Flashcards in Anatomy of muscles and nerves Deck (27):
Describe the functions of muscles
– Heart & blood vessels
• Static support
• Heat production
Briefly describe the 3 types of muscle and their primary functions
• Skeletal - attached to skeleton, locomotion, voluntary
• Cardiac - heart and blood circulation, involuntary
• Smooth - walls of vessels and organs, moves substances and restricts flow, involuntary
Describe the epimysium, fascicles, perimysium and endomysium.
Enclosing each muscle is a layer of connective tissue known as the epimysium; enclosing each fascicle is a layer called the perimysium, and enclosing each muscle fiber is a layer of connective tissue called the endomysium.
Define unipennate and multipennate muscles
The fibers in unipennate muscles are all oriented at the same (but non-zero) angle relative to the axis of force generation
The fibers in multipennate muscles are arranged at multiple angles in relation to the axis of force generation, and are the most general and most common architecture.
Describe the spinal nerves
• 31 pairs in total
• 8 cervical nerves (C1–C8)
• 12 thoracic nerve (T1 -T12)
• 5 lumbar nerves (L1-L5)
• 5 sacral nerves (S1-S5)
• 1 coccygeal nerve
• Named after associated vertebrae
• 1st spinal nerves exits between skull and C1
Describe the differences between the somatic and autonomic signalling pathway
• In the somatic pathway, the motor fibres are not synapsing (CNS -> muscle)
• In the autonomic pathway, the motor fibres do synapse at a ganglion before reaching the target area
Describe the site of spinal outflow for the sympathetic and parasympathetic nervous system
o Sympathetic - thoracolumbar
o Parasympathetic – craniosacral (top and bottom)
Describe the relative location of the ganglia in the sympathetic and parasympathetic nervous system
o Sympathetic – close to spinal cord
o Parasympathetic – close to target
Define a dermatome and a myotome
• A skin area innervated by the sensory fibres of a single nerve root is known as a dermatome.
• A group of muscles primarily innervated by the motor fibres of a single nerve root is known as a myotome.
Define the origin and insertion of a muscle
• Origin - proximal or medial attachment
• Insertion - distal or lateral attachment
Describe the innervation of axial and appendicular muscles
• Appendicular (limb) muscles are supplied by nerve plexuses, ie. nerves containing mixed fibres from more than one spinal nerve.
• Axial (trunk) muscles are supplied segmentally, ie. by separate nerves that have not mixed with others.
What is Hiltons law?
o The nerve supplying the muscles extending directly across and acting at a given joint also innervates the joint.
o A sensory nerve supplying a joint also supplies the skin overlying the joint.
What is compartment syndrome?
Compartment syndrome is an acute medical problem following injury or surgery in which increased pressure (usually caused by inflammation) occurs within a compartment
What are the distinguishing histological features of skeletal muscle?
1. Long, slender (up to 30cm!)
2. Multinucleate; peripherally located nuclei
3. Abundance of mitochondria
4. Cross striations (actin & myosin filaments)
5. Arranged into fascicles (=bundles) by connective tissue
What are the distinguishing histological features of smooth muscle?
• Found in organs and vessels
• Devoid of cross striations
• Shorter fibre length than skeletal muscle
• Centrally-situated cigar-shaped nuclei
What are the distinguishing histological features of cardiac muscle?
• Cross-striated, but involuntary.
• Single (central) rounded nucleus.
• Cells are often branched.
• The region where the ends of the cells are connected to another cell is called an intercalated disc.
• The intercalated disc contains gap junctions.
• Gap junctions allow the muscle cells to be electrically coupled, so that they beat in synchrony.
Primary functions of ligaments and tendons
• Ligaments bind bone to bone, “like to like”, vital for stabilising joints
• Tendons bind bone to muscle, vital for movement
What signals are found in the dorsal and ventral roots?
• Dorsal root = sensory
• Ventral root = motor
What dermatome are the nipples in?
What dermatome is the umbilicus found in?
What dermatome is the sternomanubrial joint found in?
Which spinal nerves form the brachial plexus?
Brachial: C5 - 8, T1
Which spinal nerves form the lumbosacral plexus?
Describe the aponeurosis
Aponeurosis – flat, thin broad tendons found on the anterior of the abdominal oblique muscles.
Describe the differences between synergist and fixator muscles
• Synergist muscles – perform or help perform the same set of joint motions as the agonist, i.e. assists movement of the joint
• Fixator/stabilising muscles – stabilise the joint so the joint can move efficiently without risk of dislocation
Describe the structure of a sphincter
• Sphincters – muscle fibres are arranged circularly and thickened around the wall of a structure (usually a tube). They are mostly composed of smooth (involuntary) muscle within the body, but are also composed of skeletal muscle (voluntary) when controlling the flow of fluids to the outside of the body. The involuntary muscle is usually the deeper of the two.