Muscles - Axial + Pelvic floor Flashcards
Connective tissue sheaths - What are the types of connective tissue sheaths in skeletal muscle?
- Endomysium: Fine layer of areolar tissue around individual muscle fibers.
- Perimysium: Dense connective tissue around fascicles (bundles of fibers).
- Epimysium: Dense, fibrous tissue surrounding the whole muscle.
- Deep Fascia: Coarse connective tissue that groups muscles into functional units.
Attachments - What are the key points about muscle attachments?
Muscles span joints and attach to bones at two points: the origin (stationary bone) and insertion (moving bone).
- Direct Attachments: Muscle epimysium fused to periosteum or perichondrium.
- Indirect Attachments: Muscles attach to bones via tendons or aponeuroses (cord-like or sheet-like structures).
Fascicle arrangement patterns - What are the first 2 patterns of fascicle arrangement in skeletal muscles and the subcategories of the second one?
- Parallel: Fascicles run parallel to the muscle’s long axis (e.g., sartorius).
- Pennate: Fascicles attach to a central tendon at angles:
- Unipennate: One side (e.g., extensor digitorum).
- Bipennate: Both sides (e.g., rectus femoris).
- Multipennate: Multiple angles (e.g., deltoid).
Fascicles arrangement patterns - What are the next 2 main patterns of fascicle arrangement in skeletal muscles?
- Circular: Fascicles form rings (e.g., orbicularis oculi).
- Convergent: Fascicles converge toward a single tendon (e.g., pectoralis major).
Functional group - What are the functional groups of muscles?
- Prime Mover (Agonist): Provides the major force for a movement.
- Antagonist: Opposes or reverses the prime mover’s action.
- Synergists: Assist the prime mover by supporting the movement or stabilizing joints (e.g., fixators).
Naming - How are skeletal muscles named?
- Location: Named for bones or regions (e.g., intercostals).
- Shape: Based on shape (e.g., deltoid = triangular).
- Size: Size descriptors (e.g., maximus, minimus).
- Fiber Direction: Based on fiber orientation (e.g., rectus, transversus).
- Number of Origins: Indicated by terms like biceps (2 origins) or triceps (3 origins).
- Attachment Points: Based on origin and insertion.
- Action: Describes muscle function (e.g., extensor).
Example: Extensor carpi radialis longus.
Head: facial expressions - What is unique about the muscles of facial expression?
- These muscles insert into the skin or other muscles, not bones.
- Innervation: All facial expression muscles are innervated by the Facial nerve (Cranial Nerve VII).
Head: facial expressions - What are the two large muscles of the head that can help with facial expression?
Epicranius:
- Frontalis: Raises eyebrows, causes forehead wrinkles.
- Occipitalis: Pulls scalp posteriorly.
Platysma: Depresses the mandible and tenses neck skin.
Head: facial expressions - What is the function of the orbicularis oculi?
- Encircles the eye socket.
- Protects the eyes from light and injury.
- Allows for eye closure, blinking, squinting, and drawing the eyebrows downward.
Head: facial expressions - What does the orbicularis oris muscle do?
- Surrounds the lips.
- Closes, purses, and protrudes the lips (e.g., kissing, whistling).
Head: facial expressions - What is the function of the mentalis?
- Located at the chin.
- Protrudes the lower lip (pouting) and creates wrinkles on the chin.
Head: facial expressions - What is the role of the zygomaticus muscle?
- Extends from the zygomatic bone to the corner of the mouth.
- Elevates the corners of the mouth, facilitating a smile.
Head: facial expressions - What is the function of the buccinator muscle?
- Located deep to the masseter muscle.
- Aids in whistling, sucking, and holding food during chewing.
- Important in nursing infants.
Head: facial expressions and emotions - Which muscles are responsible for specific facial expressions around the mouth?
- Zygomaticus Major: Smile (elevates mouth corners).
- Orbicularis Oris: Pucker lips (blowing kiss).
- Mentalis: Pout (protrudes lower lip).
- Platysma: Tension (neck and chin).
Head: facial expressions and emotions - Which muscles are responsible for specific facial expressions around the eyes?
- Corrugator Supercilii: Frown (draws eyebrows together).
- Orbicularis Oculi: Squint (closes eyes tightly).
- Frontal Belly of Epicranius: Surprise (raises eyebrows).
Tongue - What is the function of the genioglossus?
- Protrudes the tongue out of the mouth.
- Anchors the tongue to prevent it from obstructing respiration.
Tongue - What are the articulations of the genioglossus, styloglossus, and hyoglossus?
G - mandible to inferior tongue and hyoid bone
S- inferolateral tongue to styloid process
H - inferolateral tongue to hyoid bone
Tongue - What does the styloglossus muscle do?
Retracts and elevates the tongue.
Tongue - What is the role of the hyoglossus?
Depresses the tongue, especially at the lateral margins.
Mastication - What is the function of the masseter muscle?
Prime mover for jaw closure during chewing.
Mastication - What is the function of the temporalis muscle?
Elevates and retracts the mandible, aiding in jaw closure.
Neck - What does the sternocleidomastoid muscle do?
- Flexes the head when both sides contract.
- Unilateral contraction causes head rotation to the opposite side and tilts to the same side.
Neck - What is the function of the scalenes muscles?
- Elevate the first two ribs during inspiration.
- Assist in neck flexion and rotation.
Neck - What does the splenius muscle do?
- Responsible for head extension (looking up).
- Assists in head rotation and tilting to the same side when acting unilaterally.
Neck and vertebral column - What is the function of the erector spinae muscles?
- Prime movers for back extension.
- Consists of iliocostalis, longissimus, and spinalis.
- Resists forward bending and helps return the body to an erect posture.
Neck and vertebral column - What does the semispinalis muscle do?
- Extends from thoracic region to head.
- Involved in head and vertebral column extension and rotation.
- Works with the sternocleidomastoid muscles.
Neck and vertebral column - What is the function of the quadratus lumborum?
- Flexes the vertebral column laterally.
- Helps extend the lumbar spine and stabilize the 12th rib, aiding in upright posture.
Respiration - What do the external intercostals muscles do?
- Elevate the rib cage during inspiration.
- Located between the ribs, running obliquely from one rib to the next.
Respiration - What is the role of the internal intercostals muscles?
- Draw the ribs together and depress the rib cage during expiration.
- Located deep to the external intercostals.
Respiration - What is the function of the diaphragm?
- Prime mover of inspiration.
- Flattens to increase thoracic volume, drawing air into the lungs.
Abdominal wall - What do the internal obliques do?
- Assist in trunk rotation and lateral flexion.
- Located beneath the external obliques.
Abdominal wall - What is the function of the external obliques?
- Help in trunk rotation and lateral flexion.
- Located on the sides and front of the abdomen.
Abdominal wall - What is the function of the transversus abdominis?
- Deepest abdominal muscle.
- Compresses abdominal contents and stabilizes the trunk.
Abdominal wall - What does the rectus abdominis do?
- Known as “six-pack” muscles.
- Crucial for trunk flexion and stabilizing the pelvis during walking.
Pelvic floor - What is the function of the levator ani muscle?
- Supports pelvic organs and forms a sling for the anorectal junction and vagina.
- Resists increases in intra-abdominal pressure.
Pelvic floor - What does the coccygeus muscle do?
- Supports pelvic viscera and the coccyx.
- Helps with pelvic floor stability.
Pelvic floor - What is the role of the urogenital diaphragm?
- Supports the pelvic viscera.
- Plays a role in controlling urination by constricting the urethra.
