Lectures 4 & 5 - Limbs Flashcards
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?
Its action
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?
- Athletes
2. Trauma
Treatment of compartment syndrome?
Fasciotomy
What are the 6 parts of upper limbs?
- Axilla
- Arm
- Elbow joint/cubital fossa
- Forearm
- Wrist joint
- Hand
How many compartments in arm? List them.
- Anterior
2. Posterior
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
- Thigh
- Knee joint and popliteal fossa
- Leg
- Ankle
- Foot
How many compartments in thigh? List them.
- Anterior
- Posterior
- Medial
How many compartments in leg? List them.
- Posterior superficial
- Posterior deep
- Lateral
- Anterior
What are the 3 types of mesoderm (from closest to farthest from notochord)? Which 2 do limbs mainly come from?
- Paraxial*
- Intermediate
- Lateral plate*
What does the paraxial mesoderm give rise to?
Somites
What does the intermediate mesoderm give rise to?
Urogenital structures
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?
- Dermatome
- Myotome
- Sclerotome
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:
- Epimere
- Hypomere
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?
Dermis
What are the epimere muscles innervated by?
Dorsal rami
What are the hypomere muscles innervated by?
Ventral rami
When do limbs start budding in embryologic development?
4 to 5 weeks
Which form first in an embryo: upper or lower limbs?
Upper 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?
- Superficial
- Intermediate
- Deep
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?
a. Location
b. Origin/Insertion
c. Action
- Erector spinae:
a. Along spinal cord
b. Origin: inferior end of spine, insertion: superior end of spine
c. Extend spine and maintain upright posture - Transversospinales:
a. Deep to erector spinae and runs in Xmas tree pattern run in between transverse process of spine
b. ?
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?
- Trapezius
- Latissimus dorsi
- Rhomboid major
- Rhomboid minor
Trapezius:
- Origin?
- Insertion?
- Action?
- Spinal column (upper half)
- Along scapula
- Elevation, retraction, and depression of the scapula aka shoulder
What is the scapula?
Shoulder blade bone
Latissimus dorsi:
- Origin?
- Insertion?
- Action?
- Spinal column (lower half)
- Front of humerus
- Adduction, medial rotation and extension of the shoulder = swimming
What is the humerus?
Main arm bone
Rhomboids:
- Origin?
- Insertion?
- Action?
- Middle part of upper spinal column
- Medial border of scapula
- Retraction and elevation of scapula
Rhomboids’ location compared to trapezius?
Deeper
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
2. Deltoid
Deltoid:
- Origin?
- Insertion?
- Action?
- Scapula to clavicle
- Lateral side of the humerus
- Arm abduction beyond 15 degrees
Can deltoid muscles initiate abduction from the most adducted position?
NOPE
Which muscle can initiate abduction from the most adducted position? What kind of muscle is it?
Supraspinatous muscle = rotator cuff muscle
Rotator cuff muscles:
- Origin?
- Insertion?
- Action?
- Scapula
- Humerus
- Rotation, abduction, and stabilization of shoulder
How many rotator cuff muscles?
4
What is the joint of the shoulder?
Glenohumeral joint
What is the axilla? Purpose?
Armpit
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?
Biceps brachii
Common action of muscles of anterior arm?
Flexion
Innervation of muscles of anterior arm?
Muculocutaneous nerve
1 muscle of posterior arm?
Triceps brachii
Action of muscle of posterior arm?
Extension
Innervation of muscle of posterior arm?
Radial nerve
Biceps brachii:
- Origin?
- Insertion?
- Action?
- 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?
Biceps brachii
What is the radius?
Lateral forearm bone
Which bone moves during supination and pronation of arm?
Radius
What is the ulna?
Medial forearm bone
Can the ulna pivot?
NOPE
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
Triceps brachii:
- Origin?
- Insertion?
- Action?
- 3 heads from scapula and humerus
- Posterior side of ulna at olecron process
- Elbow extension