Spinal Nerves. Spinal Nerves. Protection. Spinal Cord. Spinal Nerves. Conduct sensory and motor impulses

Transcription

1 Spinal Nerves Conduct sensory and motor impulses Spinal Nerves originating in the periphery, carry impulses to the spinal cord what occurs at the spinal cord? carry impulses from the spinal cord to effectors what are the effectors? what occurs there? Vertebrae Meninges continuous with the brain meninges Dura Mater tough, dense irregular CT down to S2 (cord ends at ) Protection continuous with epineurium (outer covering of spinal and cranial ) Arachnoid Mater thin, loose collagen and elastic fibers subdural space is between dura and arachnoid, interstitial fluid Pia Mater thin, collagen and elastic fibers adheres to brain and spinal cord denticulate ligaments connect pia to arachnoid and dura to prevent movement of the meninges Spinal Cord from medulla oblongata to inches long 3/4 inch diameter widest at lower cervical and mid lumbar cervical enlargement C4-T1 lumbar enlargement T9-T12 conus medullaris, filum terminale, anchors to coccyx subarachnoid space is between pia and arachnoid, CSF Spinal Nerves 31 pairs mixed emerge from the intervertebral foramina named for the segment where they arise 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal Cervical plexus Brachial plexus Cervical enlargement Intercostal Lumbar enlargement Lumbar plexus Sacral plexus Cauda equina Cervical C 1 C 8 Thoracic T 1 T 12 Lumbar L 1 L 5 Sacral S 1 S 5 Coccygeal Co 1

2 Nerve Roots bundles of axons connect the spinal to the spinal cord dorsal root - sensory axons dorsal root ventral root - motor axons roots exit/enter through the intervertebral foramina (to approx T12) Cauda Equina - lumbar, sacral and coccygeal roots Dorsal ramus of spinal Ventral ramus of spinal Spinal Rami communicantes Sympathetic trunk Gray matter White matter Ventral root Dorsal and ventral rootlets of spinal cord is shorter than vertebral column Anterior view showing spinal cord, associated, and vertebrae. The dorsal and ventral roots arise medially as rootlets and join laterally to form the spinal. Spinal Nerves Coverings of spinal C1 - occipital bone/c1 (atlas) C2- - exit above their vertebrae - exits between and T1 T1- - exit below their vertebrae -S5, Co1 - enter sacral canal -S4 - exit via anterior and posterior sacral foramina endoneurium - wraps axon fascicle - group of axons perineurium - wraps fascicle epineurium - wraps, fuses with meninges S5, Co1 - exit via sacral hiatus Distribution of spinal sensory and motor roots exit cord unite to form a pass through intervertebral foramina begins to branch Ramus = branch / Dorsal ramus - branches to deep muscles and skin of posterior trunk Anterior / Ventral ramus - branches to muscles and structures of upper and lower limbs, skin of lateral and anterior trunk meningeal branch - reenters vertebral cavity through intervertebral foramina Dorsal ramus Ventral ramus Spinal Rami communicantes Sympathetic trunk Intercostal Ventral root Branches of intercostal Lateral cutaneous Anterior cutaneous Sternum supplies vertebrae, vertebral ligaments, blood vessels of spinal cord and meninges other small branches involved in the ANS (b) Cross section of thorax showing the main roots and branches of a spinal.

3 Plexus axons from anterior rami of spinal C1-T1, -Co1 form networks cervical plexus, brachial plexus, lumbar plexus, sacral plexus, coccygeal plexus emerge from the plexuses, with names of the region they serve (ie. ulnar, radial, femoral etc) will have several branches to innervate structures in their region -T12 - no plexus, run directly to the structures they innervate -T12 anterior rami of -T12 - intercostal/thoracic innervates intercostal muscles of second intercostal space, skin of axilla and posteromedial arm T3-T6 innervate intercostal muscles and skin of anterior and lateral chest wall T7-T12 innervate intercostal muscles and abdominal muscles and the overlying skin posterior rami -T12 supply the deep back muscles and skin of the posterior thorax

4 Cervical Plexus Ventral rami anterior rami of roots from C1-C4 skin of head, neck, superior shoulders and chest muscles of head, neck, superior shoulders and chest phrenic - to diaphragm Hypoglossal (XII) Lesser occipital Greater auricular Transverse cervical Ansa cervicalis Accessory (XI) Segmental branches Ventral rami: C 1 C 2 C 3 C 4 some branches to cranial 11 and 12 Phrenic Supraclavicular C 5 Figure 13.8 Sensory Branches: Cervical Plexus Lesser Occipital - from C2 - skin of scalp posterior and superior to ear Great Auricular - from C2, C3 - skin anterior, inferior, and over ear, and over parotid glands Transverse Cervical - from C2, C3 - skin over anterior neck Supraclavicular - from C3, C4 - skin over superior portion of chest and shoulder Motor Branches Cervical Plexus Ansa Cervicalis Superior - from C1 - to infra hyoids and geniohyoid muscles Ansa Cervicalis Inferior - from C2, C3 - to infra hyoid muscles Phrenic - from C3, C4, - to diaphragm Segmental Branches - from C1 to - to neck muscles, levator scapula, middle scalenes Brachial Plexus anterior rami of roots from -T1, innervates shoulders and arms passes above rib 1, posterior to clavicle to enter axilla roots unite to form Superior, Middle and Inferior TRUNKS (in inferior neck) each trunk divides into an anterior and posterior DIVISION (posterior to clavicle) unite to form Lateral, Medial and CORDS (in axilla) Cords Lateral Medial Axillary Musculocutaneous Radial Median Ulnar Dorsal scapular Nerve to subclavius Suprascapular (a) Roots (rami C 5 T 1 ), trunks,, and cords Roots (ventral rami): C 4 C 5 C 6 C 7 C 8 T 1 Upper Middle Lower Long thoracic Trunks Medial pectoral Lateral pectoral Upper subscapular Lower subscapular Thoracodorsal Medial cutaneous of the arm and forearm NERVES branch from the cords Anterior Trunks Roots

5 Brachial Plexus Axillary Anterior Trunks Roots Axillary, - deltoid, teres minor Musculocutaneous,, - anterior arm muscles Radial -T1 posterior arm and forearm muscles Medial -T1 anterior forearm muscles and some hand muscles Ulnar -T1 anteromedial forearm muscles and most hand muscles other smaller branches: dorsal scapular, long thoracic, to subclavius, suprascapular, lateral pectoral, upper subscapular, thoracodorsal, lower sub scapular, medial pectoral, medial cutaneous of arm, medial cutaneous of forearm Humerus Radial Musculocutaneous Ulna Radius Ulnar Median Radial (superficial branch) Dorsal branch of ulnar Superficial branch of ulnar Digital branch of ulnar Muscular branch Median Digital branch (c) The major of the upper limb Lumbar Plexus anterior rami of roots from - not as complex as brachial plexus supplies the anterolateral abdominal wall, external genitals, part of the lower limb Iliohypogastric - - muscles of anterior abdominal wall, skin of inferior abdomen and buttock Ilioinguinal - - muscles of anterolateral abdominal wall, skin of sup and med thigh, some skin of genitals Genitofemoral -, - cremaster muscle, skin over middle anterior thigh, some skin of genitals Lateral Cutaneous -, L3 - skin over lateral, anterior and posterior thigh Femoral -, L3, - hip flexors, knee extensors, skin over anterior and medial thigh, medial leg and foot Obturator -, L3, - hip adductors, skin over medial thigh anterior rami of roots from -S4 Sacral Plexus supplies buttocks, perineum, lower limbs coccygeal plexus - S4, S5, Co1 - small area of skin in coccygeal region Superior Gluteal -,, - glut min, glut med, TFL Inferior Gluteal -,, S2 - glut max Nerve to Piriformis -, S2 - piriformis Nerve to Quadratus Femoris and Inferior Gemellus -,, Nerve to Obturator Internus and Superior Gemellus -,, S2 Perforating cutaneous - S2, S3 - skin over inf medial buttocks cutaneous of thigh -, S2, S3 - skin over anal region, inf lateral buttock, sup post thigh, superior calf, some genitals Sciatic - -S3 - hamstrings, adductor magnus, 2 - Tibial and Common Fibular (splits at knee) Sacral Plexus Tibial - -S3 - gastrocnemius, plantaris, soleus, popliteus, tib post, flex dig longus, flex hallucis longus, medial plantar, lateral plantar Common Fibular - -S2-2 branches: Superficial fibular - fibularis longus and brevis, skin of distal 1/3 anterior calf and dorsum foot Deep Fibular - tib ant, ext hallucis longus, fibularis tertius, ext dig longus and brevis, skin on first and second toes Pudendal - S2-S4 - muscles of perineum, some genital skin

6 Dermatomes area of skin that provides sensory input to the CNS via one pair of spinal specific predictable segments of the body supplied by each somatic sensory C4 T1 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 S2 S3 C2 C3 C2 C3 C4 T1 T3 T4 T5 T6 T7 T8 T9 T10 S2 S3 S4 S5 T11 T12 L3 dermatomes overlap with the ones beside it L3 L3 S2 S2 knowing which spinal segment supplies which area of skin (dermatome) helps to locate damaged regions of spinal cord L3 ie. no sensation in a particular spot = supplying that area are damaged Anterior view (b) view