Overview of the human anatomy of the peripheral nervous system

1. Nervous 2Peripheral Nervous System McKinley and O’Laughlin Chapter 15&16

2. I II IV III V VII VI VIII IX XI X XII C1

3. Cranial Nerves What openings in the skull transmit the first cranial nerve? Foramina of the cribriform plate of the ethmoid bone

5. What openings in the skull transmit the second cranial nerve? Optic foramen (or optic canal)

6. Oculomotor (CN III) What is the function of the third cranial nerve? Somatic motor: 4 extrinsic eye muscles and levator palpebrae superioris Parasympathetic motor: pupil (iris) and ciliary muscle

7. Which cranial nerves innervate eye muscles?

9. Superior view showing action of superior oblique muscle (down & out)

11. Trigeminal What are the functions of the fifth cranial nerve? Sensory: Ophthalmic: cornea, nose, forehead, anterior scalp Maxillary: nasal mucosa, palate, gums, cheek, upper teeth Mandibular: anterior 2/3 of tongue, skin of chin, lower jaw and teeth, part of auricle Somatic motor: muscles of mastication and others of lower face

12. Cranial Nerves What openings in the skull transmit the fifth cranial nerve? Ophthalmic: superior orbital fissure Maxillary: foramen rotundum Mandibular: foramen ovale

14. Cranial Nerves What is the function of the seventh cranial nerve? Sensory: anterior 2/3 tongue Somatic motor: muscles of facial expression and others (e.g. digastric and stapedius) Parasympathetic motor: submandibular and sublingual glands and lacrimal gland

15. Cranial Nerves What openings in the skull transmit the seventh cranial nerve? Internal auditory canal (internal acoustic meatus). It takes a tortuous course to finally exit the: Stylomastoid foramen

17. CN VII (Facial) Passes through the parotid gland. Does it innervate it??

18. Tell me about vestibulocochlear nerve

19. Cranial Nerve IX What is the name of the ninth cranial nerve? What are its functions? Sensory: posterior 1/3 of tongue, carotid sinus (blood pressure and chemistry) Somatic motor: a muscle of the pharynx Parasympathetic motor: parotid gland What opening in the skull transmits this nerve?

20. Note the carotid sinus. . . Remember Master Long?

21. CN X Let’s talk about the vagabond.

22. Cranial Nerves What is the function of the tenth cranial nerve? Sensory: pharynx, larynx, thoracic and abdominal viscera, external auditory canal, tympanum Somatic motor: pharyngeal and laryngeal muscles Parasympathetic motor: myocardium, smooth muscle and glands of viscera

23. Cranial Nerves What is the function of the eleventh cranial nerve? Somatic motor: Cranial root: pharynx (with vagus nerve) Spinal root: trapezius and sternocleidomastoid muscles

25. Cranial Nerves What is the function of the twelfth cranial nerve? Somatic motor: intrinsic and extrinsic tongue muscles

27. Spinal Cord and Nerves What are the 2 functions of the spinal cord? Pathway for motor impulses Reflexes

28. Spinal Cord Gross Anatomy What is the general shape of the spinal cord in cross-section? Dorsoventrally compressed cylinder

29. Spinal Cord Gross Anatomy What depressions lie on the anterior and posterior surfaces of the spinal cord? Anterior median fissure (wider) Posterior median sulcus

30. Spinal Cord Gross Anatomy Where does the spinal cord end in an adult? Extends from foramen magnum to L1 Spine grows more than cord

31. Gross Anatomy List the regions of the spinal cord. Cervical Thoracic Lumbar Sacral Coccygeal

32. Spinal Cord Gross Anatomy What is the cauda equina? “Horse’s tail” Spinal nerves extending from end of the spinal cord travel through vertebral canal and exit at each of the lower levels

34. Spinal Cord Gross Anatomy How many pairs of spinal nerves are there? 31 List regions and associated spinal nerves. C1-C8 T1-T12 L1-L5 S1-S5 Co1

35. Spinal Cord Meninges From superficial to deep list the spaces and structures surrounding the spinal cord.

38. Spinal Cord Sectional Anatomy Within the spinal cord, where is the gray matter located and how is it shaped?

40. Spinal Cord Sectional Anatomy Within the spinal cord, what are the anterior masses of gray matter that contain the cell bodies of somatic motor neurons? Within the spinal cord, from T1-T12, what structures contain the cell bodies of ofautonomic motor neurons? Within the spinal cord, what are the posterior masses of gray matter that contain the axons of sensory neurons and the cell bodies of interneurons?

42. Spinal Cord Sectional Anatomy What horizontal bar of gray matter surrounds the central canal within the spinal cord? Gray commissure “commissure” just means a place where two parts join (the corners of your mouth are commissures) What fills the central canal of the spinal cord? CSF

44. Spinal Cord Sectional Anatomy Within the regions of the spinal cord’s gray matter what are the various functional groups of neuron cell bodies? Nuclei Sensory Somatic motor Autonomic motor

46. Spinal Cord Sectional Anatomy Where does the white matter of the spinal cord lie in relation to the gray matter? The white matter of the spinal cord is organized/partitioned into three regions. What is each called? Funiculus (means a “slender rope” or “cord” and is referring to a bundle of nerve fibers) Posterior, lateral, and anterior Ascending and descending

48. Spinal Nerves Anteriorly and posteriorly what are the small attachments of a spinal nerve to the spinal cord? The numerous small attachments of a spinal nerve to the spinal cord converge to form what structures?

50. Spinal Nerves The cell bodies of sensory neurons associated with the spinal cord are in what structures? The cell bodies of motor neurons within the spinal cord are found in what structures?

52. Spinal Nerves What are the 2 main branches of a spinal nerve? Anterior and posterior rami Which is larger? What branches of a spinal nerve are associated with the autonomic nervous system? Communicating rami (rami communicantes)

54. Spinal Nerves What is a specific segment of skin supplied by a single spinal nerve? Dermatome

55. Note face Which areas are innervated by cauda equina nerves?

56. Intercostal Nerves The anterior rami of T1-T11 travel in intercostal spaces. What are these nerves called? Intercostal nerves What term is used to refer to T12 because it lies below the ribs (T12) rather than between them? Subcostal nerve

57. Intercostal Nerves In general, what do intercostal nerves innervate? Intercostal muscles Abdominal muscles Associated skin area

59. A “plexus” is a combined set of spinal nerves that are going to the same area What is a network of interweaving anterior rami of spinal nerves? Nerve plexus The cervical plexus arises from what spinal nerves? C1-C4 Where is the cervical plexus located? Deep on each side of the neck

60. Cervical Plexus What regions of the body does the cervical plexus innervate? Anterior neck muscles Skin of neck, parts of face and head What branch of the cervical plexus innervates the diaphragm? Phrenic C3-C5 (primarily C4) Don’t damage your spinal cord above this

63. Brachial Plexus What regions of the body does the brachial plexus innervate? Pectoral girdle Upper limbs

64. Brachial Plexus The brachial plexus arises from what spinal nerves? C5-T1 Where is the brachial plexus located? Superior to 1st rib (subclavicular) Axilla

67. Brachial Plexus List the 5 (major) nerves that innervate the upper extremity. Axillary nerve Median nerve Musculocutaneous nerve Radial nerve Ulnar nerve I’m asking that you know the general innervation but be able to list at least 1 specific muscle for each nerve

69. Brachial Plexus: Axillary Nerve What is the motor innervation of the axillary nerve? Deltoid Teres minor What is the cutaneous innervation of the axillary nerve? Superolateral arm (deltoid region)

71. Brachial Plexus: Median Nerve What is the motor innervation of the median nerve? Most anterior antebrachial muscles (flexors/pronators) Thenar muscles Lateral 2 lumbricals What is the cutaneous innervation of the median nerve? Palmar aspects & dorsal tips of lateral 3.5digits

73. Median nerve & carpal tunnel

74. Brachial Plexus: Musculocutaneous What is the motor innervation of the musculocutaneous nerve? Anterior brachial muscles (coracobrachialis, biceps brachii, brachialis) What is the cutaneous innervation of the musculocutaneous nerve? Lateral antebrachium

76. Brachial Plexus: Radial Nerve What is the motor innervation of the radial nerve? Posterior brachial muscles (triceps brachii, anconeus) Posterior antebrachial muscles (supinator, extensors, brachioradialis)

77. Brachial Plexus: Radial Nerve What is the cutaneous innervation of the radial nerve? Posterior brachium Posterior antebrachium Dorsal portion of lateral 3.5 digits

79. Wrist Drop The radial nerve can be damaged if the humerus (the bone of the arm) is broken, because it runs through the radial groove on the lateral border of this bone Can also be caused by lead poisoning

80. Brachial Plexus: Ulnar Nerve What is the motor innervation of the ulnar nerve? Anterior antebrachial muscles (1/2 flexor digitorum profundus, flexor carpi ulnaris) Hypothenar muscles Most intrinsic muscles of the hand (interossei, adductor pollicis, medial 2 lumbricals)

81. Brachial Plexus: Ulnar Nerve What is the cutaneous innervation of the ulnar nerve? All of medial 1.5 digits and associate hand (dorsal and palmar)

83. Remember your “funny bone?”

84. Lumbar Plexus The lumbar plexus arises from the anterior rami of what spinal nerves? L1-L4 We will learn two of the nerves that branch off the lumbar plexus (there are others we won’t learn)

86. Lumbar Plexus: Femoral Nerve What is the main nerve of the posterior division of the lumbar plexus? Femoral nerve What is the motor innervation of the femoral nerve? Anterior thigh muscles (quads, iliopsoas, sartorius) Pectineus

88. Lumbar Plexus: Femoral Nerve What is the cutaneous innervation of the femoral nerve? Anterior thigh Inferomedial thigh Medial leg Medial foot Basically the pathway of the great saphenous vein

89. Femoral nerve innervations

90. Lumbar Plexus: Obturator nerve What is the main nerve of the anterior division of the lumbar plexus? Obturator nerve

91. Lumbar Plexus: Obturator Nerve What is the motor innervation of the obturator nerve? Medial thigh muscles (adductors, gracilis, pectineus*) *femoral, obturator, or both Obturator externus What is the cutaneous innervation of the obturator nerve? Superomedial thigh

93. Lumbar Plexus: Other Branches What other regions of the body do small branches of the lumbar plexus innervate? Abdominal wall Scrotum/Labia Inferior portions of abdominal muscles (also innervated by intercostal nerves)

94. Sacral Plexus The anterior rami of what spinal nerves form the sacral plexus? L4-S4 Nerves emerging from the sacral plexus innervate what portions of the body? Gluteal region Pelvis Perineum Posterior thigh Leg and Foot

97. Sacral Plexus What are the 2 main divisions of the sacral plexus? Anterior and posterior divisions Nerves of the sacral plexus arising from the anterior division tend to innervate what muscles? Muscles that flex and plantar flex Hamstrings and hamstring portion of adductor magnus Posterior crural muscles Plantar foot muscles

98. Sacral Plexus Nerves of the sacral plexus arising from the posterior division tend to innervate what muscles? Muscles that extend and dorsiflex We’ll discuss these for each branch of the posterior division

99. Sacral Plexus: Sciatic Nerve-anterior What is the largest and longest nerve in the body? Sciatic nerve What nerve is formed from the anterior divisions of the sciatic nerve? Tibial nerve

100. Sacral Plexus: Sciatic Nerve: Tibial What division of what nerve innervates the hamstrings? Tibial division of the sciatic nerve Within the leg what nerve innervates the plantar flexors of the foot and the flexors of the toes? Tibial nerve

102. Sacral Plexus: Sciatic Nerve: Fibular What nerve is formed from the posterior division of the sciatic nerve? Common fibular nerve What division of what nerve innervates the short head of the biceps femoris? Common fibular division of the sciatic nerve

103. Sacral Plexus What are the 2 main divisions of the common fibular nerve? Deep fibular nerve Superficial fibular nerve

104. Sacral Plexus: Sciatic: Deep Fibular What is the motor innervation of the deep fibular nerve? Anterior leg muscles (tibialis anterior, extensors) Dorsal muscles of foot (extensor brevia muscles) What is the cutaneous innervation of the deep fibular nerve? Dorsally between digits I and II

106. Sacral Plexus: Sciatic: Superficial Fibular What is the motor innervation of the superficial fibular nerve? Lateral leg muscles (Fibularis brevis and longus) What is the cutaneous innervation of the superficial fibular nerve? Anteroinferior leg Dorsum of foot

108. Wow! That’s the End! Now on to Autonomic Nervous System!