Week 2: Upper Limbs & Back Flashcards
What are the origin and insertion of a muscle?
Origin - attachment point that does not move during contraction of the muscle
Insertion - attachment point that does move during the contraction of the muscle
When a muscle contracts, the insertion moves closer to the origin
What organizes limbs into compartment?
Deep fascia and connective tissue wraps muscles into compartments that have their own nerves and blood supplies
What are the main components of the upper and lower limb?
Upper:
Axilla, arm, forearm (ant/post compartments), hand
Lower:
Gluteal region, thigh (ant/post/medial compartments), leg (ant/post/lat compartments), foot
What are the three main groups of back muscles?
Superficial, intermediate, and deep (intrinsic)
What are the superficial muscles of the back, what do they do, and what are they innervated by?
Latissimus dorsi, rhomboids, trapezius and levator scapulae all assist in movement of the upper limb
These are innervated by the brachial plexus, except for the trapezius muscle, which is innervated by CN XI
What are the deep muscles of the back, what do they do and what are they innervated by?
The deep/intrinsic muscles are the erector spinae and transversospinalis. They are involved in stabilizing and moving the trunk.
They are innervated by the dorsal rami of the spinal nerves.
Label A-E
A - Trapezius
B - Latissimus dorsi
C - Levator scapulae
D - Rhomboid minor
E - Rhomboid major
What are the three main muscle movements of the trapezius?
Elevation (shrug up)
Depression (shrug down)
Retraction (pull towards the back)
What are the main movements of the latissimus dorsi?
“Swimming” movements of the shoulder/upper humerus of the arm:
extension towards the back
adduction towards the midline
medial rotation of the insertion point
What are the main movements of the rhomboid major and minor?
Retraction of the scapulae torwards the back
Elevation of scapula (“shrug” movement)
What two muscles would be involved in “flapping” your arms like a bird?
Supraspinatus initiates the first 15 degrees of movement
Deltoid muscle allows for arm abduction beyond 15 degrees
What are the main rotator cuff muscles and what do they do?
These are the muscles around the scapula that rotate, abduct and stabilize the shoulder
The infraspinatus(post) allows forlateralrotation(moves shoulder towards the back). Thesupraspinatus (superior) allows for elevation and resists the downward pull of gravity
Teres minor (post) also allows for lateral rotation
Subscapularis is on the anterior side and allows for medial rotation (towards the anterior midline)
The ______________ joint is between the shoulder and humerus. What is unique about it?
Glenohumeral. It is a socket-like joint that doesn’t actually have much of a “socket,” so it depends on the muscles and ligaments of the rotator cuffs to hold it in place.
What are the main contents of the axilla, and why is it important?
Axillary area is where structures pass from the neck to the upper thorax (i.e. nerves, veins, arteries)
Contents:
Axillary artery/vein
Brachial plexus
Lymphatics and lymph nodes
The __________ _____________ starts within the ________ and carries the nerves for the skin and muscles of the upper limb and shoulder. What do these nerves form from?
Brachial plexus
Neck
Nerves form from the anterior rami of the C5 - T1 spinal segments
From proximal to distal, what is the organization of nerves deriving from the brachial plexus?
“Road To DC Baby”
Proximal:
Roots (ventral/anterior rami, C5-8, T1)
Trunks (superior (C5,6), middle (C7), inferior (C8, T1)
Divisions (anterior and posterior parts of arm)
Cords (lateral, posterior, medial)
Branches (terminal nerves
Distal
What are the four terminal nerves of the brachial plexus and what does each do?
Musculocutaneous - Anterior arm compartment
Median - Forearm: most anterior compartment (except those innervated by ulnar nerve), and Hand: thenar eminence and 2 other muscles + skin of hand
Ulnar - Forearm: 1.5 muscles, and Hand: all intrinsic muscles except those innervated by median nerve, skin of hand
Radial - Posterior compartment of arm and forearm, skin over posterior
What three nerves are responsible for the cutaneous innervation of the hand?
Median (lateral palm, fingers)
ulnar (median palm, medial 1.5 fingers)
and radial nerves (posterior lateral part of hand)
How can you injure elements of the brachial plexus, and what nerves are involved in injury?
Upper brachial injury is caused by damage to the neck like lateral overstretching, which damages C5 & C6
Lower brachial injury is caused by damage to the axillary region from pulling trauma, which damages C8 and T1
What are the major compartments of the arm, what muscles do they contain, what common actions do they commit and how are they innervated?
Compartments are anterior and posterior
Anterior contains the biceps brachii, which is the flexor compartment and is innervated by the musculocutaneous nerve
Posterior contains the triceps brachii, which is the extensor compartment and is innervated by the radial nerve
What are the muscles of the anterior arm, what do they do and where do they originate and insert?
The three biceps brachii are the load-bearing flexors and supinators of the forearm.
They originate in the scapula and proximal humerus and insert in the radius, pulling it across the ulna to pronate the hand (ulna is medial)
What are the muscles of the posterior arm, what do they do and where do they originate and insert? What innervates it?
The three triceps brachii originate from the scapula (1) and humerus (2) and insert on the posterior ulna
They activate extension of the elbow, which is mediated by the radial nerve
What is the cubital fossa and what does it contain?
It is the depression anterior to the elbow joint that contains:
Tendons of biceps muscle
Median nerve
Brachial artery
It also contains the superficial veins used for venipuncture
What are the superficial anterior muscles of the forearm, what are they innervated by, and what do they do?
Flexor carpi ulnaris - flexes and adducts the wrist (ulnar nerve)
Flexor carpi radialis - flexes and abducts the wrist (median nerve)
Flexor digitorum superficialis - flexes digits 2-5 (all but thumb) and proximal interphalangeal joint (PIP joint) (median nerve)
What is the deep anterior muscles of the forearm, what are they innervated by, and what does it do?
Flerxor digitorum profundus has tendons that go into the deep parts of the phalanges to flex them. It is innervated by the median and ulnar nerves (1/2)
The muscle inserts on the distal phalanges and can activate the distal (DIP) and proximal (PIP) interphalangeal joints between the most distal part of a finger and the “middle” part
What are the superficial posterior muscles of the forearm, what is their function, and what are they innervated by?
Extensor carpi radialis longus and brevis - extensors and abductors of the wrist
Extensor carpi ulnaris - wrist extensor and adductor
Extensor digitorum - extensors of digits 2-5
Brachioradialis - crosses over lateral elbow and is an accessory flexor of the elbow
These are all innervated by the radial nerve.
What are the deep posterior muscles of the forearm, what do they do and what are they innervated by?
The extensors pollicis longus and brevis (muscles that connect to tendons) are on the radial/lateral sides of the wrist, and form the anatomical snuffbox. They are innervated by the radial nerve.
What is a carpal tunnel and what forms it?
It is a compartment of muscles and bones formed by the arch of carpal bones and overlayiing flexor retinaculum. It is innervated by the median nerve. Carpal tunnel is characterized by feelings of numbness and pain in the thumb and first two fingers due to compression of the median nerve.
What are the extrinsic and intrinsic muscles of the hand?
Extrinsic muscles move the hand, but the bellies of the muscles themselves lie in the forearm, with tendons that extend to the hand. These are involved in the power grip.
Intrinsic muscles move the hand, and the bellies of the muscles lie in the hand. These are involved in fine, precision grip and are innervated by the ulnar and median nerves.
Thenar muscles (thumb) = median
Most other intrinsics = ulnar
