Shoulder and Upper Limb, Hand Intrinsic Muscles Notes

Joints Of Upper Limb

Question-1: Name The Factors Stabilizing Shoulder Joint

Answer:

The stability of the shoulder joint mainly depends upon the surrounding muscles

Factors Stabilizing Shoulder Joint Rotator cuff

1. Supraspinatus,
2. Infraspinatus,
3. Teres minor, and
4. Subscapularis.

Read And Learn More: Anatomy Notes And Important Question And Answers

Factors Stabilizing Shoulder Joint Long head of biceps

The long head of the biceps being intracapsular stabilizes the joint from inside the capsule.

Factors Stabilizing Shoulder Joint  Long muscles of the shoulder

1. Deltoid-laterally
2. The long head of triceps-medially
3. Pectoralis majoranteriorly
4. Latissimus dorsi posteriorly

Question-2: Name The Muscles Causing Adduction At Shoulder Joint

Answer:

1. Sternal head of pectoralis major, and

2. Latissimus dorsi.

Muscles Causing Lateral Rotation At Shoulder Joint.

Lateral rotators are (TIP)

1. Teres minor,
2. Infraspinatus, and
3. Posterior fibres of the deltoid.

Muscles Causing Medial Rotation At Shoulder Joint

1. Medial rotators are (“Lady, majors and soldier“)

1. Latissimus dorsi,
2. Pectoralis major,
3. Teres major, and
4. Subscapularis.

 

Question-3: Describe the Intrinsic Muscles Of the Hand

Answer:

Intrinsic Muscles Features

1. The intrinsic muscles of the hand serve the function of adjusting the hand during gripping and also for carrying out fine-skilled movements.

2. The origin and insertion of these muscles are within the territory of the hand.

3. There are 20 muscles in the hand. These are

1. Three muscles of the thenar eminence

1. Abductor pollicis brevis,
2. Flexor pollicis brevis, and
3. Opponens pollicis.

2. One adductor of thumb: Adductor pollicis.

3. Four hypothenar muscles

1. Palmaris brevis,
2. Abductor digiti minimi,
3. Flexor digiti minimi, and
4. Opponens digiti minimi.

4. Muscles of hypothenar eminence.

1. Abductor digiti minimi,
2. Flexor digiti minimi, and
3. Opponens digiti minimi

5. Four lumbricals,

6. Four palmar interossei, and

7. Four dorsal interossei.

Branches Of Ulnar Nerve In Hand

1. Ulnar nerve divides into

1. Superficial, and
2. Deep branches on the flexor retinaculum.

1. The superficial branch runs beneath palmaris brevis to which it supplies. It has two digital branches:

1. One supplies the ulnar 11/2 fingers, including their nail beds.
2. The other supplies the skin on the dorsum of the hand not supplied by the dorsal branch.

2. Deep branch is joined by the deep branch of the ulnar artery.

1. It passes deeply between the abductor and flexor digiti minimi.
2. It passes through the opponent’s digiti minimi and supplies all the hypothenar muscles.
3. It crosses the palm in the concavity of the deep palmar arch.
4. It supplies medial two ulnar lumbricals and, both palmar and dorsal interossei.
5. It ends its journey by resting peacefully—in adductor pollicis the graveyard of the ulnar nerve.

(ATM – Aid to Memory)

2. The muscles supplied by the ulnar nerve in the hand are subdivided into muscles of

1. Hypothenar, and
2. Thenar eminence.

1. The muscles of hypothenar eminence are remembered by a keyword

I ate a LOAF.

The word loaf means—A shaped mass of bread baked in one piece. The expansion of keywords is

1. I for interossei
2. Ate represents ‘eight.’
3. Though both words are different, they sound the same.
4. L stands for Lumbricals
5. O denotes Opponens digiti minimi
6. A represents the Abductor digiti minimi.
7. F represents Flexor digiti minimi.

2. The muscles of the thenar eminence are

1. Deep head of flexor pollicis brevis, and
2. Adductor pollicis.

Ulnar Nerve Applied anatomy

1. Cervical rib: Pressure of the cervical rib on the lowest trunk of the brachial plexus may produce

1. Wasting of the small muscles of the hand.
2. Paresthesia along the ulnar border of the forearm.

2. Ulnar nerve is most commonly injured behind the elbow or at the wrist.

3. The classical sign of a low lesion is a claw hand. There is

1. Hyperextension of metacarpophalangeal joints of the ring and little fingers, and
2. Flexion of interphalangeal joints.
3. The interossei and lumbricals of the ring and little fingers are paralyzed, so flexion at the metacarpophalangeal joint and extension at the interphalangeal joint is affected.
4. The claw hand is produced by the unopposed action of the extensors and of flexor digitorum profundus.

4. Injury at the elbow or above gives straighter fingers because the ulnar 2 of the flexor digitorum profundus is out of action and cannot flex the distal inter-phalangeal joints of the ring and little fingers.

Wasting of interossei eventually becomes obvious on the dorsum of the hand, giving the appearance of guttering between the metacarpals.

5. Testing for the abduction of the index finger by the first dorsal interosseous assesses small muscle function in the hand that is dependent on the intact ulnar nerve supply.

6. The integrity of the ulnar nerve can be confirmed by testing the sensations of the pulp of the little finger

7. Cubital tunnel is the site for ulnar nerve entrapment. Nerve entrapment is the compression of a nerve causing slowing of conduction and variable degree of demyelination.

8. When the ulnar nerve is rolled in the groove between the medial epicondyle of the humerus and the olecranon process of the ulna, one feels tingling sensations in his/her ring and little fingers.

The person often goes crazy to do so repeatedly. Hence, the humerus bone is called the ‘crazy bone (funny bone)’.