A&P - Neuroanatomy PDF

Welcome to A&P – Neuroanatomy Nursing (HTHSCI 1H06) Dr. Danielle Brewer-Deluce, PhD Health Sciences & iBioMed Asst. Professor (HTHSCI 2F03) Dept of Pathology & Molecular Medicine Engineering (HTHSCI 2L03)...

Welcome to A&P – Neuroanatomy Nursing (HTHSCI 1H06) Dr. Danielle Brewer-Deluce, PhD Health Sciences & iBioMed Asst. Professor (HTHSCI 2F03) Dept of Pathology & Molecular Medicine Engineering (HTHSCI 2L03) Education Program in Anatomy Midwifery (HTHSCI 1D06 [email protected]  B PNS Lesions For each lesion site indicate: - what information (sensory/motor) will be lost - Which region of the body * (ventral/dorsal) will be affected C A: _____________________ D A B: _____________________ C: _____________________ D: _____________________ E: _____________________ E PNS & Plexuses A quick recap  Basal Ganglia Motor System - Simplified Centralized program calling motor subroutines Corticospinal Tract Sends info from brain to body Cerebellum Modulates motor plans based on sensory (vestibular, visual and proprioceptive) inputs Corticospinal Corticobulbar Motor Vs Sensory Tracts Motor Descending 2 neuron path (brain to SC) Corticospinal (lateral + anterior) Corticobulbar (head & neck) Sensory Ascending 3 neuron path (SC to brain) Spinothalamic (pain & temp) DCML (touch, pressure, proprioception) Pain Control pain relayed through spinothalamic tract Pain Endogenous gate interneuron Spinal Cord Gate (inhibitory) Pain Control pain relayed through spinothalamic tract Pain Endogenous Spinal Cord Gate Reticular Formation Activation (endorphins) endorphins RAS descending neuron Pain Control pain relayed through spinothalamic tract Pain Endogenous Spinal Cord Gate Reticular Formation Activation (endorphins) Exogenous NSAIDs & Opiates Spinal Cord Reflexes Patellar Tendon reflex The spinal cord acts as an integrating center for some reflexes. A reflex is a fast, involuntary, unplanned sequence of actions in response to a particular stimulus. 1. Quad → Quad = 2. Quad → Hamstrings = monosynaptic reflex polysynaptic reflex Purpose: 1. Solidify your understanding of spinal cord anatomy 2. Bridge the gap between Neuro and MSK Learning Outcomes By the end of this lesson you will be able to… Describe how the CNS and PNS interface at the Spinal Cord Label specific anatomical components of the spinal cord/nerves Define the term “plexus” and describe how it is made and why it’s functionally important Understand the structure and the role of the brachial plexus in the upper limb Be able to draw and label a brachial plexus diagram Hypothesize implications of lesions at various sites throughout the plexus Spinal Cord Spinal Cord White Matter = Transmission Periphery Longitudinal Tracts of Axons Sensory (to brain) Sensory Motor (from Brain) Gray Matter = Connections Motor Central “H” Contains: Neuron Cell Bodies Glial Cell Bodies Dorsal Horn = SENSORY Ventral Horn = MOTOR Spinal Cord & Nerves Dorsal Horn Ventral Horn Spinal Cord & Nerves Dorsal Root Ganglion Sensory Dorsal Root Dorsal Horn Dorsal Rami Ventral Horn Ventral Rami Motor Spinal Nerve Ventral Root Spinal Cord & Nerves Structure Contents Ventral Root Dorsal Root Dorsal Root Ganglion Spinal Nerve Ventral Rami Dorsal Rami Spinal Rami Dorsal (posterior) Rami: Deep back muscles Zygapophyseal joints Ventral (anterior) Rami: Everything else! Thoracic Region  SPINAL NERVES Spinal Nerves are Mixed dorsal sensory root dorsal ramus epineurium ventral ramus sensory and spinal cord motor axons spinal ventral nerve motor root autonomic fibers Autonomic: Sympathetic Taken from a Thoracolumbar level = sympathetic 50% sensory 40% autonomic Taken from cervical/sacral 10% motor level = parasympathetic  Spinal Cord Dorsal Rami Ventral Rami Spinal Cord in Situ spinal cord is shorter than the vertebral canal spinal cord ends at conus medullaris vertebral level L2 nerve roots extend further via cauda equina L1-L2  Column = # vertebrae Cord = # spinal nerve pairs Spinal Colum + Nerves Cervical 7 8 C8 Thoracic 12 12 5 5+1 Lumbar 5 Sacrum + 5 fused + 1 Coccyx Total 30 31 Spinal Nerve Naming Spinal Nerve Naming: C8 Cervical: vertebra  C8: between C7 and T1 Thoracic/Lumbar: vertebra  Dermatomes Spinal levels supplying CERVICAL areas of skin Brachial Plexus: (sensory) C5 - C8 THORACIC Intercostals: T1 - T12 LUMBAR Lumbar Plexus: L2 - L5 SACRAL Sacral Plexus: S1 – S4 Plexuses Plexus & Peripheral Nerves Brachial Plexus Anterior Rami merge with other anterior rami from other spinal levels to form a network called a “plexus” Multisegmental peripheral nerves emerge from the other side of the plexus Cervical, Brachial, Lumbar & Sacral Major Plexuses cervical plexus (C1 – C4) (motor & sensory to head, neck & trunk) brachial plexus (C5 - T1) (motor & sensory to upper limbs) lumbosacral plexus (L2 - S4) (motor & sensory to lower limbs) Spinal Cord White Matter: Periphery Longitudinal Tracts of Axons Sensory (to brain) Motor (from Brain) Gray Matter: Central “H” Contains: Neuron Cell Bodies Glial Cell Bodies Dorsal Horn = SENSORY Ventral Horn = MOTOR Spinal Cord White Matter: Motor and Sensory tracts are largest superiorly as motor information hasn’t left, and all the sensory info has accumulated Grey Matter: More grey matter in areas where plexuses are forming (not thoracic) because more information is coming in/going out = more synapses + cell bodies Lateral horn in thoracic region carries sympathetic information To Summarize… The Spinal cord contains Motor information travelling from the brain to the periphery via the anterior (ventral) root Sensory information travelling from the periphery to the brain via the posterior (dorsal) root Information travelling via the ventral rami creates peripheral nerves Plexuses form when spinal nerves of various levels combine The spinal cord ends at L2 in conus medullaris, the continuing spinal nerves = cauda equina To Summarize SUPERIOR Denticulate ligament Spinal nerve Anterior (ventral) ramus Posterior (dorsal) ramus Pedicle of vertebra Anterior (ventral) rootlets (cut) Posterior (dorsal) rootlets Anterior (ventral) root Posterior (dorsal) root Dura mater and arachnoid mater (b) Anterior view and oblique section of spinal cord Brachial Plexus The Brachial Plexus Anterior Rami from C5-T1 join together Clinically important for diagnosing upper limb injury and disease 5 portions: Roots Trunks Divisions Cords Branches “really thirsty, drink cold beer!”  C5 Brachial Plexus C6 C7 Trunks = Joining together of 2+ spinal levels U (anterior rami) C8 M Divisions = Separation of flexor & extensor medial T1 lateral nerves L Extensors to the back posterior Flexors to the front Axillary Artery Roots: C5 – T1 Trunks: Upper, Middle, Lower axillary Divisions: Anterior & Posterior musculocutaneous radial Cords: Medial, Lateral, Posterior median Branches: Radial, Axial, Musculocutaneous, Median, Ulnar ulnar  Roots C4 C5-T1 Trunks C5 Brachial Plexus Divisions U, M, L C6 Ant/Post Cords C7 Lat, Med, Post C8 T1 Branches PERIPHERAL NERVES Axillary teres minor, deltoid (C5-C6) Radial posterior compartments (C5-T1) Musculocutaneous arm flexors (C5-7) “Really Median Thirsty, Drink forearm flexors (C5-T1) Cold Beer” Ulnar forearm flexors (C8-T1)  Roots Trunks Divisions Cords Branches Anterior/posterior C4 Musculocutaneous Lateral C5 Upper C5 C6 C6 Middle Axillary C7 Median Posterior C7 Radial C8 Lower T1 T1 Medial Ulnar T2  Lat. Pectoral Musculocutaneous Suprascapular C5 C6 Axillary C7 Thoracodorsal Median Radial C8 Upper & Lower Subscapular T1 Med. Pectoral Ulnar Long Thoracic  Lat. Pectoral Musculocutaneous Suprascapular C5 C6 Axillary C7 Thoracodorsal Median Radial C8 Upper & Lower Subscapular T1 Med. Pectoral Ulnar Long Thoracic Divisions of Flexion/Extension Flexion: decreases angle between bones at a joint Extension: increases angle between bones at a joint Extensor Compartment Nerves Axillary – Shoulder Radial – Post. Upper Limb Flexor Compartment Nerves Musculocutaneous: Ant Arm Ulnar: Ant Forearm/Hand – medial Median: Ant Forearm/Hand - lateral  Cutaneous Sensory Innervation Typically, the distal portion of a named nerve (motor comes off first) Musculocutaneous Median Ulnar Radial Axillary Peripheral vs Spinal C3 Nerves C5 C4 T2 T3 T4 C6 T2 T5 Radial C5 T1 Radial C6 C7 C8 Dermatomes = Origin (UMN) Peripheral Cutaneous = How (LMN) Where’s the Impairment? Lesion Site Axillary Radial Musculocutaneous Median Ulnar C5 Nerve Root ___________ X X Lower Trunk ___________ X X  Musculocutaneous C5 C6 Axillary C7 Median Radial C8 T1 Ulnar Paralysis vs Paresis Paralysis = total loss of motor function Paresis = partial loss of motor function (muscle weakness) In which of the above impairments is the loss a paralysis vs paresis? Why? *recall: sensory information will be lost in the same fashion as these are mixed spinal nerves carrying both sensory axons and motor axons Brachial Plexus Brachial plexus provides sensory + motor innervation to upper limb 5 spinal nerves (C5 – T1) create multi-segmental peripheral nerves radial, axillary, musculocutaneous, ulnar, median Peripheral nerves innervate specific muscle compartments and skin regions within the upper limb Dermatomes/Myotomes: WHERE the information originates (UMN) Peripheral Innervation maps: HOW the information gets to/from there (LMN)