Peripheral nervous system.pptx...........

Use of study

1. Peripheral nervous system 11/04/2022

2. The peripheral nervous system The  peripheral nervous system consists of the nerves that branch out from the brain and  spinal cord These nerves form the communication network between the CNS and the body parts

3. Functions of PNS The primary role of the PNS is to connect the CNS to the organs, limbs and skin The peripheral system allows the brain and spinal cord to receive and send information to other areas of the body, which allows us to react to stimuli in our environment

4. Somatic and autonomous N.S The somatic nervous system consists of nerves that go to the skin and muscles and is involved in conscious activities. The autonomic nervous system consists of nerves that connect the CNS to the visceral organs such as the heart, stomach, and intestines. It mediates unconscious activities.

5. Spinal nerves Thirty-one pairs of spinal nerves emerge laterally from the spinal cord Each pair of nerves corresponds to a segment of the cord & they are named accordingly

6. Spinal nerves This means there are 8 cervical nerves, 12 thoracic nerves, 5 lumbar nerves, 5 sacral nerves, and 1 coccygeal nerve

7. Spinal nerves Spinal nerves leave the vertebral column through the intervertebral foramina located between two successive vertebrae Each spinal nerve then divides into two branches called posterior/dorsal rami & anterior/ventral rami  

8. Spinal nerves Both rami carry mixed fibers The  posterior rami travel backward and divide into branches that supply muscles and sensation to the back The anterior rami supply the skin and muscles of the limbs and anterior trunk

9. Plexus Some groups of spinal nerves merge with each other to form a large plexus, or network of interlacing nerves . Other spinal nerves divide into smaller branches without forming a plexus There are five main plexi formed by the spinal nerves: Cervical plexus Brachial Plexus Lumbar Plexus Sacral Plexus Coccegeal Plexus

10. Plexus Cervical plexus :  Composed of the merging of spinal nerves C1 through C5, these divide into smaller nerves that carry sensory messages and provide motor control to the muscles of the neck and shoulders. Brachial plexus:  Formed by the merging of spinal nerves C5 through T1, this plexus branches into nerves that carry sensory messages and provide motor control to the muscles of the arm and upper back.

11. Brachial plexus Divided into five parts: Roots Trunks Divisions Cords Branches Functionally there is no difference in all of the above classifications

12. Brachial plexus Roots: are formed by the anterior rami of spinal nerves C5-T1 Trunks: At the base of the neck, the roots of the brachial plexus converge to form three  trunks; Superior trunk  – a combination of C5 and C6 roots. Middle trunk  – continuation of C7. Inferior trunk  – combination of C8 and T1 roots.

13. Brachial plexus Divisons : Each trunk divides into two branches. One division moves  anteriorly  (toward the front of the body) & the other  posteriorly  (towards the back of the body). Thus, they are known as the anterior and posterior divisions There are  three anterior and three posterior nerve fibres . These divisions pass into the  axilla . They  recombine  into the cords of the brachial plexus.

14. Brachial plexus Once the anterior and posterior divisions have entered the axilla , they combine together to form three cords, named by their position relative to the  axillary artery The  lateral cord  is formed by: The anterior division of the superior trunk The anterior division of the middle trunk

15. Brachial plexus 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. The cords give rise to the major branches of the brachial plexus.

16. Brachial plexus In the axilla and the proximal aspect of the upper limb, the three cords give rise to five major branches. These nerves continue into the upper limb to provide innervation to the muscles and skin present

17. Musculocutaneous Nerve Roots : C5, C6, C7 Motor Functions : Innervates the brachialis , biceps brachii and coracobrachialis muscles

18. Musculocutaneous Nerve Sensory Functions : Gives off the lateral cutaneous branch of the forearm, which innervates the lateral half of the anterior forearm, and a small lateral portion of the posterior forearm

19. Axillary Nerve Roots : C5 and C6 Motor Functions : Innervates the teres minor and deltoid muscles Sensory Functions : Gives off the superior lateral cutaneous nerve of arm, which innervates the inferior region of the deltoid

20. Median Nerve Roots : C6 – T1. (Also contains fibres from C5 in some individuals) Motor Functions : Innervates most of the flexor muscles in the forearm, the thenar muscles, and the two lateral lumbricals associated with the index and middle fingers

21. Median Nerve Sensory Functions: Gives off the palmar cutaneous branch, which innervates the lateral part of the palm, and the digital cutaneous branch, which innervates the lateral three and a half fingers on the anterior ( palmar ) surface of the hand

22. Radial Nerve Roots : C5 – T1 Motor Functions : Innervates the triceps brachii , and the muscles in the posterior compartment of the forearm (which are primarily, but not exclusively, extensors of the wrist and fingers)

23. Radial Nerve Sensory Functions : Innervates the posterior aspect of the arm and forearm, and the posterolateral aspect of the hand

24. Ulnar Nerve Roots : C8 and T1 Motor Functions : Innervates the muscles of the hand (apart from the thenar muscles and two lateral lumbricals ), flexor carpi ulnaris and medial half of flexor digitorum profundus

25. Ulnar Nerve Sensory Functions : Innervates the anterior and posterior surfaces of the medial one and half fingers, and associated palm area

26. Lumbar plexus:  Spinal nerves L1 through L4 converge to form the lumbar plexus. This plexus splits into nerves that carry sensory messages and provide motor control to the muscles of the abdomen and leg Sacral plexus:  Spinal nerves L4 through S4 join together. They then branch out into nerves that carry sensory messages and provide motor control to the muscles of the legs Coccygeal plexus:  The merging of nerves S4 through Co1, this plexus supplies motor and sensory control of the genitalia and the muscles that control defecation Plexus

27. M otor functions of spinal nerves C1–C6 Neck flexors C1–T1 Neck extensors C3, C4, C5 Supply diaphragm (mostly C4) C5, C6 Move shoulder, raise arm (deltoid); flex elbow (biceps) C6 Externally rotate (supinate) the arm C6, C7 Extend the elbow and wrist (triceps and wrist extensors); pronate wrist C7, C8 Flex wrist; supply small muscles of the hand T1–T6 Intercostals and trunk above the waist T7–L1 Abdominal muscles L1–L4 Flex thigh L2, L3, L4 Adduct thigh; extend leg at the knee (quadriceps femoris ) L4, L5, S1 Abduct thigh; flex leg at the knee (hamstrings); dorsiflex foot (tibialis anterior); extend toes L5, S1, S2 Extend leg at the hip (gluteus maximus); plantar flex foot and flex toes Branches of Spinal Nerves

28. The Somatic Nervous System The  somatic system is the part of the peripheral nervous system responsible for carrying sensory and motor information to and from the central nervous system The somatic system is responsible for transmitting sensory information as well as for voluntary movement

29. The Somatic Nervous System Sensory neurons : Also called afferent neurons C arry information from the nerves to the central nervous system It is these sensory neurons that allow us to take in sensory information and send it to the brain and spinal cord E.g :

30. The Somatic Nervous System Motor neurons : Also called efferent neurons, motor neurons carry information from the brain and spinal cord to muscle fibers throughout the body. These motor neurons allow us to take physical action in response to stimuli in the environment E.g. when a phone rings you answer the call

31. The Autonomic Nervous System It  is the part of the peripheral nervous system that's responsible for regulating involuntary body functions such as blood flow, heartbeat, digestion, and breathing The autonomic system is further divided into two branches:

32. Sympathetic system  By regulating the  flight-or-fight response the sympathetic system prepares the body to expend energy to respond to environmental threats. When action is needed, the sympathetic system triggers a response by accelerating heart rate increasing breathing rate boosting blood flow to muscles activating sweat secretion dilating the pupils

33. The Autonomic Nervous System Parasympathetic system:  This helps maintain normal body functions and conserve physical resources. Once a threat has passed, this system will slow the heart rate, slow breathing, reduce blood flow to muscles, and constrict the pupils. This allows us to return our bodies to a normal resting state.

34. Sympathetic Vs Parasympathetic

35. Injuries to peripheral nerve Injuries or infections can occur at any point in peripheral nerves and could break the connection between the brain and the other parts of the body

36. Injuries to peripheral nerve Symptoms: Can result in changes in sensation(numbness , pain, tingling, burning, sensitivity to touch), muscle weakness, or muscle paralysis Some of the conditions that can affect the PNS include: Amyotrophic lateral sclerosis (ALS) Carpal tunnel syndrome Diabetes Guillain-Barre syndrome Peripheral neuropathy Peripheral nerve injuries Rheumatoid arthritis Tumors Vitamin deficiency