Spinal Nerves Flashcards
3 layers of connective tissues in a spinal nerve
Endoneurium (most superficial) Perineurium (Organized into fascicles) Epineurium (most deep)
How are spinal nerves designated?
Letter + Number C (1-8) T (1-12) L (1-5) S (1-5) Co Coccygeal nerve (when designated)
Dermatome
Area of skin supplied with sensory innervation by a pair of spinal nerves
Ramus
A major branch of a psinal nerve
Doral rami v ventral rami
Dorsal - innervate most of the deep muscles of the dorsal trunk, responsible for moving the vertebral column Ventral rami
Intercostal nerves
Formed by ventral rami in the thoracic region
Plexuses
ventral rami of remaining spinal nerves. The ventral rami of different spianl nerves, called roots, join with each other to form a plexus.
The 5 major spinal plexuses
Cervical (C1-C4) brachial (C5 - T1) Lumbar (L1-L4) Sacral (L4-S4) Coccygeal (Co)
Cervical plexus // Origination, innervation
C1-C4 Innervates superficial neck structures, including hyoid bone.
Ansa cervicalis
A loop between C1 and C3, which has branches of nerves that go to the infrahyoid muscles.
Phrenic nerve
an important nerve for breathing bc it innervates diaphragm Originates from c3-c5
Brachial plexus // Origination, innervation
C5 - T1
Organization fo the brachial plexes
5 ventral rami > join to form 3 trunks > separate into 6 divisions (posterior and anterior) > going again to create 3 cords > separate into 5 branches of upper limb nerves.
5 major nerves emerging from brachial plexus
Axillary
Radial
Musculocutaneous
Ulnar
Median
Why can the entire limb be anesthetized at once?
The anatomical organization of the brachial plexus allows for brachial anesthesia.
Axillary nerve
Shoulder - deltoid and teres minor muscles.
Radial nerve
innervates extensor muscles of upper limb
posterior portion of upper limb (incl. hand)
Musculocutaneous Nerve
Anterior muscles of the arm and cutaneous sensory innervation to some of the forearm.
If the radial nerve is damaged due to compression against the humorous from improper use of crutches, what results?
crutch paralysis
What is the major symptom of crutch paralysis?
Wrist Drop - elbow, wrist, and fingers are constantly flexed
Median nerve
C5 - T1
innervates all but one of the flexor muscles of the forearm, most the hand at the base of the thumb
Carpal tunnel syndrome
Damage to the median nerve
Causes numbness, tingling, and pain in the fingers.
Ulnar Nerve
C8 - T1
Innervate two forearm muscles and most intrinsic hand muscles.
Thoracic outlet syndrome
compression inferior root of the brachial plexus, causes pain, tingling, numbness, pain in the elbow.
Lumbar Plexus
L1-L4
Sacral plexus
L4-S4
4 major nerves of the lumbosacral plexus
Obturator
femoral
tibial
common fibular
Obturator nerve
L2-L4
Innervates muscles that adduct the thigh
Femoral nerve
Innervates iliopsoas and sartorius muslces and quadriceps.
Tibial and common fibular nerves - sciatic nerve
L4-S3
Bound together in connective tissue sheath fo rlegth of thigh.
Collectively referred to as the sciatic nerve.
Medial and lateral plantar nerves
Tibial nerve branches to form
Innervate plantar muscles of foot.
Sural nerve
branch from the tibial nerve
Innervates calf of leg and plantar surface of foot
Deep and superficial fibular nerves
brances of the common fibular nerve.
Innervate anterior and lateral muscles of leg and foot.
Pudendal nerve
Supplies muscles of the abdominal floor; sexual stimulation
Coccygeal plexus
Small plexus from S5 - Co
Motor innervation to pelvic floor muscles
