The Brachial Plexus Anatomy and Function
Dr. Mohammed Hussein
Dr. Mohammed Hussein
MBChB – MSc – PhD – MRCPCH – DCH (UK)
MBChB – MSc – PhD – MRCPCH – DCH (UK)
•
Nerve plexuses are combined nerve fibers from different sources or levels
to form new nerves with specific targets or destinations.
•
Nerve plexuses are either somatic or visceral.
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The brachial plexus is a somatic nerve plexus formed by:
1.
The
anterior rami
anterior rami
of
C5
to
C8
2.
Most of the
anterior ramus
anterior ramus
of
T1
•
The plexus originates in the
neck
, passes laterally
and inferiorly over
rib I
, and enters the
axilla
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•
Proximal parts of the brachial plexus are
posterior to the
subclavian artery
in the neck.
•
While more distal regions of the plexus surround
the
axillary artery
.
Subclavian artery
Axillary artery
The parts of the brachial plexus, from
medial to lateral
medial to lateral
, are:
Roots
Trunks
Divisions
Cords
Branches
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+
÷
÷
+
+
÷
÷
T1
C8
C7
C6
C5
Roots
Trunks
Anterior rami of spinal
nerves C5-T1
Divisions
Cords
Terminal branches
CI
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CII
CII
CIV
CIV
CIII
CIII
CV
CV
CVI
CVI
CVII
CVII
TI
TI
C5
C6
C7
C8
T1
Superior
Middle
Inferior
Divisions
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Trunk
Cords
Lateral
Posterior
Medial
Roots
Terminal Branches
T1
C8
C7
C6
C5
Subclavian A.
Middle
scalene
Anterior
scalene
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•
The three trunks of the brachial plexus originate from the roots,
pass laterally
over rib I
over rib I
, and enter the axilla.
•
The
Superior (Upper) Trunk
•
The
Middle Trunk
•
The
Inferior (Lower) Trunk
Union of C5 and C6 roots
Continuation of the C7 root
Union of the C8 and T1 roots
T1
C8
C7
C6
C5
is formed by
is a
is formed by
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•
Each of the three trunks of the brachial plexus divides into an
anterior
and a
posterior division:
•
The
three posterior divisions
combine to form parts of the
brachial plexus that give rise to nerves associated with the
posterior compartments
of the arm and forearm.
•
The
three anterior divisions
form parts of the brachial plexus that
ultimately give rise to peripheral nerves associated with the
anterior compartments
of the arm and forearm.
•
No
peripheral nerves originate directly from the divisions of the
brachial plexus.
The Trunks
The Divisions
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The three cords of the brachial plexus originate from the divisions
•
The
posterior
cord
is formed by the union of
all posterior divisions
•
The
lateral cord
is
the union of the
anterior divisions
of
superior
and
middle trunks
•
The
medial cord
is
the direct continuation of the
anterior division
of
inferior trunk
The Divisions
Posterior cord
Lateral cord
Medial cord
The cords are related to the
2
nd
part of the axillary artery
.
The
lateral cord
is
lateral
to the artery.
The
medial cord
is
medial
to the artery.
The
posterior
cord is
posterior
to the artery.
Sup. Trunk
Sup. Trunk
Inf. Trunk
Inf. Trunk
M. Trunk
M. Trunk
•
Generally:
•
Nerves associated with the
anterior compartments
of the upper
limb arise from the
medial
and
lateral cords
•
Nerves associated with the
posterior compartments
of the
upper limb arise from the
posterior cord
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Generally there are
16
branches
•
2
from the
Roots
•
2
from the
Superior Trunk
•
0
from the
Divisions
•
12
from the
Cords
o
3
form the
lateral cord
o
5
from the
medial cord
o
5
from the
posterior cord
2
2
0
12
3
5
5
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C1
C2
C3
C4
C5
C6
C7
T1
T2
Dorsal scapular nerve
C1
C2
C3
C4
C5
C6
C7
T1
T2
Long thoracic nerve
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Suprascapular nerve
Superior trunk
Superior trunk
Suprascapular nerve
Suprascapular foramen
Supraspinatus and
infraspinatus muscles
Nerve to subclavius
Superior trunk
Superior trunk
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3
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Lateral pectoral nerve
Musculocutaneous nerve
Lateral root of median nerve
Branches of lateral cord
1.
Lateral pectoral nerve
2.
Musculocutaneous nerve
3.
Lateral root of median nerve
Median nerve
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Branches of medial cord
1.
Medial pectoral nerve
2.
Medial cutaneous nerve of arm
3.
Medial cutaneous nerve of forearm
4.
Medial root of median nerve
5.
Ulnar nerve
Medial pectoral nerve
Medial cutaneous nerve of arm
Medial cutaneous nerve of forearm
Medial root of median nerve
Ulnar nerve
Median
nerve
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5
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Branches of posterior cord
1.
Superior
S
S
ubscapular nerve
2.
T
T
horacodorsal nerve
3.
A
A
xillary nerve
4.
R
R
adial nerve
5.
Inferior
S
ubscapular nerve
Subscapularis
Latissimus
Teres major
Triceps
Branches of posterior cord
1.
Superior
S
S
ubscapular nerve
2.
T
T
horacodorsal nerve
3.
A
A
xillary nerve
4.
R
R
adial nerve
5.
Inferior
S
ubscapular nerve
Superior subscapular nerve
Inferior subscapular nerve
Thoracodorsal nerve
Axillary nerve
Radial nerve
Posterior cutaneous nerve of arm
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The brachial plexus is a crucial network of nerves in the upper limb, formed by nerve fibers originating from C5 to T1 spinal levels. It plays a significant role in innervating the upper extremity muscles and providing sensory feedback. The plexus is categorized into roots, trunks, divisions, cords, and branches, with each part serving specific functions in nerve transmission. Knowledge of the brachial plexus structure is essential for understanding upper limb pathology, diagnosing nerve injuries, and performing surgical interventions.
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Presentation Transcript
Brachial Plexus Brachial Plexus Dr. Mohammed Hussein MBChB MSc PhD MRCPCH DCH (UK)
Nerve Nerve plexuses plexuses Nerve plexuses are combined nerve fibers from different sources or levels to form new nerves with specific targets or destinations. Nerve plexuses are either somatic or visceral.
Brachial Plexus Brachial Plexus The brachial plexus is a somatic nerve plexus formed by: 1. The anterior rami of C5 to C8 2. Most of the anterior ramus of T1
Brachial Plexus Brachial Plexus The plexus originates in the neck, passes laterally and inferiorly over rib I, and enters the axilla
Brachial Plexus Brachial Plexus Proximal parts of the brachial plexus are posterior to the subclavian artery in the neck. While more distal regions of the plexus surround the axillary artery. Subclavian artery Axillary artery
The parts of the brachial plexus, from medial to lateral, are: Roots + Trunks Divisions + Cords Branches
CI CII Roots CIII Trunks CIV C5 Anterior rami of spinal nerves C5-T1 CV C6 CVI Divisions C7 CVII C8 Cords T1 TI Terminal branches
Cords Roots Terminal Branches Divisions Trunk C5 Anterior Lateral Superior C6 C7 Posterior Posterior Middle C8 Medial Anterior Inferior T1
Roots Roots C5 C6 C7 Subclavian A. C8 T1
Trunks Trunks The three trunks of the brachial plexus originate from the roots, pass laterally over rib I, and enter the axilla. The Superior (Upper) Trunk Union of C5 and C6 roots C5 is formed by C6 C7 The Middle Trunk Continuation of the C7 root is a C8 T1 The Inferior (Lower) Trunk Union of the C8 and T1 roots is formed by
Divisions Divisions Each of the three trunks of the brachial plexus divides into an anterior and a posterior division: The three posterior divisions combine to form parts of the brachial plexus that give rise to nerves associated with the posterior compartments of the arm and forearm. The three anterior divisions form parts of the brachial plexus that ultimately give rise to peripheral nerves associated with the anterior compartments of the arm and forearm. No peripheral nerves originate directly from the divisions of the brachial plexus.
The Trunks The Divisions
Cords Cords The three cords of the brachial plexus originate from the divisions The posterior cord is formed by the union of all posterior divisions The lateral cord is the union of the anterior divisions of superior and middle trunks The medial cord is the direct continuation of the anterior division of inferior trunk
The Divisions The cords are related to the 2nd part of the axillary artery. The lateral cord is lateral to the artery. The medial cord is medial to the artery. The posterior cord is posterior to the artery.
Generally: Nerves associated with the anterior compartments of the upper limb arise from the medial and lateral cords Nerves associated with the posterior compartments of the upper limb arise from the posterior cord
Branches Branches Generally there are 16 branches 2 from the Roots 2 from the Superior Trunk 0from the Divisions 12 from the Cords o 3 form the lateral cord o 5 from the medial cord o 5 from the posterior cord
12 0 2 2 3 5 5
Branches of Roots Branches of Roots 2 2 Branches Branches 1. Dorsal scapular N. 1. Dorsal scapular N. 2. Long thoracic N. 2. Long thoracic N.
C1 C2 C3 C4 C5 Dorsal scapular nerve C6 C7 T1 T2
C1 C2 C3 C4 C5 C6 Long thoracic nerve C7 T1 T2
2 2 Branches of Branches of Superior Superior Trunk Trunk Branches Branches 1. 1. Supra Suprascapular N. scapular N. 2. Nerve to 2. Nerve to Sub Subclavius clavius
Superior trunk Suprascapular nerve
Suprascapular nerve Suprascapular foramen Supraspinatus and infraspinatus muscles
Superior trunk Nerve to subclavius
3 3 Branches of Branches of Lateral Lateral Cord Cord Branches Branches 1. 1. Lateral Lateral pectoral N. pectoral N. 2. Musculocutaneous N. 2. Musculocutaneous N. 3. The 3. The lateral lateral root of median N. root of median N.
Lateral pectoral nerve Musculocutaneous nerve Lateral root of median nerve Median nerve Branches of lateral cord 1. Lateral pectoral nerve 2. Musculocutaneous nerve 3. Lateral root of median nerve
5 5 Branches of Branches of Medial Medial Cord Cord Branches Branches 1. 1. Medial Medial pectoral N. pectoral N. 2. 2. Medial Medial Cut. N. of arm Cut. N. of arm 3. 3. Medial Medial Cut. N. of forearm Cut. N. of forearm 4. The 4. The medial medial root of median N. root of median N. 5. Ulnar N. 5. Ulnar N.
Medial pectoral nerve Medial cutaneous nerve of arm Median nerve Medial cutaneous nerve of forearm Ulnar nerve Branches of medial cord 1. Medial pectoral nerve 2. Medial cutaneous nerve of arm 3. Medial cutaneous nerve of forearm 4. Medial root of median nerve 5. Ulnar nerve
5 5 Branches of Posterior Cord Branches of Posterior Cord Branches Branches STARS STARS 1. Superior 1. Superior S Subscapular N. ubscapular N. 2. 2. T Thoracodorsal N. horacodorsal N. 3. 3. A Axillary N. xillary N. 4. 4. R Radial N. adial N. 5. Inferior 5. Inferior S Subscapular N. ubscapular N.
Branches of posterior cord 1. Superior Subscapular nerve 2. Thoracodorsal nerve 3. Axillary nerve 4. Radial nerve 5. Inferior Subscapular nerve
Superior subscapular nerve Thoracodorsal nerve Inferior subscapular nerve Posterior cutaneous nerve of arm Branches of posterior cord 1. Superior Subscapular nerve 2. Thoracodorsal nerve 3. Axillary nerve 4. Radial nerve 5. Inferior Subscapular nerve
Branches of the roots Branches of the roots Branch name Dorsal scapular Origin C5 root Root value (Spinal segment) C5 Function Motor: Rhomboid major, Rhomboid minor, Levator scapulae
Branches of the roots Branches of the roots Branch name Long thoracic Origin C5 to C7 roots Root value (Spinal segment) C5 to C7 Function Motor: Serratus anterior
Branches of the superior trunk Branches of the superior trunk Branch name Suprascapular Origin Superior trunk Root value (Spinal segment) C5, C6 Function Motor: Supraspinatus, infraspinatus
Branches of the superior trunk Branches of the superior trunk Branch name Nerve to subclavius Origin Superior trunk Root value (Spinal segment) C5, C6 Function Motor: Subclavius
Branches of the lateral cord Branches of the lateral cord Branch name Lateral pectoral Origin Lateral cord Root value (Spinal segment) C5 to C7 Function Motor: Pectoralis major
Branches of the lateral cord Branches of the lateral cord Branch name Musculocutaneous Origin Lateral cord Root value (Spinal segment) C5 to C7 Motor: All muscles in the anterior compartment of the arm Sensory: Skin on lateral side of forearm Function
Branches of the medial cord Branches of the medial cord Branch name Medial pectoral Origin Medial cord Root value (Spinal segment) C8, T1 Function Motor: Pectoralis major, pectoralis minor
Branches of the medial cord Branches of the medial cord Branch name Medial cutaneous nerve of arm Origin Medial cord Root value (Spinal segment) C8, T1 Function Sensory: Skin on medial side of distal one-third of arm
Branches of the medial cord Branches of the medial cord Branch name Medial cutaneous nerve of forearm Origin Medial cord Root value (Spinal segment) C8, T1 Function Sensory: Skin on medial side of side of forearm
Branches of the medial cord Branches of the medial cord Branch name Ulnar Origin Medial cord Root value (Spinal segment) C8, T1 Motor: All intrinsic muscles of the hand (except three thenar muscles and two lateral lumbricals) and FCU and medial of FDP Sensory: medial 1 fingers Function
The median nerve The median nerve Branch name Median nerve Origin Medial and lateral cords Root value (Spinal segment) (C5), C6 to T1 Motor: All muscles in the anterior compartment of the forearm (except 1 & 1/2 muscles) and thenar and lateral 2 lumbricals Sensory: lateral 3 fingers Function
Branches of the posterior cord Branches of the posterior cord Branch name Superior subscapular Origin Posterior cord Root value (Spinal segment) C5, C6 Function Motor: Subscapularis
Branches of the posterior cord Branches of the posterior cord Branch name Inferior subscapular Origin Posterior cord Root value (Spinal segment) C5, C6 Function Motor: Subscapularis, teres major
