Back and Spinal Cord HSC 360 Undergraduate Anatomy PDF

Back and Spinal Cord Dr. Meghan M. Moran HSC 360 Undergraduate Anatomy  Learning Objectives 1. Describe the vertebral column. 2. Number and identify the cervical, thoracic, lumbar, sacral and coccygeal vertebrae. 3. Name and identify the features of a typical vertebra. 4. Name unique features...

Back and Spinal Cord Dr. Meghan M. Moran HSC 360 Undergraduate Anatomy  Learning Objectives 1. Describe the vertebral column. 2. Number and identify the cervical, thoracic, lumbar, sacral and coccygeal vertebrae. 3. Name and identify the features of a typical vertebra. 4. Name unique features of the individual cervical, thoracic, lumbar, sacral and coccygeal vertebrae. 5. Describe the primary and secondary vertebral curvatures. 6. Be familiar with clinical correlations presented here. 7. Describe and identify landmarks of the spinal cord. 8. Name and identify the spinal meninges (dura mater, arachnoid membrane, pia mater), the denticulate ligaments and filum terminale. 9. Name and identify the spaces made by the meninges. 1. Identify and describe the location for a lumbar puncture to obtain cerebrospinal fluid. 10.Name and identify the regions of a spinal nerve. 11.Describe and identify the innervation of the back. 12.Describe the movements of the scapula, trunk and neck. 13.Name and identify the superficial back muscles and know the action. 14.Name and identify the erector spinae muscles and know the action.  Vertebral Column Cervical vertebrae. (n = 7) 1st prominent spinous process that is palpable is C7. Thoracic vertebrae. (n = 12) long spinous processes that point downward; ribs articulate with thoracic vertebrae. Lumbar vertebrae. (n = 5) largest vertebral bodies; covered by the erector spinae muscles. Sacrum. (n = 5) fused together; sacral hiatus is the location where the extradural space terminates. Coccyx. (number vary) can be palpated approximately 2.5 cm posterior to the anus. FUNCTIONS: Houses and protects spinal cord Supports weight of upper body Transmits force to lower limbs Coccyx Movement of trunk  Spinal Curvatures “S”-curve of the spine: Cervical curvature (Lordosis, secondary) - Lordosis = posteriorly concave - Kyphosis = posteriorly convex, ‘humpback’ Thoracic curvature A primary kyphosis of (Kyphosis, primary) the entire vertebral column is present at birth as a result of the flexed position of the Lumbar curvature developing fetus. (Lordosis, secondary) ‘swayback’= exaggerated Secondary (lordotic) curvatures curve in lower back develop in response to adoption of Sacral curvature a more adult (bipedal) posture (Kyphosis, primary) throughout childhood.  Scoliosis Scoliosis – abnormal lateral curvature & rotation May be due to muscular dominance of one side over the other or poor posture or congenital problems. Treatments: bracing during growth or surgery  Intervertebral notch (foramen) – allows Typical Vertebra passage of spinal nerves Vertebral foramen (canal) – allows passage of spinal cord Superior View Spinous process Lateral View Lamina Transverse Superior articular process Process Superior articular Vertebral facet Body foramen Body (Centrum) Spinous Pedicle process *Intervertebral notch Pedicle + lamina = vertebral (neural) arch Inferior articular facet (on the inferior articular process)  Intervertebral Discs The intervertebral discs permit 1- Annulus movement between adjacent fibrosus vertebral bodies and act as shock absorbers. Composed of 2 main parts: 1- Annulus fibrosus- tough exterior of the 2- Nucleus intervertebral disc, pulposus made of layers of fibrocartilage 2- Nucleus pulposus- soft, gelatinous central portion of the Intervertebral intervertebral disk that foramen moves within the disk with changes in posture Space for intervertebral The annulus fibrosus is thinner discs Hernia posteriorly, and consequently weaker in this region. This can lead to herniation of the nucleus pulposus and compression of the intervertebral foramen (& spinal Zygapophyseal nerve). (facet) joint  Articular tubercle Cervical Vertebrae Typical Cervical: C1 (Atlas): Horizontal Bifid spinous process position of articular facets C2 (Axis): Odontoid process Small (dens) body Uncinate process Transverse foramen allow Three specialized cervical vertebrae: 1- C1- is the atlas. passage of vertebral artery 2- C2- the axis. - has a tooth like projection called the dens- dens in Latin means tooth. 3- C7 -- vertebra prominens, has long spinous process that is easy to palpate  Articular tubercle Specialized Cervical C1 (Atlas): Vertebrae C2 (Axis): Odontoid process (dens) C7: Three specialized cervical vertebrae: 1- C1- is the atlas. 2- C2- the axis. - has a tooth like projection called the dens- dens in Latin means tooth. 3- C7- vertebra prominens, - has long spinous process that is easy to vertebra prominens palpate on the back of neck  Cervical Vertebral Joints Articular tubercle C1 (Atlas): Atlanto-occipital joint: Between the occipital bones of the skull and C1 atlas. C2 (Axis): MOTION- mainly flexion/extension Odontoid process Allows you to shake your head ‘yes’. (dens) Atlanto-axial joint: Between C1 and C2 vertebrae MOTION- mainly rotation of atlas on odontoid process. Allows you to shake your head ‘no’ (left/right, side-to-side)  Articulate with the ribs Thoracic Vertebrae Flat articular facets, oriented coronally Superior costal Transverse T1 facet costal facet (demifacet) Spinous process Downward transverse oriented Inferior costal process spinous Heart- facet process Pedicle Body (demifacet) shaped body Vertebral Lamina foramen Costo-transversal joint Transverse process of vert. + RIB RIB transverse facet joint of rib/tubercle. T12 Costo-vertebral joint Vertebral bodies + superior/inferior facets of rib (head of rib)  Lumbar Vertebrae, Sacrum & Coccyx 5 lumbar vertebrae Sacral 5 fused sacral vertebrae promontory 2 – 4 fused coccygeal vertebrae SACRUM LUMBAR Anterior sacral foramina Short & deep (“hatchet- shaped”) spinous process Mammillary Curved process articular facets Short Median transverse sacral crest processes Large bean- Posterior sacral shaped body foramina Sacral hiatus COCCYX  Surface Anatomy Trapezius Spine of scapula Spine of scapula Trapezius Teres major Teres major Medial border Angle of scapula Medial border Inferior angle of scapula of scapula of scapula Latissimus dorsi Latissimus dorsi Erector spinae Sacrum Erector spinae Posterior superior Posterior superior iliac spine iliac spine “sacral dimple”  Muscle Overview Splenius Erector spinae (n=3) Extrinsic (superficial) Originate on the back but primary action is elsewhere (e.g., upper limb) Trapezius Latissimus dorsi Levator scapulae Rhomboid major Intrinsic (deep) Rhomboid minor Deep to the extrinsic back muscles Muscles originate & insert on the back Primary action is on the vertebral column Innervated by dorsal primary rami Extrinsic Back Muscles  Extrinsic (superficial) muscles Trapezius Origin (O) = place that remains immobile for O – Occipital bone, nuchal ligament, spinous an action processes of cervical and thoracic vertebrae Insertion (I) = place is on the bone that I – Scapular spine, acromion process, 1/3 of moves during the action clavicle N – Accessory nerve (CN XI) A – varies by fibers: elevates, retracts, rotates, and depresses scapula Spinal accessory n. (CN. XI) Transverse cervical a. Scapular Movements (and Associated Muscles) Elevation Superior rotation Levator scapulae Trapezius Trapezius Serratus anterior (Rhomboid major & minor) Depression Retraction Trapezius Rhomboid major Pectoralis major & & minor minor Trapezius Serratus anterior (Gravity)  Extrinsic (superficial) muscles Latissimus Dorsi O – Spinous processes of lower thoracic vertebrae, thoracolumbar fascia I – Intertubercular sulcus (bicipital groove) of humerus N – Thoracodorsal nerve (C5-C7) A – Adducts, extends, and medially (internally) rotates humerus Supplied by Thoracodorsal nerve & artery Thoracolumbar fascia (Artery from Axillary artery)  Triangle of Auscultation BORDERS: Inferior—latissimus dorsi Medial—trapezius Trapezius Spine of scapula Lateral—medial border of scapula Teres Medial border major of scapula Rhomboid R6 major IC6 R7 Latissimus dorsi Triangle of auscultation Triangle of Erector spinae auscultation ** Overlies 6th intercostal space! The triangle of auscultation of the lungs is a relative thinning of the musculature of the back, situated along the medial border of the scapula. An important anatomical landmark that allows for better auscultation (listening) during the pulmonary examination to listen to the patient’s heart and lung sounds.  Extrinsic (superficial) muscles Levator Scapulae O – Transverse processes of upper cervical vertebrae I – Medial border/superior angle of scapula N – Dorsal scapular nerve (C5) Levator scapulae A – Elevates & inferiorly rotates scapula Rhomboid minor Rhomboid major & minor Rhomboid major O – Spinous processes of lower cervical & upper thoracic vertebrae I – Medial border of scapula N – Dorsal scapular nerve (C5) A – Retract and elevate scapula Levator and Rhomboids supplied by Dorsal scapular artery Branch of thyrocervical trunk Runs w/ dorsal scapular nerve Anastomoses w/ thoracodorsal artery Intrinsic Back Muscles  Muscle Overview Splenius Erector spinae (n=3) Extrinsic (superficial) Originate on the back but primary action is elsewhere (e.g., upper limb) Trapezius Latissimus dorsi Levator scapulae Rhomboid major Intrinsic (deep) Rhomboid minor Deep to the extrinsic back muscles Muscles originate & insert on the back Primary action is on the vertebral column Innervated by dorsal primary rami Intrinsic Back Muscles: Overview Extrinsic muscles Erector Spinae Transverse View: Superficial Group: Intermediate Group: Splenius (n=2) Erector Spinae (n=3) Posterior View:  Intrinsic (deep) muscles: Superficial Group Splenius O – Nuchal ligament & spinous processes of C7-T6 I – Mastoid process (1- capitis) & transverse 1. Splenius capitis processes of C1-C3 (2- cervicis) N – Local dorsal primary rami of spinal nerves 2. Splenius cervicis A – Extend head and neck (bilateral); laterally flex and rotate the head ipsilaterally (unilateral, same side) Splenius Splenius Splenius means ‘bandage’ cervicis capitis *** Lab tip: look at fiber directions!  Flexion Extension Lateral flexion (forwards) (backwards) Rotation Splenius Trapezius Iliocostalis Splenius (i) Longissimus Levator scapulae Semispinalis Semispinalis (c) Iliocostalis Splenius Longissimus iliocostalis (i) Longissimus All erector spinae longissimus (i) Iliocostalis i= Ipsilateral= same side c= contralateral= ‘other’ side  Intrinsic (deep) muscles: Intermediate Group Erector Spinae ILS 1. Illocostalis, 2. Longissimus, & 3. Spinalis Mneumonic: I Love Spaghetti! From lateral to medial O – iliac crest, sacrum, lumbar spinous processes, supraspinous lig Spinalis (S) I – Rib angles (iliocostalis); transverse processes (longissimus); spinous processes Longissimus (L) (spinalis) N – Local dorsal primary rami of spinal nerves A – Extend vertebral column (bilateral); Iliocostalis (I) laterally flex vertebral column (unilateral) Erector Spinae  Intrinsic (deep) muscles: Deep Group Transversospinalis Muscles: Semispinalis Semispinalis (Capitis, cervices, thoracis) O – Transverse processes (generally) I – Spinous processes (generally) Rotatores N – Local dorsal primary rami of spinal nerves (Longus, brevis) A – Extend and stabilize vertebral column (bilateral); Contralaterally rotate vertebral column (unilateral) ** Fibers run superomedially (opposite of erector Multifidus spinae) Transversospinalis Spinal Cord Spinal roots, nerves and rami Spinal ROOTS VENTRAL connect the peripheral nervous system to the spinal cord Paired dorsal and ventral roots The dorsal and ventral roots exit the lateral sides of the cord to form left and right spinal L R nerves. Spinal NERVES Spinal roots unite to form spinal nerves contain a mixture of sensory and motor neurons. near the intervertebral foramen 31 pairs of spinal nerves: 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccyx DORSAL Spinal RAMI Each spinal nerve splits/bifurcates into a dorsal primary ramus and ventral primary ramus contain a mixture of sensory and motor neurons. Dorsal primary rami supply the skin of the back as well as deep back muscles Ventral primary rami supply the torso as well as the upper and lower limbs.  ** three layers of connective tissue meninges called the Spinal meninges dura mater, the arachnoid mater, and the pia mater. 1. DURA MATER most superficial layer extends from the internal surface of the skull to the S2 vertebral The dura mater defines the epidural space and the subdural space. epidural space is located between the dura mater and the vertebral canal 2. ARACHNOID MATER intermediate meningeal layer attached to the underlying pia subarachnoid space is the cavity between the arachnoid and pial layers and contains cerebrospinal fluid spinal cord terminates in an adult at the L1-L2 3. PIA MATER deepest meningeal layer Denticulate ligaments. lateral extensions of the pia mater that support the entire spinal cord by attaching to the arachnoid and dura mater and maintaining a centralized location of the spinal cord in the subarachnoid space. Filum terminale. An extension of the pia mater beyond the tip of the spinal cord (conus medullaris) that attaches to the coccyx.  Spinal tap for CSF and Epidural Anesthesia To perform a lumbar puncture for cerebrospinal fluid (CSF) enter the L4 vertebral spine level deep to arachnoid. In subarachnoid space This is between the arachnoid and pia mater. Epidural anesthesia is placed in the epidural space. The epidural space is the area between the dura mater (a membrane) and the vertebral wall, containing fat and small blood vessels. The space is located just outside the dural sac which surrounds the nerve roots and is filled with cerebrospinal fluid Can be placed anywhere along the spine  Spinal meninges 3. PIA MATER deepest meningeal layer Denticulate ligaments. lateral extensions of the pia mater that support the entire spinal cord by attaching to the arachnoid and dura mater maintaining a centralized location of the spinal cord in the subarachnoid space. Gray’s Atlas of Anatomy Spinal meninges 3. PIA MATER deepest meningeal layer Filum terminale. An extension of the pia mater beyond the tip of the spinal cord (conus medullaris) that attaches to the coccyx. Think: Conus medullaris Filum terminale Cauda equina Gray’s Atlas of Anatomy  Meningitis An inflammation (swelling) of the protective membranes covering the brain and spinal cord (meninges). A bacterial or viral infection of the fluid surrounding the brain and spinal cord usually causes the swelling. One of the physically demonstrable symptoms of meningitis is Brudzinski's sign. Severe neck stiffness causes a patient's hips and knees to flex when the neck is flexed https://medlineplus.gov/ency/imagepages/19069.htm  Image Credits Copyright Notice: This presentation may contain copyrighted material used for educational purposes under the guidelines of Fair Use and the TEACH Act. It is intended only for use by students enrolled in this course. Reproduction or distribution is prohibited. Unauthorized use is a violation of the Rush University Integrity Code and may also violate federal copyright protection laws. Schuenke et al., 2007. THIEME Agur and Dalley. 2013. Moore, et al. 2014. Clinically Netter. 2014. Atlas of Human General Anatomy of the Grant’s Atlas of Anatomy, Oriented Anatomy, 7th ed. Anatomy, 6th Ed. Elsevier Musculoskeletal System. CD- 13th ed. Lippincott Williams Lippincott Williams & Wilkins Saunders. Rom. Thieme Medical & Wilkins / Wolters Kluwer / Wolters Kluwer Health. Publishers, Inc. Health.