Anat Scapular Region (6)

• deep fascia that surrounds the Arm (analogous to the fascia lata of the thigh)
• sends septa INWARD toward the humerus that divides the Arm into an anterior & posterior compartment

• flex the arm at the shoulder joint or flex the forearm at the elbow joint
• all these muscles are supplied by the Musculocutaneous nerve

• really just 1 muscle - the Triceps
• extend the arm at the shoulder joint or extend the forearm at the elbow joint
• supplied by the Radial nerve

• the interosseuous membrane (a fibrous sheet) of the forearm
• (just like the one between the tibia & fibula in the leg)

• deep fascia of forearm that's continuous w/ the brachial fascia
• a dense, membranous investment, which forms a general sheath for the muscles in the forearm region

• flex the hand at the wrist joint or continue into the hand to flex the digits
• also pronate the forearm (turn the back of the hand up)
• are supplied mainly by the Median nerve but also have some assistance from the Ulnar nerve

• extend the hand at the wrist joint or continue into the hand to extend the digits
• also supinate the forearm (turn the palm of the hand up)
• like the muscles in the posterior compartment of the Arm, these muscles are supplied by the Radial nerve

• flex, abduct, & adduct digits
• are innervated by the Ulnar & Median nerve (which travel down from the anterior compartment of the Forearm)

to the greater or lesser tubercles

exists about halfway down the humerus, is the point of insertion for the DELTOID muscle

groove on the posterior part of the humerus that serves as a pathway for the Radial nerve to traverse as it makes it way down the arm & innervates the muscles in the posterior compartment of the forearm

• is made up of 2 parts
• 1. Capitulum: rounded head on the lateral side of the humerus
• 2. Trochlea: on the medial side ('like a pulley')

• Radius (more lateral) & Ulna (more medial & is longer)
• Radius has a rounded head at its proximal end in the elbow joint, a shaft that flares out at its distal end, & a distal head that articulates w/ bones in the wrist
• Ulna has an indentation at its proximal head called the Trochleal notch, the posterior Olecranon, the Ulnar tuberosity right below the proximal head, a shaft that narrows as it progresses toward the wrist joint, where it ends in the HEAD of the ulna (distal part = head)
• 

• the Radius can PIVOT around the fixed Ulna
• when the hand is supinated, the bones lie 'parallel' to each other
• when the hand is pronated, the Radius is crossed over the Ulna
• 

located just distal to the head of the radius (just below the elbow joint) where the tendon of the biceps brachii attaches

• found at the proximal end of the ulna
• acts sort of like the mouth of a pipe wrench that grabs onto the trochleal part of the humerus
• allows flexion & extension of the forearm at the elbow joint
• 

• articulation between the head of the radius & the capitulum of the humerus; this is where the radius can pivot
• trochlear notch of the ulna fits into the trochlea of the humerus
• 
• at this joint have flexion, extension, pronation, & supination
• 
• can see posterior displacement of the ulna in the dislocation picture

• posterior part of the proximal end of the Ulna which on the surface feels like the hard part of the elbow
• is where the Triceps Branchii muscle inserts

• located below the proximal end of the Ulna on the 'anterior' side of the bone
• where the arm's Brachialis muscle tendon inserts

• the Brachial Artery
• Radial & Ulnar Arteries
• the Cephalic, Basilic, & Median Cubital Veins

• distal continuation of the Axillary artery
• name changes from Axillary → Brachial when the artery passes the lower edge of the Teres Major muscle
• runs on the medial side of the humerus

• branches off the Brachial Artery as soon as it turns into the Brachial from the Axillary (at that border defined by the Teres Major)
• winds around the back of the humerus (in company w/ the Radial nerve), comes down around the lateral side of the elbow joint, & connects with a branch of the Radial artery
• provides an anastamoses around the elbow joint
• 

• branch off the Brachial artery, go anterior & posterior to the medial side of the elbow joint, then anastamose w/ the Ulnar artery
• also provide collateral circulation around the elbow joint

• it will branch into 2 arteries that run through the forearm: the Ulnar (medial) & Radial (lateral) Artery
• so Subclavian → Axillary → Brachial → Ulnar & Radial

• they 'meet up' in the hand & form 2 arches
• Superficial Palmar Arch
• Deep Palmar Arch
• these provide collateral circulation around the hand
• 

superficial veins that lie just deep to the skin

• lies in the anterior part of the elbow joint
• connects the Cephalic & Basilic veins
• is often used for vena puncture to get a sample of blood or to inject blood into the circulation
• 

• run alongside the aforementioned arteries w/ the same names
• lie deep to the fascia

• Thoraco-appendicular Group: from the thorax → the scapula or humerus
• Scapulo-humeral Group: from the scapula → the humerus

the Rotator Cuff muscles

• Trapezius
• Latissimus Dorsi
• Rhomboids
• Serratus Anterior
• Levator Scapulae
• 

• the Upper part attaches to the back of the base of the skull (occipital region) or the spinous processes of the cervical vertebrae (in the midline) & can ELEVATE the scapula

• the Middle part originates on the upper spinous processes of the thoracic vertebrae (fibers run practically horizontally) & can RETRACT the scapula

• the Lower part originates on the lower spinous processes of the thoracic vertebrae & can DEPRESS the scapula

• all parts insert on the spine of the scapula & serve to ROTATE the scapula

• • supplied by the Spinal Accessory nerve, CN XI (one of the cranial nerves, NOT one from the brachial plexus)
• 

• when the muscle contracts, it pulls toward the midline & posteriorly → extends, adducts, & medially rotates the humerus

• the lower part originates from the Thoraco-lumbar fascia (very thick fascia)

• its muscle fibers run up laterally to attach to the floor of the intertuburcular groove on the humerus

• is supplied by the Thoracodorsal (or Middle Subscapular) nerve which comes off the posterior cord of the brachial plexus

• is the widest muscle of the back

• Lat pulls (gym)
• Rowing (canoeing)
• Climbing a rope
• Skiing
• Chopping Wood
• (lots of other muscles are used for these processes too…)

• the scapula is moved posteriorly & medially along the chest wall
• rhomboideus major, minor, & trapezius are the prime movers
• 

• pulls the scapula in toward the midline to RETRACT it & can also rotates it inferiorly
• seen under/if you cut the Trapezius
• made up of 2 parts, the rhomboid major & minor
• both originate off the medial border of the scapula
• the minor part inserts on lower cervical/upper thoracic spinous processes
• the major (larger) part inserts on lower thoracic spinous processes
• supplied by the Dorsal scapular nerve (comes off of the C5 root of the brachial plexus)
• 

• small muscle that elevates the scapula
• runs from the posterior tubercles of transverse processes of C1 - C4 vertebrae to the superior part of the medial border of the scapula
• supplied by cervical nerves C3, 4, & the Dorsal scapular nerve (comes off of the C5 root of the brachial plexus)
• 

• protracts (hunch) & rotates the scapula superiorly
• supplied by the Long thoracic (C5, 6, 7) nerve [branches off the roots of C5, 6, 7 cervical nerves]

• the scapula is moved laterally & anteriorly along the chest wall
• Serratus anterior is the prime mover
• Pectoralis minor & major, the latter acting through the humerus, may assist (act as synergists)
• 

• Supraspinatus
• Infraspinatus
• Teres minor
• Subscapularis: Upper & Lower
• deltoid
• teres major
• 

• middle part ABDUCTS the arm (main purpose)
• anterior part helps to FLEX the arm
• posterior part helps to EXTEND the arm
• originates off the lateral part of the spine of the scapula, the lateral part of the clavicle, & the acromion
• muscle fibers come together to form a tendon that inserts on the deltoid tuberosity (~halfway down the lateral part of the humerus)
• is innervated by Axillary nerve (comes off the posterior cord)
• looks like an upside down 'delta'
• 

• abduction of the upper limb to 180^o requires ROTATION OF THE SCAPULA
• serratus anterior fibers pull on the lower part of the scapula
• lateral fibers of the trapezius pull on the acromion (lateral part of the scapula spine)
• 

• when abducting the arm to 180^o, motion occurs at the glenohumeral, scapulo-thoracic, sternoclavicular, & acromioclavicular joints
• for every ~2^o of abduction by the deltoid, there's ~1^o of rotation of the scapula

both a “winged scapula” & the inability to abduct to 180^o (serratus anterior can't pull down on the lower part of the scapula, meaning it's unable to rotate)

• adducts & medially rotates the humerus
• originates off the lower lateral edge of the scapula (posterior surface of inferior angle of the scapula)
• runs anterior to the long head of the triceps
• inserts on the intertubercular groove of the humerus
• 
• is supplied by the lower subscapular nerve
• (not a true rotator cuff muscle b/c it doesn't insert on the head of the humerus)