ARM

•           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.