Spinal Nerves - Chapter 14b PDF

Dermatome (section of skin): D for dorsal; area of skin innervated by the nerves coming out of a single spinal root or from the spinal nerve coming out of a spinal cord segment Sometimes dermatomes overlap. They are responsible from the coordination of senses. Myotome (section of muscle): M for...

Dermatome (section of skin): D for dorsal; area of skin innervated by the nerves coming out of a single spinal root or from the spinal nerve coming out of a spinal cord segment Sometimes dermatomes overlap. They are responsible from the coordination of senses. Myotome (section of muscle): M for motor; refers to group of muscles innervated by the nerves of a single spinal root or by a single spinal nerve from a spinal cord segment. Some are innervated by more than one spinal nerve. Responsible for the coordination of voluntary muscle movement.  Referred Pain: Visceral and somatic sensory together enter at the same level of the spinal cord, so brain perceives pain from heart as originating from the dermatome of that level.  Main plexuses: cervical, brachial, lumbar, and sacral Innervates anterior neck muscles and skin, portions of head and shoulders Spinal Nerves: Brachial Plexus: C5-T1 Superior trunk Middle trunk Inferior trunk  No thoracic plexus: these are called intercostal nerves and go directly to walls of thorax and pursue and independent course. Spinal Nerves: Lumbar Plexus The lumbar plexus is formed from the anterior rami of spinal nerves L1-L4 (or L2-L4) obturator nerve, femoral nerve Lumbo-sacral” trunk Sacral plexus – L4-S3 – innervates gluteal region, pelvis, perineum, posterior thigh, most of leg and foot Forms sciatic nerve (made of 5 nerve roots) which divides into: – Tibial nerve – Fibular nerve or common fibular nerve or peroneal nerve or common peroneal nerve Spinal Nerves: Sacral Plexus  Sciatica: injury to sciatic nerve – Characterized by extreme pain down posterior thigh and leg Clinical – May be caused by herniated intervertebral disc View: Sacral – Common: L4-L5 Common fibular/peroneal nerve: Plexus – Prone to injury due to fracture of neck or compression from cast Injuries – May cause paralysis of anterior and lateral leg muscles – Person unable to dorsiflex and evert the foot 18  Characteristics of Reflexes Reflexes: are involuntary responses – Stimulus to initiate reflex – Response is rapid: a chain of only a few neurons – Response Preprogrammed: always the same – Response involuntary A reflex is a survival mechanism Can be monosynaptic or polysynaptic Reflex Arc: 5 Steps  Reflexes to Know 1. Stretch Reflex 2. Stretch (monosynaptic) + Reciprocal Inhibition (polysynaptic) 3. Golgi Tendon 4. Withdrawal-Crossed Extension  Patellar reflex test https://www.youtube.com/watch?v =Ll8r5i0eaT8 Achille’s reflex/ankle jerk reflex www.youtube.com/watch?v= BEQ6BbLLucA  Biceps tendon reflex www.youtube.com/watch?v=KUtD5 TVjc6A  Triceps tendon reflex www.youtube.com/watch?v=2-Ny0 Bi3VGk Planar reflex/Babinski www.youtube.com/watch?v= kOq5Np0eZ6A  Pupillary light reflex www.youtube.com/watch?v=iTncbh fbl6A Neurological assessment of all cranial nerves www.youtube.com/ watch?v=jdRJqbB0 ZyA