Anatomy of the Shoulder + Superior Upper Limb Flashcards
What are the boundaries of the axilla?
Base – Skin (armpit)
Apex – Root of neck
Anterior wall – Pectoral muscles
Posterior wall - latissimus dorsi, subscapularis, teres major
Medial wall – Chest and serratus anterior
Lateral wall – Humerus and muscles
What are the boundaries and contents of the Triangular space (finger trick)?
Lateral - Long Head of Triceps Brachii
Superior - Teres Minor
Inferior - Tees Major
- Contains the Circumflex Scapular Artery
What are the boundaries and contents of the Quadrangular space (finger trick)?
Medial - Long head of triceps brachii
Superior - Teres minor
Inferior - Teres Major
Lateral - Humerus
- Contains the Axillary Nerve + Posterior Circumflex Humeral Artery
What are the boundaries and contents of the Triangular Interval (finger trick)?
Superior - Teres Major
Lateral - Humerus
Medial - Long head of triceps brachii
- Contains the Radial Nerve & Profunda Brachii
Describe the glenohumeral joint
The glenohumeral joint is a Multiaxial synovial ball and socket joint. It joins the head of the humerus to the glenoid fossa of the scapula.
It is an unstable joint due to the poor bony fit and the lack of supporting ligaments. The glenoid fossa is deepened by a glenoid labrum.
Describe the Supraspinatus muscle
Origin: Supraspinous fossa of scapula
Insertion: Greater tubercle of humerus
Innervation: Suprascapular nerve (C5-C6)
Action: Initiates abduction *, assists deltoid in abduction, holds humerus in glenoid
Describe the Infraspinatus muscle
Origin: Infraspinous fossa of scapula
Insertion: Greater tubercle of humerus
Innervation: Suprascapular nerve (C5-C6)
Action: Lateral Rotation, Holds the humerus in glenoid fossa
Describe the Teres Minor Muscle
Origin: Lateral border of the scapula
Insertion: Greater tubercle of humerus
Innervation: Axillary nerve (C5-C6)
Action: Lateral rotation of the arm, Holds the humerus in glenoid fossa
Describe the Subscapularis muscle
Origin: Subscapular fossa of the scapula
Insertion: Lesser tubercle of humerus
Innervation: Upper and lower subscapular nerves (C5-C6)
Action: Internal rotation of the arm, adduction, Holds the humerus in glenoid fossa
How would you assess each rotator cuff muscle?
Actions to assess individual muscles:
Supraspinatus: Abduction (1st 15º)
Infraspinatus: Lateral rotation
Teres minor: Lateral rotation
Subscapularis: Medial rotation
Describe the deltoid muscle
Origin: Lateral 1/3 of clavicle, Acromion, Spine of scapula
Insertion: Deltoid tuberosity of humerus
Innervation: Axillary nerve (C5-C6)
Action:
-Anterior -> Flexion and medial rotation
-Middle -> Abduction
-Posterior -> Extension and lateral rotation
Name the ligaments of the glenohumeral joints and describe what they do
Superior glenohumeral ligament:
Limits external rotation and inferior translation of the humeral head.
Arises from the glenoid and inserts on the anatomical neck of the humerus.
Middle glenohumeral ligament:
Limits external rotation and anterior translation of the humeral head.
Arises from the glenoid and inserts on the anatomical neck of the humerus.
Inferior glenohumeral ligament:
Limits external rotation and superior and anterior translation of the humeral head (anterior portion);
Limits internal rotation and anterior translation (posterior portion).
Arises from the glenoid and inserts on the humerus just beyond the lesser tuberosity.
Coracohumeral ligament:
Split into anterior and posterior divisions by the biceps tendon.
Anterior portion limits extension while the posterior portion limits flexion.
Both divisions limit inferior and posterior translation of the humeral head.
Helps to support the weight of the resting arm against gravity.
Runs laterally from the coracoid process to the humerus, covering the superior glenohumeral ligament and blending with the superior joint capsule and supraspinatus tendon superiorly.
Transverse humeral ligament:
This ligament serves to keep the tendon of the long head of the biceps in the bicipital groove.
