Flashcards in Shoulder, Arm, and Back Deck (55):
What are the three functions of the deltoid?
1. Anterior fibers from lateral 1/3 of clavicle - Arm flexion
2. Middle fibers from acromion - Arm abduction
3. Posterior fibers from spine of the scapula - Arm extension
What is the musculotendinous cuff, and tendons from which muscles make it up? What is its function?
Rotator cuff. Tendons from supraspinatus, infraspinatus, teres minor, and subscapular muscles make it up.
These tendons across the glenohumeral joint prevent posterior displacement of head of humerus
Tendons from which muscles form a sheath around the long head of biceps tendon?
Supraspinatus and subscapular
Where does the suprascapular artery come from?
Either directly from the subclavian artery, or a branch from the thyrocervical trunk from the subclavian artery
What is the dorsal scapular artery?
Also called the transverse cervical artery. Runs with dorsal scapular nerve, can come directly from subclavian artery but most often the thyrocervical trunk. Supplies blood to trapezius and medially to the scapula
What is the best example of collateral circulation in the shoulder?
If blood supply to the brachial artery is cut, blood can still reach the circumflex scapular artery via the suprascapular artery and the transverse cervical artery (dorsal scapular)
What are the borders of the triangular space? What runs through it?
Teres minor, teres major, long head of triceps (medial side). Circumflex scapular artery runs through (an offshoot of the subscapular artery)
What are the borders of the quadrangular space? What runs through it?
teres major, teres minor, lateral border of long head of triceps, surgical neck of humerus. Axillary nerve and posterior circumflex artery runs through
What are the borders of the triangular interval? What runs through?
Inferior border of teres major, long head of triceps (lateral), shaft of humerus. Radial nerve and profunda brachii artery run through
How are the anterior and posterior compartments of the humerus defined? What separates them?
Anterior - contains flexors innervated by musculocutaneous nerve
Posterior - contains extensors innervated by the radial nerve.
Separated by the intermuscular septa (arm's deep fascia)
What are the origin, insertion, innervation, and action of the coracobrachialis?
Origin: Coracoid process
Insertion: Medial mid-shaft of humerus
Innervation: Musculocutaneous nerve
Weak flexor of arm
What are the origin, insertion, innervation, and action of the biceps brachii?
Origin: Long head from superglenoid tubercule, short head from coracoid process
Insertion: Radial tuberosity of radius
Innervation: Musculocutaneous nerve
Flexor of forearm, supinator of forearm, minor flexor of arm through short head
What are the origin, insertion, innervation, and action of the brachialis muscle?
Origin: Anterior aspect of distal humerus and intermuscular septum
Insertion: tuberosity of ulna
Innervation: Musculocutaneous nerve (it's in the anterior compartment)
Flexor of forearm
What are the origins, insertion, innervation, and actions of the triceps brachii?
Origin: Long head - infraglenoid tubercule
Medial head - humeral shaft inferior to radial (spiral) groove. This head cannot be palpated
Lateral head - humeral shaft superior to radial groove
Insertion: Olecranon (of ulna)
Innervation: Radial nerve
Forearm extension, long head can also extend / adduct the arm
What defines the transition from axillary artery to brachial artery? What does it do?
It is renamed brachial artery at the inferior border of the teres major. It supplies blood to the anterior compartment.
What accompanies the radial nerve through the triangular interval and what is its function?
The profunda brachii artery. Its function is to supply blood to the posterior compartment
What accompanies the brachial artery? Where does it run?
Paired brachial veins accompany it. It joins the basilic vein medially to form the axillary vein. It runs medially to the short head of the biceps, and superficially to the brachialis muscle.
Where does the basilic vein run?
It runs medially to biceps brachii and the brachial artery, but penetrates the deep fascia
How does the musculocutaneous nerve run and what is its fate?
After piercing through the coracobrachialis muscle, it runs deep to the biceps brachii and superficially over the brachialis muscle. It emerges from under the biceps as the lateral cutaneous nerve of the forearm
How does the ulnar nerve move as it travels through the arm?
Arising from the medial cord, it accompanies the brachial artery medially and posteriorly as it travels down the distal forearm. It will pierce the IMS around the fattest portion of the brachialis muscle, before running posterior to the medial epicondyle of humerus.
How does the median nerve move as it travels through the arm.
Arising from the lateral and medial cords, it accompanies the brachial artery laterally and anteriorly as it travels down the distal forearm. Around the fattest part of the brachialis muscle, it moves anteriorly over the brachial artery to become medial to it.
How does the radial nerve move as it travels through the arm?
After passing through the triangular interval (with profunda brachii artery), it moves medially to laterally through the spiral / radial groove of the humerus. it is susceptible to injury at this time. It runs anteriorly just proximal to the elbow and runs between the brachialis and brachioradialis muscles.
What is the function of the medial cutaneous nerve of the arm and where does it come from?
Arises from medial cord (C8, T1). Provides sensory nerves to majority of medial arm
What is the function of the intercostobrachial nerve of the arm and where does it come from?
Arises from lateral cutaneous branch of T2, provides sensory nerves to majority of superior medial arm (along with medial cutaneous nerve)
What is the function of the medial cutaneous nerve of the forearm and where does it come from?
Comes from medial cord (C8, T1), also called medial antebrachial cutaneous nerve. Innervates the medial forearm
What is the function of the posterior cutaneous nerve of the arm and where does it come from?
It is a branch of the radial nerve, sensory innervation of posterior arm
What is the function of the lower lateral cutaneous nerve of the arm and where does it come from?
It is a branch of the radial nerve, sensory innervation of lower lateral arm, along with posterior cutaneous nerve
What is the function of the lateral cutaneous nerve of the forearm and where does it come from?
Arises from musculocutaneous nerve, sensory innervation of lateral forearm
What is the function of the upper lateral cutaneous nerve of the arm and where does it come from?
Arises from axillary nerve, provides sensation to anterior and posterior deltoid
What are the three types of joints?
Fibrous, cartilaginous, and synovial. Fibrous joints are joined by fibrous tissue and no movement occurs (i.e. skull sutures). Cartilaginous are joined by hyaline cartilage or fibrocartilage, variable movement occurs (i.e. pubic symphysis). Synovial have the articular surfaces separated by a fluid filled cavity, allowing greatest freedom of movement
What is the articular cartilage of synovial joints?
It is hyaline cartilage which is avascular and will not regenerate. Has no perichondrium
What is the fibrous capsule of synovial joints?
Composed of collagen fibers, encloses the joint cavity and is anchored by the periosteum. It IS highly vascularized and innervated by pain and proprioreceptors
What is the structure and function of the synovial membrane?
Highly vascularized connective tissue which lies on the inner surface of the joint capsule (inside of fibrous capsule) which produces synovial fluid which is a lubricant and a nutrient source for articular cartilage.
What are the three types of ligaments?
Capsular, extra-capsular, or intra-articular
What are intra-articular discs / menisci and where are they found?
They are fibrous / fibrocartilage structures attached at their periphery to a joint capsule. Present where flexion / extension are associated with gliding motion (knee or wrist)
What innervates a joint?
The same nerve trunks innervating the muscles acting upon the joint
What type of joint is the sternoclavicular joint?
A synovial joint. It is the only attachment of the uper limb with the axial skeleton. There is an articular disc between the clavicle and the clavicular notch of the manubrium
What are the stabilizing structures of the sternoclavicular joint?
Anterior and posterior sternoclavicular ligaments, interclavicular ligament, and most importantly, the costoclavicular ligament (most important in preventing displacement, it is a fibrous joint)
What is the significance of the costoclavicular ligament?
Runs between the first rib and the clavicle. It is a fibrous joint that prevents displacement
What type of joint is the acromioclavicular joint (AC), and how strong is it / why?
It is a weak synovial joint because the acromioclavicular ligament is quite weak. The structure is mostly stabilized by the coracoclavicular ligament. When this ruptures, the clavicle is driven superior to the acromion
What is the glenoid labrum?
Also called the glenoid ligament, it is a "lip" that extends around the glenohumeral joint. It is continuous superiorly with the tendon of the long head of the biceps brachii
What shape do the three glenohumeral ligaments make?
What are the stabilizing structures of the glenohumeral joint?
The three glenohumeral ligaments (making a Z)
The coracohumeral ligament (most superior)
What ligament does the long head of the biceps run beneath to enter the synovial sheath?
Transverse humeral ligament (transverses the intertubercular groove)
What are two important bursae of the glenohumeral joint?
1. Subdeltoid bursae - between supraspinatus tendon and overlying acromion, CA ligament, and anterior deltoid
2. Subscapular - often continuous with joint capsule, runs between the subscapularis tendon and glenoid fossa and helps when arm is adducted
What is the chief medial rotator?
Subscapularis (attaches at lesser tubercule)
What muscle is chiefly involved with the most motions?
Deltoid (flexion, extension, and abduction of upper limb).
What must happen for full abduction to occur?
Scapula must be rotated laterally (base towards peak of shoulder) by the serratus anterior (where it attaches at inferior angle) and trapezius
What is more complex, abduction in coronal or scapular plane?
Coronal. Involves lateral rotation to avoid greater tubercule of humerus hitting acromion
What are the main muscles involved in protraction of the scapula?
Serratus anterior, antagonized by rhomboids
What muscles are used to retract the scapula?
Middle fibers of trapezius, and rhomboids
What encloses the erector spinae muscles?
The thoracolumbar fascia?
What is the general function of the deep back muscles?
When both sides are contracted, they extend the trunk / head neck. Unilateral contraction rotates the structures
What are the erector spinae muscles?
I love standing, lateral to medial
Iliocostalis, longissimus, and spinalis