Brachial Plexus Flashcards
Brachial plexus
network of somatic nerves formed by union of cervical ventral rami C5-T1
All somatic plexuses are formed by:
ventral rami of spinal nerves
responsible for:
innervating most of the upper limb
originates:
runs:
in the cervical region
distal - laterally
inferior to the clavicle
enters the axilla
5 Major components
Roots (the ventral rami of spinal nerves) Trunks (superior, middle, inferior) Divisions (anterior, posterior) Cords (medial, lateral, posterior) Terminal Nerves (aka terminal branches)
Roots
ventral rami from spinal nerves C5-T1
variable contributions from C4 and T2
Roots carry both:
somatomotor and somatosensory fibers
Roots emerge from:
in the neck between the anterior scalene and middle scalene muscles
Roots give off:
the dorsal scapular nerve (C5) long thoracic nerve (C5-C7) phrenic nerve (supplies the diaphragm)
Roots unite to form
three trunks
upper, middle, lower trunks
proximal to clavicle
Upper trunk formed by:
union of ventral rami C5-C6
Lower trunk formed by:
union of ventral rami C8-T1
Middle trunk formed by:
ventral ramus of C7
Upper trunk only trunk that:
gives rise to nerve branches
those nerve branches are
- Suprascapular nerve (supplies Supra&Infraspinatus)
2. Nerve to subclavius
Three Trunks split into
divisions
Divisions have
anterior division
posterior division
may be:
proximal to the clavicle or
between the clavicle and first rib
there are no
branches formed off the divisions
Three cords are:
named according to:
Lateral, Medial, Posterior
according to their position relative to the axillary artery (major artery to the upper limb)
It becomes the axillary artery when:
the subclavian artery emerges distal-laterally from under the clavicle
Cords generally run:
deep to the clavicle &
deep to the tendon of insertion of the pec minor
Lateral cord gives off one branch
lateral pectoral nerve
Medial cord gives off three branches
- medial pectoral nerve
- medial brachial cutaneous nerve
- medial antebrachial cutaneous nerve
medial pectoral nerve supplies:
pectoralis major and minor
cutaneous nerves convey
sensory information from the skin only
Posterior cord gives off three branches
- upper subscapular nerve
- thoracodorsal nerve
- lower subscapular nerve
Upper subscapular nerve supplies:
subscapularis
Thoracodorasal nerve supplies:
latissimus dorsi
Lower subscapular nerves supplies:
- subscapularis
2. teres major
Terminal nerves
how many?
provide:
5
provide innervation to the remainder of the upper limb
5 Terminal Nerves
- Musculocutaneous
- Median
- Radian
- Axillary
- Ulnar
Musculocutaneous nerve derives from:
lateral cord
Median nerve derives from:
both lateral and medial cords
Radial and axillary nerve derive from:
posterior cord
axillary nerve supplies:
then terminates:
supplies: teres minor and deltoid
terminates: upper lateral brachial cutaneous nerve
Spinal cord contributions to each of these terminal nerves:
grays anatomy pg 364
Axillary nerve travels
leaves the posterior cord of plexus, runs posteriorly through the axilla, inferior to the humeral head, exits the quadrangular space to supply teres minor and deltoid, then terminates as a cutaneous nerve
musculotaneous nerves is innervated by
C5
C6
C7
Axillary nerves is innervated by
C5
C6
Radial nerve is innervated by
C5 C6 C7 C8 T1
Median nerve is innervated by
C5 C6 C7 C8 T1
Ulnar nerve is innervated by
C7
C8
T1
dorsal scapular nerve
C5
Long thoracic
C5
C6
C7
Suprascapular nerve
C5
C6
nerve to Subclavius
C5
C6
Lateral pectoral nerve
C5
C6
C7
Medial Pectoral nerve
C8
T1
Medial cutaneous of arm nerve
C8
T1
Medial cutaneous of forearm nerve
C8
T1
Superior Subscapular nerve
C5
C6
Thoracodorsal nerve
C6
C7
C8
Inferior Subscapular nerve
C5
C6