Biology 211 Anatomy & Physiology I

1. Biology 211Anatomy & Physiology I Peripheral Nervous System

3. Recall: All organs are composed of, at most, four tissues Epithelial tissue Connective tissue Muscle tissue Nervous tissue Nervous tissue: Excitable cells (neurons) Nonexcitable (supporting) cells Connective tissue: Meninges - in central nervous system Endoneurium Perineurium in peripheral nervous system Epineurium Epithelium found only in blood vessels of PNS Muscle (smooth)

4. Cells of Nervous Tissue: 1) Excitable cells = Neurons Carry electrical signals from one place to another Pass these signals to other cells 2) Nonexcitable cells = Glia in CNS in PNS

5. surrounding neuron cell bodies Axon of neuron Cell body of neuron surrounding neuron processes (axons and dendrites)

6. In PNS: Neuron cell bodies grouped into (single = ) Axons and dendrites grouped into nerves

7. Nerve: Each axon (and some dendrites) surrounded by Schwann cells, which may or may not form a myelin sheath. Outside the Schwann cells, each axon / dendrite surrounded by layer of connective tissue called

8. Axons / dendrites (surrounded by Schwann cells and endoneureum) form bundles called each of which is surrounded by a thicker layer of connective tissue called

9. Fascicles group together to form a nerve, which is surrounded by an even thicker layer of connective tissue called

11. Nerves originate from both Brain Spinal Cord Except for three cranial nerves, all nerves contain both afferent and efferent neuron processes (axons & dendrites)

12. Cranial Nerves: - Originate from the brain - Pass through foramina in the skull to reach the periphery 12 pairs, Numbered from superior to inferior. I, II, VIII purely sensory: Contain only afferent neuron processes All others mixed: Contain both afferent and efferent neuron processes

14. The names, functions, origins, terminations, foramina, and effects of damage are listed in your Saladin text for all of the cranial nerves. Using this information, you will be expected to know a) The names and numbers of all 12 pairs of cranial nerves, including the subdivisions of cranial nerve V b) The foramen through which each cranial nerve passes c) The primary functions of each cranial nerve d) The effects of damage to each cranial nerve

15. Using this information, you will be expected to know a) The names and numbers of all 12 pairs of cranial nerves, including the subdivisions of cranial nerve V b) The foramen through which each cranial nerve passes c) The primary functions of each cranial nerve d) The effects of damage to each cranial nerve Example: The abducens nerve (VI) originates from the pons and exits the skull through the superior orbital fissure. It innervates the lateral rectus muscle which causes the eye to rotate laterally. Injury to this nerve on either side causes an inability to rotate that eye laterally, and unopposed function of the other muscles often cause the eye rotate medially.

16. Spinal Nerves: - Originate from the spinal cord by dorsal and ventral roots - Pass between vertebrae through intervertebral foramina to reach the periphery

17. Spinal Nerves: - Originate from the spinal cord by dorsal and ventral roots - Pass between vertebrae through intervertebral foramina to reach the periphery - 31 pairs, numbered from superior to inferior in each region of the back

18. Naming Spinal Nerves: Cervical nerves #1 through #7 leave the vertebral canal through the intervertebral foramina ABOVE the vertebrae with the same numbers. Example: Cervical nerve #3 passes above cervical vertebra #3 (between cervical vertebra #2 and #3) Cervical nerve #8 leaves the vertebral canal through the intervertebral foramen between cervical vertebra #7 and thoracic vertebra #1 .

19. Naming Spinal Nerves: Cervical nerve #8 leaves the vertebral canal through the intervertebral foramen between cervical vertebra #7 and thoracic vertebra #1 . All thoracic, lumbar, and sacral nerves plus the single coccygeal nerve leave the vertebral canal through the intervertebral foramina BELOW the vertebrae with the same numbers. Example: Thoracic nerve #3 passes below thoracic vertebra #3 (between thoracic vertebra #3 and #4)

20. Spinal nerves passing through intervertebral foramina

22. Immediately distal to the intervertebral foramen, each spinal nerve divides into a and a Both rami are mixed, carrying both afferent & efferent information

23. Dorsal rami of all spinal nerves innervate muscles and skin of medial back.

24. Ventral rami of spinal nerves Thoracic 2 -12 innervate muscles and skin of body wall (thorax and abdomen)

25. Ventral rami of spinal nerves Thoracic 2 -12 innervate muscles and skin of body wall (thorax and abdomen) But: Ventral rami of all other spinal nerves Cervical 1 - 8, Thoracic 1, Lumbar 1-5, Sacral 1-5 enter into a plexus

26. A plexus is an interchange which allows nerves from different spinal cord levels to combine to serve common structures. 1. Each nerve distal to a plexus carries axons to & from more than one level of the spinal cord. Example: Radial nerve carries information to & from five levels of the spinal cord: C5, C6, C7, C8, T1

27. 1. Each nerve distal to a plexus carries axons to / from more than one level of the spinal cord. Example: Radial nerve carries information to and from five levels of the spinal cord: C5, C6, C7, C8, T1 2. Axons carrying information to / from a single spinal cord level are distributed through more than one nerve distal to the plexus Example: Spinal cord level C7 sends and receives information through more than 20 different nerves

28. Four plexes:

29. Cervical Plexus Originates from ventral rami of nerves C1, C2, C3, C4 (+C5) Carries efferent neurons to many muscles of the neck. Carries afferent neurons from skin of the neck, shoulder, and scalp near ear

30. Brachial Plexus Originates from ventral rami of nerves C5, C6, C7, C8, T1, (+C4) Carries efferent neurons to muscles of the shoulder, arm, forearm, and hand Carries afferent neurons from skin of the shoulder, arm, forearm, and hand

31. Lumbar Plexus Originates from ventral rami of nerves L1, L2, L3, L4 (+T12, +L5) Carries efferent neurons to muscles of the anterior pelvis, anterior and medial thigh Carries afferent neurons from skin of the anterior pelvis, anterior and medial thigh, and medial leg.

32. Sacral Plexus Originates from ventral rami of nerves (+L4), L5, S1, S2, S3, S4, (+S5, Cx1) Carries efferent neurons to muscles of the posterior pelvis, posterior thigh, anterior and posterior leg, and foot Carries afferent neurons from skin of the posterior pelvis, posterior thigh, anterior and posterior leg, and foot.

33. We will go into greater detail about the cervical plexus, but you will not be held responsible for details of the cervical, lumbar, or sacral plexes EXCEPT: You need to know which spinal nerves contribute their ventral rami to each plexus. You need to know which plexus gives rise to each of the following nerves, and which area of the body each of them innervates: Common peroneal Obturator Femoral Phrenic Genitofemoral Pudendal Inferior and superior gluteal Tibial (Sciatic)

34. Summary of the Brachial Plexus

41. More than 20 nerves leave the brachial plexus to supply both afferent (sensory) and efferent (motor) innervation to the shoulder, arm, forearm, hand, and parts of the neck and thoracic wall. We will follow five of these: 1. Musculocutaneous nerve: Arises from the lateral cord of the brachial plexus. Innervates muscles of the anterior compartment of the arm; skin of lateral forearm

42. 1. Musculocutaneous nerve: Arises from the lateral cord of the brachial plexus. Innervates muscles of the anterior compartment of the arm; skin of lateral forearm 2. Ulnar Nerve: Arises from the medial cord of the brachial plexus. Innervates muscles in the anterior compartment of the forearm & some intrinsic muscles of the hand; skin on medial third of hand (both anterior and posterior surfaces)

43. 2. Ulnar nerve: Arises from the medial cord of brachial plexus. Innervates muscles of the anterior compartment of forearm & some muscles of hand; skin on medial third of hand (posterior & anterior) 3. Median Nerve: Arises from medial AND lateral cords of the brachial plexus. Innervates muscles in the anterior compartment of the forearm & some intrinsic muscles of the hand; skin on anterior surface of lateral two-thirds of hand

44. 3. Median Nerve: Arises from medial AND lateral cords of the brachial plexus. Innervates muscles in the anterior compartment of the forearm & some muscles of hand; skin on anterior surface of lateral two-thirds of hand 4. Radial Nerve: Arises from posterior cord of brachial plexus. Innervates muscles in posterior compartment of arm & posterior compartment of forearm; skin on posterior surface of lateral two-thirds of hand & skin on posterior surfaces of forearm and arm

45. 4. Radial Nerve: Arises: posterior cord of brachial plexus. Innervates muscles in posterior compartments of arm & forearm; skin on posterior surface of lateral two-thirds of hand & skin on posterior surfaces of forearm and arm 5. Axillary Nerve: Arises from posterior cord of brachial plexus. Innervates shoulder joint, deltoid and teres minor muscles; skin of shoulder

47. Cutaneous Innervation Axillary (Medial antebrachial cutaneous) Radial Musculocutaneous Ulnar Median Anterior Posterior