•
arm is divided into compartments ----anterior
, posterior by medial & lateral intermuscular septums.
•
these septa provide additional surfaces for
attachment of muscles, also form planes along which nerves & blood vessels
travel.
•
medial
septum is pierced by ulnar
nerve & superior ulnar collateral artery.
•
lateral
septum is pierced by radial
nerve & anterior descending
branch of profunda brachii artery.
Muscles of anterior compartment of arm
•
coracobrachialis
•
biceps brachii
•
brachialis
• nerve supply----
•
musculocutaneous nerve( C5,6)
•
radial nerve ( proprioception) for brachialis muscle.
Coracobrachialis
•
from tip of coracoid process, along with short head of
biceps
•
to medial border of humerus
•
Action--• Flexion of
arm
Biceps brachii
•
has two heads of origin---
•
short head arises from tip of coracoid process along
with coracobrachialis,
•
long head from supraglenoid tubercle of scapula & glenoidal
labrum
•
insertion on radial
tuberosity with a bursa intervening,
gives of an extension as apponeurosis that goes to posterior aspect of ulna.
• Action—
•
strong supinator when forearm is flexed( all screwing movements are done with it)
•
flexor of elbow
•
short head is flexor of arm.
•
Long head prevents upward displacement of head of
humerus ( as tendon is intracapsular)
brachialis
• From lower
½ of front of humerus, from medial & lateral intermuscular septae.
• to ulnar
tuberosity, rough anterior surface of coronoid process of ulna.
• Action---
• flexion of forearm at elbow joint.
Musculocutaneous nerve
•
main nerve of front of
arm
•
continues below
elbow as lateral cutaneous nerve of forearm
• branches---
• A) muscular---to brachialis ,biceps
,coracobrachialis( B B C)
• B) cutaneous ---lateral cutaneous nerve of
forearm
Back of arm
•
Triceps muscle ---
•
Three heads ---long, lateral & medial head.
•
Long head ---from infraglenoid tubercle on scapula
•
Lateral
head— oblique ridge on upper part
of posterior surface of humerus,i.e above spiral groove.
•
medial head
---from large triangular area on posterior surface of humerus below s[piral groove.
•
Insertion
on—posterior part of superior surface of olecranon process.
•
nerve supply ----radial
nerve.
• Action—
•
extension of elbow.
•
applied---
•
in radial nerve injuries in arm triceps usually
escapes because the nerve supplying it arises in axilla.
Radial nerve
•
largest branch of posterior cord of brachial plexus.(
C5,6,7,8,T1)
•
course—
•
in lower part
of axilla it passes downward ,
•
in upper part
of arm it continues behind brachial artery and passes posterolaterally with
profunda brachii vessels ,enters radial groove.
•
in radial
groove it turns downward and laterally between lateral and medial head of triceps,
•
at lower end of groove about 5 cm below deltoid tuberosity it pierces lateral intermuscular septum
and enters anterior compartment of arm.
Branches
muscular
• before entering spiral groove— Medial ,
long head of triceps,
• In spiral groove— lateral , medial head of
triceps, anconeus.
• below spiral groove---
• brachialis,
brachioradialis, extensor carpi radialis longus
cutaneous
• posterior
cutaneous nerve of arm,( given of above
radial groove)
Given of in radial groove
•
lower lateral cutaneous nerve of arm,(
•
posterior cutaneous nerve of forearm, articular
branches to elbow joint
Applied
•
A) radial nerve
is commonly damaged in region of radial groove due to---
•
intramuscular injections in triceps,
•
sleeping in an arm chair with limb hanging by
side of chair( Saturday night palsy)
•
pressure by a crutch( crutch paralysis)
•
fractures of shaft of humerus.
•
results in ---weakness
or loss of power of extension at wrist ( wrist drop), sensory loss over a
narrow strip on back of forearm, lateral
side of dorsum of hand.
•
B) in fracture of radial groove where nerve is injured in groove , extension
of arm is still possible because long and medial head of triceps are
supplied before the nerve enters radial groove.
Brachial artery
•
continuation of
axillary artery
•
Extends from lower border of teres major muscle to a point in front of elbow,at level
of neck of radius,just medial to tendon
of biceps brachii.
•
course--- runs
downwards & laterally from medial side of arm to the front of elbow,
superficial throughout its extent&
accompanied by two venae comitents.
•
In front of elbow it is covered by bicipital apponeurosis & medial cubital
vein.
•
The structures from
lateral----to---medial side are
---radial nerve, biceps tendon, brachial artery,median nerve.
•
Branches---muscular
arteries,
•
profunda brachii artery
•
superior ulnar collateral artery
•
inferior ulnar collateral artery
•
nutrient artery
•
artery divides into two terminal branches --radial
& ulnar arteries.
•
Applied—brachial
pulsations can be felt or ascultated in front of elbow just medial to tendon of
biceps ,while recording blood pressure.
•
artery can be compressed most favourably in middle of
arm, where it lies on tendon of coracobrachialis.
Anastamosis around elbow joint
•
links brachial
artery with upper end of
radial & ulnar arteries.
•
supplies ligaments
& bones of the joint
In front
of lateral epicondyle---
•
anterior descending branch of profunda brachii, with
radial recurrent branch of radial
artery,
behind
lateral epicondyle---
•
posterior descending branch of profunda brachii anatamosis with interosseus recurrent branch of
posterior interosseus artery
•
front of
medial epicondyle---
•
inferior ulnar collateral branch ofbrachial artery ( & sometimes
branch from superior ulnar collateral
artery) with anterior recurrent branch
of ulnar artery.
• Behind medial
epicondyle—
• Superior ulnar collateral branch of brachial artery anastamosis with posterior ulnar recurrent branch of ulnar artery & branch from inferior ulnar collateral artery.
• just above olecranon fossa ---
• A branch
from posterior descendind branch of
profunda brachii artery with inferior
ulnar collateral artery.
Profunda brachii artery
• large branch of brachial artery,
• Branches---
•
anterior descending,( radial collateral)
•
posterior descending
•
ascending branch with anastamosis with posterior
circumflex humeral artery
•
nutrient artery
mcq
•
1) all of
following are retractors of scapula except--• trepazius
•
rhomboid major
•
rhomboid minor
•
levator scapulae
•
2) muscles
attached on greater tubercle of humerus are all except—
•
supraspinatus
•
teres minor
•
infraspinatus
•
pectoralis major
•
3) all the muscles are used to abduct the
shoulder except—
•
deltoid
•
Supraspinatus
•
Serratus anterior
•
pectoralis major
•
4) axillary
nerve supplies--• deltoid + teres major,
•
deltoid+ teres minor
•
teres major + minor,
•
coracobrachialis+ short head of biceps
5) all of following features can be observed after injury to axillary
nerve except—
•
loss of rounded contour of shoulder,
•
Loss of sensation over
lateral side of upper arm,
•
Loss of overhead abduction,
•
atrophy of deltoid muscle,
•
6) all of
following are features of musculocutaneous nerve injury at axilla except— • loss of flexion of shoulder, • loss of
flexion at elbow,
Loss of
supination of forearm, loss of sensation on radial side
7) which among
the following is a branch from trunk of brachial plexus— • Suprascapular
nerve,
•
Long thoracic nerve,
•
anterior thoracic nerve,
•
Nerve to subclavius
•
8) all of
following muscle undergo paralysis after injury to C5,6 spinal nerve—
•
biceps,
•
coracobrachialis brachialis brachioradialis
9) arterial supply of latissmis dorsi is--• subscapular
artery,
•
circumflex humeral artery • thoracodorsal
artery •
lateral artery.
•
10) a 19 yr old
boy fell from motor bike on his shoulder . The doctor diagnosed him a case of
erb’s paralysis. The following s/s will be observed except— • loss of
abduction at shoulder joint,
•
Loss of lateral rotation, loss of pronation at
radioulnar joint, loss of flexion at elbow joint.
