Neuroanatomy of the Peripheral Nervous System PDF

Neuroanatomy Nick Hurst Picture: https://www.mmphysiotherapy.com/team-talk/peripheral-nerve-pain-explained.html Spinal Nerves The PNS conducts impulses to and from the CN...

Neuroanatomy Nick Hurst Picture: https://www.mmphysiotherapy.com/team-talk/peripheral-nerve-pain-explained.html Spinal Nerves The PNS conducts impulses to and from the CNS Contains both motor and sensory neurons Consists primarily of 31 pairs of nerves with connection to the spinal cord: - 8 Cervical - 12 thoracic - 5 Lumber - 5 Sacral  Voluntary & Involuntary Actions - With the help of the PNS, you are able to carry out voluntary and involuntary actions -Voluntary (somatic) – Picking up a cup, etc. - The somatic nervous system consists of afferent nerves or sensory nerves, and efferent nerves or motor nerves. -Involuntary (autonomic - Heart beating, digestion, intestinal motility, etc.). This system is divided into: Sympathetic nervous system – Fight or Flight - Prepares body for emergencies. It shunts your blood to your muscles and increases your blood pressure, heart rate and breathing rate Parasympathetic nervous system – Rest & Digest - Maintains and restores energy. It directs blood to the digestive tract, maintains blood pressure, heart rate and breathing rate at a low level The plexuses The cervical plexus provides nerve connections to the head, neck, and shoulder. The brachial plexus provides connections to the chest, shoulders, upper arms, forearms, and hands. The lumbar plexus provides connections to the back, abdomen, groin, thighs, knees, and calves. The sacral plexus provides connections to the pelvis, buttocks, genitals, thighs, calves, and feet https://www.msdmanuals.com/en-gb/home/brain,-spinal-cord,-and-nerve-disorders/peripheral-nerve-disorders/plexus-disorders  Cervical Nerves 7 Cervical vertebrae (C1-C7) BUT 8 Cervical nerves (C1-C8) C8 – emerges below C7 vertebrae Cervical Plexus (C1-C4) 2 groups – Muscular and sensory Cervical Plexus (C1-C4) – Motor branches Motor branches Located deeper than sensory branches Supply muscle of neck, back and diaphragm Phrenic nerve Arises from C3-C5 Motor innervation for the diaphragm https://www.sciencedirect.com/topics/engineering/phrenic-nerve C1. C2 and C3 Innovate: Sternohyoid muscle Sternothyroid muscle Omohyoid muscle (Via Ansa Cervicallis) Ansa Cervicallis Loop of nerves Part of the cervical plexus https://teachmeanatomy.info/neck/muscles/infrahyoid/  Other minor branches Supply muscle of neck and back C2-C3: Prevertebral muscles and sternocleidomastoid C3-C4: Levator scapulae, trapezius and scalenus mediu Cervical Plexus (C1-C4) – sensory branches Enter skin at posterior boarder of the sternocleidomastoid (Erb’s point) Supply the skin of the neck, upper thorax, scalp and ear  Greater Auricular nerve (C2,C3) Sensation to external ear Sensation over parotid gland Transverse Cervical nerve (C2.C3) Sensation to anterior neck Lessor Occipital nerve (C2) Sensation to posterosuperior scalp Supraclavicular nerves (C3,C4) Sensation over supraclavicular fossa Sensation upper thoracic region and stenoclavicular joint https://neupsykey.com/plexuses/  Brachial plexus (C5-T1) Network supplies skin and musculature of upper limb Begin in the neck, passes through axilla to the upper extremities Divided into 5 parts Roots, Trunks, Divisions, Cords, Branches Read That Damn Cadaver Book Roots Each pair leave the spinal cord via intervertebral foramina Each pair divides in to posterior and anterior ramus Posterior innervate the skin and muscle of the back https://teachmeanatomy.info/upper-limb/nerves/brachial-plexus/ Trunks and divisions At the base of the neck the roots converge to form 3 trunks Superior trunk – C5 and C6 roots Middle trunk – C7 roots Inferior trunk – C8 and T1 roots Within the posterior triangle of the neck, each trunk divides into 2 branches 1 anteriorly, 1 posteriorly Each passes through the axilla Cords Once in the axilla they recombine to make 3 cords Named due to their position to the axillary artery The lateral cord is formed by: The anterior division of the superior trunk The anterior division of the middle trunk The posterior cord is formed by: The posterior division of the superior trunk The posterior division of the middle trunk The posterior division of the inferior trunk The medial cord is formed by: The anterior division of the inferior trunk. Branches 5 major branches Musculocutaneous Nerve (C5, C6, C7) innervates: brachialis, biceps brachii Sensory functions: lateral half of anterior forearm, small portion of posterior forearm Axillary Nerve (C5, C6) innervates: Teres minor and deltoid muscles Sensory functions: inferior region of deltoid £regimental badge”  Median Nerve (C6, C7, C8, T1) innervates: Flexor muscles in forearm, thenar muscle, index and middle fingers Sensory functions: lateral part of palm, lateral 3 ½ fingers on palmer surface of hand Radial Nerve (C5, C6, C7, C8, T1) innervates: Triceps brachii, extensors wrist and fingers Sensory functions: posterior aspect of arm and forearm, posterolateral aspect of hand Ulna Nerve (C8, T1) innervates: muscle of the hand Sensory functions: Anterior and posterior surface of medial 1 ½ fingers and associated palm area https://teachmeanatomy.info/upper-limb/nerves/brachial-plexus/ Injury to Brachial Plexus Upper brachial plexus injury – Erb’s Palsy C5, C6 affected Muscles paralysed: Supraspinatus, infraspinatus, subclavius, biceps brachii, brachialis, coracobrachialis, deltoid and teres minor. Motor functions: Movements that are lost or greatly weakened include abduction at shoulder, lateral rotation of arm, supination of forearm, and flexion at shoulder. Sensory functions: Loss of sensation down lateral aspect of arm, which covers the sensory innervation of the axillary and musculocutaneous nerves. Injury to Brachial Plexus Upper brachial plexus injury – Klumpke Palsy Nerves affected: Nerves derived from the T1 root – ulnar and median nerves. Muscles paralysed: All the intrinsic hand muscles (the flexor muscles in the forearm are also supplied by the ulnar and median nerves, but are innervated by different roots). The primary symptom is a “claw hand,” caused by the unopposed action of the finger extensor muscles. The lumbrical muscles flex the metacarpophalangeal joints and extend the interphalangeal joints, so their paralysis will cause the opposite: extension of the MCP and flexion of the IP joints. Sensory functions: Loss of sensation along medial side of arm.  Thoracic Nerves 12 spinal nerves – emerge from Thoracic vertebrea (T1-T12) Branches also go direct to paravertebral ganglia of the ANS Anterior division Intercostal nerves (T1-T11) T2 and T3 – branch to intercostobrachial nerve Subcostal nerve (T12) Posterior division Medial branches (Upper 6 thoracic nerves) Pierce the rhomboid and trapezious muscle to reach the skin Called medial cutaneous ramus https://theodora.com/anatomy/the_thoracic_nerves.html Function of thoracic nerves T1-T5 Affect: muscles of upper chest, mid-back and abdomen Function: Control rib cage, lungs, diaphragm T6-T12 Affect: Abdominal and back muscles Function: assist with balance, posture. Help with coughing and expel F/B from airways Injury to thoracic nerves Injury T1-T5 – usually affects, abdominal, lower back and legs Paraplegia Hands and arm function usually normal Injury T6-T12 – usually result in paraplegia Little or no control to bowel and bladder Thoracic Area of Body Affected Nerve Section T-1 Hands and fingers T-2 – T-5 Chest muscles T-6 – T-8 Chest and abdominal muscles T-9 – T-12 Abdominal muscles Lumbar nerves 5 Spinal nerves (L1-L5) Lumbar plexus https://teachmeanatomy.info/lower-limb/nerves/lumbar-plexus/ Lumbar plexus Iliohypogastric Nerve (L1, with contribution from T12) Motor Functions: Innervates the internal oblique and transversus abdominis. Sensory Functions: Innervates the posterolateral gluteal skin in the pubic region. Ilioinguinal Nerve (L1) Motor Functions: Innervates the internal oblique and transversus abdominis. Sensory Functions: Innervates the skin on the upper middle thigh. In males, it also supplies the skin over the root of the penis and anterior scrotum. In females, it supplies the skin over mons pubis and labia majora. Genitofemoral Nerve (L1, L2) Motor Functions: The genital branch innervates the cremasteric muscle. Sensory Functions: The genital branch innervates the skin of the anterior scrotum (in males) or the skin over mons pubis and labia majora (in females). The femoral branch innervates the skin on the upper anterior thigh.  Lateral Cutaneous Nerve of the Thigh (L2, L3) Motor Functions: None. Sensory Functions: Innervates the anterior and lateral thigh down to the level of the knee. Obturator Nerve (L2, L3, L4) Motor Functions: Innervates the muscles: obturator externus, pectineus, adductor longus, adductor brevis, adductor magnus, gracilis. Sensory Functions: Innervates the skin over the medial thigh. Femoral Nerve (L2, L3, L4) Motor Functions: Innervates the muscles: Illiacus, pectineus, sartorius, all the muscles of quadriceps femoris. Sensory Functions: Innervates the skin on the anterior thigh and the medial leg.  Sacral Nerves 5 pairs of nerves Begining at cuada equina – descending into sacrum Sacral plexus and lumbosacral plexus Supply much of Hip, thigh, leg and foot Efferent and afferent fibres Sensory perception and movements of lower body  ‘Some Irish Sailor Pesters Polly’. Superior Gluteal, Inferior Gluteal, Sciatic, Posterior cutaneous nerve of thigh, Pudendal Sacral plexus Superior Gluteal Nerve (L4, L5, S1) Motor Functions: Innervates the gluteus minimus, gluteus medius and tensor fascia lata. Sensory Functions: None. Inferior Gluteal Nerve (L5. S1, S2) Motor Functions: Innervates gluteus maximus. Sensory Functions: None.  Sciatic Nerve (L4, L5, S1, S2, S3) Motor Functions: Tibial portion – Innervates the muscles in the posterior compartment of the thigh (apart from the short head of the biceps femoris), and the hamstring component of adductor magnus. Innervates all the muscles in the posterior compartment of the leg and sole of the foot. Common fibular portion – Short head of biceps femoris, all muscles in the anterior and lateral compartments of the leg and extensor digitorum brevis. Sensory Functions: Tibial portion: Innervates the skin on the posterolateral and medial surfaces of the foot as well as the sole of the foot. Common fibular portion: Innervates the skin on the anterolateral surface of the leg and the dorsal aspect of the foot. Sciatica – disorder to sciatic nerve  Posterior Femoral Cutaneous (S1, S2, S3) Motor Functions: None Sensory Functions: Innervates the skin on the posterior surface of the thigh and leg. Also innervates the skin of the perineum. Pudendal Nerve (S2, S3, S4) Motor Functions: Innervates the skeletal muscles in the perineum, the external urethral sphincter, the external anal sphincter, levator ani. Sensory Functions: Innervates the penis and the clitoris and most of the skin of the perineum.