Arm and Cubital Fossa

 Learning Objectives

After reading this post you will know:

  • Names of the muscles of  flexor (anterior) and extensor(posterior) compartment of arm, their action and nerve supply.
  • Branches of brachial and profunda brachii arteries.
  • Nerves closely related to humerus that may get injured in fractures of humerus.
  • Boundaries, contents and applied anatomy  of cubital fossa.
  • Arteries participating in anastomosis around elbow joint.

Anterior compartment of Arm

Q. write the origin, insertion, action/s & nerve supply of muscles of anterior (flexor) compartment of arm.

A a. Muscles of anterior (flexor) compartment of arm, their origin, insertion, action/s and nerve supply.

MuscleOriginInsertionActionNerve Supply
Biceps brachii Short head - from tip of the coracoid process of scapulaTendon is inserted into the posterior rough part of radial tuberosity. Bicipital aponeurosis is attached to the fascia on the medial side of the forearm. Flexor of forearmMusculocutaneous
Long head - from supraglenoid tubercle of scapula Supinator when the forearm is flexed
Short head – Flexor of arm
Long head – Prevents upward displacement of the head of humerus
CorachobrachialisFrom tip of the coracoid processAt the midle of the medial border of humerusFlexor of armMusculocutaneous
BrachialisLower half of anterolateral and anteromedial surfaces of humerus incluing anterior borderCoronoid process and ulnar tuberosity of ulna.Flexor of forearmMusculocutaneous and
Radial (proprioceptive)

Muscles of flexor (anterior compartment of arm)

Q. Enumerate:

a. Branches of brachial artery
b. Branches of profunda bracii artery.
c. Nerves closely related to humerus.
d. Structures piercing lateral intermuscular septum.
e. Structures piercing medial intermuscular septum

a. Branches of brachial artery
Brachial artery extends from lower border of the teres major muscle above to neck of radius below. Its branches are:

i. Profunda brachii
ii. Superior ulnar collateral
iii. Inferior ulnar collateral
iv. Muscular branches
v. Nutrient artery to humerus
vi. Terminal branches – Radial and ulnar arteries

b. Branches of profunda brachii artery

i. Anterior descending (radial collateral)
ii. Posterior descending ( middle collateral)
iii. Deltoid (ascending)
iv. Nutrient artery to the humerus

c. Nerves closely related to humerus are

i. Axillary nerve to surgical neck of humerus
ii. Radial nerve – radial groove
iii. Ulnar nerve – posterior aspect of medial epicondyle.

d. Structures piercing lateral intermuscular septum.

i. Radial nerve
ii. Anterior descending branch of profunda brachii artery.

e. Structures piercing medial intermuscular septum

i. Ulnar nerve
ii. Superior ulnar collateral branch of brachial artery.

Q. Draw a labelled diagram to show branches of profunda brachii artery.

A.

Branches of brachial arteryCubital Fossa

Q. Describe cubital fossa under the following headings:

i. Location and boundaries
ii. Structures forming roof and floor
iii. Contents
iv. Applied

A. a. Location: Triangular region in front of the elbow.boundaries of cubital fossa

b. Boundaries

i. Base is formed by imaginary line joining the medial and lateral epicondyles.

ii. Apex is formed by the point where pronator teres meets brachioradialis.

iii. Medial boundary is formed by lateral border of pronator teres.

iv. Lateral boundary is formed by medial border of brachioradialis.

c. Structures forming roof 

i. Skin
ii. Superficial fascia containing

• Lateral cutaneous nerve of forearm
• Medial cutaneous nerve of forearm
• Median cubital vein

iii. Deep fascia
iv. Bicipital aponeurosis

d. Muscles forming floor

• Brachialis
• Supinator

e. Contents ( from medial to lateral)

• Median nerve

• Brachial artery and its terminal branches – radial and    ulnar arteries

• Tendon of biceps brachii

• Superficial branch of radial nerve

f. Applied anatomy 

i. The median cubital vein present in the roof of cubital fossa is the vein of choice for venipuncture because

        a. Is connected to deep vein by perforator vein, therefore it does not slip.

        b.   Bicipital aponeurosis protects underlying  brachial artery and median nerve.

       ii. Blood pressure is recorded by auscultating brachial artery in the cubital fossa.

Extensor Compartment of Arm

Q. Enumerate :

a. Muscle /s of the extensor compartment of arm and its nerve supply
b. Structures in the spiral/radial groove
c. The muscular and cutaneous branches of radial nerve given in the arm.

A. a. Muscle of the extensor compartment of arm and its nerve supply.

• Triceps – radial nerve

b. Structures in the spiral/radial groove

• Radial nerve
• Profunda brachii vessels

c. Radial nerve gives  muscular branches  to the following muscles in the arm 

• triceps
• brachioradialis
• extensor carpi radialis longus
• brachialis (propriceptive fibers)

d. Cutaneous branches in the arm

• posterior cutaneous nerve of the arm
• lower lateral cutaneous nerve of the arm
• posterior cutaneous nerve of the forearm

Anastomosis Around Elbow Joint

Q. Draw labeled diagram to show anastomosis around elbow.

anastomosis around elbow joint

Applied Anatomy

Q. What is the anatomical basis of  Volkman’s ischaemic contracture 

A. Cause of ischemia is  Injury/compression of  brachial artery:

  • supracondylar fracture of humerus
  • Improper use of tourniquet
  • Tight plaster cast
  • It is characterised by:

It leads to fibrosis and contracture of the muscles of forearm  (especially flexor digitorum profundus and flexor pollicis longus).

Deformity of hand presents: Flexion at wrist and at interphalangeal  joints.

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