Peripheral Nervous System Overview
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Questions and Answers

What is the primary function of the peripheral nervous system (PNS)?

  • To process information in the brain
  • To produce hormones
  • To control voluntary muscle movement only
  • To conduct impulses to and from the central nervous system (CNS) (correct)

    • Which statement is true about spinal nerves?

  • Spinal nerves contain only sensory neurons.
  • Spinal nerves contain only motor neurons.
  • Spinal nerves contain both motor and sensory neurons. (correct)
  • Spinal nerves are part of the CNS only.

    • How many pairs of spinal nerves are connected to the spinal cord?

  • 36 pairs
  • 24 pairs
  • 12 pairs
  • 31 pairs (correct)

    • Which of the following is the correct breakdown of the 31 pairs of spinal nerves?

    <p>8 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral</p> Signup and view all the answers

    Which part of the nervous system facilitates the movement and sensory input throughout the body?

    <p>Spinal nerves containing both motor and sensory neurons</p> Signup and view all the answers

    Which part of the nervous system is involved in controlling involuntary actions like heart rate?

    <p>Autonomic nervous system</p> Signup and view all the answers

    Which type of nerves are responsible for transmitting signals from the CNS to muscles?

    <p>Efferent nerves</p> Signup and view all the answers

    What physiological state does the sympathetic nervous system induce?

    <p>Fight or flight response</p> Signup and view all the answers

    In which situation would the parasympathetic nervous system be most active?

    <p>After a large meal</p> Signup and view all the answers

    Which type of nerve would convey sensory information from the skin to the CNS?

    <p>Afferent nerves</p> Signup and view all the answers

    What is a characteristic effect of the sympathetic nervous system on the body?

    <p>Increased heart rate and blood pressure</p> Signup and view all the answers

    Which nervous system is primarily responsible for voluntary movements?

    <p>Somatic nervous system</p> Signup and view all the answers

    What is the role of efferent nerves in the nervous system?

    <p>Carrying commands from the brain to effectors</p> Signup and view all the answers

    Which part of the nervous system primarily regulates involuntary bodily functions such as breathing and heartbeat?

    <p>Autonomic nervous system</p> Signup and view all the answers

    What is the primary distinction between afferent and efferent nerves?

    <p>Afferent nerves carry sensory information to the CNS while efferent nerves carry signals from the CNS.</p> Signup and view all the answers

    Which of the following best describes the function of the parasympathetic nervous system?

    <p>Conserves energy and promotes relaxation.</p> Signup and view all the answers

    What physiological changes occur in the body as a result of sympathetic nervous system activation?

    <p>Increased heart rate and blood flow to muscles.</p> Signup and view all the answers

    Which nervous system specifically involves the transmission of signals responsible for voluntary muscle movement?

    <p>Somatic nervous system</p> Signup and view all the answers

    In response to a stressful situation, the sympathetic nervous system does which of the following?

    <p>Increases blood pressure and heart rate.</p> Signup and view all the answers

    Which of the following actions is primarily controlled by the somatic nervous system?

    <p>Picking up a pencil</p> Signup and view all the answers

    What role do efferent nerves play within the nervous system?

    <p>Carry motor commands from the CNS to muscles.</p> Signup and view all the answers

    Which spinal nerves constitute the lumbar plexus?

    <p>L1 to L4</p> Signup and view all the answers

    What regions does the brachial plexus primarily supply with nerves?

    <p>Chest, shoulders, upper arms, forearms, and hands</p> Signup and view all the answers

    The sacral plexus connects to which of the following body parts?

    <p>Pelvis, buttocks, genitals, thighs, calves, and feet</p> Signup and view all the answers

    Which of these spinal nerves form the cervical plexus?

    <p>C1 to C4</p> Signup and view all the answers

    Which plexus is responsible for nerve connections to the upper limbs?

    <p>Brachial plexus</p> Signup and view all the answers

    What is the total number of cervical vertebrae present in adults?

    <p>7</p> Signup and view all the answers

    Which cervical nerve is positioned differently by emerging below its corresponding vertebra?

    <p>C8</p> Signup and view all the answers

    What specific group of cervical nerves contributes to the formation of the cervical plexus?

    <p>C1 to C4</p> Signup and view all the answers

    What is the main function of the sensory group within the cervical plexus?

    <p>Supplies sensory input from areas of the neck and skin</p> Signup and view all the answers

    What is the primary role of the cervical plexus in the human body?

    <p>Supplies motor and sensory functions to the neck and parts of the head and shoulders</p> Signup and view all the answers

    How many cervical vertebrae and cervical nerves are present in the human body?

    <p>7 cervical vertebrae and 8 cervical nerves</p> Signup and view all the answers

    Which nerve emerges below the C7 vertebra?

    <p>C8 nerve</p> Signup and view all the answers

    What is the function of the suboccipital nerve (C1)?

    <p>Supplies muscles at the base of the skull</p> Signup and view all the answers

    Which nerve provides sensation to the back of the scalp?

    <p>Greater occipital nerve (C2)</p> Signup and view all the answers

    What is the primary function of the third occipital nerve (C3)?

    <p>Supplies sensation to the lower part of the scalp and neck</p> Signup and view all the answers

    What area does the anterior distribution of the cervical plexus (C1-C4) primarily affect?

    <p>Supplying motor and sensory functions to the neck region</p> Signup and view all the answers

    Which plexus extends from C5 to T1 and supplies nerves to the chest, shoulders, arms, and hands?

    <p>Brachial plexus</p> Signup and view all the answers

    Which nerve supplies motor innervation to muscles at the base of the skull?

    <p>Suboccipital nerve (C1)</p> Signup and view all the answers

    Which nerve primarily innervates the muscles located at the back of the scalp?

    <p>Greater occipital nerve (C2)</p> Signup and view all the answers

    Which nerve is incorrectly paired with its function?

    <p>Cervical plexus - Sensory innervation to the arms</p> Signup and view all the answers

    Which of the following statements about the cervical plexus is true?

    <p>It includes both motor and sensory components.</p> Signup and view all the answers

    Which nerve originates from the upper cervical region and is primarily motor in function?

    <p>Suboccipital nerve (C1)</p> Signup and view all the answers

    Which nerve does not play a role in sensory innervation to the scalp?

    <p>Suboccipital nerve (C1)</p> Signup and view all the answers

    Which statement best describes the location of the C1 nerve?

    <p>Emerges above the C2 vertebra</p> Signup and view all the answers

    Which of the following is not directly associated with the cervical plexus?

    <p>Lumbar plexus</p> Signup and view all the answers

    Which function is primarily attributed to the phrenic nerve?

    <p>Controlling diaphragm movement for respiration</p> Signup and view all the answers

    Where are the motor branches of the cervical plexus situated in relation to the sensory branches?

    <p>Deeper than the sensory branches</p> Signup and view all the answers

    What is a primary role of the phrenic nerve?

    <p>Motor innervation to the diaphragm</p> Signup and view all the answers

    Which cervical spinal nerves give rise to the phrenic nerve?

    <p>C3 to C5</p> Signup and view all the answers

    What effect does the phrenic nerve have on breathing?

    <p>Enables diaphragmatic contraction for breathing</p> Signup and view all the answers

    Which function is not associated with the motor branches of the cervical plexus?

    <p>Sensory feedback from the diaphragm</p> Signup and view all the answers

    Which statement accurately describes the role of the phrenic nerve in respiration?

    <p>Facilitates inhalation by enabling diaphragm contraction</p> Signup and view all the answers

    Which of the following best describes the anatomical position of the cervical plexus motor branches?

    <p>Deeper than their sensory counterparts</p> Signup and view all the answers

    What is the primary innervation target of the phrenic nerve?

    <p>Diaphragm</p> Signup and view all the answers

    Which muscle is primarily responsible for depressing the larynx?

    <p>Sternothyroid muscle</p> Signup and view all the answers

    What anatomical feature does the sternohyoid muscle specifically affect?

    <p>Hyoid bone</p> Signup and view all the answers

    What is the historical name of the Ansa Cervicalis?

    <p>Ansa hypoglossi</p> Signup and view all the answers

    Which muscles are primarily innervated by the Ansa Cervicalis?

    <p>Sternohyoid, sternothyroid, and omohyoid muscles</p> Signup and view all the answers

    What does the term 'Ansa Cervicalis' translate to in English?

    <p>Loop of the neck</p> Signup and view all the answers

    Which structure does the hyoid bone articulate with?

    <p>Mandible</p> Signup and view all the answers

    What role does the sternohyroid muscle play in vocalization?

    <p>Depresses the larynx</p> Signup and view all the answers

    Which nerve group is primarily responsible for innervating the muscles involved in tongue movement?

    <p>C1 to C3</p> Signup and view all the answers

    Which cervical nerves are responsible for innervating the sternocleidomastoid muscle?

    <p>C2-C3</p> Signup and view all the answers

    Identify the cervical nerves that innervate the trapezius muscle.

    <p>C3-C4</p> Signup and view all the answers

    Which muscle is primarily innervated by the C3-C4 cervical nerves?

    <p>Levator scapulae</p> Signup and view all the answers

    Which of the following functions is linked to the trapezius muscle?

    <p>Stabilizing the shoulder joint</p> Signup and view all the answers

    Which cervical nerve group innervates the scalenus medius muscle?

    <p>C3-C4</p> Signup and view all the answers

    Which muscle is involved in lateral neck flexion and elevates the first rib during forced inspiration?

    <p>Scalenus medius</p> Signup and view all the answers

    Which of these muscles is innervated by the C2-C3 nerve roots?

    <p>Sternocleidomastoid</p> Signup and view all the answers

    What is the primary function of the sternocleidomastoid muscle?

    <p>Neck flexion, rotation, and lateral flexion</p> Signup and view all the answers

    What is the entry point where sensory branches of the cervical plexus enter the skin?

    <p>Erb’s point (nerve point of the neck)</p> Signup and view all the answers

    The sensory branches of the cervical plexus supply which areas?

    <p>Skin of the neck, upper thorax, scalp, and ear</p> Signup and view all the answers

    Where is Erb’s point located?

    <p>Posterior border of the sternocleidomastoid muscle</p> Signup and view all the answers

    Which of the following areas is not supplied by the sensory branches of the cervical plexus?

    <p>Diaphragm</p> Signup and view all the answers

    The sensory branches that supply the ear emerge from which location?

    <p>Erb’s point at the posterior border of the sternocleidomastoid muscle</p> Signup and view all the answers

    Which landmark is known for the emergence of sensory nerves in the neck?

    <p>Erb’s point</p> Signup and view all the answers

    From which cervical spinal nerves do the sensory branches that supply the skin of the neck originate?

    <p>C2-C4</p> Signup and view all the answers

    What is the primary function of the sensory branches of the cervical plexus?

    <p>Sensory supply to the skin of the neck, upper thorax, scalp, and ear</p> Signup and view all the answers

    What area does the greater auricular nerve provide sensation to?

    <p>The external ear and over the parotid gland</p> Signup and view all the answers

    Which nerve is responsible for sensation in the posterosuperior scalp?

    <p>Lesser occipital nerve (C2)</p> Signup and view all the answers

    What is the primary sensory area innervated by the transverse cervical nerve?

    <p>The anterior neck</p> Signup and view all the answers

    Which of the following nerves provides sensation to the supraclavicular region?

    <p>Supraclavicular nerves (C3, C4)</p> Signup and view all the answers

    Which cervical nerves contribute to the origination of the greater auricular nerve?

    <p>C2 and C3</p> Signup and view all the answers

    Which nerve primarily innervates the area over the parotid gland?

    <p>Greater auricular nerve (C2, C3)</p> Signup and view all the answers

    Sensation in the anterior neck is primarily supplied by which nerve?

    <p>Transverse cervical nerve (C2, C3)</p> Signup and view all the answers

    Which nerve supplies the supraclavicular fossa along with the upper thoracic region?

    <p>Supraclavicular nerves (C3, C4)</p> Signup and view all the answers

    Which sensory nerve of the cervical plexus provides sensation over the parotid gland?

    <p>Greater auricular nerve (C2, C3)</p> Signup and view all the answers

    What area does the lesser occipital nerve (C2) primarily provide sensory innervation to?

    <p>The posterosuperior scalp</p> Signup and view all the answers

    Which nerves are responsible for sensory input to the supraclavicular fossa?

    <p>Supraclavicular nerves (C3, C4)</p> Signup and view all the answers

    Which nerve primarily supplies sensation to the anterior neck?

    <p>Transverse cervical nerve (C2, C3)</p> Signup and view all the answers

    If a patient loses sensation of the external ear, which nerve is most likely affected?

    <p>Greater auricular nerve (C2, C3)</p> Signup and view all the answers

    Which joint does the supraclavicular nerves (C3, C4) innervate?

    <p>Sternoclavicular joint</p> Signup and view all the answers

    Which nerve would be primarily involved if there is reduced sensation over the parotid gland?

    <p>Greater auricular nerve (C2, C3)</p> Signup and view all the answers

    Damage to which nerve could lead to loss of sensation in the anterior neck region?

    <p>Transverse cervical nerve (C2, C3)</p> Signup and view all the answers

    Which spinal nerves are responsible for the roots of the brachial plexus?

    <p>C5-T1</p> Signup and view all the answers

    What structure of the brachial plexus directly connects the roots to the divisions?

    <p>Trunks</p> Signup and view all the answers

    In which area does the brachial plexus primarily pass through to reach the upper limbs?

    <p>Axilla (armpit)</p> Signup and view all the answers

    What mnemonic is used to remember the order of the parts of the brachial plexus?

    <p>Read That Damn Cadaver Book</p> Signup and view all the answers

    How many main parts is the brachial plexus organized into?

    <p>Five</p> Signup and view all the answers

    What is the primary function of the brachial plexus?

    <p>Providing motor innervation to upper limb musculature</p> Signup and view all the answers

    What is the correct order of parts in the brachial plexus?

    <p>Roots, Trunks, Divisions, Cords, Branches</p> Signup and view all the answers

    Which part of the brachial plexus is situated nearest to the spinal cord?

    <p>Roots</p> Signup and view all the answers

    What is the primary function of the anterior rami of C5-T1?

    <p>Form the roots of the brachial plexus</p> Signup and view all the answers

    What is the initial pathway of the roots of the brachial plexus?

    <p>Exiting the spinal cord via the intervertebral foramina</p> Signup and view all the answers

    Which statement correctly describes the region innervated by the posterior rami?

    <p>They innervate the muscles and skin of the posterior aspect of the body</p> Signup and view all the answers

    Which option best describes a function of the cervical plexus?

    <p>Innervate the skin of the neck and shoulders</p> Signup and view all the answers

    What anatomical feature is characteristic of the brachial plexus pathway?

    <p>It passes between the anterior and middle scalene muscles before forming nerves</p> Signup and view all the answers

    From which spinal nerves do the roots of the brachial plexus originate?

    <p>C5-T1</p> Signup and view all the answers

    Where do the roots of the brachial plexus exit the spinal cord?

    <p>Intervertebral foramina</p> Signup and view all the answers

    After exiting the spinal cord, what do the roots of the brachial plexus do?

    <p>Divide into anterior and posterior rami</p> Signup and view all the answers

    Which rami of the spinal nerves contribute to the formation of the brachial plexus?

    <p>Anterior rami</p> Signup and view all the answers

    What do the posterior rami of the spinal nerves primarily innervate?

    <p>The skin and muscles of the back</p> Signup and view all the answers

    What is the primary function of the posterior rami?

    <p>Provide sensory and motor functions to the back</p> Signup and view all the answers

    What describes the initial pathway that the roots of the brachial plexus take?

    <p>They exit through the intervertebral foramina and divide into anterior and posterior rami.</p> Signup and view all the answers

    Which statement about the posterior rami of the spinal nerves is true?

    <p>They innervate the muscles and skin of the posterior aspect of the body.</p> Signup and view all the answers

    How many main trunks are formed at the base of the neck by the roots of the brachial plexus?

    <p>Three</p> Signup and view all the answers

    Which roots contribute to forming the superior trunk of the brachial plexus?

    <p>C5 and C6</p> Signup and view all the answers

    What is the structure formed by each trunk of the brachial plexus?

    <p>Two branches</p> Signup and view all the answers

    Which division of the trunks is primarily responsible for innervating the extensors of the upper limb?

    <p>Posterior division</p> Signup and view all the answers

    What comprises the inferior trunk of the brachial plexus?

    <p>C8 and T1</p> Signup and view all the answers

    Which structures do the divisions of the trunks contribute to forming?

    <p>The cords of the brachial plexus</p> Signup and view all the answers

    Where do the divisions of the brachial plexus trunks pass through?

    <p>The axilla (armpit area)</p> Signup and view all the answers

    Which two branches does each trunk of the brachial plexus divide into?

    <p>Anterior and posterior divisions</p> Signup and view all the answers

    How many main cords are formed in the axilla by the divisions of the brachial plexus trunks?

    <p>Three</p> Signup and view all the answers

    The cords of the brachial plexus are named based on their position relative to which structure?

    <p>Axillary artery</p> Signup and view all the answers

    Which cord of the brachial plexus is formed by the anterior division of the superior and middle trunks?

    <p>Lateral cord</p> Signup and view all the answers

    The posterior cord of the brachial plexus is formed by:

    <p>The posterior divisions of the superior, middle, and inferior trunks</p> Signup and view all the answers

    Which cord is formed solely by the anterior division of the inferior trunk?

    <p>Medial cord</p> Signup and view all the answers

    What structure do the cords of the brachial plexus surround as they pass through the axilla?

    <p>Axillary artery</p> Signup and view all the answers

    Which of the following correctly describes the lateral cord's formation?

    <p>Anterior division of the superior trunk and anterior division of the middle trunk</p> Signup and view all the answers

    The medial cord of the brachial plexus is positioned:

    <p>Medial to the axillary artery</p> Signup and view all the answers

    Which nerve is responsible for innervating the biceps brachii and brachialis muscles?

    <p>Musculocutaneous nerve</p> Signup and view all the answers

    What sensory function does the axillary nerve provide?

    <p>The inferior region of the deltoid</p> Signup and view all the answers

    Which of the following muscles is NOT innervated by the median nerve?

    <p>Extensor muscles of the wrist</p> Signup and view all the answers

    Which nerve innervates the triceps brachii muscle?

    <p>Radial nerve</p> Signup and view all the answers

    What area does the radial nerve provide sensory information to?

    <p>The posterior aspect of the arm and forearm</p> Signup and view all the answers

    Which nerve is responsible for providing motor innervation to both the teres minor and deltoid muscles?

    <p>Axillary nerve</p> Signup and view all the answers

    Which muscles does the ulnar nerve NOT innervate?

    <p>Thenar muscles</p> Signup and view all the answers

    Which area does the sensory function of the ulnar nerve cover?

    <p>The anterior and posterior surfaces of the medial 1½ fingers</p> Signup and view all the answers

    Which nerve is primarily responsible for motor innervation to the thenar muscles and the index and middle fingers?

    <p>Median nerve</p> Signup and view all the answers

    Damage to which nerve is most likely to impair the ability to flex the elbow?

    <p>Musculocutaneous nerve</p> Signup and view all the answers

    The axillary nerve provides sensory innervation primarily to which area of the body?

    <p>Inferior region of the deltoid</p> Signup and view all the answers

    Which nerve is crucial for motor control of the triceps brachii muscle?

    <p>Radial nerve</p> Signup and view all the answers

    Sensory loss in the posterolateral aspect of the hand most likely indicates damage to which nerve?

    <p>Radial nerve</p> Signup and view all the answers

    The ulnar nerve is primarily associated with which muscle group?

    <p>The muscles of the hand</p> Signup and view all the answers

    Damage to the median nerve may lead to difficulty in what specific function?

    <p>Opposing the thumb</p> Signup and view all the answers

    Which nerve is responsible for sensory innervation to the anterior and posterior surfaces of the medial 1½ fingers?

    <p>Ulnar nerve</p> Signup and view all the answers

    What is the range of spinal nerves that form the roots of the brachial plexus?

    <p>C5 to T1</p> Signup and view all the answers

    The medial cord of the brachial plexus is formed by which of the following?

    <p>The anterior division of the inferior trunk</p> Signup and view all the answers

    From which cord does the axillary nerve arise?

    <p>Posterior cord</p> Signup and view all the answers

    How many trunks are formed by the roots of the brachial plexus?

    <p>Three</p> Signup and view all the answers

    Which nerve is primarily associated with the lateral cord of the brachial plexus?

    <p>Musculocutaneous nerve</p> Signup and view all the answers

    Which nerves contribute to the formation of the median nerve?

    <p>Both the lateral and medial cords</p> Signup and view all the answers

    What major nerve arises from the posterior cord of the brachial plexus?

    <p>Radial nerve</p> Signup and view all the answers

    How many divisions are created when the trunks of the brachial plexus split?

    <p>Six</p> Signup and view all the answers

    Which nerve roots are primarily affected in Erb’s Palsy?

    <p>C5 and C6</p> Signup and view all the answers

    Which of the following muscles is not typically paralyzed in Erb’s Palsy?

    <p>Triceps brachii</p> Signup and view all the answers

    What motor functions are especially affected in Erb’s Palsy?

    <p>Abduction at the shoulder, lateral rotation of the arm, supination of the forearm, and flexion at the shoulder</p> Signup and view all the answers

    The typical appearance of the arm in Erb’s Palsy is commonly referred to as what?

    <p>‘Waiter’s tip’ position</p> Signup and view all the answers

    Where is loss of sensation typically observed in Erb’s Palsy?

    <p>Down the lateral aspect of the arm</p> Signup and view all the answers

    Which nerves are associated with sensory loss in Erb’s Palsy?

    <p>Axillary and musculocutaneous nerves</p> Signup and view all the answers

    Which characteristic defines the ‘waiter’s tip’ position in Erb’s Palsy?

    <p>Medial rotation of the arm, pronation of the forearm, and weak wrist flexion</p> Signup and view all the answers

    What is a common cause of Erb’s Palsy?

    <p>Excessive increase in the angle between the neck and shoulder during birth or shoulder trauma</p> Signup and view all the answers

    Which nerve root is primarily affected in Klumpke Palsy?

    <p>T1</p> Signup and view all the answers

    Which nerves are primarily impacted in Klumpke Palsy?

    <p>Ulnar and median nerves</p> Signup and view all the answers

    What is the typical posture of the hand seen in Klumpke Palsy?

    <p>‘Claw hand’ posture</p> Signup and view all the answers

    Which muscles become paralyzed in Klumpke Palsy, resulting in a ‘claw hand’ posture?

    <p>All intrinsic hand muscles</p> Signup and view all the answers

    Which loss of function leads to extension at the metacarpophalangeal (MCP) joints and flexion at the interphalangeal (IP) joints?

    <p>Lumbrical muscles</p> Signup and view all the answers

    In which area of the arm is sensory loss typically experienced in Klumpke Palsy?

    <p>Medial side of the arm</p> Signup and view all the answers

    Which mechanism is most commonly associated with the onset of Klumpke Palsy?

    <p>Excessive abduction of the arm</p> Signup and view all the answers

    Which statement accurately describes the effects of Klumpke Palsy?

    <p>It leads to significant impairment of hand function.</p> Signup and view all the answers

    How many thoracic spinal nerves are there?

    <p>12</p> Signup and view all the answers

    Which thoracic nerves form the intercostal nerves that run between the ribs?

    <p>T1-T11</p> Signup and view all the answers

    What is the last thoracic nerve that runs below the twelfth rib known as?

    <p>Subcostal nerve</p> Signup and view all the answers

    Which thoracic nerves contribute to the formation of the intercostobrachial nerve?

    <p>T2 and T3</p> Signup and view all the answers

    What does the anterior division of the thoracic nerves include?

    <p>Intercostal nerves (T1-T11) and the subcostal nerve (T12)</p> Signup and view all the answers

    The posterior division of the upper six thoracic nerves gives rise to what?

    <p>Medial branches that pierce the rhomboid and trapezius muscles</p> Signup and view all the answers

    What is the primary function of the intercostal nerves?

    <p>Innervation of the thoracic wall and aiding in breathing</p> Signup and view all the answers

    What does the intercostobrachial nerve primarily provide sensory innervation to?

    <p>Upper arm and chest</p> Signup and view all the answers

    Which nerve is identified as the last intercostal nerve?

    <p>Subcostal nerve</p> Signup and view all the answers

    The intercostal nerves primarily help with what physiological function?

    <p>Facilitating respiration</p> Signup and view all the answers

    Which thoracic nerves are specifically involved in sensory innervation to the skin over the upper arm and chest?

    <p>T2 and T3</p> Signup and view all the answers

    What is the primary role of the anterior divisions of the thoracic nerves?

    <p>Forming the intercostal nerves and subcostal nerve</p> Signup and view all the answers

    Which thoracic nerve branch is associated with connecting to the autonomic nervous system?

    <p>Branches to the paravertebral ganglia</p> Signup and view all the answers

    How do the intercostal nerves contribute to sensory information?

    <p>By providing both sensory and motor fibers</p> Signup and view all the answers

    Where do the medial branches of the upper six thoracic nerves primarily penetrate?

    <p>Rhomboid and trapezius</p> Signup and view all the answers

    What distinguishes the subcostal nerve from the intercostal nerves?

    <p>It runs below the twelfth rib</p> Signup and view all the answers

    What type of nerve fibers do intercostal nerves contain?

    <p>Both sensory and motor fibers</p> Signup and view all the answers

    What role do the T6-T12 thoracic nerves play in relation to core strength?

    <p>Supporting abdominal and back muscles for core strength and posture</p> Signup and view all the answers

    Which of the following best describes the primary function of the thoracic nerves T6-T12?

    <p>Supporting abdominal and back muscles for stability</p> Signup and view all the answers

    In what manner do the T1-T5 thoracic nerves differ from the T6-T12 nerves concerning core stability?

    <p>T1-T5 do not contribute to core stability</p> Signup and view all the answers

    Which statement about the T6-T12 thoracic nerves is accurate?

    <p>They stabilize core muscles and posture</p> Signup and view all the answers

    What is one of the key functions of the thoracic nerves in relation to respiratory mechanics?

    <p>Facilitating the expansion and contraction of the rib cage</p> Signup and view all the answers

    Which muscles are primarily affected by the T1-T5 thoracic nerves?

    <p>Muscles of the upper chest, mid-back, and abdomen</p> Signup and view all the answers

    What specific function is primarily associated with the T1-T5 thoracic nerves?

    <p>Controlling the rib cage, lungs, and diaphragm for respiratory movements</p> Signup and view all the answers

    The T6-T12 thoracic nerves primarily affect which muscles?

    <p>Abdominal and back muscles</p> Signup and view all the answers

    What is the primary role of the T6-T12 thoracic nerves?

    <p>Assisting with balance, posture, and core stability</p> Signup and view all the answers

    Which function is associated with the T6-T12 thoracic nerves?

    <p>Aiding in actions like coughing and expelling foreign bodies from the airways</p> Signup and view all the answers

    The thoracic nerves from T1 to T5 are crucial for which aspect of human function?

    <p>Respiratory movements and upper chest stability</p> Signup and view all the answers

    Damage to which section of thoracic nerves would most likely impair coughing?

    <p>T6-T12</p> Signup and view all the answers

    The functions of the T1-T5 thoracic nerves include which of the following?

    <p>Facilitating respiratory movements</p> Signup and view all the answers

    What is a likely impact of an injury to the T1-T5 thoracic nerves?

    <p>Paraplegia (paralysis of the lower body)</p> Signup and view all the answers

    Which aspect of bodily function is most likely to be impaired following a T6-T12 nerve injury?

    <p>Bowel and bladder control</p> Signup and view all the answers

    Injuries to the T9-T12 thoracic nerves primarily affect which muscle group?

    <p>Chest muscles</p> Signup and view all the answers

    What is one consequence of injury to the T1 thoracic nerve?

    <p>Impaired function of hands and fingers</p> Signup and view all the answers

    Which statement is correct regarding T6-T8 thoracic nerve injuries?

    <p>They impair chest and abdominal muscle function</p> Signup and view all the answers

    Following an injury to the T1-T5 nerves, which function is least likely to be affected?

    <p>Function of the arms and hands</p> Signup and view all the answers

    Which of the following injuries would most affect abdominal function?

    <p>Injury to T6-T12</p> Signup and view all the answers

    Which is a result of injury to T2-T5 thoracic nerves?

    <p>Impaired strength of chest muscles</p> Signup and view all the answers

    How many spinal nerves comprise the lumbar region?

    <p>Five</p> Signup and view all the answers

    Which spinal nerves contribute to the formation of the lumbar plexus?

    <p>L1-L4, with some contribution from T12</p> Signup and view all the answers

    Which area does the lumbar plexus primarily supply with nerves?

    <p>The lower abdomen, pelvis, and anterior and medial thigh</p> Signup and view all the answers

    Which nerve is responsible for hip flexion and knee extension in the lumbar plexus?

    <p>Femoral nerve</p> Signup and view all the answers

    What is the primary responsibility of the obturator nerve?

    <p>Supplying the medial thigh muscles for adduction</p> Signup and view all the answers

    The ilioinguinal and iliohypogastric nerves arise from which spinal nerve?

    <p>L1</p> Signup and view all the answers

    Which spinal nerves contribute to the lateral cutaneous nerve of the thigh?

    <p>L2-L3</p> Signup and view all the answers

    Which nerve supplies sensory and motor innervation to the genital region and upper thigh?

    <p>Genitofemoral nerve</p> Signup and view all the answers

    Which spinal nerves contribute to the iliohypogastric nerve?

    <p>T12 and L1</p> Signup and view all the answers

    Which two muscles are innervated by both the iliohypogastric and ilioinguinal nerves?

    <p>Internal oblique and transversus abdominis</p> Signup and view all the answers

    What area does the sensory function of the iliohypogastric nerve primarily cover?

    <p>The posterolateral gluteal skin and the pubic region</p> Signup and view all the answers

    Which nerve is responsible for sensory innervation of the skin over the root of the penis in males?

    <p>Ilioinguinal nerve</p> Signup and view all the answers

    What muscle does the genital branch of the genitofemoral nerve innervate?

    <p>The cremasteric muscle</p> Signup and view all the answers

    Which sensory area is associated with the femoral branch of the genitofemoral nerve?

    <p>Innervating the skin on the upper anterior thigh</p> Signup and view all the answers

    In females, which nerve provides sensory innervation over the mons pubis and labia majora?

    <p>Genital branch of the genitofemoral nerve</p> Signup and view all the answers

    What region does the ilioinguinal nerve provide sensory innervation to?

    <p>The skin on the upper middle thigh and the mons pubis or anterior scrotum</p> Signup and view all the answers

    What type of innervation does the lateral cutaneous nerve of the thigh provide?

    <p>Sensory innervation to the anterior and lateral thigh down to the knee</p> Signup and view all the answers

    Which nerve primarily innervates the sartorius muscle?

    <p>Femoral nerve</p> Signup and view all the answers

    Which nerve is responsible for sensory innervation over the medial thigh?

    <p>Obturator nerve</p> Signup and view all the answers

    Which of the following muscles are innervated by the femoral nerve?

    <p>Iliacus, pectineus, sartorius, and quadriceps femoris group</p> Signup and view all the answers

    Which statement accurately describes the motor function of the lateral cutaneous nerve of the thigh?

    <p>It has no motor functions.</p> Signup and view all the answers

    Which of the following nerves does not provide sensory innervation to the lower limb?

    <p>Ilioinguinal nerve</p> Signup and view all the answers

    The obturator nerve is responsible for motor innervation to which muscles?

    <p>Gracilis and adductor longus</p> Signup and view all the answers

    What sensory function does the femoral nerve provide?

    <p>Sensation to the anterior thigh and medial leg</p> Signup and view all the answers

    Which spinal nerves are the main contributors to the obturator nerve?

    <p>L2-L4</p> Signup and view all the answers

    What is the primary function of the lateral cutaneous nerve of the thigh?

    <p>Sensory innervation to the skin over the lateral thigh</p> Signup and view all the answers

    Which statement accurately describes the function of the femoral nerve?

    <p>Innervates the iliacus and quadriceps femoris muscles</p> Signup and view all the answers

    Damage to the obturator nerve commonly leads to weakness in which movement?

    <p>Thigh adduction</p> Signup and view all the answers

    Which nerve is solely responsible for sensory innervation without any motor functions to the thigh?

    <p>Lateral cutaneous nerve of the thigh</p> Signup and view all the answers

    What area of the thigh does the obturator nerve provide sensory innervation to?

    <p>Medial thigh</p> Signup and view all the answers

    Which of the following options describes a potential injury caused by damage to the lateral cutaneous nerve of the thigh?

    <p>Loss of sensation on the lateral thigh</p> Signup and view all the answers

    Which nerve provides sensory innervation to the medial thigh region?

    <p>Obturator nerve</p> Signup and view all the answers

    How many pairs of sacral nerves are present in the human body?

    <p>5</p> Signup and view all the answers

    From which structure do the sacral nerves originate?

    <p>Cauda equina</p> Signup and view all the answers

    Which areas are primarily supplied by the sacral plexus?

    <p>The hip, thigh, leg, and foot</p> Signup and view all the answers

    What types of fibers does the sacral plexus contain?

    <p>Both motor and sensory fibers</p> Signup and view all the answers

    Which major plexus do the sacral nerves contribute to?

    <p>Sacral plexus and lumbosacral plexus</p> Signup and view all the answers

    Which motor function is specifically attributed to the sacral plexus?

    <p>Facilitating hip and leg movement and strength</p> Signup and view all the answers

    Which sensory function is primarily performed by the sacral nerves?

    <p>Sensory perception in the lower body regions</p> Signup and view all the answers

    In which part of the nervous system are the sacral nerves classified?

    <p>Peripheral nervous system</p> Signup and view all the answers

    What is the main function of the sacral plexus?

    <p>To provide motor and sensory innervation to the lower limbs and pelvic region</p> Signup and view all the answers

    Which nerve is responsible for innervating the muscles that abduct the hip?

    <p>Superior gluteal nerve</p> Signup and view all the answers

    Which structures are primarily supplied by the tibial nerve?

    <p>Gastrocnemius and soleus muscles</p> Signup and view all the answers

    Which nerve exits the pelvis along with the sciatic nerve?

    <p>Pudendal nerve</p> Signup and view all the answers

    Which nerve is primarily responsible for providing sensory innervation to the perineum?

    <p>Pudendal nerve</p> Signup and view all the answers

    What are the primary branches of the sciatic nerve?

    <p>Tibial and common fibular nerves</p> Signup and view all the answers

    What is the major role of the inferior gluteal nerve?

    <p>Innervating the gluteus maximus</p> Signup and view all the answers

    The mnemonic 'Some Irish Sailor Pesters Polly' is used to remember which anatomical structure?

    <p>Nerves of the sacral plexus</p> Signup and view all the answers

    Which spinal nerve roots comprise the inferior gluteal nerve?

    <p>L5, S1, S2</p> Signup and view all the answers

    What is the primary action facilitated by the gluteus maximus, innervated by the inferior gluteal nerve?

    <p>Extension of the hip</p> Signup and view all the answers

    The superior gluteal nerve is responsible for innervating which of the following muscles?

    <p>Gluteus medius, gluteus minimus, and tensor fasciae latae</p> Signup and view all the answers

    Which statement about the sensory function of the superior gluteal nerve is accurate?

    <p>It has no sensory function.</p> Signup and view all the answers

    What is the primary role of the gluteus minimus and gluteus medius muscles innervated by the superior gluteal nerve?

    <p>Hip abduction and stabilization</p> Signup and view all the answers

    The inferior gluteal nerve plays a vital role in which functional movement?

    <p>Extending the hip while rising from a seated position</p> Signup and view all the answers

    Which of the following movements is NOT facilitated by the muscles innervated by the inferior gluteal nerve?

    <p>Knee flexion</p> Signup and view all the answers

    What is a shared function of the muscles innervated by both the superior and inferior gluteal nerves?

    <p>They stabilize the pelvis during walking.</p> Signup and view all the answers

    What spinal nerve roots comprise the sciatic nerve?

    <p>L4, L5, S1, S2, S3</p> Signup and view all the answers

    Which portion of the sciatic nerve innervates the majority of the posterior thigh muscles?

    <p>Tibial portion</p> Signup and view all the answers

    Which muscles are supplied by the tibial portion of the sciatic nerve?

    <p>Posterior compartment of the leg and sole of the foot</p> Signup and view all the answers

    Which muscle is specifically innervated by the common fibular portion of the sciatic nerve?

    <p>Short head of the biceps femoris</p> Signup and view all the answers

    What compartments of the leg does the common fibular portion of the sciatic nerve supply?

    <p>Anterior and lateral</p> Signup and view all the answers

    What areas does the tibial portion of the sciatic nerve provide sensory innervation to?

    <p>Posterolateral and medial surfaces of the foot and the sole of the foot</p> Signup and view all the answers

    Which region does the common fibular portion of the sciatic nerve provide sensory innervation to?

    <p>Anterolateral surface of the leg and the dorsal aspect of the foot</p> Signup and view all the answers

    What is the primary characteristic of sciatica?

    <p>Pain radiating along the path of the sciatic nerve from the lower back down the leg</p> Signup and view all the answers

    Which spinal nerve roots compose the posterior femoral cutaneous nerve?

    <p>S1, S2, S3</p> Signup and view all the answers

    What sensory area does the posterior femoral cutaneous nerve innervate?

    <p>The posterior surface of the thigh and leg, and the perineum</p> Signup and view all the answers

    Which spinal nerve roots form the pudendal nerve?

    <p>S2, S3, S4</p> Signup and view all the answers

    Which motor function is controlled by the pudendal nerve?

    <p>Control of the external urethral sphincter and levator ani</p> Signup and view all the answers

    What is the primary sensory function of the pudendal nerve?

    <p>Sensory innervation to the penis and clitoris</p> Signup and view all the answers

    Which area does the posterior femoral cutaneous nerve NOT contribute to concerning sensory perception?

    <p>The anterior thigh</p> Signup and view all the answers

    The pudendal nerve plays a significant role in which bodily functions?

    <p>Reproductive and excretory functions</p> Signup and view all the answers

    Which option is TRUE regarding the motor involvement of the posterior femoral cutaneous nerve?

    <p>It has no motor functions.</p> Signup and view all the answers

    Study Notes

    Peripheral Nervous System (PNS)

    • The PNS is responsible for transmitting information between the central nervous system (CNS) and the rest of the body.

    Spinal Nerves

    • Spinal nerves contain both motor and sensory neurons, allowing for communication between the CNS and the body.
    • There are 31 pairs of spinal nerves connected to the spinal cord.
    • The 31 pairs of nerves are broken down into the following:
      • 8 Cervical
      • 12 Thoracic
      • 5 Lumbar
      • 5 Sacral
    • Spinal nerves facilitate movement and sensory input throughout the body.

    Nervous System Function and Divisions

    • Somatic Nervous System: Controls voluntary movements, such as picking up a cup.
    • Autonomic Nervous System: Controls involuntary actions such as heartbeat.
    • Afferent Nerves: Carry sensory information to the central nervous system (CNS).
    • Efferent Nerves: Send signals from the CNS to muscles for movement.
    • Sympathetic Nervous System: Prepares the body for "fight or flight" responses by increasing blood pressure, heart rate, and breathing rate.
    • Parasympathetic Nervous System: Promotes energy conservation and normal body functions like digestion, often described as the "rest and digest" system.

    Nervous System Divisions

    • The somatic nervous system controls voluntary movements, such as picking up a cup.
    • The autonomic nervous system regulates unconscious bodily functions.
    • The central nervous system (CNS) is made up of the brain and spinal cord.
    • The sympathetic nervous system prepares the body for "fight or flight" responses - increasing heart rate, blood pressure, and breathing rate.
    • The parasympathetic nervous system is responsible for "rest and digest" functions, promoting energy conservation and normal body functions.

    Nerve Types

    • Afferent nerves carry sensory information from the body to the CNS.
    • Efferent nerves send signals from the CNS to muscles for movement.

    Autonomic Nervous System Actions

    • Involuntary actions, such as heartbeat, are controlled by the autonomic nervous system.
    • Emergency situations activate the sympathetic nervous system, leading to increased heart rate, blood pressure, and breathing rate, preparing the body to respond to threats.

    Spinal Nerves and Plexuses

    • Cervical Plexus
      • Formed by spinal nerves C1 to C4
      • Provides nerve connections to the head, neck, and shoulder
    • Brachial Plexus
      • Formed by spinal nerves C5 to T1
      • Supplies nerves to the chest, shoulders, upper arms, forearms, and hands
    • Lumbar Plexus
      • Formed by spinal nerves L1 to L4
      • Responsible for nerve connections to the thighs and knees
    • Sacral Plexus
      • Formed by spinal nerves L4 to S4
      • Provides nerve connections to the pelvis, buttocks, genitals, thighs, calves, and feet

    Cervical Vertebrae and Nerves

    • There are seven cervical vertebrae in the human body, labeled C1 to C7.
    • There are eight cervical nerves, labeled C1 to C8.
    • C8 is unique, it emerges below its corresponding vertebra (C7).

    Cervical Plexus

    • The cervical plexus is formed by the first four cervical nerves (C1 to C4).
    • The cervical plexus is responsible for motor and sensory innervation to the neck and parts of the head and shoulders.
    • The cervical plexus is divided into two main groups:
      • Muscular group: Provides motor control to certain neck muscles.
      • Sensory group: Provides sensory input from areas of the neck and skin.

    Cervical Vertebrae and Nerves

    • There are 7 cervical vertebrae (C1-C7) in the human body.
    • There are 8 cervical nerves (C1-C8).
    • Cervical nerves C1 to C7 emerge above their corresponding vertebra.
    • Cervical nerve C8 emerges below vertebra C7.

    Cervical Plexus

    • The cervical plexus is formed by the first four cervical nerves (C1-C4).
    • It supplies motor and sensory innervation to the neck region.
    • The cervical plexus contains two main groups of nerves:
      • Muscular (motor) group: controls muscles in the neck.
      • Sensory group: responsible for sensation in the neck, scalp, and shoulders.

    Suboccipital Nerve (C1)

    • The suboccipital nerve (C1) is a motor nerve.
    • It supplies muscles at the base of the skull.

    Greater Occipital Nerve (C2)

    • The greater occipital nerve (C2) is a sensory nerve.
    • It provides sensation to the back of the scalp.

    Third Occipital Nerve (C3)

    • The third occipital nerve (C3) is a sensory nerve.
    • It provides sensation to the lower part of the scalp and neck.

    Brachial Plexus

    • The brachial plexus, formed from the spinal nerves C5-T1, supplies nerves to the chest, shoulders, arms, and hands.
    • It is not part of the cervical plexus.

    Other Key Points

    • The phrenic nerve, essential for breathing, originates from the cervical plexus (C3-C5).
    • The radial nerve is part of the brachial plexus and is responsible for extending the elbow and wrist.
    • The cervical plexus does not extend to the arms and hands.
    • The lumbar plexus is a different plexus responsible for innervating the lower limbs.

    Cervical Plexus Motor Branches

    • Located deeper than the sensory branches of the cervical plexus.
    • Primarily responsible for motor innervation of muscles in the neck, back, and diaphragm.

    Phrenic Nerve

    • Most notable motor branch of the cervical plexus.
    • Originates from cervical spinal nerves C3 to C5.
    • Responsible for motor innervation of the diaphragm, enabling diaphragmatic contraction for breathing.

    Importance of the Phrenic Nerve

    • Crucial for breathing as it controls the diaphragm's contraction.

    Sternohyoid muscle

    • Innervated by C1, C2, and C3 nerves
    • Acts on the hyoid bone, located below the mandible
    • Primary function: Depresses the larynx
    • Works alongside the sternohyoid muscle to depress the hyoid bone

    Ansa Cervicalis

    • A loop of nerves that is part of the cervical plexus (C1-C3)
    • Translates to "Handle of the neck" in Latin
    • Historically referred to as Ansa hypoglossi
    • Innervates the sternohyoid, sternothyroid, and omohyoid muscles

    Sternothyroid muscle

    • Contributes to controlling vocal pitch and volume

    Neck muscles

    • Innervated by C1 to C3 nerve group, which also innervates muscles involved in tongue movement and swallowing

    Cervical Nerve Innervations

    • C1-C2: Primarily involved in innervating the prevertebral muscles, which are responsible for neck flexion and stabilization.
    • C2-C3: Innervate the sternocleidomastoid muscle, which aids in neck flexion, rotation, and lateral flexion. They also innervate the prevertebral muscles.
    • C3-C4: Innervate both the levator scapulae and trapezius muscles. The levator scapulae assists in elevating the scapula, while the trapezius helps with scapular movement, rotation, and stabilization. They also innervate the scalenus medius muscle.
    • C4-C5: Play a role in the innervation of the trapezius muscle.
    • C4-T1: The trapezius muscle, which supports scapular movement, is primarily innervated by the C4-T1 nerves.
    • Scalenus Medius: This muscle assists in lateral neck flexion and elevates the first rib during forced inspiration. It is innervated by the C3-C4 nerves.
    • Sternohyoid and Omohyoid: These muscles play a role in depressing the hyoid bone and are innervated by the C1-C3 nerve roots.
    • Sternothyroid: Depresses the larynx and is innervated by the C2-C3 nerve roots.
    • Scalenus Anterior: Assists in elevating the first rib during forced inspiration and is innervated by the C4-C5 nerve roots.

    Muscle Functions

    • Trapezius: Its primary function is to move, rotate, and stabilize the scapula.
    • Sternocleidomastoid: Facilitates flexion, rotation, and lateral flexion of the neck.

    Cervical Plexus

    • The cervical plexus is a network of nerves that emerge from the spinal cord in the neck region.
    • The sensory branches of the cervical plexus are responsible for supplying sensation to the skin of the neck, upper thorax, scalp, and ear.
    • Erb’s point, also known as the nerve point of the neck, is a crucial landmark located at the posterior border of the sternocleidomastoid muscle.
    • Sensory branches of the cervical plexus emerge from Erb’s point to innervate the skin of the neck, upper thorax, scalp, and ear.
    • The sensory branches that supply the ear also emerge from Erb’s point.
    • The sensory branches responsible for supplying the skin of the neck arise from spinal nerves C2-C4.
    • The sensory branches of the cervical plexus do not innervate the diaphragm.

    Cervical Plexus Sensory Innervation

    • The greater auricular nerve (C2, C3) provides sensation to the external ear and the parotid gland.
    • The transverse cervical nerve (C2, C3) supplies sensation to the anterior neck.
    • The lesser occipital nerve (C2) provides sensory input to the posterosuperior scalp.
    • The supraclavicular nerves (C3, C4) supply sensation to the supraclavicular fossa, upper thoracic region, and sternoclavicular joint.
    • The greater auricular nerve originates from cervical nerves C2 and C3.
    • The supraclavicular nerves provide sensory input to the supraclavicular fossa and sternoclavicular joint.

    Cervical Plexus Sensory Innervation

    • Greater Auricular Nerve (C2, C3): Provides sensation to the parotid gland, external ear, and skin over the mastoid process.
    • Lesser Occipital Nerve (C2): Supplies sensory innervation to the posterosuperior scalp.
    • Transverse Cervical Nerve (C2, C3): Provides sensation to the anterior neck region.
    • Supraclavicular Nerves (C3, C4): Involved in sensory innervation of the supraclavicular fossa, upper thoracic region, and the sternoclavicular joint.

    Brachial Plexus Overview

    • The brachial plexus is a network of nerves that originates from the spinal cord and supplies the upper limb.
    • It emerges from spinal nerves C5-T1.
    • The plexus is responsible for providing sensory and motor innervation to the upper limb.
    • It passes through the axilla (armpit) to reach the upper extremities.
    • The brachial plexus is divided into five main parts: roots, trunks, divisions, cords, and branches.

    Parts of the Brachial Plexus

    • Roots: Formed by spinal nerves C5-T1
    • Trunks: Three trunks are formed by the roots.
      • Superior trunk: C5-C6 roots
      • Middle trunk: C7 root
      • Inferior trunk: C8-T1 roots
    • Divisions: Each trunk divides into anterior and posterior divisions.
    • Cords: The divisions converge to form three cords:
      • Lateral cord: Anterior divisions of the superior and middle trunks
      • Posterior cord: Posterior divisions of all three trunks
      • Medial cord: Anterior division of the inferior trunk
    • Branches: The cords give rise to numerous branches which innervate specific muscles and structures of the upper limb.

    Mnemonic for Ordering

    • "Read That Damn Cadaver Book" can help remember the order: Roots, Trunks, Divisions, Cords, Branches

    Brachial Plexus Location

    • The brachial plexus starts at the neck, passes through the axilla (armpit), and descends into the upper limb.

    Key Functions

    • Sensory: Receives sensory information from the skin and structures of the upper limb.
    • Motor: Controls the movement of muscles in the upper limb.

    Brachial Plexus Roots

    • The brachial plexus is formed by the anterior rami of spinal nerves C5-T1.
    • These roots exit the spinal cord through the intervertebral foramina.
    • After exiting, the roots divide into anterior and posterior rami.
    • The anterior rami are responsible for forming the brachial plexus.
    • The posterior rami innervate the muscles and skin of the back.

    Brachial Plexus Pathway

    • The brachial plexus roots exit the spinal cord through the intervertebral foramina.
    • They then divide into anterior and posterior rami.
    • The anterior rami are responsible for forming the brachial plexus.
    • The posterior rami innervate the muscles and skin of the back.

    Function of the Brachial Plexus

    • The brachial plexus provides sensory and motor innervation to the upper limb.
    • It is responsible for controlling the movement of the arm, hand, and fingers.
    • It also provides sensory input from the skin and muscles of the upper limb.

    Brachial Plexus Trunks & Divisions

    • The brachial plexus originates from the ventral rami of spinal nerves C5-T1.
    • The roots of the brachial plexus converge to form three trunks:
      • Superior trunk: Formed by the convergence of C5 and C6 roots.
      • Middle trunk: Formed by the C7 root.
      • Inferior trunk: Formed by the convergence of C8 and T1 roots.
    • Each trunk then divides into two divisions:
      • Anterior division: Primarily innervates the flexor muscles of the upper limb.
      • Posterior division: Primarily innervates the extensor muscles of the upper limb.
    • The divisions of the trunks then converge to form three cords which ultimately give rise to the terminal branches of the brachial plexus.
    • The divisions of the trunks pass through the axilla (armpit area).

    Brachial Plexus Cords

    • The brachial plexus is a network of nerves that arise from the spinal cord and supply the upper limb.
    • The brachial plexus is formed by the ventral rami of spinal nerves C5-T1.
    • The brachial plexus is divided into:
      • Roots
      • Trunks
      • Divisions
      • Cords
      • Branches
    • Three main cords are formed in the axilla by the divisions of the brachial plexus trunks:
      • Lateral cord - formed by the anterior divisions of the superior and middle trunks
      • Posterior cord - formed by the posterior divisions of the superior, middle, and inferior trunks
      • Medial cord - formed solely by the anterior division of the inferior trunk
    • The cords of the brachial plexus are named based on their position relative to the axillary artery.
    • The lateral cord is positioned lateral to the axillary artery.
    • The medial cord is positioned medial to the axillary artery.
    • The posterior cord is positioned posterior to the axillary artery.
    • The posterior cord contributes to the formation of the radial nerve.

    Brachial Plexus and Nerves

    • The brachial plexus is a network of nerves that innervates the upper limb.
    • It is formed from the ventral rami of spinal nerves C5-T1.
    • The brachial plexus is divided into five major branches: the axillary, musculocutaneous, median, radial, and ulnar nerves.

    Axillary Nerve (C5, C6):

    • Motor function: Innervates the deltoid and teres minor muscles.
    • Sensory function: Provides sensation to the inferior region of the deltoid, also known as the "regimental badge" area.

    Musculocutaneous Nerve (C5-C7):

    • Motor function: Innervates the biceps brachii, brachialis, and coracobrachialis muscles, primarily responsible for elbow flexion.
    • Sensory function: Provides sensation to the lateral half of the anterior forearm and a small portion of the posterior forearm.

    Median Nerve (C5-T1):

    • Motor function: Innervates most of the flexor muscles in the forearm, including the pronators, and the thenar muscles of the hand.
    • Sensory function: Provides sensation to the lateral 3½ fingers on the palmar surface of the hand.

    Radial Nerve (C5-T1):

    • Motor function: Innervates the triceps brachii, brachioradialis, and extensor muscles of the wrist and fingers.
    • Sensory function: Provides sensation to the posterior aspect of the arm and forearm, as well as the posterolateral hand.

    Ulnar Nerve (C7-T1):

    • Motor function: Innervates the flexor carpi ulnaris, most of the intrinsic muscles of the hand, and some finger flexors.
    • Sensory function: Provides sensation to the medial 1½ fingers (including associated palm area) on both the anterior and posterior surfaces of these fingers.

    Brachial Plexus and Innervation

    • Median Nerve:

      • Innervates thenar muscles, index, and middle fingers
      • Involved in opposing the thumb
      • Provides sensory innervation to lateral palm and 3 1/2 fingers on the palmar side

    • Musculocutaneous Nerve:

      • Responsible for elbow flexion
      • Originates from C5, C6, and C7 roots

    • Radial Nerve:

      • Provides sensory innervation to posterolateral aspect of the hand
      • Innervates the triceps brachii muscle
      • Responsible for wrist extension

    • Axillary Nerve:

      • Provides sensory innervation to the inferior deltoid ("regimental badge" area)
      • Innervates deltoid and teres minor muscles

    • Ulnar Nerve:

      • Innervates most hand muscles, excluding thenar muscles
      • Provides sensory innervation to medial 1 1/2 fingers and associated palm area
      • Necessary for finger abduction and adduction

    • Nerve Damage and Symptoms:

      • Median Nerve Damage: Difficulty opposing thumb
      • Musculocutaneous Nerve Damage: Weakness in elbow flexion
      • Radial Nerve Damage: Weakness in wrist extension, sensory loss in dorsal hand
      • Axillary Nerve Damage: Sensory loss in the deltoid region
      • Ulnar Nerve Damage: Weakness in hand, sensory loss in medial fingers

    Brachial Plexus Formation

    • The brachial plexus is a network of nerves that arises from the ventral rami of spinal nerves C5-T1.
    • The roots (C5-T1) merge to form three trunks: superior, middle, and inferior.
    • The superior trunk is formed by the combination of C5 and C6 roots.
    • The middle trunk is formed by the single C7 root.
    • The inferior trunk is formed by the combination of C8 and T1 roots.
    • Each trunk then splits into an anterior and posterior division, resulting in six divisions.
    • The anterior divisions of the superior and middle trunks combine to form the lateral cord.
    • The posterior divisions of all three trunks combine to form the posterior cord.
    • The anterior division of the inferior trunk forms the medial cord.

    Major Nerves of the Brachial Plexus

    • The lateral cord gives rise to the musculocutaneous nerve.
    • The medial cord gives rise to the ulnar nerve.
    • The posterior cord gives rise to the axillary and radial nerves.
    • The median nerve is a combination of branches from both the lateral and medial cords.

    Key Innervations

    • The musculocutaneous nerve innervates the anterior compartment muscles of the arm and provides sensory innervation to the lateral forearm.
    • The axillary nerve innervates the deltoid and teres minor muscles and provides sensory innervation to the skin over the deltoid and lateral shoulder.
    • The radial nerve innervates the posterior compartment muscles of the arm and forearm and provides sensory innervation to the posterior arm and forearm.
    • The median nerve innervates the anterior compartment muscles of the forearm and provides sensory innervation to the palmar aspect of the thumb, index, middle, and radial half of the ring finger.
    • The ulnar nerve innervates the flexor carpi ulnaris and medial half of the flexor digitorum profundus muscles in the forearm, as well as the intrinsic hand muscles, and provides sensory innervation to the palmar and dorsal aspects of the little finger and medial half of the ring finger.

    Location and Relationship to Axillary Artery

    • The cords of the brachial plexus are named based on their position relative to the axillary artery.
    • The lateral cord is located lateral to the axillary artery.
    • The medial cord is located medial to the axillary artery.
    • The posterior cord is located posterior to the axillary artery.

    Erb's Palsy

    • Nerve Roots Affected: Erb's Palsy involves injury to the C5 and C6 nerve roots of the brachial plexus.
    • Muscles Affected: The muscles typically paralyzed in Erb's Palsy include supraspinatus, teres minor, and subclavius, but not the triceps brachii.
    • Motor Function Impairment: Individuals with Erb's Palsy experience difficulty with abduction at the shoulder, lateral rotation of the arm, supination of the forearm, and flexion at the shoulder.
    • Characteristic Appearance: The characteristic arm position in Erb's Palsy is known as the "waiter's tip" position, which is marked by medial rotation of the arm, pronation of the forearm, and weak wrist flexion.
    • Sensory Loss: Sensory loss in Erb's Palsy typically occurs down the lateral aspect of the arm, affecting the axillary and musculocutaneous nerves.
    • Common Cause: Erb's Palsy is frequently caused by excessive stretching or trauma to the shoulder during birth or due to shoulder trauma in adults.
    • Muscle Involved in Supination: The biceps brachii muscle, responsible for supination of the forearm, is affected in Erb's Palsy.
    • Shoulder Abduction: The deltoid muscle, which plays a crucial role in shoulder abduction, is paralyzed in Erb's Palsy, significantly impacting this movement.

    Klumpke Palsy

    • Nerve roots affected: Primarily T1, but C8 can also be involved.
    • Nerves affected: Ulnar and median nerves.
    • Hand posture: Characteristic "claw hand" posture.
    • Cause of claw hand: Paralysis of all intrinsic hand muscles.
    • Muscle responsible for the claw hand: Lumbrical muscles.
    • Function of the lumbrical muscles: Flexion at the metacarpophalangeal (MCP) joints and extension at the interphalangeal (IP) joints of the fingers.
    • Affected muscle groups: Intrinsic muscles of the hand.
    • Sensory loss: Medial side of the arm.
    • Common cause: Excessive abduction of the arm, such as catching oneself on a branch during a fall.
    • Key fact: Klumpke Palsy leads to significant impairment of hand function.
    • Mechanism of claw hand: Loss of lumbrical function leads to unopposed action of finger extensor muscles.

    Overview of Thoracic Nerves

    • There are 12 thoracic spinal nerves (T1-T12) located in the thoracic region of the spinal cord.
    • Each thoracic nerve divides into anterior and posterior divisions.

    Thoracic Nerves and Intercostal Nerves

    • Thoracic nerves T1-T11 form the intercostal nerves which run between the ribs, providing innervation to the thoracic wall.
    • The last thoracic nerve, T12, is called the subcostal nerve and runs below the twelfth rib.

    Intercostobrachial Nerve

    • The intercostobrachial nerve is formed by branches of the second and third thoracic nerves (T2 and T3).
    • Provides sensory innervation to the upper arm and chest.

    Anterior Thoracic Nerve Divisions

    • The anterior divisions of the thoracic nerves primarily form the intercostal nerves (T1-T11) and the subcostal nerve (T12).

    Posterior Thoracic Nerve Divisions

    • The posterior divisions of the upper six thoracic nerves (T1-T6) have medial branches that pierce the rhomboid and trapezius muscles, providing sensory innervation to the skin of the back.

    Functions of Thoracic Nerves

    • Intercostal Nerves: innervate the intercostal muscles, aiding in respiration, and provide sensory innervation to the skin of the chest.
    • Subcostal Nerve: provides sensory innervation to the abdominal region.
    • Medial Branches: (Upper six thoracic nerves) provide sensory innervation to the skin of the back.
    • Intercostobrachial Nerve: provides sensory innervation to the upper arm and chest.

    Autonomic Nervous System (ANS) Connection

    • Thoracic nerves connect to the paravertebral ganglia, which are part of the sympathetic nervous system of the ANS.

    Thoracic Nerve Function

    • T1-T5 Thoracic Nerves: Primarily responsible for controlling the muscles of the upper chest, mid-back, and abdomen. They play a crucial role in respiratory movements by controlling the rib cage, lungs, and diaphragm.

    • T6-T12 Thoracic Nerves: Primarily involved in supporting abdominal and back muscles for core strength and posture, contributing to balance and core stability. They also aid in protective respiratory reflexes like coughing and expelling foreign bodies from the airways.

    Key Points

    • T1-T5: Contribute to upper chest stability and respiratory movements
    • T6-T12: Essential for core stability, posture, and protective respiratory reflexes
    • Damage to T6-T12: Can impair coughing and other protective respiratory reflexes
    • T1-T5: Do not directly innervate the diaphragm, but contribute to its function through rib cage control
    • T6-T12: Do not directly control arm movements

    Thoracic Nerve Injuries and their Effects

    • Injury to T1-T5 thoracic nerves results in paraplegia (paralysis of the lower body).
    • T1-T5 nerve injuries do not affect hand and finger movement.
    • T1-T5 nerve injuries impair the function of abdominal muscles and the lower back.
    • Injury to T6-T12 thoracic nerves may lead to little or no control over the bowel and bladder.
    • T9-T12 thoracic nerve injuries affect abdominal muscles.
    • T1 thoracic nerve injury can affect hands and fingers.
    • T6-T8 thoracic nerve injury leads to impaired chest and abdominal muscle function.
    • T1-T5 nerve injuries do not affect arm and hand function.
    • T6-T12 nerve injuries result in impaired control over abdominal muscles and some bowel/bladder functions.
    • T2-T5 thoracic nerve injuries primarily affect chest muscles.
    • T1-T5 injury results in paraplegia, but arm and hand function is retained.

    Lumbar Nerves and the Lumbar Plexus

    • The lumbar region of the spine is composed of five spinal nerves (L1-L5).
    • The lumbar plexus is formed by the anterior rami of spinal nerves L1-L4, with some contribution from T12.
    • The lumbar plexus innervates the lower abdomen, pelvis, and anterior and medial thigh.

    Key Nerves of the Lumbar Plexus

    • Femoral nerve (L2-L4): Responsible for hip flexion and knee extension.
    • Obturator nerve (L2-L4): Supplies the medial thigh muscles for adduction.
    • Ilioinguinal and iliohypogastric nerves (L1): Supply the lower abdomen and groin area.
    • Lateral cutaneous nerve of the thigh (L2-L3): Provides sensory innervation to the lateral thigh.
    • Genitofemoral nerve (L1-L2): Supplies sensory and motor innervation to the genital region and upper part of the thigh.

    Lumbar Plexus Nerves

    • Iliohypogastric nerve:
      • Originates from T12 and L1 spinal nerves.
      • Innervates internal oblique and transversus abdominis muscles.
      • Provides sensory innervation to the posterolateral gluteal skin and the pubic region.
      • Motor function contributes to abdominal wall strength and movement.
    • Ilioinguinal nerve:
      • Originates from L1 spinal nerve.
      • Innervates internal oblique and transversus abdominis muscles.
      • Provides sensory innervation to the skin on the upper middle thigh, and in males: the skin over the root of the penis and the anterior scrotum; in females: the mons pubis.
    • Genitofemoral nerve:
      • Originates from L1 and L2 spinal nerves.
      • Genital branch:
        • Motor innervation to the cremasteric muscle.
        • Sensory innervation to the skin over the mons pubis and labia majora in females.
      • Femoral branch:
        • Sensory innervation to the skin on the upper anterior thigh.
    • Lateral cutaneous nerve of the thigh:
      • Originates from L2 and L3 spinal nerves.
      • Provides sensory innervation to the skin on the anterolateral thigh.
    • Femoral nerve:
      • Originates from L2, L3, and L4 spinal nerves.
      • Largest branch of the lumbar plexus.
      • Provides motor innervation to the muscles of the anterior thigh, such as the quadriceps femoris, pectineus, sartorius.
      • Provides sensory innervation to the skin of the anterior thigh, medial leg, and foot.
    • Obturator nerve:
      • Originates from L2, L3, and L4 spinal nerves.
      • Provides motor innervation to the muscles of the medial thigh, such as the adductor longus, adductor brevis, adductor magnus, gracilis.
      • Provides sensory innervation to the skin of the medial thigh.
    • Lumbosacral trunk:
      • Continuation of L4 and L5 spinal nerves.
      • Contributes to the sacral plexus.
    • Cremasteric reflex:
      • Genital branch of the genitofemoral nerve innervates the cremasteric muscle.
      • When the skin of the medial thigh is stroked, the cremasteric muscle contracts, causing the ipsilateral testicle to elevate.

    Lateral Cutaneous Nerve of the Thigh

    • Sensory nerve
    • Innervates the skin of the anterior and lateral thigh, extending down to the knee
    • Does not have motor functions

    Obturator Nerve

    • Mixed nerve with both motor and sensory functions
    • Motor innervation to the following muscles:
      • Pectineus
      • Adductor longus
    • Sensory innervation to the skin over the medial thigh

    Femoral Nerve

    • Mixed nerve with both motor and sensory functions
    • Motor innervation to the following muscles:
      • Iliacus
      • Pectineus
      • Sartorius
      • Quadriceps femoris group
    • Sensory innervation to the skin of the anterior thigh and the medial leg

    Comparing the Three Nerves:

    • Lateral cutaneous nerve of the thigh: purely sensory, covering anterior and lateral thigh
    • Obturator nerve: motor to adductors, sensory to medial thigh
    • Femoral nerve: motor to quadriceps, and iliopsoas, sensory to anterior thigh and medial leg

    Obturator Nerve

    • Originates from spinal nerve roots L2-L4.
    • Innervates the adductor muscles, responsible for thigh adduction.
    • Provides sensory innervation to the skin over the medial thigh.

    Lateral Cutaneous Nerve of the Thigh

    • Originates from spinal nerve roots L2-L3.
    • Provides sensory innervation to the skin over the anterior and lateral aspects of the thigh.
    • No motor innervation.

    Femoral Nerve

    • Originates from spinal nerve roots L2-L4.
    • Innervates the quadriceps femoris group, responsible for knee extension, including sartorius muscle.
    • Innervates the iliacus muscle.
    • Provides sensory innervation to the anterior thigh.

    Iliohypogastric and Ilioinguinal Nerves

    • Share a common origin from L1 spinal nerve root.

    Additional Notes

    • Damage to the obturator nerve will result in weakness in thigh adduction.
    • Damage to the lateral cutaneous nerve of the thigh will result in loss of sensation on the anterior and lateral aspects of the thigh.

    Sacral Nerves: Structure and Function

    • There are five pairs of sacral nerves.
    • They originate from the cauda equina, which is a collection of nerve roots in the spinal canal.
    • Sacral nerves supply the hip, thigh, leg, and foot.
    • They contain both motor (efferent) and sensory (afferent) fibers.
    • They contribute to both the sacral plexus and lumbosacral plexus.
    • The sacral plexus is responsible for motor control of the hip and leg, and for sensory perception of the lower body.
    • Sacral nerves belong to the peripheral nervous system.
    • The lumbosacral plexus primarily affects the lower limbs.
    • The sacral plexus is crucial for movement, strength, and sensory perception in the lower body.

    The Sacral Plexus

    • The sacral plexus is a network of nerves formed by the ventral rami of spinal nerves L4-S4.
    • The sacral plexus gives rise to several important nerves that innervate the lower limb, gluteal region, and perineum.

    Main Nerves of the Sacral Plexus

    • Superior Gluteal Nerve:

      • Innervates gluteus medius, gluteus minimus, and tensor fasciae latae.
      • Responsible for hip abduction and external rotation.
      • Arises from L4-S1 roots of the sacral plexus.

    • Inferior Gluteal Nerve:

      • Innervates gluteus maximus.
      • Plays a role in hip extension and external rotation.

    • Sciatic Nerve:

      • The largest nerve in the body.
      • A major nerve of the sacral plexus, formed by the L4-S3 roots.
      • Innervates muscles in both the anterior and posterior compartments of the leg leading to hip extension and knee flexion.
      • Branches into the tibial nerve and common fibular nerve.

    • Tibial Nerve:

      • A branch of the sciatic nerve.
      • Innervates muscles in the posterior compartment of the leg responsible for plantarflexion and inversion of the foot.

    • Common Fibular Nerve:

      • A branch of the sciatic nerve.
      • Innervates muscles in the anterior and lateral compartments of the leg responsible for dorsiflexion and eversion of the foot.

    • Pudendal Nerve:

      • Provides sensory and motor innervation to the perineum.
      • Innervates muscles involved in urinary and fecal continence.

    • Posterior Femoral Cutaneous Nerve:

      • Provides sensory innervation to the skin of the posterior thigh and perineum.
      • Arises from the S1-S3 roots of the sacral plexus.

    Mnemonic for Sacral Plexus Nerves

    • The mnemonic "Some Irish Sailor Pesters Polly" helps remember the key nerves of the sacral plexus:
      • Superior gluteal nerve
      • Inferior gluteal nerve
      • Sciatic nerve
      • Posterior femoral cutaneous nerve
      • Pudendal nerve

    Superior Gluteal Nerve

    • Composed of spinal nerve roots L4, L5, and S1
    • Innervates gluteus minimus, gluteus medius, and tensor fasciae latae muscles
    • Responsible for hip abduction and stabilization during walking
    • Does not have any sensory function
    • Plays a key role in stabilizing the pelvis during walking

    Inferior Gluteal Nerve

    • Composed of spinal nerve roots L5, S1, and S2
    • Innervates gluteus maximus muscle
    • Responsible for hip extension and movements like climbing stairs or rising from a seated position
    • Does not have any sensory function
    • Enables the powerful hip extension needed for essential movements like standing up from a chair

    Sciatic Nerve Anatomy and Function

    • The sciatic nerve is the largest nerve in the human body.
    • It is formed by the fusion of the ventral rami of spinal nerve roots L4, L5, S1, S2, and S3.
    • It descends through the pelvis and posterior thigh, dividing into the tibial and common fibular nerves in the popliteal fossa.

    Sciatic Nerve Branches

    • Tibial portion:
      • Innervates the posterior compartment of the thigh (excluding the short head of biceps femoris), the posterior compartment of the leg and the sole of the foot.
      • Provides sensory innervation to the posterolateral and medial surfaces of the foot and the sole of the foot.
    • Common fibular portion:
      • Innervates the short head of the biceps femoris, the anterior and lateral compartments of the leg, and the dorsal aspect of the foot.
      • Provides sensory innervation to the anterolateral surface of the leg and the dorsal aspect of the foot.

    Sciatica

    • Sciatica is a condition characterized by pain radiating along the path of the sciatic nerve, from the lower back through the hip and down the leg.
    • This pain can be caused by compression or irritation of the sciatic nerve.

    Muscle Innervation

    • Tibial Branch:
      • Semimembranosus
      • Gastrocnemius
    • Common Fibular Branch:
      • Short head of the biceps femoris
      • Extensor digitorum brevis.
    • Not Innervated by the Sciatic Nerve:
      • Sartorius (innervated by the femoral nerve)

    Important Note

    • The extensor digitorum brevis is innervated by the deep fibular nerve, a branch of the common fibular portion of the sciatic nerve.

    Posterior Femoral Cutaneous Nerve

    • Originates from spinal nerve roots S1, S2, and S3
    • Provides sensory innervation to the posterior surface of the thigh and leg, as well as the perineum
    • Doesn't have any motor functions

    Pudendal Nerve

    • Originates from spinal nerve roots S2, S3, and S4
    • Controls motor functions of the external urethral sphincter, external anal sphincter, and levator ani muscles
    • Provides sensory innervation to the penis, clitoris, and most of the perineal skin
    • Plays a crucial role in reproductive and excretory functions due to its innervation of perineal structures

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    Description

    Explore the structure and function of the Peripheral Nervous System, focusing on spinal nerves and their crucial role in communication between the central nervous system and the body. Learn about the 31 pairs of spinal nerves and their classifications, including cervical, thoracic, lumbar, and sacral divisions.

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