading Clinically Oriented Anatomy, 7th ed. (or more recent edition), Moore, Dalley, and Agur, 2013, pp. 440–482 Objectives 1. Describe which vertebra are palpable using anatomical landmarks. 2. Describe the characteristics of a “typical” vertebra. 3. Distinguish features of cervical, thoracic, lumbar, and sacral vertebrae, including any specialized vertebrae within each region. 4. Describe the number of vertebrae present in each region and deviations from those typical numbers. 5. Describe the significance of the lumbosacral angle. 6. Describe and discuss major joints and ligaments of the vertebral column including their morphology and function. 7. Describe and characterize normal and abnormal curvatures of the vertebral column. Lecture Outline I. 33 total vertebrae A. 7 cervical (C1–7) B. 12 thoracic (T1–12) C. 5 lumbar (L1–5) D. 5 sacral (S1–5) 1. fused into one structure, the sacrum E. 2–4 coccygeal (Co1–4) 1. often fused into one bone, the coccyx F. the number of vertebrae in each region can sometimes vary 1. cervical region is the most constant in terms of number of vertebrae 2. thoracic, lumbar, and sacral regions can vary in number, however if one region has an extra vertebra, another one will often have one fewer 3. different disciplines differ in how they refer to regional variations (see discussion under “sacrum” below) II. function: weight-bearing, protection of spinal cord, movements of trunk III. Surface anatomy A. C7: base of the neck 1. “vertebra prominens” B. T3: level of the scapular spine C. T7: inferior angle of scapula D. T12: last rib E. L4: iliac crest F. S2: posterior superior iliac spine (PSIS) IV. Components of a “typical” vertebra A. vertebral body  B. vertebral arch 1. pedicle 2. lamina C. spinous process D. transverse processes E. articular processes and facets F. related structural elements 1. vertebral foramen/canal 2. intervertebral foramina a. formed by superior and inferior notches b. passageway for spinal nerves V. Regional morphology A. cervical 1. bifid spinous process (most) 2. small body 3. horizontal articular facets 4. transverse foramina for vertebral arteries 5. uncinate processes to protect against over-lateral flexion 6. C1: atlas a. no body b. no spinous process c. atlanto-occipital joint = mostly flexion & extension (“yes”) 7. C2: axis a. odontoid process (= dens) b. atlanto-axial joint = mostly rotation (“no”) 8. C7: vertebra prominens B. thoracic – by definition have attachments for ribs 1. costal facets on tips of transverse processes and bodies for attachment of ribs a. T1 has one whole facet and one demi-facet (inferiorly) b. T2–T9 have two demi-facets, one superior and one inferior i. Ribs articulate to vert body of its own # and the one above, and to the transverse process of its own # (e.g., rib 5 articulates with vertebral bodies T4 & T5 and transverse process of T5) c. T11 & T12 have one whole facet on their body (no facets on their transverse processes) 2. Sup & inf articular facets oriented anteriorly/posteriorly 3. heart-shaped body C. lumbar 1. spinous process short and deep 2. transverse processes short 3. large body 4. curved, sagittally-oriented articular facets, limiting rotation 5. mammillary processes D. sacrum  1. 5 fused vertebrae 2. median sacral crest: fused spines 3. lateral sacral crest: fused transverse processes 4. sacral hiatus, inferior opening above coccyx 5. sacrum can sometimes comprise 6 or 4 fused elements a. when 6 elements are fused this is typically due to a fusion of L5 with the sacrum, resulting in only 4 free lumbar vertebrae i. referred to as “sacralization” of L5 b. when 4 elements are fused this is typically due to a failure of S1 to fuse with the rest of the sacral vertebrae and there will be 6 free pre-sacral vertebrae i. referred to as “lumbarization” of S1 VI. Curvatures A. vertebral column has four normal curvatures, two anteriorly concave and two posteriorly convex B. allow head and center of mass to be centered over the pelvis while providing strength and flexibility C. primary 1. a single primary kyphosis is present in the fetus reflecting the flexed position of the trunk during development D. secondary 1. secondary curvatures (lordosis) develop as children begin to develop an adult posture and form of locomotion E. normal 1. lordosis—posteriorly concave a. cervical, lumbar b. secondary 2. kyphosis—posteriorly convex a. thoracic, sacral b. primary F. abnormal 1. you will hear the terms “lordosis” and “kyphosis” to describe pathological conditions, but recognize that both types of curvatures are normal and that pathological expressions represent exaggerated or excessive curvatures 2. excessive thoracic kyphosis a. e.g. dowager’s hump (p. 480) b. osteoporosis leads to brittle vertebrae which are prone to compression fractures c. compression fractures of successive thoracic vertebrae lead to an exaggerated thoracic kyphosis d. most common in elderly women 3. excessive lordosis a. increased anterior loading (as in pregnancy or with increased abdominal fat) causes center of mass to shift anteriorly b. individual compensates by leaning back to shift weight back to center  c. puts strain on intervertebral discs and ligaments, especially anterior longitudinal ligament d. can lead to lumbar instability and lower back pain 4. scoliosis a. lateral vertebral curvature usually accompanied by vertebral torsion G. lumbosacral angle a. strong lordosis of lumbar region combined with strong kyphosis of sacral region results in a posterior angle at the junction of two regions i. creates an anterior loading vector at point of maximum loading of the vertebral column ii. increases risk of injury at this location VII. Intervertebral discs A. permit movement between adjacent vertebral bodies B. act as shock absorbers C. disc structure 1. annulus fibrosus a. fibrocartilaginous ring running the circumference of the disc b. thickest anteriorly c. thinnest posteriorly 2. nucleus pulposus a. semi-fluid center of intervertebral disc b. provides much of the flexibility of the disc 3. axial loading causes compression of the disc and bulging of the nucleus pulposus and anulus fibrosus outward 4. bending causes compression on one side and tension on the other 5. increased loading while bending anteriorly (flexing) can lead to excessive pressure on and rupture of the stretched posterior surface of the anulus fibrosus VIII. Vertebral ligaments A. anterior longitudinal 1. prevents hyperextension B. posterior longitudinal 1. prevents hyperflexion 2. very narrow C. supraspinous 1. located between dorsal spinous processes D. interspinous 1. located between adjacent spinous processes E. intertransverse 1. located between transverse processes F. ligamentum flavum 1. yellow in color (flavus = L. yellow) 2. located on ventral aspect of vertebral arch between adjacent laminae 3. help resist sudden separation of laminae, maintain normal vertebral curvature G. ligamentum nuchae (nuchal ligament)  1. spans from the external occipital protuberance to spinous processes of cervical vertebrae 2. serves as site of muscle attachment H. atlanto-axial ligaments 1. alar ligament a. attaches odontoid process to occipital bone b. limits lateral flexion and rotation of head 2. cruciate ligament a. transverse ligament of the atlas i. holds dens against anterior arch of atlas ii. prevents anterior of displacement of C1 on C2 b. superior longitudinal band i. connects transverse ligament to occipital bone c. inferior longitudinal band i. connects transverse ligament to body of C2 I. tectorial membrane a. superior continuation of the posterior longitudinal ligament b. wider and thicker in this region that inferiorly Quiz Yourself 1. Which of the following ligaments runs between adjacent vertebral laminae? a. anterior longitudinal b. posterior longitudinal c. supraspinous d. interspinous e. ligamentum flavum 2. Which of the following vertebrae will have transverse foramina? a. C3 b. T1 c. T6 d. L4 e. S1 3. Rib 3 would articulate to the costal facet on the transverse process of which vertebra? a. T1 b. T2 c.T3 d.T4 e. T5 4. When shaking your head “no”, which vertebra is primarily responsible for that range of motion? a. C1 b. C2 c. C7 d. T1 ANS: 1-e, 2-a, 3-c, 4-b