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Questions and Answers
Which cervical nerves are primarily responsible for innervating the diaphragm?
Which cervical nerves are primarily responsible for innervating the diaphragm?
In the context of the brachial plexus, which of the following nerves specifically innervate the muscles responsible for shoulder abduction?
In the context of the brachial plexus, which of the following nerves specifically innervate the muscles responsible for shoulder abduction?
What is the primary function of motor neurons in the peripheral nervous system?
What is the primary function of motor neurons in the peripheral nervous system?
Which neurological assessment technique is most effective in evaluating sensory function?
Which neurological assessment technique is most effective in evaluating sensory function?
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Which of the following accurately describes the role of afferent nerves within the somatic nervous system?
Which of the following accurately describes the role of afferent nerves within the somatic nervous system?
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What characterization is used for the sympathetic nervous system's activation during stress?
What characterization is used for the sympathetic nervous system's activation during stress?
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Which region of the body primarily receives sensory innervation from the lumbar nerves?
Which region of the body primarily receives sensory innervation from the lumbar nerves?
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Which of the following is a common method to assess motor function in a neurological examination?
Which of the following is a common method to assess motor function in a neurological examination?
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What is the primary role of the ansa cervicalis in relation to the infrahyoid muscles?
What is the primary role of the ansa cervicalis in relation to the infrahyoid muscles?
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Which cervical nerve supplies sensation to the anterior neck region?
Which cervical nerve supplies sensation to the anterior neck region?
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Which structure does the brachial plexus primarily originate from?
Which structure does the brachial plexus primarily originate from?
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What distinguishes sensory nerves from motor nerves in the cervical plexus?
What distinguishes sensory nerves from motor nerves in the cervical plexus?
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What is a critical consideration when assessing the function of the cervical nerves during neurological evaluation?
What is a critical consideration when assessing the function of the cervical nerves during neurological evaluation?
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Which plexus is primarily responsible for supplying the muscles of the neck and diaphragm?
Which plexus is primarily responsible for supplying the muscles of the neck and diaphragm?
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What is the main function of the phrenic nerve?
What is the main function of the phrenic nerve?
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How many cervical nerves are there in total?
How many cervical nerves are there in total?
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Which plexus provides nerve connections to the upper arms and hands?
Which plexus provides nerve connections to the upper arms and hands?
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Which statement is true regarding sensory branches of the cervical plexus?
Which statement is true regarding sensory branches of the cervical plexus?
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Which segment of the spinal cord contributes to the creation of the phrenic nerve?
Which segment of the spinal cord contributes to the creation of the phrenic nerve?
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What area does the lumbar plexus primarily innervate?
What area does the lumbar plexus primarily innervate?
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Which of the following is a primary difference between motor and sensory nerves in the cervical plexus?
Which of the following is a primary difference between motor and sensory nerves in the cervical plexus?
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Which nerve is crucial for maintaining proper breathing through diaphragm control?
Which nerve is crucial for maintaining proper breathing through diaphragm control?
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What does the sacral plexus innervate?
What does the sacral plexus innervate?
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What impact does injury to thoracic nerves T1-T5 generally have on the body?
What impact does injury to thoracic nerves T1-T5 generally have on the body?
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Which of the following statements is true regarding the function of T6-T12 thoracic nerves?
Which of the following statements is true regarding the function of T6-T12 thoracic nerves?
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Which thoracic nerves are responsible for transmitting sensation to the medial side of the arm?
Which thoracic nerves are responsible for transmitting sensation to the medial side of the arm?
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What role does the subcostal nerve (T12) play in the human body?
What role does the subcostal nerve (T12) play in the human body?
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Which thoracic spinal nerves influence the control of the rib cage and diaphragm?
Which thoracic spinal nerves influence the control of the rib cage and diaphragm?
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When thoracic nerves weaken with aging, what specific bodily functions are primarily affected?
When thoracic nerves weaken with aging, what specific bodily functions are primarily affected?
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What can be the consequence of an injury to thoracic nerves T6-T12?
What can be the consequence of an injury to thoracic nerves T6-T12?
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Which anatomical structures do the medial branches of the upper 6 thoracic nerves pierce to reach the skin?
Which anatomical structures do the medial branches of the upper 6 thoracic nerves pierce to reach the skin?
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What is the dominant function of the lumbar plexus?
What is the dominant function of the lumbar plexus?
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Which nerve is responsible for innervating the skin on the upper middle thigh?
Which nerve is responsible for innervating the skin on the upper middle thigh?
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Which motor function is NOT associated with the Femoral Nerve?
Which motor function is NOT associated with the Femoral Nerve?
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What is the primary sensory function of the Lateral Cutaneous Nerve of the Thigh?
What is the primary sensory function of the Lateral Cutaneous Nerve of the Thigh?
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Which nerves comprise the sacral plexus?
Which nerves comprise the sacral plexus?
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Which nerve does NOT provide any motor function?
Which nerve does NOT provide any motor function?
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What sensory area does the Sacral plexus primarily supply?
What sensory area does the Sacral plexus primarily supply?
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Which motor function is associated with the Sciatic Nerve?
Which motor function is associated with the Sciatic Nerve?
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Which nerve supplies the skin over the anterior scrotum in males?
Which nerve supplies the skin over the anterior scrotum in males?
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Which of the following nerves innervates the gluteus maximus?
Which of the following nerves innervates the gluteus maximus?
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What does the Ilioinguinal Nerve NOT innervate?
What does the Ilioinguinal Nerve NOT innervate?
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Study Notes
Peripheral Nervous System
- The PNS conducts impulses to and from the CNS
- Contains both motor and sensory neurons
- Contains 31 pairs of nerves with connection to the spinal cord:
- 8 Cervical
- 12 thoracic
- 5 Lumber
- 5 Sacral
Voluntary and Involuntary Actions
- Voluntary (somatic) - The somatic nervous system consists of afferent nerves or sensory nerves, and efferent nerves or motor nerves.
- Examples: picking up a cup
- Involuntary (autonomic) - This system is divided into:
- Sympathetic nervous system – Fight or Flight
- Prepares body for emergencies
- Shunts blood to muscles
- Increases blood pressure, heart rate and breathing rate
- Parasympathetic nervous system – Rest & Digest
- Maintains and restores energy
- Directs blood to the digestive tract
- Maintains blood pressure, heart rate and breathing rate at a low level
- Sympathetic nervous system – Fight or Flight
The Plexuses
- Groups of nerves
- Cervical plexus provides nerve connections to the head, neck, and shoulder
- Brachial plexus provides connections to the chest, shoulders, upper arms, forearms, and hands
- Lumbar plexus provides connections to the back, abdomen, groin, thighs, knees, and calves
- Sacral plexus provides connections to the pelvis, buttocks, genitals, thighs, calves, and feet
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
- Located deeper than sensory branches
- Supply muscle of neck, back, and diaphragm
- Phrenic nerve
- Arises from C3-C5
- Motor innervation for the diaphragm
- Contracts/relaxes diaphragm
- “C3 4 5, keeps you alive”
- Phrenic nerve
Cervical Plexus (C1-C4) - Sensory branches
- Enter skin at the 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 sternoclavicular joint
Thoracic Nerves
- 12 spinal nerves – emerge from Thoracic vertebrea (T1-T12)
- Branches go direct to paravertebral ganglia of the ANS
- Anterior division:
- Intercostal nerves (T1-T11)
- T2 and T3 – branch to intercostobrachial nerve
- Subcostal nerve (T12)
- Intercostal nerves (T1-T11)
- Posterior division
- Medial branches (Upper 6 thoracic nerves)
- Pierce the rhomboid and trapezious muscle to reach the skin
- Called medial cutaneous ramus
- Medial branches (Upper 6 thoracic nerves)
Function of Thoracic nerves
- T1-T5
- Affect: muscles of upper chest, mid-back and abdomen
- Function: Control rib cage, lungs, diaphragm
- Higher ones- allow chest to expand
- T6-T12
- Affect: Abdominal and back muscles
- Function: assist with balance, posture, help with coughing and expel F/B from airways
- Lower and focuses on posture, balance
Injury to Thoracic nerves
- Injury T1-T5 – usually affects, abdominal, lower back and legs
- If injured can get: Paraplegia
- Hands and arm function usually normal
- Injury T6-T12 – usually results in paraplegia
- Little or no control to bowel and bladder
Lumbar Nerves
- 5 Spinal nerves (L1-L5)
- 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
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
- Sensory Functions:
- Tibial portion - Innervates the skin over the posterior surface of the leg and foot, as well as the skin of the sole.
- Common peroneal portion - Innervates the skin over the lateral portion of the leg and foot, as well as the skin of the dorsal aspect of the foot
- Motor Functions:
Brachial plexus (C5-T1)
- Network supplies skin and musculature of upper limb
- Begins in the neck, passes through axilla to the upper extremities
- Divided into 5 parts:
- Roots, Trunks, Divisions, Cords, Branches
Brachial Plexus: Roots
- Each pair leave the spinal cord via intervertebral foramina
- Each pair divides into posterior and anterior ramus
- Posterior innervate the skin and muscle of the back
Brachial Plexus: Trunks
- 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
Brachial Plexus: 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.
C2 and C3 Innovate:
- Sternohyoid muscle
- Sternothyroid muscle
- Omohyoid muscle (Via Ansa Cervicallis)
Ansa Cervicallis
- Loop of nerves
- Part of the cervical plexus
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Description
Explore the essential components of the Peripheral Nervous System (PNS) in this quiz. Learn about the divisions between voluntary and involuntary actions, and discover the different types of nerves and plexuses involved in these processes. Test your knowledge on the structure and function of the PNS!
