Attachments
Tendons: muscle to bone
Ligaments: bone to bone
Muscles consist of bundles of bundles
Muscle: bundles of fascicles (covered by a layer of connective tissue called epimysium)
Fascicle: bundles of muscle fibers (covered by a layer of connective tissue called perimysium)
Muscle fiber: bundles of myofibrils (covered by a layer of connective tissue called endomysium)
skeletal (striated) muscle fibers consist of myofibrils (which are rows of sarcomeres)
this is not the case in smooth muscle, which has thin and thick filaments that don’t arrange into sarcomeres
Myofibril: bundles of myofilaments; sarcomere level
Myofilament (actin and myosin): interact to generate contraction of sarcomere
Muscle: Basic Histology
Sarcomeres: the contractile units of a muscle bundle
Sarcomere boundaries are Z disks (aka Z-lines) that hold thin filaments in position
in other words, a sarcomere is a region between 2 adjacent z-lines, containing thin actin filaments and thick myosin filaments
as a muscle is contracting, you’re bringing the two adjacent z-lines together (Z-disks are pulled together to shorten muscle and contract)
The sarcomere’s M-line (middle) holds thick filaments in position
Overlapping thick and thin filaments make up the A-band (dark) with the M-line in the center
The area of the sarcomeres that only consist of thin filaments makes up the I-band (light) with the Z line in the middle
Muscle Actions (antagonist pairing)
Extensors vs Flexors:
increase vs decrease joint angle
ex: quadriceps extend the knee, while hamstrings flex it
Abductors vs Adductors:
away from vs toward the body’s midline
ex: pectoralis major adducts the arm
Retractors vs Protractors:
move back vs move forward
Supinators vs Pronators:
palm/sole anterior vs palm/sole posterior
Muscle Orientation
Origin:
fixed end of the muscle
sometimes difficult to determine (i.e., back muscles)
the end closest to the midline of the body
Limbs: proximal, trunk: Medial
Insertion:
portion that causes motion when muscle contracts
the end that is furthest from the midline of the body
Limbs: distal, trunk: Lateral
Anatomical Orientation
Superior vs Inferior
closer to the head/upper part of the body vs closer to the feet/away from head
Medial vs Lateral
toward the midline vs away from the midline of the body
Proximal vs Distal
toward the origin or trunk of the body vs away from the origin or trunk
Superficial vs Deep
closer to the body's surface vs away from the body's surface (closer to the body’s interior)
Anterior = Ventral vs Posterior = Dorsal
the front of the body or structure vs the back
Cranial vs Caudal
towards the head or skull vs towards the tail end of the body
Frontal (coronal) Plane
divides the body into a front half and a back half
Transverse Plane
divides the body into an upper half and lower half
Sagittal Plane
dividing the body into a left section and a right section
Dorsal/Lateral Aspect Muscles
The trapezius is divided into portions name for their different origins:
Clavotrapezius
Acromiotrapezius
Spinotrapezius
The trapezius, spinodeltoideus, bicep brachii, latissimus dorsi cross the shoulder joint and move the arm
External and internal obliques contain the abdomen
Tensor fasciae latae, gluteus maximus, semitendinosus, and biceps femoris cross the hip joint to move the leg
Gastrocnemius is the calf muscle that moves the foot
Ventral Aspect Muscles
Sternohyoid muscle is used for swallowing
Pectoralis major and pectoralis minor are parts of the same muscle with different origins that cross the shoulder joint
Linea alba (white line) is connective tissue joining the right and left obliques
Organs
Organs are composed of tissues that work together to perform a function
The skin is our largest organ and is composed of each tissue type.
The nervous system is also composed of all four types, primarily nervous
note: in this lab, we are just focusing on the thoracic and abdominal organs
Body Cavities of Rat
Thoracic cavity (upper)
Abdominal cavity (lower)
Thoracic Organs of Rat
Diaphragm separates thoracic and abdominal cavities and sits inferior to lungs
Function: primary muscle for breathing (inhalation and exhalation)
During inhalation, the diaphragm contracts and moves downward, expanding the thoracic cavity and lowering lung pressure, causing air to flow in
During exhalation, the diaphragm relaxes and moves upward, reducing thoracic cavity space and increasing lung pressure, pushing air out
Heart is intermediate to the lungs (located between both lungs)
Right Atrium – receives deoxygenated blood from the body through veins and sends it to right ventricle
Right Ventricle – pumps deoxygenated blood to the lungs to pick up oxygen
Left Atrium – receives oxygenated blood from the lungs
Left Ventricle – pumps oxygenated blood to the entire body through arteries
Myocardium = Heart Muscle
Pericardium = Membrane enclosing heart (fluid-filled sac that surrounds and protects the heart)
Thymus gland superior to (above) heart
Function: immunity – it matures lymphocytes (which is important for fighting infections)
The trachea (tube that carries air from the mouth/nose to the lungs) lies anterior to the esophagus (which carries food to the stomach)
Epiglottis: a flap that keeps food from entering trachea
Lined with cartilaginous rings anteriorly (reinforced to keep it from collapsing when breathing)
The trachea bifurcates (splits) at a structure called the carina into bronchial tubes, which enter lungs
bronchial tubes lead to bronchioles and then tiny alveoli, where gas exchange occurs → high surface area of the alveoli allows for efficient oxygen intake and CO₂ removal
Lungs have lobes – 4 in right lung of rat and 1 in the left lung
Abdominal Organs (located in the coelom- main body cavity)
Esophagus (thoracic organ) leads to stomach (carries food to the stomach)
The stomach breaks down food, begins protein digestion, and empties into the small intestine through the pyloric sphincter
Small intestine is divided into three sections: duodenum to jejunum to ileum, where digestion and absorption of nutrients
The pancreas releases digestive enzymes (and secretes insulin and glucagon, which regulate blood sugar levels)
The liver produces bile (digestion of fats)
Liver is composed of lobes, like the R lung
Aside from secreting bile, it also stores glucose as glycogen, filters toxins, and synthesizes macromolecules
Blood from the digestive system goes here to get cleaned before traveling back to the heart
The ileum passes remnants of food into the colon (large intestine) through the ileocecal sphincter
The colon follows this path: cecum → ascending colon → transverse colon → descending colon → rectum → anus, where waste is processed and eliminated
The spleen is located posterior and to the left of the stomach, and it filters and stores blood
Organ Coverings
Body cavities are lined with membranes that provide protection, lubrication, and support
Visceral membrane: lines organs
Parietal membrane: lines the cavity wall
Thoracic cavity:
Heart: covered by the pericardial membrane
Lungs: covered by the pleural membrane
Abdominal cavity:
Peritoneal membrane: lines and protects the abdominal organs
Mesentery: connects organs to the body wall (holding them in place)
Omentum: connects organ to organ (providing cushioning)
Lab 8 Vertebrate Anatomy Muscle and Organs- MAKE SURE TO MAKE A WHOLE SLIDE DEDICATED TO PICTURES
Attachments
Tendons: muscle to bone
Ligaments: bone to bone
Muscles consist of bundles of bundles
Muscle: bundles of fascicles (covered by a layer of connective tissue called epimysium)
Fascicle: bundles of muscle fibers (covered by a layer of connective tissue called perimysium)
Muscle fiber: bundles of myofibrils (covered by a layer of connective tissue called endomysium)
skeletal (striated) muscle fibers consist of myofibrils (which are rows of sarcomeres)
this is not the case in smooth muscle, which has thin and thick filaments that don’t arrange into sarcomeres
Myofibril: bundles of myofilaments; sarcomere level
Myofilament (actin and myosin): interact to generate contraction of sarcomere
Muscle: Basic Histology
Sarcomeres: the contractile units of a muscle bundle
Sarcomere boundaries are Z disks (aka Z-lines) that hold thin filaments in position
in other words, a sarcomere is a region between 2 adjacent z-lines, containing thin actin filaments and thick myosin filaments
as a muscle is contracting, you’re bringing the two adjacent z-lines together (Z-disks are pulled together to shorten muscle and contract)
The sarcomere’s M-line (middle) holds thick filaments in position
Overlapping thick and thin filaments make up the A-band (dark) with the M-line in the center
The area of the sarcomeres that only consist of thin filaments makes up the I-band (light) with the Z line in the middle
Muscle Actions (antagonist pairing)
Extensors vs Flexors:
increase vs decrease joint angle
ex: quadriceps extend the knee, while hamstrings flex it
Abductors vs Adductors:
away from vs toward the body’s midline
ex: pectoralis major adducts the arm
Retractors vs Protractors:
move back vs move forward
Supinators vs Pronators:
palm/sole anterior vs palm/sole posterior
Muscle Orientation
Origin:
fixed end of the muscle
sometimes difficult to determine (i.e., back muscles)
the end closest to the midline of the body
Limbs: proximal, trunk: Medial
Insertion:
portion that causes motion when muscle contracts
the end that is furthest from the midline of the body
Limbs: distal, trunk: Lateral
Anatomical Orientation
Superior vs Inferior
closer to the head/upper part of the body vs closer to the feet/away from head
Medial vs Lateral
toward the midline vs away from the midline of the body
Proximal vs Distal
toward the origin or trunk of the body vs away from the origin or trunk
Superficial vs Deep
closer to the body's surface vs away from the body's surface (closer to the body’s interior)
Anterior = Ventral vs Posterior = Dorsal
the front of the body or structure vs the back
Cranial vs Caudal
towards the head or skull vs towards the tail end of the body
Frontal (coronal) Plane
divides the body into a front half and a back half
Transverse Plane
divides the body into an upper half and lower half
Sagittal Plane
dividing the body into a left section and a right section
Dorsal/Lateral Aspect Muscles
The trapezius is divided into portions name for their different origins:
Clavotrapezius
Acromiotrapezius
Spinotrapezius
The trapezius, spinodeltoideus, bicep brachii, latissimus dorsi cross the shoulder joint and move the arm
External and internal obliques contain the abdomen
Tensor fasciae latae, gluteus maximus, semitendinosus, and biceps femoris cross the hip joint to move the leg
Gastrocnemius is the calf muscle that moves the foot
Ventral Aspect Muscles
Sternohyoid muscle is used for swallowing
Pectoralis major and pectoralis minor are parts of the same muscle with different origins that cross the shoulder joint
Linea alba (white line) is connective tissue joining the right and left obliques
Organs
Organs are composed of tissues that work together to perform a function
The skin is our largest organ and is composed of each tissue type.
The nervous system is also composed of all four types, primarily nervous
note: in this lab, we are just focusing on the thoracic and abdominal organs
Body Cavities of Rat
Thoracic cavity (upper)
Abdominal cavity (lower)
Thoracic Organs of Rat
Diaphragm separates thoracic and abdominal cavities and sits inferior to lungs
Function: primary muscle for breathing (inhalation and exhalation)
During inhalation, the diaphragm contracts and moves downward, expanding the thoracic cavity and lowering lung pressure, causing air to flow in
During exhalation, the diaphragm relaxes and moves upward, reducing thoracic cavity space and increasing lung pressure, pushing air out
Heart is intermediate to the lungs (located between both lungs)
Right Atrium – receives deoxygenated blood from the body through veins and sends it to right ventricle
Right Ventricle – pumps deoxygenated blood to the lungs to pick up oxygen
Left Atrium – receives oxygenated blood from the lungs
Left Ventricle – pumps oxygenated blood to the entire body through arteries
Myocardium = Heart Muscle
Pericardium = Membrane enclosing heart (fluid-filled sac that surrounds and protects the heart)
Thymus gland superior to (above) heart
Function: immunity – it matures lymphocytes (which is important for fighting infections)
The trachea (tube that carries air from the mouth/nose to the lungs) lies anterior to the esophagus (which carries food to the stomach)
Epiglottis: a flap that keeps food from entering trachea
Lined with cartilaginous rings anteriorly (reinforced to keep it from collapsing when breathing)
The trachea bifurcates (splits) at a structure called the carina into bronchial tubes, which enter lungs
bronchial tubes lead to bronchioles and then tiny alveoli, where gas exchange occurs → high surface area of the alveoli allows for efficient oxygen intake and CO₂ removal
Lungs have lobes – 4 in right lung of rat and 1 in the left lung
Abdominal Organs (located in the coelom- main body cavity)
Esophagus (thoracic organ) leads to stomach (carries food to the stomach)
The stomach breaks down food, begins protein digestion, and empties into the small intestine through the pyloric sphincter
Small intestine is divided into three sections: duodenum to jejunum to ileum, where digestion and absorption of nutrients
The pancreas releases digestive enzymes (and secretes insulin and glucagon, which regulate blood sugar levels)
The liver produces bile (digestion of fats)
Liver is composed of lobes, like the R lung
Aside from secreting bile, it also stores glucose as glycogen, filters toxins, and synthesizes macromolecules
Blood from the digestive system goes here to get cleaned before traveling back to the heart
The ileum passes remnants of food into the colon (large intestine) through the ileocecal sphincter
The colon follows this path: cecum → ascending colon → transverse colon → descending colon → rectum → anus, where waste is processed and eliminated
The spleen is located posterior and to the left of the stomach, and it filters and stores blood
Organ Coverings
Body cavities are lined with membranes that provide protection, lubrication, and support
Visceral membrane: lines organs
Parietal membrane: lines the cavity wall
Thoracic cavity:
Heart: covered by the pericardial membrane
Lungs: covered by the pleural membrane
Abdominal cavity:
Peritoneal membrane: lines and protects the abdominal organs
Mesentery: connects organs to the body wall (holding them in place)
Omentum: connects organ to organ (providing cushioning)