Nervous System - Spinal Nerves and Branches Flashcards
How many Spinal Nerves are there? How are they Named?
of Nerves
- 31 Pairs
Named
- Based on segment of spinal cord they leave the vertebral column at
What is the Structure of the Spinal Nerve before it exits the Vertebral Canal?
- Ventral Root
- Dorsal Root
What happens when the Dorsal and Ventral Root Join? What does this mean?
Joined
- This is what the Spinal Nerve
- It means Spinal Nerves are Mixed: have both Sensory and Motor Fibers
What are the Spinal Nerves Split into After they leave the Vertebral Column?
- Ventral Rami
- Dorsal Rami
Where does the Ventral Root come from and What does it carry?
- Arises from the Ventral Horn
- Carries Motor Fibers (efferent)
Where does the Dorsal Root go and what does it carry?
- enters Dorsal Horn
- Carry Afferent (sensory) fibers
What do Ventral Rami Form? Where? (3)
- Somatic Nerve Plexuses: Cervical, Lumbar, and Sacral Regions
- Intercostal Nerves: T1-T11
- Subcostal Nerve: T12
What does the Dorsal Rami do?
- Supplies motor, visceral, and sensory nerves to the dorsal muscles of the back and the overlying skin
What are paravertebral muscles? what supplies their nerves?
Paravertebral Muscles
- Muscles that lie close to the vertebral column
Supplies Nerves
- Dorsal Rami
What are the 5 names for spinal nerves? how many of each?
- Cervical Spinal Nerves: C1-C8
- Thoracic Spinal Nerves: T1-T12
- Lumbar Spinal Nerves: L1-L5
- Sacral Spinal Nerves: S1-S5
- Coccygeal Spinal Nerves: Co
What is a Dermatome?
- An area of skin that is innervated by a single spinal nerve or spinal cord segment
What is a Myotome?
- A part of the skeletal muscle that is innervated by a single nerve or spinal cord segment
What is the Cauda Equina? What does it do?
Cauda Equina
- The continuation of Dorsal and Ventral Roots in the vertebral column past the end of the Spinal Cord
Function
- supplies Spinal Nerves to the Lumbar, Sacral, and Coccygeal spinal segments
What Spinal Nerves form the Cervical Plexus?
- Ventral Rami of C1-C4
What Spinal Nerves form the Brachial Plexus?
- Ventral Rami of the C5-T1
How do the Cervical Spinal Nerves exit the Lumbar Column?
- C1-C7: Exit through the vertebral canal above their corresponding cervical vertebrae
- C8: Exits Between the CVII and TI vertebrae
How do the Thoracic Spinal Nerves exit the spinal column?
- T1-T12: exit through the lower corresponding vertebrae
How do the Sacral Spinal Nerves exit the Vertebral Column?
- Through the corresponding sacral foramina
What forms the Sacral Plexus? what else does it contribute to?
- Ventral Rami of L4-S4
- also contributes to the coccygeal plexus
What forms the Lumbar Plexus? what else does it contribute to?
- Ventral Rami of the L1-L4
- Also contributes to the sacral plexus
What forms the coccygeal plexus? what other spinal nerves contribute to this?
- The Single pair of Coccygeal spinal nerves
- The S4 and S5 spinal nerves contribute to it
Where is the Cervical Plexus located?
- Deep to the Sternocleidomastoid Muscle
What are the important branches of the Cervical Plexus? What kind of nerves do they provide and to where?
- Cutaneous Branch: sensory from ventral and lateral neck
- Ansa Cervicalis: Motor to Infrahyoid Muscles
- Phrenic Nerve: Motor to the Diaphragm
What does the Brachial Plexus Supply?
- the upper limbs
What is the Mnemonic for remembering the subdivisions of the Brachial Plexus?
Read That Daunting Cadaver Book
What are the important branches of the Brachial Plexus? (4)
- Musculocutaneous
- Median
- Ulna
- Radial
Where does the Musculocutaneous branch of the Brachial Plexus provide motor nerves to and receive sensory nerves from?
- Motor: the Muscles of the anterior compartment of the arm
- Sensory: From the lateral side of the arm
Where does the Median Branch of the Brachial Plexus send motor nerves and receive sensory nerves from?
- Motor: to (almost) all muscles of the anterior Forearm and some of the muscles of the hand
- Sensory: From the skin of the lateral palm (thumb side) and the lateral 3 1/2 fingers
Where does the Ulnar Branch of the Brachial Plexus supply motor nerves? where does it receive sensory nerves from?
Motor: Some muscles in the anterior forearm, most intrinsic muscles of the hand
Sensory: From the medial third of the palmar and dorsal aspect of the hand / and medial 1 1/2 fingers.
Where does the Radial Branch of the Brachial Plexus send motor nerves to and receive sensory nerves from?
Motor: To the posterior compartment of the arm and the forearm
Sensory: from the skin of the posterior arm and forearm / lateral 2/3rds of back of hand
What Spinal Nerves make up the Roots of the Brachial Plexus?
- C5-T1 (neck region)
How do the Roots of the Brachial Plexus differentiate into the Trunks?
- Upper: C5 & C6
- Middle: C7
- Lower: C8-T1
What divides into anterior and posterior axilla (divisions) in the Brachial Plexus?
- The Trunks
What divides into anterior and posterior divisions in the Brachial Plexus?
- The Trunks
What are the names of the 3 Cords in the Brachial Plexus?
- Lateral
- Medial
- Posterior
What forms the Lumbar Plexus?
- The Ventral Rami of Spinal Nerves L1-L4
What are the Important branches of the Lumbar Plexus?
- Lateral Femoral Cutaneous
- Femoral
- Obturator
What does the Lateral Femoral Cutaneous branch of the Lumbar Plexus do?
- Sensory: Receives senses from the lateral side of the thigh
What type of nerve is the Femoral Branch of the Lumbar Plexus? what do they do?
- Motor: to muscles of the anterior compartment of the thigh and iliacus muscle
- Sensory: from anterior and medial thigh and medial aspect of the leg and foot
What type of nerve is the Obturator Branch of the Lumbar Plexus? what does it do?
Mixed
- Motor: to muscles of the medial compartment of the thigh
- Sensory: From the skin of the medial side of thigh
What forms the Sacral Plexus?
- The Roots of L4-Co Spinal Nerves
What are the Important Branches of the Sacral Plexus?
- Superior Gluteal
- Inferior Gluteal
- Sciatic Nerve
- Pudendal
What does the Superior Gluteal Branch of the Sacral Plexus do?
- Motor: To some of the gluteal muscles (pure motor)
What does the Inferior Gluteal Branch of the Sacral Plexus do?
- Motor: to the Gluteus Maximus (motor)
What are the two divisions of the Sciatic Nerve Branch of the Sacral Plexus?
- Anterior Division
- Posterior Division
Where does the tibial and common fibular division of the Siatic Nerve come from?
- Tibial: the Anterior division
- Common Fibular: The Posterior Division
What does the Tibial Nerve of the Sciatic Nerve do?
- Motor: to most muscles of the posterior thigh, all posterior muscles of the leg, and all muscles of the plantar aspect of the foot
- Sensory: from posterior aspect of the leg and the entire plantar aspect of the foot
What does the Common Fibular division of the Sciatic Nerve do?
- Motor: to muscles of the anterior and lateral compartmetns of the leg and some muscles on the dorsum of the foot
- Sensory: from the skin on the lateral side of the leg and the dorsum of the foot
What does the Pudendal Branch of the Sacral Plexus do?
- Motor: to muscles of the perineum
- Sensory: from skin of the perineum
