Anatomy Of The Shoulder + Pectoral Girdle

Question 1

What is the sternocleidomastoid ?

Answer 1

sternocleidomastoid muscle is the largest muscle in the front of your neck. It’s located just below your skin. You can use your fingers to feel it on both the right and left sides of your neck

s given the name sternocleidomastoid because it originates at the manubrium of the sternum (sterno-) and the clavicle (cleido-) and has an insertion at the mastoid process of the temporal bone of the skull.

Question 2

What is the acromion

Answer 2

In human anatomy, the acromion (from Greek: akros, “highest”, ōmos, “shoulder”, pl. : acromia) is a bony process on the scapula (shoulder blade). Together with the coracoid process it extends laterally over the shoulder joint. The acromion is a continuation of the scapular spine, and hooks over anteriorly.

Question 3

the movements of the shoulder are controlled by which 3 bones and what 4 joints

Answer 3

Bones:
- clavicle
- scapula
- humerus

Joints:
* * sternoclavicular joint
* acromioclavicular joint
* glenohumeral joint
* scapulothoracic ‘joint’

Question 4

what is the only articulation (another word for joint) between upper limb + axial skeleton

Answer 4

sternoclavicular joint
= it’s a synovial saddle joint with fibrous capsule

Question 5

what is the ONLY bony attachment of upper limb with body

Answer 5

Clavicle is ONLY bony attachment of upper limb with body

Question 6

the acromioclavicular joint is a plane type of ______ joint , which allows a ______ movement. No muscles cross AC joint

Answer 6

the acromioclavicular joint is a plane type of synovial joint , which allows a gliding movement. No muscles cross AC joint

Question 7

Shoulder dislocation is by far the commonest type of dislocation across the body. Usually anterior shoulder dislocation which usually results from forced abduction, external rotation and extension. Which joint is ‘a shoulder dislocation’ referring to and why is it vulnerable to dislocation

Answer 7

Glenohumeral joint; super flexible but not stable. Its susceptible to dislocation (usually anterior shoulder dislocation). It’s vulnerable because glenoid fossa is really shallow for the big humeral head,

Question 8

the glenoid fossa is deepened by a fibrocartilaginous disc, what is it called?

Answer 8

the glenoid fossa is deepened by a fibrocartilaginous disc= called glenoid labrum (increases stability of joint) forms a lip at edge of glenoid fossa to hold humeral head

Question 9

the scapula + humerus move in1:2 ratio, what does this mean. Knowing this, in what ratio do you think the glenohumeral + scapulothoracic articulation move together at

Answer 9

the scapula + humerus move in 1:2 ratio, so when arm is elevated to 180 degrees, 2/3 of this came from humeral movement + 1/3 from scapula rotating.

the glenohumeral + scapulothoracic articulation move in 2:1 ratio

Question 10

what nerve is the trapezius muscle innervated by

Answer 10

the trapezius is innvervated by the spinal accessory nerve (cranial nerve XI)

Question 11

what muscles of the shoulder act together to extend, adduct + medially rotate

Answer 11

latissimus dorsi + teres major

Question 12

1) what muscle grp is responsible for scapula retraction
2) what muscle is responsible for scapula elevation

Answer 12

1) scapula retraction= rhomboids
2) scapula elevation= levator scapulae

Question 13

The serratus anterior muscle originates from the medial border of the scapula + wraps underneath scapula + inserts onto ribs. It is the protractor of the scapula. What nerve is the serratus anterior innervated by?

Answer 13

serratus anterior is innervated solely by long thoracic nerve

the serratus anterior, aka “boxer’s muscle,” which when the king thoracic nerve is damaged results in paralysis of the muscle, a phenomenon known as a winged scapula.

Question 14

Pectoralis ____ adducts, medially rotates + flexes the shoulder. Pectoralis ____ stabilises the shoulder joint. Both are innervated by ____ nerves

Answer 14

Pectoralis major adducts, medially rotates + flexes the shoulder. Pectoralis minor stabilises the shoulder joint. Both are innervated by pectoral nerves

Question 15

Explain the location of the deltoid muscle and it’s nerve supply

Answer 15

the DELTOID muscle is a fan-shaped muscle wrapping around the shoulder. It has 3 heads: anterior, posterior + medial. Movements it permits is abduction, flexion + extension
The deltoid is innervated by axillary nerve

Question 16

what muscles surround the glenohumeral joint + help to support it. Describe how they each move the joint

Answer 16

the rotator cuff muscles (supraspinatus, infraspinatus, teres minor, subscapularis) surround the glenohumeral joint + help to support the joint.

the rotator muscles contract and prevent the sliding of the head of the humerus, allowing full range of motion and providing stability. Additionally, rotator cuff muscles help in the mobility of the shoulder joint by facilitating abduction, medial rotation, and lateral rotation.

detail:
Supraspinatus does first 10° of abduction
Infraspinatus + teres minor does external rotation
Subscapularis (on anterior aspect of scapula) responsible for internal rotation

Question 17

What are the BBC muscles of anterior compartment of the arm. What nerve innervates these?

Answer 17

• biceps brachii
• brachialis
• coracobrachialis
  The musculocutaneous nerve innervates the three muscles of the anterior compartment of the arm: the coracobrachialis, biceps brachii, and brachialis muscles.