Shoulder Girdle Anatomy Quiz

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Questions and Answers

Which ligament is considered the major stabilizing factor of the sternoclavicular joint?

Costoclavicular ligament (correct)

Coracoclavicular ligament

Acromioclavicular ligament

Anterior sternoclavicular ligament

What type of joint is the acromioclavicular joint classified as?

Pivot joint

Ball-and-socket joint

Plane synovial joint (correct)

Hinge joint

Which part of the coracoclavicular ligament is involved in providing stability to the acromioclavicular joint?

Lateral part

Medial part

Serratus part

Trapezoid part (correct)

Which muscle is NOT involved in movements of the shoulder girdle?

Latissimus dorsi Signup and view all the answers

What type of surface covers the articular surfaces of the sternoclavicular joint?

Fibrocartilage Signup and view all the answers

Which muscles are primarily responsible for the elevation of the scapula?

Upper fibers of trapezius and levator scapulae Signup and view all the answers

What mechanism is most commonly associated with a clavicle fracture?

Direct fall on the shoulder with the arm at the side Signup and view all the answers

Which joint is likely to become separated due to a fall onto the shoulder?

Acromioclavicular joint Signup and view all the answers

What is the result of paralysis of the serratus anterior muscle?

Winging of the scapula Signup and view all the answers

Where is the cervicoaxillary canal located in relation to the axilla?

At the apex of the axilla Signup and view all the answers

What is the primary action of the pectoralis minor muscle?

Protraction and depression of the scapula Signup and view all the answers

Which nerve supplies the serratus anterior muscle?

Long thoracic nerve Signup and view all the answers

What is a consequence of a long thoracic nerve injury?

Winging of the scapula Signup and view all the answers

Which muscle acts with the serratus anterior to raise the arm above 90 degrees?

Trapezius Signup and view all the answers

What is the role of the subclavius muscle's primary action?

Stabilization of the clavicle Signup and view all the answers

Which bones form the shoulder girdle?

Clavicle and scapula Signup and view all the answers

Which statement regarding the trapezius muscle is true?

It has upper, middle, and lower fibers with different actions. Signup and view all the answers

What action is primarily performed by rhomboideus minor and major muscles?

Retraction of the scapula Signup and view all the answers

What is the type of joint formed by the sternoclavicular joint?

Saddle synovial joint Signup and view all the answers

Which of the following is an important feature of the clavicle?

It ossifies in membrane Signup and view all the answers

How is the paralysis of the trapezius muscle characterized?

Weakness in raising the arm above 90 degrees Signup and view all the answers

What movements are permitted at the sternoclavicular joint?

Limited gliding and rotation Signup and view all the answers

Which muscle groups are attached to the scapula?

Muscles of the neck and back Signup and view all the answers

What is the primary function of the clavicle in the shoulder girdle?

To transmit forces to the axial skeleton Signup and view all the answers

Which feature is characteristic of the scapula?

A prominent spine on the posterior surface Signup and view all the answers

Which supporting ligaments are important for the stability of the shoulder girdle joints?

Sternoclavicular ligaments Signup and view all the answers

Study Notes

Shoulder Girdle

Consists of clavicle (collar bone) & scapula (shoulder blade).
Provides a mobile base for upper limbs to attach to the trunk.

Clavicle

Bone shaped like an "S".
Distances scapula and upper limb from chest wall.
Articulates with sternum and acromion of scapula.
Transmits forces to axial skeleton.
Lacks marrow.
Ossifies in membrane.

Scapula

Triangular bone.
Articulates with humerus at glenoid fossa.
Prominent spine on posterior surface.
Large, flat surfaces and roughened processes for muscle attachments.

Shoulder Girdle joints

Sternoclavicular joint:
- Saddle synovial joint.
- Articular surfaces: sternal end of clavicle and clavicular notch of manubrium sterni and 1st costal cartilage.
- Articular surfaces are covered by fibrocartilage
- Synovial capsule encloses the joint.
- Accessory ligaments: anterior and posterior sternoclavicular ligaments, costoclavicular ligament which is the major stabilizer of the joint, and a fibrocartilaginous disc dividing joint into two cavities.
** Acromioclavicular joint:**
- Plane synovial joint.
- Articular surfaces: acromial end of clavicle and clavicular facet of the acromion process of the scapula.
- Accessory ligaments: acromioclavicular ligament and the strong coracoclavicular ligament, which has two parts-trapezoid and conoid, that provide stability.

Scapular Movements

** Elevation:** upward movement.
** Depression:** downward movement.
** Retraction:** backward movement,
** Protraction:** forward movement.
** Upward rotation:** rotating scapula upwards.
** Downward rotation:** rotating scapula downwards.

Muscles of the Pectoral region

Location: Anterior chest wall.
Consists of:
- Pectoralis major.
- Pectoralis minor.
- Serratus anterior.
- Subclavius.

Pectoralis Minor

Attachments: Between upper ribs and coracoid process of scapula.
Action: Protraction and depression of scapula.

Subclavius

Attachments: Between first rib (costal cartilage) and clavicle.
Nerve Supply: Nerve to subclavius.
Action: Stabilizes the clavicle.

Serratus Anterior

Attachments: From upper 8 or 9 ribs anteriorly to the medial border of scapula posteriorly.
Nerve Supply: Long thoracic nerve.
Action: Protraction and rotates the scapula to raise arm above 90 degrees.
Long thoracic nerve can be injured in radical mastectomy operations.

Long thoracic nerve injury

Results in paralysis of serratus anterior.
Causes weakness in arm abduction above 90 degrees.
Inability to push with arm.
"Winging of the scapula": medial and inferior borders of scapula become prominent.
Tested by patients pushing against the wall.

Muscles of the back involved in movements of the shoulder girdle

Superficial Layer: Trapezius.
Deep Layer: Levator scapulae, Rhomboideus minor, Rhomboideus major.

Trapezius muscle

Attachments: From skull and upper half of vertebral column to scapula and clavicle.
Nerve Supply: Spinal part of the accessory nerve (11th cranial nerve).
Action: Works with serratus anterior to rotate the scapula to raise arm above 90 degrees.
- Upper fibers: elevate scapula.
- Middle fibers: retract scapula.
- Lower fibers: depress scapula.

Paralysis of Trapezius muscle

Weakness in raising arm above 90 degrees.
Weakness in retracting scapula.
Flattening of lower neck.
Sagging of shoulder.

Deeper Layer of muscles of the back

Levator scapulae, Rhomboideus minor, Rhomboideus major
Attachments: Extend between the vertebral column and medial border of the scapula.
Nerve Supply: Dorsal scapular nerve.
Action:
- Levator scapulae: elevates the scapula.
- Rhomboideus minor & major: retract the scapula.

Movements of the Scapula

** Elevation:** by upper fibers of trapezius and levator scapulae.
Depression: by lower fibers of trapezius and pectoralis minor.
** Protraction:** by serratus anterior and pectoralis minor.
Retraction: by middle fibers of trapezius, and rhomboideus minor and major.
** Lateral (upward) rotation:** by upper and lower fibers of trapezius and lower 5 digitations of serratus anterior.
** Medial (downward) rotation:** by levator scapulae and rhomboids (minor and major).

Clavicle Injury

Most common: fall directly on the shoulder with arm at the side.
Usually occurs in middle one-third of the clavicle.
Proximal piece is lifted superiorly by the sternocleidomastoid muscle.
Distal fragment is pulled inferiorly by the arm.
Treatment: usually non-operative.

Acromioclavicular Joint Injury

Despite strong ligaments, joint can separate following a fall on shoulder or outstretched arm.
Acromion is pushed under the clavicle, tearing the coracoclavicular ligament.

Axilla

Arm pit.
Has an apex, base, and 4 walls (anterior, posterior, medial & lateral).

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Description

Test your knowledge on the anatomy of the shoulder girdle, including the clavicle and scapula. This quiz covers the structure, function, and joints associated with the shoulder girdle. Delve into details about the bones and their articulations.