anatomy med test 2.1

spinal nerve

a nerve containing sensory, motor and postganglionic sympathetic axons that arise from one spinal cord segment

peripheral nerve

a nerve containing sensory, motor and postganglionic sympathetic axons that arise from one or more spinal cord segments

anterior vs posterior migrating cells of dermatomytome

A: give rise to hypaxial muscles and dermis of anterior trunk

P: give rise to deep back muscles and overlying dermis

For precise dermatomal sensory testing one uses

autonomous zones

autonomous zones

C5: deltoid

C6: thumb

C7: middle finger

C8: pinky

T1: medial forearm

radiculopathy

affects spinal root

muscle weakness

affect one dermatome

neuropathy

affecting peripheral nerve

muscle paralysis and affects many dermatomes

ventral mass gives rise to

flexors, adductors, and medial rotators

dorsal mass gives rise to

extensors, abductors, and lateral rotators

axilla is gateway for

nerves, vessels and lymphatics to enter or leave upper limb

also location of lymph nodes that drain upper limb and pectoral region

what is an important site for breast cancer metastasis

axillary lymph nodes

stripping of these can impair lymphatic drainage from upper limb

more than what percent of lymphatic drainage is to axillary nodes

75%

excision of axillary nodes risk damage to

long thoracic nerve or the thoracodorsal. more so long thoracic

4 muscles that attach upper limb to anterior thoracic wall

serratus anterior

pectoralis major

pec minor

subclavius

serratus anterior muscle innervation

Long thoracic nerve (C5, C6, C7) hwich runs on superficial side of muscle

main actions of serratus anterior

protracts scapula

holds scapula against body wall

assists in rotating scapula during adduction of upper limb

winged scapula

injury to long thoracic nerve

affected scapula protrudes when patient push on wall with outstretched arms

serratus anterior with trap muscle is needed fir

abduction above 90 degrees

so injury to long thoracic affects abduction above 90 degrees

Pec Major

large fan shaped muscle that covers antero-superior aspect of thorax

has clavicular and sternocostal heads

attachment of pec major

lateral lip of intertubercular groove

action of pec major

adducts and medially rotates humerus

innervation of pec major

lateral and medial pectoral nerves from the lateral and medial cords of brachial plexus

C5,C6 to clavicular head mostly C6

C7,C8,T1 to sternocostal head mostly C7,C8

pec minor attachments

proximal is 3rd-5th ribs near their costal cartilages

distal is the coracoid processes of scapula

innervation of pec minor

medial pectoral nerve (C8,T1)

action of pec minor

stabilize scapula during upper limb movements

subclavius muscle attachments

arises from the 1st rib near costal cartilage

attaches to inferior surface of middle 3rd clavicle

innervation of subclavius

subclavius (C5,C6) mostly C5

main action of subclavius

anchor and stabilize clavicle

axilla apex

lies between 1st rib, clavicle, and superior edge of subscapularis

base of axilla

formed by ski, subcutaneous tissue and axillary fascia

anterior wall of axilla

lateral part of pec major

underlying pec minor

clavipectoral fascia

posterior wall of axilla

scapula

subscapularis muscle on anterior wall of scapula

inferiorly: teres major, lat

posterior fold: lat, teres major, overlying integument

lateral wall of axilla

intertubercular groove of humerus

in this groove is the long head of biceps

medial wall of axilla

thoracic wall (1st-4thribs and intercostal muscles)

overlying serratus anterior muscle

axillary artery begins at

lateral border of 1st rib and has three parts

1st part of axillary artery

between lateral border of 1st rib and medial border of pec minor

has 1 branch: superior thoracic

2nd part of axillary artery

posterior to pec minor with two branches

lateral thoracic, thoracoacromial

3rd part of axillary artery

from lateral border of pec minor to inferior border of teres major with 3 branches: anterior and posterior circumflex humeral artery

subscapular artery

one nerve that C5 gives off

dorsal scapular which innervates levator scapula and rhomboid muscles

long thoracic nerve

innervates serratus anterior

C5,C6,C7 mostly 5,6

trunks of brachial plexus lie between

anterior and middle scalene muscles and superior and posterior subclavian artery

C5 and C6 combine to form the

superior trunk

gives off two nerves: suprascapular nerve (C5,C6mostly 5) and subclavian (C5,C6 mostly 6)

C7 continues as the

middle trunk with no branches

C8 and T1 form the

inferior trunk which lies on the 1st rib posterior to subclavian artery

no branches

divisions on brachial plexus

each trunk gives an anterior and posterior division

the divisions give off no nerves

lateral cord is formed by

anterior divisions of superior and middle trunk

C5-C7

posterior cord is formed by

posterior divisions of all 3 trunks

C5-T1

medial cord is formed by

anterior division of inferior trunk

C8-T1

how are cords named

according to relationship to the second part of the axillary artery

branches of lateral cord

lateral pec

musculocutaneous

lateral root of median nerve

lateral pec nerve

for pec major

C5-C7 mostly C6

musculocutaneous nerve

goes to coracobrachialis, biceps brachii and brachialis

C5-C7

continues as lateral cutaneous nerve of forearm

lateral root of median nerve

largest branch of lateral cord

C6-C7

branches of medial cord

medial pectoral nerve

medial cutaneous nerve of arm

medial cutaneous nerve of forearm

medial root of median nerve

ulnar nerve

medial pec nerve

to pec minor and pec major

C8-T1

medial cutaneous nerve of arm

T1

medial cutaneous nerve of forearm

C8,T1

medial root of median nerve

C8,T1

ulnar nerve

C8, T1 sometimes C7

innervates flexor carpi ulnaris

medial 1/2 of flexor digitorum profundus

all intrinsic hand muscles of hand except 3 thenar and lateral 2 lumbricals

branches of posterior cord

Upper subscapular nerve

Lower subscapular nerve

Thoracodorsal nerve

Radial nerve

Axillary nerve

superior lateral cutaneous nerve of arm

upper subscapular nerve

subscapular muscle

C5

thoracodorsal nerve

for lat

C6,C7,C8 mostly C7

lower subscapular nerve

subscapular and teres major

C6

axillary nerve

C5,C6

supplies deltoid and teres minor

superior lateral cutaneous nerve of arm

C5,C6

radial nerve

supplies triceps, muscles of extensor compartment of forearm and brachioradialis

C5-T1

Erbs palsy

upper plexus injury

common cause is infants shoulder getting stuck in birth canal which can damage C5 and C6 roots

presentation of Erbs palsy

waiters tip with upper limb adducted and medially rotated, elbow extended, forearm pronated and wrist flexed

Klumpke's palsy

lower brachial plexus injury

caused by hyperabduction maybe falling and grabbing limb

injuries affect forearm and hand

decreased sensation along medial aspect of forearm

can also have claw hand

what can be accompanied with Klumpke's palsy

horners syndrome bc of involvement of T1

can affect the preganglionic sympathetic axons in the T1 root or the white ramus communicantes