What are skeletal muscles attached to?
Attached to bones or skin
Describe the cell shape and appearance of skeletal muscle.
Single, very long, cylindrical, multinucleated cells with obvious striations
Describe the cell shape and appearance of cardiac muscle.
Branching chains of cells, uni or bi-nucleated and have some striations
Describe the cell shape and appearance of smooth muscle.
Single, fusiform, uninucleated, no striations
What is the only movement that a skeletal muscle can do? Explain how.
Shortening by moving the insertion closer to the origin
What is the origin of a muscle?
Attachment point that is NOT moved during a contraction
What is the insertion of a muscle?
Attachment point that is moved during a contraction
What can you predict if you know the origin and insertion of a muscle?
What is necessary for a muscle to be a able to move a joint?
It needs to cross it
What is necessary for a muscle to be a able to move a bone?
It needs to be attached to it
How are the limbs organized?
Muscle compartments separated by deep fascia/connective tissue that is stiff
What do the muscles in one muscle compartment in a limb have in common?
They usually work together to produce similar actions and usually have a common innervation and vascularization
What happens if the pressure increases within a muscle compartment of a limb? What is this called? What can this lead to?
Compression of nerve and blood supply of that compartment = compartment syndrome => tissue necrosis
What kind of patients get compartment syndrome?
Treatment of compartment syndrome?
What are the 6 parts of upper limbs?
- Elbow joint/cubital fossa
- Wrist joint
How many compartments in arm? List them.
How many compartments in forearm? List them.
- Anterior deep
- Anterior superficial
- Posterior deep
- Posterior superficial
What are the 7 parts of lower limbs?
- Gluteal region
- Hip joint
- Knee joint and popliteal fossa
How many compartments in thigh? List them.
How many compartments in leg? List them.
- Posterior superficial
- Posterior deep
What are the 3 types of mesoderm (from closest to farthest from notochord)? Which 2 do limbs mainly come from?
- Lateral plate*
What does the paraxial mesoderm give rise to?
What does the intermediate mesoderm give rise to?
What does the lateral plate give rise to?
- Somatic mesoderm
2. Splanchnic mesoderm
What does the somatic mesoderm give rise to?
- Limb skeleton and connective tissues
2. Parietal serous membranes
What does the splanchnic mesoderm give rise to?
- Smooth muscle in internal organs
- CV system
- Visceral serous membrane
What does each somite form?
What are somites?
Bilaterally paired blocks of paraxial mesoderm that form along the neural tube of the developing embryo
What will the sclerotomes give rise to?
Vertebral column + skull
What will the dermatomes give rise to?
Dermis of skin in back
What will the myotomes give rise to?
Skeletal muscles of the body:
What will the epimere give rise to?
Epaxial skeletal muscles = deep back skeletal muscles
What will the hypomere give rise to?
Hypaxial skeletal muscles =
- Abdominal and thoracic wall skeletal muscles
- Superficial back muscles
- Limb skeletal muscles
Which layer of the skin is innervated?
What are the epimere muscles innervated by?
What are the hypomere muscles innervated by?
When do limbs start budding in embryologic development?
4 to 5 weeks
Which form first in an embryo: upper or lower limbs?
Describe the budding of limbs in embryologic development.
- Tissue from lateral plate mesoderm migrates and forms the blood vessels, bone, cartilage, and connective tissue of the limbs
- Hypomere migrates from myotome and forms skeletal muscles on either side of the connective tissue and bones = compartment formation
- Signaling factors form the proximal/distal, anterior/posterior, and medial/lateral axes of the limbs
- Endochondral ossification: cartilaginous bones ossify
- Limbs rotate: upper limbs do so laterally and lower limbs do so medially
What are teratogens?
Agents that cause defects in embryonic development
What is the relationship between muscles on opposite side of a bone?
Usually perform opposing actions
What used to be a very common embryological limb defect?
Thalidomide was being prescribed to pregnant women for nausea in first trimester in the 70s and caused the hand to develop from the proximal portion of the arm
What are the 3 types of back muscles?
What is another name for deep back muscles?
Intrinsic back muscles
What is the common action of the superficial back muscles?
Movement of upper limbs and shoulders
What are superficial back muscles innervated by?
Anterior rami organized in brachial plexus, except for trapezius which is innervated by the accessory cranial nerve
What are the 2 deep back muscles?
- Erector spinae:
a. Along spinal cord
b. Origin: inferior end of spine, insertion: superior end of spine
c. Extend spine and maintain upright posture
a. Deep to erector spinae and runs in Xmas tree pattern run in between transverse process of spine
c. Maintain upright posture
What is the common action of the deep back muscles?
Movement and support of trunk: extend spine, posture, some spine/head movements
What are the 4 superficial back muscles?
- Latissimus dorsi
- Rhomboid major
- Rhomboid minor
- Spinal column (upper half)
- Along scapula
- Elevation, retraction, and depression of the scapula aka shoulder
What is the scapula?
Shoulder blade bone
- Spinal column (lower half)
- Front of humerus
- Adduction, medial rotation and extension of the shoulder = swimming
What is the humerus?
Main arm bone
- Middle part of upper spinal column
- Medial border of scapula
- Retraction and elevation of scapula
Rhomboids’ location compared to trapezius?
Describe the composition of erector spinae.
3 groups of muscles arranged in vertical columns
Describe the composition of transversospinales.
3 groups of muscles arranged superficial to deep
What are the 2 muscles of the shoulder?
- Rotator cuff muscles
- Scapula to clavicle
- Lateral side of the humerus
- Arm abduction beyond 15 degrees
Can deltoid muscles initiate abduction from the most adducted position?
Which muscle can initiate abduction from the most adducted position? What kind of muscle is it?
Supraspinatous muscle = rotator cuff muscle
Rotator cuff muscles:
- Rotation, abduction, and stabilization of shoulder
How many rotator cuff muscles?
What is the joint of the shoulder?
What is the axilla? Purpose?
Important area that passes structures from neck to upper limb
What are 4 contents of the axilla?
- Axillary artery and vein
- Brachial plexus
- Lymphatics and lymph nodes
- Axillary tail of breast
Purpose of axillary artery?
Biggest blood supply for upper limbs
1 muscle of anterior arm?
Common action of muscles of anterior arm?
Innervation of muscles of anterior arm?
1 muscle of posterior arm?
Action of muscle of posterior arm?
Innervation of muscle of posterior arm?
- 2 parts of the scapula
- Radius by biceps tendon
- Elbow load bearing flexor and forearm supinator (better when flexed)
Where does the name biceps come from?
The muscle has 2 heads aka 2 origins
What is the most superficial muscle of the arm?
What is the radius?
Lateral forearm bone
Which bone moves during supination and pronation of arm?
What is the ulna?
Medial forearm bone
Can the ulna pivot?
What is the most common biceps tendon that ruptures? What is this called? Why?
Long head tendon between scapula and biceps
Popeye’s sign because forms a bulge on the arm
How many tendons does the biceps have?
- 3 heads from scapula and humerus
- Posterior side of ulna at olecron process
- Elbow extension
Where does the name triceps come from?
The muscle has 3 heads aka 3 origins
What is the cubital fossa?
Depression anterior to the elbow joint
What are the 4 contents of the cubital fossa? List them from lateral to medial.
- Tendon of biceps muscle
- Brachial artery
- Median nerve
- Superficial veins used for venipuncture pass superficially (throughout the cubital fossa)
What is the brachial artery?
The second part of the axillary artery
Main action of forearm anterior muscles?
Flexion of wrist and digits
Main action of forearm posterior muscles?
Extension of wrist and digits
Innervation of posterior forearm muscles?
Innervation of anterior forearm muscles?
- Median nerve (mostly)
2. Ulnar nerve (1.5 muscles)
4 muscles of the superficial anterior forearm? List from lateral to medial
- Flexor carpi radialis
- Palmaris longus
- Flexor carpi ulnaris
- Flexor digitorum superficialis (deeper than all first 3 muscles)
What does carpi mean?
Where do the 4 muscles of the superficial anterior forearm originate?
Action of flexor carpi ulnaris?
Flexes and adducts the wrist
Action of flexor carpi radialis?
Flexes and abducts the wrist
Action of flexor digitorum superficialis?
Flexes digits = Proximal Interphalangeal (PIP) Joint
Action of palmaris longus?
Why is the palmaris longus interesting?
Missing in 10-15% of the pop
Insertion of flexor digitorum superficialis?
Middle phalanges of digits (split tendon on each side), except thumb
Muscle of deep anterior forearm?
Flexor digitorium profundus
Action of flexor digitorium profundus?
Flexes digits except thumb = Proximal AND Distal Interphalangeal (PIP and DIP) joints
Insertion of flexor digitorum profundus?
Most distal bone of the fingers
Innervation of flexor digitorum profundus?
1/2 median nerve
1/2 ulnar nerve
Innervation of the superficial anterior forearm?
- Flexor carpi radialis: median
- Palmaris longus: median
- Flexor carpi ulnaris: ulnar
- Flexor digitorum superficialis: median
5 muscles of the superficial posterior forearm? List from lateral to medial
- Extensor carpi radialis brevis
- Extensor carpi radialis longus
- Extensor digitorum
- Extensor carpi ulnaris
Action of extensor carpi radialis longus and brevis?
Extensors and abductors of the wrist
Action of extensor carpi ulnaris?
Extensors and adductors of the wrist
Action of extensor digitorum?
Extensor of digits except the thumb
Action of brachioradialis?
Where is the brachioradialis muscle located?
Posterior superficial forearm but crosses over lateral elbow
Innervation of all 5 superficial posterior forearm muscles?
What does radial deviation mean?
What does ulnar deviation mean?
2 muscles of deep posterior forearm? List from lateral to medial
- Extensor pollicis brevis
2. Extensor pollicis longus
What does pollicis mean?
Function of extensor pollicis longus and brevis? What does this create?
What passes through the tendons of the extensor pollicis longus and brevis
Branch of radial artery
What can cause anatomical snuffbox injuries?
What does FOOSH stand for?
Fall On an OutStretched Hand
What is the bone posterior to the anatomical snuffbox?
What 3 bones are often fractured due to FOOSH injuries?
- Distal radius (Colles’ fracture)
What is the carpal tunnel?
Narrow, tunnel-like structure in the wrist with median nerve and flexor tendons from anterior forearm in the center:
- Dorsal and lateral sides of the tunnel formed by wrist bones
- Ventral side of the tunnel covered by a strong band of connective tissue: flexor retinaculum
What is carpal tunnel syndrome (CTS) caused by? Symptoms?
Injury to the median nerve due to narrowing/inflammation of the carpal tunnel
Starts with sensory symptoms and then severe carpal tunnel will cause impairement/Loss of innervation of muscles distal to the carpal tunnel: thenar muscles on bulge of thumb that allow it to oppose
What are the 2 types of muscles of the hand?
Innervation of extrinsic hand muscles?
Action of extrinsic muscles of hand?
Where are the extrinsic muscles of the hand located?
Forearm with tendons extending in the hand
Where are the intrinsic hand muscles?
In the hand
Action of intrinsic muscles of hand?
Innervation of intrinsic hand muscles?
- Median (thenar eminance)
2. Ulnar (all others)
Innervation of thenar eminence muscles?
Intrinsic hand muscles of the pinky?
Where is the gluteal region?
- Between iliac crest and inferior border of butt
- Posterior and lateral to pelvic bone
What passes through the gluteal region?
Important nerves from pelvis
What are the 2 compartments of gluteal region?
What are the 3 muscles of the superficial gluteal region?
- Gluteus maximus
- Gluteus medius
- Gluteus minimus
- Pelvic bone
- Posterior side of femur and IT band (connective tissue on lateral side of thigh)
- Extension, lateral rotation, and abduction of thigh (getting up from flexed position)
Gluteus medius and minimus
- Pelvic bone (top of crests)
- Top of femur
- Medial rotation and abduction of hip/thigh and secures its position when walking
Position of gluteus medius and minimus in relation to gluteus maximus?
Innervation of superficial gluteus region muscles?
What happens when people lose the innervation to their gluteus medius and minimus muscles?
Their hips drop every time they step forward
Muscle of the deep gluteal region? What is special about it?
Muscle of both the pelvic wall and the gluteal region and forms important landmarks (above and below) in gluteal region where blood vessels and nerves will exit pelvis to travel to gluteal region
Common action of muscles of the deep gluteal region?
Lateral rotation of the thigh/hip
Origin of piriformis? Insertion? Through what?
Pelvis and then comes out through the greater sciatic foramen to insert on the femur
What are the 2 nerves that pass below the piriformis? Describe location of each.
- Sciatic nerve: passes below and travels to posterior thigh
- Pudendal nerve: passes below and enters perineum
Where do we do injections in the buttocks?
Superior lateral quadrant
Most vulnerable portion of buttocks where you should NOT do injections?
Lower medial quadrant
Most common procedure done on gluteal region?
What are the 3 compartments of the thigh muscles?
Action of anterior thigh muscles?
Most extend knee (except for sartorius)
Action of posterior thigh muscles?
Flex knee (some also extend hip and rotate thigh)
Action of medial thigh muscles?
Innervation of anterior thigh muscles?
Innervation of posterior thigh muscles?
Innervation of medial thigh muscles?
5 muscles of anterior thigh? List from lateral to medial
Quadriceps femoris group = quads:
- Vastus lateralis
- Rectus femoris
- Vastus medialis
- Vastus intermedius (deep to rectus femoris)
Insertion of quads?
Common insertion on patella via quadriceps tendon all the way to the tibia
What is the patella?
Rectus femoris origin? Implication?
Can move 2 joints: flex the hip and extend the knee
Location of sartorius muscle?
Diagonally in anterior thigh
Action of sartorius muscle?
Flexes knee and hip, external rotation and abduction of thigh = is there gum on my shoe muscle
4 muscles of medial thigh?
- Adductor longus
- Adductor brevis
- Adductor magnus
- Pelvic bone
3 muscles of posterior thigh? What are they called? List from lateral to medial (if looking at back of thigh)
- Biceps femoris
What 3 muscles insert on the medial side of the knee? From what compartment are they? Purpose? What is this called? What else is found here?
- Gracilis (medial thigh)
- Semitendinosus (posterior thigh)
- Sartorius (anterior thigh)
=> a muscle from each thigh compartment to stabilize knee on medial side = pes anserinus
Also IT band
What does pes anserinus mean?
Where is the femoral triangle?
Top of anterior thigh near hip crease
4 contents of femoral triangle?
- Femoral nerve
- Femoral artery
- Femoral vein
Biggest blood supply of lower limbs?
Mnemonic to remember order of contents in femoral triangle?
Lateral to Medial: NAVeL
Passage of contents of femoral triangle?
Continue inferiorly to adductor canal into the popliteal fossa
4 contents of popliteal fossa? List from lateral to medial
- Common fibular nerve
- Tibial nerve
- Popliteal vein
- Popliteal artery
What are the popliteal artery/vein?
Continuations of femoral vessels
Common injury to lower leg? What is this called?
Rupture of common fibular nerve because it wraps around the tibia from the popliteal fossa to the front of tibia and is unprotected (car bumper) = foot drop because you cannot dorsiflex your foot
Innervation of posterior leg muscles?
Innervation of anterior leg muscles?
Common fibular nerve
Innervation of lateral leg muscles?
Common fibular nerve
Action of superficial posterior leg muscles?
Plantar flexion (especially when leg is extended)
Action of deep posterior leg muscles?
Toe flexion and foot inversion (suponation)
Action of anterior leg muscles?
Dorsiflexion, foot inversion (suponation), toe extension
Action of lateral leg muscles?
Foot eversion (pronation) and plantarflexion (weak)
Other name for common fibular nerve?
Common peroneal nerve
2 muscles of superficial posterior leg?
Where do both muscles of the superficial posterior leg insert? What what tendon (2 names)?
Calcaneal tendon = Achilles tendon onto calcaneus bone
What is the calcaneus bone?
Where is the origin of gastrocnemius of the superficial posterior leg? What does this mean?
Can also flex the knee
How many heads in gastrocnemius muscle?
Origin of soleus?
Top of tibia
Where does the name soleus come from?
Sole because it’s really flat
3 muscles of deep posterior leg?
- Tibialis posterior
- Flexor digitorum longus
- Flexor hallucis longus
2 muscles of foot inversion?
- Tibilias posterior
2. Tibialis anterior
Action of flexor digitorum longus and
flexor hallucis longus?
- Flexor digitorum longus: 4 toes
- Hallucis longus: big toes
3 muscles of anterior leg?
- Tibialis anterior
- Extensor digitorum longus
- Extensor hallucis longus
Where does the tibialis posterior insert?
Which muscle is responsible for shin splints?
Action and insertion of tibialis anterior?
Action: foot dorsiflexion and inversion
Insertion: medial foot
Actions of extensor digitorum longus and extensor hallucis longus?
Dorsiflexion and toe extension
2 muscles of lateral leg?
- Fibularis longus
2. Fibularis brevis
Insertion of lateral leg muscles?
Lateral foot and base of big toe
Which leg compartment is most important for walking?
What causes a similar gait to the one with foot drop?
Impaired gluteus abductor (gluteus medius and minimus) muscles
2 types of foot muscles?
Intrinsic and extrinsic
2 nerves innervating the foot muscles? Mostly from which one?
- Tibial nerve***
2. Common fibular nerve
What is the tarsal tunnel?
Medial side of ankle and similar to carpal tunnel containing the posterior tibial artery and the tibial nerve
What does splanchnic mean? What is the opposite?
Relating to the viscera
Opposite = parietal
Other name for hip bone?
What can be found between the triceps heads?
What are the 3 boundaries of the femoral triangle?
- Adductor longus
- Inguinal ligament