Axial Muscle Flashcards
What are the two major regions in the muscular system?
- Axial musculature: associated with axial skeleton (skull, vertebral column, ribs)
- Appendicular musculature: associated with appendicular skeleton (limb bones, shoulder and pelvic girdles)
What are two main characteristics of the axial musculature?
- Innervation: by cranial nerves (CNs) or spinal nerves
- Attachments: on axial skeleton associated organs or soft tissue (eyeball, skin and face)
What are the major functions of the axial musculature?
- Vision, mastication, facial expression, swallowing
- Upright posture and movement of the back
- Support of abdominal and pelvic viscera
- Respiration
- Urination, defecation, and parturition
What are the four major groups of the axial musculature?
- Muscles of the head and neck (face, oral cavity, pharynx, larynx)
- Muscles of the back
- Muscles of thorax and abdominopelvic cavities
- Muscles of the pelvis and perineum
What are the 6 groups of muscles found in the head and neck?
- Extraocular muscles: innervated by oculomotor, trochlear and abducens (cranial nerve III, IV, VI)
- Muscles of mastication: innervated by trigeminal nerve (CN V3)
- Muscles of facial expression: innervated mostly by facial nerve (CN VII)
- Pharyngeal muscles: innervated by trigeminal nerve (CN V3)
- Tongue muscles: innervated mostly by hypoglossal (CN XII)
- Neck muscles: innervated by the CNs or cervical nn.
What are the extraocular muscles? What are the two main types of muscles?
Innervated by CN III, involved in moving the eyeball
1. Rectus: straight muscles on tops and sides, so helps eyes move in that directions
1. Oblique: pulls your eyes up and down but also turns it medially and laterally
What are the 4 rectus muscles in the eye?
- Superior rectus (CNIII): helps move eye up
- Inferior rectus (CNIII): helps move eyes down
- Medial rectus (CN III): helps move eye medially
- Lateral rectus (CN VI): helps moves eye laterally
What are the two oblique muscles in the eye? What movement do they help in?
Superior oblique (CN IV): by the top of the eye
Inferior oblique (CN III): by bottom of eye
Looking up and down: but this uses two muscles because the S/I rectus but they twist (superior twists medially) thus they have to work with the S/I obliques to not twist it
What is the muscle in the eye that is not a rectus or an oblique muscle?
Levator palpebrae superioris (CNIII) and elevates the eyelids
What happens when the lateral rectus is paralyzed?
CN VI palsy, and they will not be able to look to the side where the lateral rectus is impaired (if impaired in the RT eye then the patient cannot look left)
What are the two major muscles of mastication? What is their main function?
Temporalis- attached in temporal area (on F and P bone) all fibers converge (convergent muscle), attaches deep in mandible
Masseter: attaches on zygomatic arch and fibers attach on the ramus
Main function: elevators of the mandible when chewing on food and closing mouth
What are the two muscles that lie deeper than the temporalis and masseter?
Lateral pterygoid: closes mouth, depressor of mandible to open the mouth, can also move mandible side to side, above the medial one and is perpendicular to the face
Medial pterygoid: elevator of mandible to close mouth when chewing or closing mouth, parallel to face
What happens when your mouth opens?
The lateral pterygoid moves anterior and slightly down, only uses one muscle when the mouth is open (depression of mandible)
What happens when you close your mouth?
3 muscles involved: temporalis moves up and back, medial pterygoid moves up and forward, masseter moves in same direction as the medial pterygoid
Elevation of mandible and mouth closing
What are the muscles of facial expression? What CN are they innervated by?
Occipitofrontalis (frontal belly)- raises eyebrows, wrinkles forehead, parallel muscles
Buccinator: tenses cheeks and suction
Platysma: tenses skin of neck
Orbicularis oculi: closes lids
Orbicularis oris: purses lips for kissing
All innervated by cranial nerve VII
What happens when CN VII (facial nerve) is damaged?
Bells palsy
What are the 4 pharyngeal muscles?
Tensor and levator veli palatini (tenses and elevates soft palate, prevents food from going down trachea)
Superior constrictor (constriction of pharynx)
Middle constrictor (constriction of pharynx)
Inferior constrictor (constriction of pharynx)
All three constrictors are used to push food/material down
What are the tongue muscles from superior to inferior? What is their function and what CN innervates them?
Palatoglossus, styloglossus, hyoglossus, genioglossus
All control position of tongue and are innervated by CN XII
What are the two superior neck muscles?
Mylohyoid: tenses floor of mouth during swallowing
Digastric (2 bellies): assist in depression of mandible to open mouth wide and has attach to hyoid
What are the 4 steps in swallowing?
- Contraction of mylohyoid and tongue muscles (floor of mouth and tongue pushes bolus to oral pharynx)
- Contraction of tensor and levator veli palatini muscles (soft palate up/tense thus food goes down)
- Elevation of larynx by many muscles (closing airway and opening esophagus)
4.Sequential contraction from the top of constrictor muscles (push down into esophagus)
What are the two inferior neck muscles?
Infrahyoid- pull down on hyoid bone after swallowing
Sternocleidomastoid- turns head to opposite site of contraction, contract RT side= turn LT and vice versa
What are the 3 muscles that lie by the vertebral column?
Longus capitis (crosses joint) and longus colli are both flexors of the neck (and head for L. capitis)
Scalene: lateral flexors of neck, elevators of rib 1/2, bend sideways, attaches at transverse processes
What is the group of 4 back muscles called? What are the 4 muscles called?
Erector spinae (longissimus, spinalis, iliocostalis) and they all are extensors of the back (vital to maintain upright posture)
The longissimus is always active
What is the groups if muscles called in the back?
Transversospinal group: delicate adjustments at zygapophyseal joints of vertebrae (can be source of back pain)
Hard to treat b/c so small
What are the muscles that are by the ribs?
Intercostal muscles (3 different layers) most superficial are elevators of ribs during respirations (inhalation phase)
All in the front of the trunk
What happens to the intercostal muscles during respiration?
Contraction of intercostal muscles produces elevation of the ribs and increases volume of the thoracic cavity
What are the 4 trunk muscles?
Rectus abdominis: flexors of trunk
Abdominal (3 layers):
- 2 obliques: internal and external, flexors, lateral flexors, and rotators of trunk (external is synergist to RA)
-1 transverse (deepest): there to contract and increase intra-abdominal pressure to birth/ urinate. etc
All 4 abdominal muscles can increase intra-abdominal pressure
What do the three abdominal muscles do as you move superiorly in the body?
Turn into the intercostal muscles (3 of them as well)
What are the 3 structures on the diaphragm? What 3 structures pass through the diaphragm? What is the main functions of diaphragm?
Central tendon (muscles go towards this)
Muscle fibers
Crura (legs that attach to lumbar vertebra)
3 structures: inferior vena cava, esophagus, aorta
Function: separates thoracic and abdominal cavities, chief muscle of respiration, innervated by the phrenic nerve (C3-C5 levels of spinal cord)
If you fracture neck above C3 you cannot breath because diaphragm does not work
What happens during inhalation and exhalation to the diaphragm?
Relaxation of diaphragm during exhalation
Contraction of diaphragm during inhalation bringing central tendon down to increase volume of thoracic cavity to increase chest volume
What are the two pelvic muscles and what do they do?
Coccygeus (back)
Levator ani (front)
Form the pelvic diaphragm (pelvic floor), provide support to pelvic viscera such as urinary bladder, rectum, uterus, prostate gland
What are the two sphincters found in the perineum? What are the two cavities in the perineum?
External urethral sphincter in urogenital cavity- regulates urethral opening (urinary continence) more developed in males
External anal sphincter in anal cavity- regulates anal opening (fecal continence)
Both innervated by the pudendal nerve
What are the 2 perineal muscles?
Ischiocavernosus (x2)
Bulbospongiosus
Both regulate contraction blood flow into erectile tissues of genitalia, innervated by pudendal nerve
