Spinal Nerves Flashcards
What is the brachial plexus?
A large nervous system structure that is formed from the ventral rami of spinal nerves C5-C8 and T1.
- innervates muscles of upper limbs, neck and shoulders
- result of injury: causes weakness or paralysis of upper limbs
What is the advantage of forming nerves from a mix of many spinal nerves rather than from individual spinal nerves?
If a spinal nerve is damaged, you wouldn’t lose total innervation to a limb or limb region.
Which major nerve arises from the Posterior Cord?
Radial & Axillary Nerve
What major nerve arises from the Lateral Cord?
Musculocutaneous
What major nerve arises from the Medial Cord?
Ulnar Nerve
What major nerve is formed from branches of the lateral and medial cords?
Median nerve
What are the five roots of the brachial plexus?
Ventral Rami C5-T1
The five roots unite to form?
Upper, Middle, and Lower Trunks
The three trunks bifurcate to form?
Anterior and Posterior Division
Anterior and Posterior Divisions give rise to?
Three large fiber bundles:
Lateral, Medial and Posterior Cords
Give Location, Areas Innervated and the Result of Injury for Musculocutaneous Nerve:
Location: From Lateral Cord
Areas innervated: innervates flexor muscles in anterior arm (biceps, brachialis & coracobrachialis)
Result of Injury: weakness or loss of elbow flexion
Give Location, Areas Innervated and the Result of Injury for Median Nerve:
Location: from a branch of lateral and medial cord
Areas innervated: innervates flexor muscles of forearm, the first two fingers, pronates forearm, flexes wrist & fingers & opposes thumb.
Result of Injury: Loss of pincer grasp
Give Location, Areas Innervated and the Result of Injury for Ulnar Nerve:
Location: From Medial Cord
Areas innervated: innervates some flexor muscles in forearm and intrinsic hand muscles; also adducts and abducts medial fingers
Result of Injury: Clawhand (last two fingers become hyperextended)
Give Location, Areas Innervated and the Result of Injury for Radial nerve:
Location: From Posterior Cord
Areas innervated: innervates extensors of forearm & hand (elbow extension, supination of forearm, extension of wrist & fingers & abduction of thumb); extends forearm (triceps, brachioradialis)
Result of Injury: Wristdrop (unable to extend hand at wrist)
Give Location, and Areas Innervated for Axillary Nerve:
Location: From Posterior Cord
Areas innervated: innervates deltoid & teres minor muscles
What areas does Medial Pectoral innervate?
Medial Pectoral: innervates pectoralis minor and pectoralis major
What area does Thoracodorsal nerve innervate?
Latissimus Dorsi
What area does Long Thoracic nerve innervate?
Serratus Anterior
What area does Lateral Pectoral nerve innervate?
Pectoralis Major
What area does Subscapular nerve innervate?
Teres major & subscapularis
What area does Suprascapular nerve innervate?
Supraspinatus & Infraspinatus
What are the roots and areas it innervates for the Cervical Plexus?
From ventral rami of C1-C4
It innervates muscles of neck, shoulder & skin on back of the head, on neck and shoulders.
What nerve from the cervical plexus innervates the diaphragm for breathing?
What are its spinal roots?
Phrenic Nerve
Ventral Rami: C3-C5
Dorsal Rami
Innervate the deep muscles of the back for motor control and skin for sensory input.
Ventral Rami
Form Nerve Plexuses
Intercostal Nerves
Ventral rami T2-T12 do not form nerve plexuses. It innervates muscles for breathing
How is the Brachial Plexus Organized?
Roots (Ventral Rami) C5-T1 ► Trunks (Upper, Middle, Lower) ►Divisions (Anterior, Posterior of each Trunk) ► Cords (Lateral, Medial, Posterior) ► Peripheral Nerves
