Arm Flashcards
What holds the radius and ulna together (and is b/w them)?
Interosseous membrane
What dermatome innervates lateral arm, lateral forearm, and thumb?
C6
What dermatome innervates back of arm, back of forearm, and 2nd + 3rd digits?
C7
What dermatome innervates medial arm, medial forearm, and hypothenar?
C8
What dermatome innervates the nipple line?
T4
What vein runs medial in the brachium and branches to form the median cubital vein?
Basalic v.
The anterior compartment of the brachium is supplied by what nerve?
Musculocutaneous n.
The posterior compartment of the brachium is supplied by what nerve?
Radial n.
What is the most powerful flexor of the brachium?
Brachialis m.
Brachialis m: innervation & action
- Musculocutaneous n. and radial n. (C7)
- Flexes forearm at elbow
Biceps brachii m: innervation & action
- Musculocutaneous n. (C5, C6)
- Supinates and flexes forearm at elbow
What muscle is the primary supinator of the brachium?
Biceps brachii m.
Which head of the biceps brachii is lateral and which is medial?
Long head is lateral, short head is medial
Coracobrachialis m: innervation & action
- Musculocutaneous n.
- Flexes and adducts arm at shoulder
Triceps brachii m: innervation & action.
- Radial n.
- Extends arm at elbow. Long head stabilizes head of abducted humerus and extends and adducts arm at shoulder.
What divides the posterior and anterior compartments of the brachium?
Medial and lateral intermuscular septa
What three muscles are attached to the coracoid process?
Pectoralis minor m., coracobrachialis m., short head of the biceps brachii m.
The musculocutaneous n. pierces through what muscle?
Coracobrachialis m.
The biceps brachii tendon comes off what part of what bone?
Radial tuberosity of the radius bone (because it’s a supinator!)
Where is the bicipital apneurosis? What does it overly/protect, and what does it support during venipuncture?
- It’s at the antecubitum
- Overlies/protects the brachial a.
- Supports the median cubital v. during venipuncture
Which head of the triceps is least active? What does it do?
Long head–aids primarily in extending the arm (attached to infra-glenoid tubercle of scapula)
Which head of the triceps is the “workhorse” of forearm extension (works during passive motions), and where is it on the arm?
Medial head–found deep to the long head
Which head of the triceps generates the most force, but functions primarily against active resistance?
Lateral head
The brachial a. branches into what main aa.? Where does it branch?
Radial a. and ulnar a. Branches at elbow.
What are the anastomoses about the elbow?
M.R. Deep
SIMR
PAIR
Superior ulnar colateral, Inferior ulnar colateral, Middle colateral, Radial colateral
Posterior ulnar recurrent, Anterior ulnar recurrent, Interosseous recurrent, radial recurrent
What muscle overlays the 2nd group of arteriole branches of the axillary a. (Screw the lawyer, save a patient)
Pectoralis minor m. (*Dr. I)
What is the muscular landmark indicating transition from axillary a. –> brachial a.?
Lower border of teres major m.
What 3 mm. constitute the floor on which the brachial a. runs?
Superior to inferior: long head of the triceps, coracobrachialis, and brachialis mm.
What are the 3 main branches of the brachial a.?
Deep brachial a. (profunda brachii, runs in radial groove posteriorly), superior ulnar colateral a., inferior ulnar colateral a.
What 3 important nerves are associated w/the brachial a.?
Radial, ulnar, and median nn.
What 3 veins are associated w/the brachial a.?
2 venae comitantes (brachial veins), and the basilic v.
What does injury at the musculocutaneous n. cause?
Flexion at the elbow (but not complete, due to brachioradialis and flexor forearm mm.)
What does the musculocutaneous n. turn into?
Lateral antebrachial cutaneous n.
(musculoCUTaneous, cuts, gives you a LAC (laceration).
The radial n. passes thru the radial groove of the humerus w/what artery?
Deep brachial a.
What nerves does the radial nerve branch into?
Posterior brachial n., inferior lateral brachial n., and posterior antebrachial cutaneous n.
A sharp blow to the medial elbow (“funny bone”) is affecting what nerve?
Ulnar nerve
- Has no branches in arm
What nerve is lateral, crosses, and is then medial to the brachial a. in the arm?
Median n.
What large vein is on the lateral anterior side of the arm? Which os on the medial anterior side?
- Lateral: cephalic v.
- Medial: basilic v.
Explain the boundaries of the cubital fossa.
- Superior: imaginary line connecting medial and lateral epicondyles.
- Medial: lateral border of pronator teres m.
- Lateral: medial border of brachioradialis
- Floor: brachialis and supinator mm.
- Roof: brachial and antebrachial fascia, reinforced by the bicipital apneurosis (protects)
What are the contents of the cubital fossa?
- Terminal part of the brachial a. (bifurcates into ulnar and radial aa.)
- Medial n.
- Radial n. (brach point into superficial and deep radial nn.)
- Tendon of the biceps brachii m.
- Deep veins in the area
What area does the medial antebrachial cutaneous n. supply?
Some skin of bicep, but all skin of medial forearm down to the wrist
What gives rise to the superior lateral cutaneous n of the brachium?
Axillary n.
What dermatomes innervate the skin over the biceps mm.?
C5 and T1
What m. inserts onto the ulnar tuberosity?
Brachialis m. (it’s merely a flexor, not a supinator)
The long head of the biceps originates from the _________________________.
Supraglenoid tubercle of the scapula
The lateral head of the triceps originates from the _______________________.
Upper half of posterior humerus
Where do the biceps insert?
Posterior border of bicipital tuberosity of radius (over bursa) and bicipital aponeurosis to deep fascia and subcutaneous ulna
Where do the triceps insert?
Posterior part of upper surface of olecranon process of ulna and posterior capsule
The short head of the biceps originates from the _______________________.
Corocoid process of the scapula
The long head of the triceps originates from the _________________________.
Infraglenoid tubercle of the scapula
The medial head of the triceps originates from the _______________________
Deep to lower half of posterior humerus
