1. Organization of the Upper Limb
d-etre.blogspot.com
Organization of the Upper Limb
Audrone Biknevicius, Ph.D.
Dept. Biomedical Sciences, OU HCOM at Dublin
Clinical Anatomy Immersion 2014

2. “Anatomical Tool-Kit”
virtuallaboratory.colorado.edu
www2.warwick.ac.uk

3. Week 7
and rotation
[More detailed limb embryology in MS course]
Week 5
RULE #1
Limbs are outgrowths of the ventral body wall that undergo distal growth and differentiation…

4. The upper limbs are innervated by :
Dorsal rami of spinal nn.
Ventral rami of spinal nn.

5. Primitive Pectoral Limb
DEVELOPMENTAL/EVOLUTIONARY BASIS
Developmentally-dorsal limb mm.
Developmentally-ventral limb mm.
Primitive Pectoral Limb
Stern Essential of Gross Anatomy

6. DEVELOPMENTAL/EVOLUTIONARY BASIS
90◦ lateral rotation (forearm mm. undergo incomplete rotation)
Limb adduction
Stern Essential of Gross Anatomy

7. * RULE #2A: Ventral vs. dorsal limb mm.
Developmentally-dorsal muscles:
Lie posterior to the long bones in anatomical position (* exceptions)
Developmentally-ventral muscles:
Lie anterior to the long bones in anatomical position
Stern Essential of Gross Anatomy

8. Upper Limb Muscle Compartments
Anterior
Humerus
Posterior
Radius
5th metacarpal
FOREARM
HAND
ARM
Ulnar
Upper Limb
Muscle Compartments
Stern Essential of Gross Anatomy

9. * ARM FOREARM HAND Anterior Humerus Posterior
Radius
5th metacarpal
FOREARM
HAND
ARM
Ulnar
Some posterior compartment mm. are found on the anterolateral aspect of the forearm (*brachioradialis, supinator) *
Stern Essential of Gross Anatomy
No posterior compartment in the hand

10. RULE #2B: Innervation of anterior vs. posterior compartment mm.
Spinal nerve
Dorsal primary ramus
Ventral primary ramus (C5-T1)
Anterior division
Posterior division
limb axis
Stern Essential of Gross Anatomy

11. (right side; simplified)
“Roots of BP”
(=ventral rami) C5 C6 C7 C8 T1
Brachial Plexus
(right side; simplified)
Trunks U M L
“Randy Travis Drinks Cold Beer”
Divisions
Anterior (ventral) division
Posterior (dorsal) division
Cord
Lat
Post
Med
Terminal Branches
Stern Essential of Gross Anatomy

12. (right side; simplified)
“Roots of BP”
(=ventral rami) C5 C6 C7 C8 T1
Brachial Plexus
(right side; simplified)
Trunks U M L
Divisions
Anterior (ventral) division
Posterior (dorsal) division
Cord
Lat
Post
Med
Terminal Branches
Musculocutaneous n.
Median n.
Ulnar n.
Radial n.
Stern Essential of Gross Anatomy

13. Muscle Compartments of the Upper Limb
Anterior
Musculocutaneous n.
Humerus
Radial n.
Ulna
Radius
Median n. & Ulnar n.
5th metacarpal
Ulnar n. & Median n.
Posterior
MOTOR INNERVATION
Muscle Compartments of the Upper Limb
Stern Essential of Gross Anatomy

14. Musculocutaneous Nerve (arm)
All mm. in anterior (flexor) compartment of arm
MRI of arm
Biceps brachii m.
Brachialis m.
Brachial a.
Humerus.
Triceps brachii m.

15. Radial Nerve (arm) All mm. in posterior (extensor) compartment of armBB B
TLong
TLat
TMed

16. The brachialis m. is innervated by which division of the brachial plexus: :
Anterior division
Posterior division

17. The brachialis m. is innervated by:
Median n.
Musculocutaneous n.
Radial n.
Ulnar n.

18. The triceps brachii m. is innervated by:
Musculocutaneous n.
Radial n.

19. Radial Nerve (forearm)
All mm. in posterior (extensor) compartment of forearm
Also * brachioradialis and supinator mm. *

20. Ulnar Nerve (forearm)
Limited mm. in anterior (flexor) compartment of forearm:
Flexor carpi ulnaris
Flexor digitorum profundus (medial ½)
Med 1/2

21. Median Nerve (forearm)
All anterior (flexor) compartment mm. of forearm except:
Flexor carpi ulnaris m.
Flexor digitorum profundus m. (med ½)
en.wikipedia.org

22. RULE #2C

23. The extensor digitorum m
The extensor digitorum m. lies in the posterior compartment, originates on the lateral epicondyle, and is innervated by:
Median n.
Musculocutaneous n.
Radial n.
Ulnar n.
Lateral epicondyle
Extensor digitorum m.

24. “Be specific”
thepainsource.com

25. The flexor carpi radialis m
The flexor carpi radialis m. is in the anterior compartment, attaches to the medial epicondyle, and is innervated by:
Median n.
Radial n.
Ulnar n.

26. The flexor digitorum profundus m
The flexor digitorum profundus m. is the anterior compartment, attaches to the medial epicondyle, and is innervated by:
Median n.
Median n. & Ulnar n.
Ulnar n.
healthfavo.com

27. The brachioradialis and supinator mm
The brachioradialis and supinator mm. lie in the anterior aspect of the forearm but attach to the lateral epicondyle of the humerus. They are innervated by:
Median n.
Radial n.
Ulnar n.

28. Median Nerve (hand) Limited hand mm.: Thenar mm.
Lateral two lumbricals

29. Ulnar Nerve (hand) All hand mm. not innervated by median n. cnx.org

30. What about the most proximal muscles of the upper limb?
medicine.academic.ru

31. RULE #2D * Developmentally-dorsal muscles:
Lie posterior to the long bones in anatomical position (* exception = brachioradialis, supinator)
-or-
Arise from:
scapular blade ossification
vertebral column
Developmentally-ventral muscles:
Lie anterior to the long bones in anatomical position
-or-
Arise from:
coracoid ossification
sternum and costal cartilages *
Stern Essential of Gross Anatomy

32. Given the attachments of the latissimus dorsi muscle, its innervation will be from which of division of the brachial plexus:
Anterior division
Posterior division
blog.corewalking.com

33. Brachial Plexus (branches) C5 C6 C7 C8 T1 supraspinatus
suprascapular n.
supraspinatus
& infraspinatus mm. * **
upper subscapular n.
thoracodorsal n.
lower subscapular n.
subscapularis m.
latissimus dorsi m.
subscapularis & teres major mm.
Stern Essential of Gross Anatomy
axillary n.
deltoid & teres minor mm.

34. Given the attachments of the pectoralis muscles muscle, its innervation will be from which of division of the brachial plexus:
Anterior division
Posterior division

35. Brachial Plexus (branches) C5 C6 C7 C8 T1 radial n. axillary n.
medial n.
musculoskeletal n.
suprascapular n.
upper subscapular n.
thoracodorsal n.
lower subscapular n.
medial pectoral n.
lateral pectoral n.
long
thoracic n.
dorsal
scapular n. ** *
ulnar n.
rhomboid mm.
pectoralis mm.
serratus anterior m.
Stern Essential of Gross Anatomy

36. RULE #3 Proximal-to-Distal Rule
posterior anterior
RULE #3 Proximal-to-Distal Rule
Upper “roots” of the brachial plexus (C5-6 ventral rami) innervate proximal muscles (shoulder, elbow)
Lower “roots” of the brachial plexus (C8-T1 ventral rami) innervate distal muscles (hand)
Somatic motor nerve
(GSE, with GSA)
Cutaneous nerves
(GSA, GVE, GVA)

37. - group of muscles innervated by a single spinal nerve root
MYOTOME
- group of muscles innervated by a single spinal nerve root
sciartmag.blogspot.com

39. Brachial Plexus (all branches) C5 C6 C7 * C8 T1 ** Dorsal scapular n.
Radial n.
Axillary n.
Medial n.
Musculoskeletal n.
Suprascapular n.
Upper & lower subscapular nn.
Thoracodorsal n.
Medial pectoral n.
Lateral pectoral n.
Long
thoracic n.
Dorsal
scapular n. ** *
Ulnar n.
Brachial Plexus
(all branches)
Stern Essential of Gross Anatomy
* Nerve to subclavius
** Medial brachial & antebrachial cutaneous nn.

40. RULE #3 “MIXED FUNCTIONAL MODALITIES” posterior anterior
Most terminal branches of the brachial plexus are mixed fiber nerves:
Somatic motor and somatic sensory (prioprioception) to skeletal mm.
Then, cutaneous innervation with somatic sensory and sympathetics to skin
Somatic motor nerve
(GSE, with GSA)
Cutaneous nerves
(GSA, GVE, GVA)

41. Musculocutaneous n.
Tank et al. Lippincott Williams & Wilkins Atlas of Anatomy

42. Some purely cutaneous brs. of brachial plexus
Tank et al. Lippincott Williams & Wilkins Atlas of Anatomy

43. RULE #5: Dermatome vs. Cutaneous Nerve Distribution
Segmental innervation
(C5-T1)
Dermatomes

44. Segmental (Dermatome) Innervation of Upper Limb
Foerster (1933) – based on clinical findings (used by neurologists)
Keegan and Garrett (1948)
– based on limb development
Moore et al. Essential Clinical Anatomy

45. Segmental (Dermatome) Innervation of Upper Limb
Preaxial: C5-C7
Postaxial: C8-T1
Thumb: C6
3rd Digit: C7
5th Digit: C8
Moore et al. Essential Clinical Anatomy

46. Dermatomes vs. Cutaneous Nerve Distribution
Segmental innervation
(C5-T1)
Dermatomes
Terminal
branches
Cutaneous
nn.

47. Peripheral (Cutaneous ) Innervation of Upper Limb
Moore et al. Essential Clinical Anatomy
Anterior
Posterior

48. Test for Peripheral Nerve Sensory Function:
Ulnar n. – Tip of 5th digit (little finger)
Median n. – Tip of 2nd digit (index finger)
Radial n. – Webbing b/w thumb & index finger (dorsum) U M R

49. C7 M U C8 C6 R

50. Stretch Reflex Reciprocal inhibition of antagonist muscles
apbrwww5.apsu.edu/

51. Stretch Reflex
academic.scranton.edu
Bicipital reflex (C6 cord level) Triceps reflex (C7 cord level)

52. UPPER LIMB RADICULAR SYNDROMES
IVD Root Sensory Loss Motor Weakness
C4-C5 C5 Shoulder Shoulder weakness
C5-C6 C6 Anterior upper arm, Forearm flexion
Lateral forearm, thumb Biceps reflex
C6-C7 C7 3rd digits Forearm extension
Triceps reflex
Wrist extension
Hand grip
C7-C8 C8 5th digits Wrist flexion
Medial forearm Intrinsic hand mm.
Source: Devinsky et al. Neurologic Pearls
Cranial
Caudal
Proximal
Distal